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Srisutha J, Watari I, Akakura M, Watanabe M, Changsiripun C, Ono T. P2X7R and P2X4R expression of mice submandibular gland in high-fat diet/streptozotocin-induced type 2 diabetes. Sci Rep 2024; 14:10855. [PMID: 38740782 PMCID: PMC11091137 DOI: 10.1038/s41598-024-60519-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Accepted: 04/24/2024] [Indexed: 05/16/2024] Open
Abstract
Type 2 diabetes mellitus (T2DM) is a chronic inflammatory disease that can compromise the functioning of various organs, including the salivary glands (SG). The purinergic system is one of the most important inflammatory pathways in T2DM condition, and P2X7R and P2X4R are the primary purinergic receptors in SG that regulate inflammatory homeostasis. This study aimed to evaluate P2X7R and P2X4R expression, and morphological changes in the submandibular gland (SMG) in T2DM. Twenty-four 5-week-old mice were randomly assigned to control (CON) and diabetes mellitus (DM) groups (n = 12 each). Body weight, diet, and blood glucose levels were monitored weekly. The histomorphology of the SMG and the expression of the P2X7R, and P2X7R was evaluated by immunohistochemistry (IHC) staining and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) at 11 and 13 weeks of age. Our findings indicate a significant increase in food consumption, body weight, and blood glucose levels in the DM group. Although a significant increase in P2X7R and P2X4R expression was observed in the DM groups, the receptor location remained unchanged. We also observed a significant increase in the acinar area in the DM13w group, and a significant decrease in the ductal area in the DM11w and DM13w groups. Targeting purinergic receptors may offer novel therapeutic methods for diabetic complications.
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MESH Headings
- Animals
- Mice
- Blood Glucose/metabolism
- Body Weight
- Diabetes Mellitus, Experimental/chemically induced
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Experimental/pathology
- Diabetes Mellitus, Type 2/chemically induced
- Diabetes Mellitus, Type 2/metabolism
- Diabetes Mellitus, Type 2/pathology
- Diet, High-Fat/adverse effects
- Mice, Inbred C57BL
- Receptors, Purinergic P2X4/metabolism
- Receptors, Purinergic P2X4/genetics
- Receptors, Purinergic P2X7/metabolism
- Receptors, Purinergic P2X7/genetics
- Streptozocin
- Submandibular Gland/metabolism
- Submandibular Gland/pathology
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Affiliation(s)
- Jiratchaya Srisutha
- Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo city, Tokyo, 113-8510, Japan
- Department of Orthodontics, Faculty of Dentistry, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Ippei Watari
- Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo city, Tokyo, 113-8510, Japan.
| | - Masato Akakura
- Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo city, Tokyo, 113-8510, Japan
| | - Minami Watanabe
- Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo city, Tokyo, 113-8510, Japan
| | - Chidsanu Changsiripun
- Department of Orthodontics, Faculty of Dentistry, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Takashi Ono
- Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Yushima 1-5-45, Bunkyo city, Tokyo, 113-8510, Japan
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2
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Calcaterra V, Zuccotti G, Mari A, Iafusco F, Maione G, Iafusco D, Tinto N. Can obesity exacerbate hyperinsulinaemia in the presence of the mutation of an insulin receptor gene? Clin Obes 2023; 13:e12619. [PMID: 37717597 DOI: 10.1111/cob.12619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 07/27/2023] [Accepted: 08/06/2023] [Indexed: 09/19/2023]
Abstract
Insulin receptor gene (INSR) mutations are a relatively rare and diverse cause of insulin resistance (IR), typically associated with a lean phenotype. However, we present a unique case of severe obesity and Type A severe IR syndrome in a patient with a heterozygous mutation of the INSR gene. Next Generation Sequencing (NGS) analysis was conducted to identify the genetic variant. A 16-year-old girl with severe obesity (BMI-SDS +2.79) exhibited markedly elevated basal insulin levels (>800 mcU/L). Despite obesity being a known cause of hyperinsulinism, further investigation was pursued due to the severity of hyperinsulinaemia. A heterozygous nucleotide variant at the donor splicing site of intron 13 (c.2682 + 1G > A) of the INSR gene was identified. This mutation was also present in the proband's normal-weight mother and her two younger brothers with obesity. Metformin treatment provided limited benefits, but subsequent liraglutide therapy resulted in weight loss and decreased IR 3 months after initiation. Our findings suggest that obesity can exacerbate hyperinsulinaemia in individuals with an INSR gene mutation. Although INSR signalling defects play a minor role in the aetiology of IR, they should still be considered in the diagnostic pathway, particularly in severe phenotypes. Clinicians should not overlook the possibility of genetic causes in patients with obesity and IR, as they may require personalized management approaches.
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Affiliation(s)
- Valeria Calcaterra
- Department of Internal Medicine, University of Pavia, Pavia, Italy
- Pediatric Department, Buzzi Children's Hospital, Milan, Italy
| | - Gianvincenzo Zuccotti
- Pediatric Department, Buzzi Children's Hospital, Milan, Italy
- Department of Biomedical and Clinical Science, University of Milano, Milan, Italy
| | - Alessandra Mari
- Pediatric Department, Buzzi Children's Hospital, Milan, Italy
| | - Fernanda Iafusco
- Department of Molecular Medicine and Medical Biotechnology, University of Napoli "Federico II", Naples, Italy
- Department of Molecular Medicine and Medical Biotechnology, CEINGE Advanced Biotechnologies, Naples, Italy
| | - Giovanna Maione
- Department of Molecular Medicine and Medical Biotechnology, University of Napoli "Federico II", Naples, Italy
- Department of Molecular Medicine and Medical Biotechnology, CEINGE Advanced Biotechnologies, Naples, Italy
| | - Dario Iafusco
- Department of Pediatrics, Regional Center of Pediatric Diabetology "G.Stoppoloni", University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Nadia Tinto
- Department of Molecular Medicine and Medical Biotechnology, University of Napoli "Federico II", Naples, Italy
- Department of Molecular Medicine and Medical Biotechnology, CEINGE Advanced Biotechnologies, Naples, Italy
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Finnell JE, Ferrario CR. Intra-NAc insulin reduces the motivation for food and food intake without altering cue-triggered food-seeking. Physiol Behav 2022; 254:113892. [PMID: 35753434 PMCID: PMC10583176 DOI: 10.1016/j.physbeh.2022.113892] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 06/21/2022] [Accepted: 06/22/2022] [Indexed: 11/24/2022]
Abstract
Insulin receptors are expressed throughout the adult brain, and insulin from the periphery reaches the central nervous system. In humans and rodents, actions of insulin in the brain decrease food intake. Furthermore, insulin receptor activation alters dopamine and glutamate transmission within mesolimbic regions that influence food-seeking and feeding including the nucleus accumbens (NAc). Here we determined how intra-NAc insulin affects conditioned approach (a measure of cue-triggered food-seeking), free food intake, and the motivation to obtain food in hungry rats using Pavlovian and instrumental approaches. Intra-NAc insulin did not affect conditioned approach but did reduce home cage chow intake immediately following conditioned approach testing. Consistent with reduced chow intake, intra-NAc insulin also reduced the motivation to work for flavored food pellets (assessed by a progressive ratio procedure). This effect was partially reversed by insulin receptor blockade and was not driven by insulin-induced sickness or malaise. Taken together, these data show that insulin within the NAc does not alter behavioral responses to a food cue, but instead reduces the motivation to work for and consume food in hungry animals. These data are discussed in light of insulin's role in the regulation of feeding, and its dysregulation by obesity.
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Affiliation(s)
- Julie E Finnell
- Department of Pharmacology, University of Michigan, United States
| | - Carrie R Ferrario
- Department of Pharmacology, University of Michigan, United States; Psychology Department (Biopsychology), University of Michigan, Ann Arbor MI 48109, United States.
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Mitchell CS, Begg DP. The regulation of food intake by insulin in the central nervous system. J Neuroendocrinol 2021; 33:e12952. [PMID: 33656205 DOI: 10.1111/jne.12952] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 01/31/2021] [Accepted: 02/03/2021] [Indexed: 01/02/2023]
Abstract
Food intake and energy expenditure are regulated by peripheral signals providing feedback on nutrient status and adiposity to the central nervous system. One of these signals is the pancreatic hormone, insulin. Unlike peripheral administration of insulin, which often causes weight gain, central administration of insulin leads to a reduction in food intake and body weight when administered long-term. This is a result of feedback processes in regions of the brain that regulate food intake. Within the hypothalamus, the arcuate nucleus (ARC) contains subpopulations of neurones that produce orexinergic neuropeptides agouti-related peptide (AgRP)/neuropeptide Y (NPY) and anorexigenic neuropeptides, pro-opiomelanocortin (POMC)/cocaine- and amphetamine-regulated transcript (CART). Intracerebroventricular infusion of insulin down-regulates the expression of AgRP/NPY at the same time as up-regulating expression of POMC/CART. Recent evidence suggests that insulin activity within the amygdala may play an important role in regulating energy balance. Insulin infusion into the central nucleus of the amygdala (CeA) can decrease food intake, possibly by modulating activity of NPY and other neurone subpopulations. Insulin signalling within the CeA can also influence stress-induced obesity. Overall, it is evident that the CeA is a critical target for insulin signalling and the regulation of energy balance.
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Affiliation(s)
| | - Denovan P Begg
- School of Psychology, UNSW Sydney, Sydney, NSW, Australia
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Ladyman SR, Brooks VL. Central actions of insulin during pregnancy and lactation. J Neuroendocrinol 2021; 33:e12946. [PMID: 33710714 PMCID: PMC9198112 DOI: 10.1111/jne.12946] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 01/24/2021] [Accepted: 01/27/2021] [Indexed: 12/17/2022]
Abstract
Pregnancy and lactation are highly metabolically demanding states. Maternal glucose is a key fuel source for the growth and development of the fetus, as well as for the production of milk during lactation. Hence, the maternal body undergoes major adaptations in the systems regulating glucose homeostasis to cope with the increased demand for glucose. As part of these changes, insulin levels are elevated during pregnancy and lower in lactation. The increased insulin secretion during pregnancy plays a vital role in the periphery; however, the potential effects of increased insulin action in the brain have not been widely investigated. In this review, we consider the impact of pregnancy on brain access and brain levels of insulin. Moreover, we explore the hypothesis that pregnancy is associated with site-specific central insulin resistance that is adaptive, allowing for the increases in peripheral insulin secretion without the consequences of increased central and peripheral insulin functions, such as to stimulate glucose uptake into maternal tissues or to inhibit food intake. Conversely, the loss of central insulin actions may impair other functions, such as insulin control of the autonomic nervous system. The potential role of low insulin in facilitating adaptive responses to lactation, such as hyperphagia and suppression of reproductive function, are also discussed. We end the review with a list of key research questions requiring resolution.
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Affiliation(s)
- Sharon R Ladyman
- Centre for Neuroendocrinology and Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, Auckland, New Zealand
| | - Virginia L Brooks
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, OR, USA
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Stoelzel CR, Zhang Y, Cincotta AH. Circadian-timed dopamine agonist treatment reverses high-fat diet-induced diabetogenic shift in ventromedial hypothalamic glucose sensing. Endocrinol Diabetes Metab 2020; 3:e00139. [PMID: 32704560 PMCID: PMC7375120 DOI: 10.1002/edm2.139] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 03/28/2020] [Indexed: 12/19/2022] Open
Abstract
INTRODUCTION Within the ventromedial hypothalamus (VMH), glucose inhibitory (GI) neurons sense hypoglycaemia while glucose excitatory (GE) neurons sense hyperglycaemia to initiate counter control mechanisms under normal conditions. However, potential electrophysiological alterations of these two neuronal types in vivo in insulin-resistant states have never been simultaneously fully documented. Further, the anti-diabetic effect of dopamine agonism on this VMH system under insulin resistance has not been studied. METHODS This study examined the impact of a high-fat diet (HFD) on in vivo electrophysiological recordings from VMH GE and GI neurons and the ability of circadian-timed dopamine agonist therapy to reverse any adverse effect of the HFD on such VMH activities and peripheral glucose metabolism. RESULTS HFD significantly inhibited VMH GE neuronal electrophysiological response to local hyperglycaemia (36.3%) and augmented GI neuronal excitation response to local hypoglycaemia (47.0%). Bromocriptine (dopamine agonist) administration at onset of daily activity (but not during the daily sleep phase) completely reversed both VMH GE and GI neuronal aberrations induced by HFD. Such timed treatment also normalized glucose intolerance and insulin resistance. These VMH and peripheral glucose metabolism effects of circadian-timed bromocriptine may involve its known effect to reduce elevated VMH noradrenergic activity in insulin-resistant states as local VMH administration of norepinephrine was observed to significantly inhibit VMH GE neuronal sensing of local hyperglycaemia in insulin-sensitive animals on regular chow diet (52.4%). CONCLUSIONS HFD alters VMH glucose sensing in a manner that potentiates hyperglycaemia and this effect on the VMH can be reversed by appropriately circadian-timed dopamine agonist administration.
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Abstract
Obesity increases sympathetic nerve activity (SNA) in men, but not women. Here, we review current evidence suggesting that sexually dimorphic sympathoexcitatory responses to leptin and insulin may contribute. More specifically, while insulin increases SNA similarly in lean males and females, this response is markedly amplified in obese males, but is abolished in obese females. In lean female rats, leptin increases a subset of sympathetic nerves only during the high estrogen proestrus reproductive phase; thus, in obese females, because reproductive cycling can become impaired, the sporadic nature of leptin-induced sympathoexcitaton could minimize its action, despite elevated leptin levels. In contrast, in males, obesity preserves or enhances the central sympathoexcitatory response to leptin, and current evidence favors leptin’s contribution to the well-established increases in SNA induced by obesity in men. Leptin and insulin increase SNA via receptor binding in the hypothalamic arcuate nucleus and a neuropathway that includes arcuate neuropeptide Y (NPY) and proopiomelanocortin (POMC) projections to the paraventricular nucleus. These metabolic hormones normally suppress sympathoinhibitory NPY neurons and activate sympathoexcitatory POMC neurons. However, obesity appears to alter the ongoing activity and responsiveness of arcuate NPY and POMC neurons in a sexually dimorphic way, such that SNA increases in males but not females. We propose hypotheses to explain these sex differences and suggest areas of future research.
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Affiliation(s)
- Zhigang Shi
- Department of Physiology and Pharmacology, L-334, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd, Portland, OR, 97239, USA
| | - Jennifer Wong
- Department of Physiology and Pharmacology, L-334, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd, Portland, OR, 97239, USA
| | - Virginia L Brooks
- Department of Physiology and Pharmacology, L-334, Oregon Health & Science University, 3181 SW Sam Jackson Park Rd, Portland, OR, 97239, USA.
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Shi Z, Zhao D, Cassaglia PA, Brooks VL. Sites and sources of sympathoexcitation in obese male rats: role of brain insulin. Am J Physiol Regul Integr Comp Physiol 2020; 318:R634-R648. [PMID: 31967846 PMCID: PMC7099464 DOI: 10.1152/ajpregu.00317.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 01/13/2020] [Accepted: 01/13/2020] [Indexed: 12/21/2022]
Abstract
In males, obesity increases sympathetic nerve activity (SNA), but the mechanisms are unclear. Here, we investigate insulin, via an action in the arcuate nucleus (ArcN), and downstream neuropathways, including melanocortin receptor 3/4 (MC3/4R) in the hypothalamic paraventricular nucleus (PVN) and dorsal medial hypothalamus (DMH). We studied conscious and α-chloralose-anesthetized Sprague-Dawley rats fed a high-fat diet, which causes obesity prone (OP) rats to accrue excess fat and obesity-resistant (OR) rats to maintain fat content, similar to rats fed a standard control (CON) diet. Nonspecific blockade of the ArcN with muscimol and specific blockade of ArcN insulin receptors (InsR) decreased lumbar SNA (LSNA), heart rate (HR), and mean arterial pressure (MAP) in OP, but not OR or CON, rats, indicating that insulin supports LSNA in obese males. In conscious rats, intracerebroventricular infusion of insulin increased MAP only in OP rats and also improved HR baroreflex function from subnormal to supranormal. The brain sensitization to insulin may elucidate how insulin can drive central SNA pathways when transport of insulin across the blood-brain barrier may be impaired. Blockade of PVN, but not DMH, MC3/4R with SHU9119 decreased LSNA, HR, and, MAP in OP, but not OR or CON, rats. Interestingly, nanoinjection of the MC3/4R agonist melanotan II (MTII) into the PVN increased LSNA only in OP rats, similar to PVN MTII-induced increases in LSNA in CON rats after blockade of sympathoinhibitory neuropeptide Y Y1 receptors. ArcN InsR expression was not increased in OP rats. Collectively, these data indicate that obesity increases SNA, in part via increased InsR signaling and downstream PVN MC3/4R.
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Affiliation(s)
- Zhigang Shi
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon
| | - Ding Zhao
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon
- School of Pharmacy, Hebei Medical University, Shijiazhuang, People's Republic of China
| | - Priscila A Cassaglia
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon
| | - Virginia L Brooks
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon
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McNay EC, Pearson-Leary J. GluT4: A central player in hippocampal memory and brain insulin resistance. Exp Neurol 2020; 323:113076. [PMID: 31614121 PMCID: PMC6936336 DOI: 10.1016/j.expneurol.2019.113076] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 09/19/2019] [Accepted: 10/01/2019] [Indexed: 12/24/2022]
Abstract
Insulin is now well-established as playing multiple roles within the brain, and specifically as regulating hippocampal cognitive processes and metabolism. Impairments to insulin signaling, such as those seen in type 2 diabetes and Alzheimer's disease, are associated with brain hypometabolism and cognitive impairment, but the mechanisms of insulin's central effects are not determined. Several lines of research converge to suggest that the insulin-responsive glucose transporter GluT4 plays a central role in hippocampal memory processes, and that reduced activation of this transporter may underpin the cognitive impairments seen as a consequence of insulin resistance.
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Affiliation(s)
- Ewan C McNay
- Behavioral Neuroscience, University at Albany, Albany, NY, USA.
| | - Jiah Pearson-Leary
- Department of Anesthesiology, Abramson Research Center, Children's Hospital of Philadelphia, Philadelphia, PA, USA
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10
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Abstract
In order to better understand the events that precede and precipitate the onset of type 2 diabetes (T2DM), several nutritional animal models have been developed. These models are generated by manipulating the diet of either the animal itself, or its mother during her pregnancy, and in comparison to traditional genetic and knock out models, have the advantage that they more accurately reflect the etiology of human T2DM. This chapter will discuss some of the most widely used nutritional models of T2DM: Diet-induced obesity (DIO) in adult rodents, and studies of offspring of mothers fed a low-protein, high-fat and/or high-sugar diet during pregnancy and/or lactation. Several common mechanisms have been identified through which these nutritional manipulations can lead to metabolic disease, including pancreatic beta-cell dysfunction, impaired insulin signaling in skeletal muscle, and the excess accumulation of visceral adipose tissue and consequent deposition of nonesterified fatty acids in peripheral tissues. In addition, there is an emerging concept that obesity/poor quality diets result in increased production and release of pro-inflammatory cytokines from adipose tissue leading to a state of chronic low-grade inflammation, and that this is likely to represent an important link between obesity/diet and metabolic dysfunction. The following chapter will discuss the most common nutritional models of T2DM in experimental animals, their application, and relationship to human etiology, and will highlight the important insights these models have provided into the pathogenesis of T2DM.
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Affiliation(s)
- Beverly Sara Mühlhäusler
- Food and Nutrition Research Group, Department of Food and Wine Sciences, School of Agriculture, Food and Wine, The University of Adelaide, Adelaide, SA, Australia.
- FOODplus Research Centre, School of Agriculture, Food and Wine, The University of Adelaide, Adelaide, SA, Australia.
- CSIRO, Health and Biosecurity, Adelaide, SA, Australia.
| | - Carla Toop
- Sansom Institute for Health Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA, Australia
| | - Sheridan Gentili
- Sansom Institute for Health Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA, Australia
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Laurentius T, Raffetseder U, Fellner C, Kob R, Nourbakhsh M, Floege J, Bertsch T, Bollheimer LC, Ostendorf T. High-fat diet-induced obesity causes an inflammatory microenvironment in the kidneys of aging Long-Evans rats. JOURNAL OF INFLAMMATION-LONDON 2019; 16:14. [PMID: 31289451 PMCID: PMC6593534 DOI: 10.1186/s12950-019-0219-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 06/13/2019] [Indexed: 12/12/2022]
Abstract
Background Obesity is a risk factor for chronic kidney disease (CKD). While the exact mechanisms remain unclear, inflammation may be a consequence of obesity that directly impacts the kidneys. The aim of this study was to examine the inflammatory status of the kidneys and potential ongoing renal damage, i.e., tubular damage and fibrosis after long-term obesity maintained through persistent consumption of a high-fat diet (HFD). Results Twenty-four-week-old male Long-Evans (LEV) rats were continuously fed a control diet (CD) or HFD for 51 weeks. The mean body weight was higher in HFD-fed rats than in control diet-fed rats and markedly elevated during the last 24 weeks. Blood analyses revealed no substantial alterations in renal functional parameters by HFD consumption but a substantial increase in creatine kinase, a muscle loss marker. Magnetic resonance imaging (MRI) was utilized to quantify rat quadriceps muscle mass. The data showed that HFD-induced obesity in LEV rats was accompanied by minor decreases in muscle mass and strength at 75 weeks of age. Rat kidney inflammatory status was evaluated using histological and immunohistological techniques. The number of foci with immune cell infiltrates and infiltrating monocytes/macrophages was significantly increased in HFD-fed rat kidneys at week 75. Renal fibrosis parameters, including glomerulosclerosis and tubular damage, were also markedly increased in renal tissues from HFD-fed rats compared to the controls. The significant increase in tubular protein casts in HFD-fed rat tissues indicated that renal function was already disturbed. Rat kidney inflammatory status was further evaluated using the simultaneous profiling of twenty-two inflammatory markers in kidney tissue extracts. Consistently, MCP-1 and eotaxin (CCL11) levels were elevated in obese LEV rat kidneys. Conclusions Compared to CD-fed rats, HFD-fed obese LEV rats show significant damage of renal structures with aging. These subtle changes may sensitize the kidneys to the development of progressive CKD. Electronic supplementary material The online version of this article (10.1186/s12950-019-0219-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Thea Laurentius
- 1Department of Geriatric Medicine, RWTH University Hospital, Pauwelsstrasse 30, 52074 Aachen, Germany
| | - Ute Raffetseder
- 2Department of Nephrology and Clinical Immunology, RWTH University Hospital, Pauwelsstrasse 30, 52074 Aachen, Germany
| | - Claudia Fellner
- 3Institute of Radiology, University Hospital Regensburg, Regensburg, Germany
| | - Robert Kob
- 4Institute for Biomedicine of Aging, Friedrich-Alexander-Universität Erlangen-Nürnberg, General Hospital Nuremberg, Paracelsus Medical University, Nuremberg, Germany
| | - Mahtab Nourbakhsh
- 1Department of Geriatric Medicine, RWTH University Hospital, Pauwelsstrasse 30, 52074 Aachen, Germany.,6Department of Geriatric Medicine, RWTH University Hospital, Pauwelsstrasse 30, 52057 Aachen, Germany
| | - Jürgen Floege
- 2Department of Nephrology and Clinical Immunology, RWTH University Hospital, Pauwelsstrasse 30, 52074 Aachen, Germany
| | - Thomas Bertsch
- Institute of Clinical Chemistry, Laboratory Medicine and Transfusion Medicine, General Hospital Nuremberg, Paracelsus Medical University, Nuremberg, Germany
| | - Leo Cornelius Bollheimer
- 1Department of Geriatric Medicine, RWTH University Hospital, Pauwelsstrasse 30, 52074 Aachen, Germany
| | - Tammo Ostendorf
- 2Department of Nephrology and Clinical Immunology, RWTH University Hospital, Pauwelsstrasse 30, 52074 Aachen, Germany
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12
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Nakhate KT, Subhedar NK, Kokare DM. Involvement of neuropeptide CART in the central effects of insulin on feeding and body weight. Pharmacol Biochem Behav 2019; 181:101-109. [PMID: 31054945 DOI: 10.1016/j.pbb.2019.05.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Revised: 04/23/2019] [Accepted: 05/01/2019] [Indexed: 12/15/2022]
Abstract
While insulin secreted from pancreas plays a pivotal role in the control of glucose homeostasis, it also interacts with hypothalamic sites and negatively influences the energy balance. The present study was undertaken to reveal the functional interaction between cocaine- and amphetamine-regulated transcript (CART), a well-known anorexic peptide, and insulin within the framework of hypothalamus in the regulation of feeding behavior and body weight. Insulin was administered daily by intracerebroventricular (icv) route, alone or in combination with CART (icv) for a period of seven days. Immediately thereafter, preweighed food was offered to the animals at the commencement of the dark phase. The food intake and body weight were measured daily just prior to next injection. Furthermore, brains of insulin-treated rats were processed for the immunohistochemical analysis of CART-containing elements in the hypothalamus. Treatment with insulin (6 mU, icv) for a period of 7 days caused a significant decrease in food intake and body weight as compared to control. Concomitant administration of CART (0.5 μg, icv) potentiated insulin-induced anorexia and weight loss. Insulin administration resulted in a significant increase in CART immunoreactivity in the hypothalamic arcuate, paraventricular, dorsomedial and ventromedial nuclei. We suggest that increased CART contents in the hypothalamus may be causally linked with anorexia and weight loss induced by insulin.
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Affiliation(s)
- Kartik T Nakhate
- Rungta College of Pharmaceutical Sciences and Research, Rungta Educational Campus, Kohka-Kurud Road, Bhilai 490 024, Chhattisgarh, India
| | - Nishikant K Subhedar
- Indian Institute of Science Education and Research (IISER), Dr. Homi Bhabha Road, Near NCL, Pune 411 021, Maharashtra, India
| | - Dadasaheb M Kokare
- Department of Pharmaceutical Sciences, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur 440 033, Maharashtra, India.
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13
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Shi Z, Cassaglia PA, Pelletier NE, Brooks VL. Sex differences in the sympathoexcitatory response to insulin in obese rats: role of neuropeptide Y. J Physiol 2019; 597:1757-1775. [PMID: 30628058 DOI: 10.1113/jp277517] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 12/20/2018] [Indexed: 12/17/2022] Open
Abstract
KEY POINTS Intracerebroventricular insulin increased sympathetic nerve activity (SNA) and baroreflex control of SNA and heart rate more dramatically in obese male rats; in obese females, the responses were abolished. In obese males, the enhanced lumbar SNA (LSNA) responses were associated with reduced tonic inhibition of LSNA by neuropeptide Y (NPY) in the PVN. However, PVN NPY injection decreased LSNA similarly in obesity prone/obesity resistant/control rats. Collectively, these results suggest that NPY inputs were decreased. In obese females, NPY inhibition in the PVN was maintained. Moreover, NPY neurons in the arcuate nucleus became resistant to the inhibitory effects of insulin. A high-fat diet did not alter arcuate NPY neuronal InsR expression in males or females. Obesity-induced 'selective sensitization' of the brain to the sympathoexcitatory effects of insulin and leptin may contribute to elevated basal SNA, and therefore hypertension development, in males with obesity. These data may explain in part why obesity increases SNA less in women compared to men. ABSTRACT Obesity increases sympathetic nerve activity (SNA) in men but not women; however, the mechanisms are unknown. We investigated whether intracerebroventricular insulin infusion increases SNA more in obese male than female rats and if sex differences are mediated by changes in tonic inhibition of SNA by neuropeptide Y (NPY) in the paraventricular nucleus (PVN). When consuming a high-fat diet, obesity prone (OP) rats accrued excess fat, whereas obesity resistant (OR) rats maintained adiposity as in rats eating a control (CON) diet. Insulin increased lumbar SNA (LSNA) similarly in CON/OR males and females under urethane anaesthesia. The LSNA response was magnified in OP males but abolished in OP females. In males, blockade of PVN NPY Y1 receptors with BIBO3304 increased LSNA in CON/OR rats but not OP rats. Yet, PVN nanoinjections of NPY decreased LSNA similarly between groups. Thus, tonic PVN NPY inhibition of LSNA may be lost in obese males as a result of a decrease in NPY inputs. By contrast, in females, PVN BIBO3304 increased LSNA similarly in OP, OR and CON rats. After insulin, PVN BIBO3304 failed to increase LSNA in CON/OR females but increased LSNA in OP females, suggesting that with obesity NPY neurons become resistant to the inhibitory effects of insulin. These sex differences were not associated with changes in arcuate NPY neuronal insulin receptor expression. Collectively, these data reveal a marked sex difference in the impact of obesity on the sympathoexcitatory actions of insulin and implicate sexually dimorphic changes in NPY inhibition of SNA in the PVN as one mechanism.
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Affiliation(s)
- Zhigang Shi
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR, USA
| | - Priscila A Cassaglia
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR, USA
| | - Nicole E Pelletier
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR, USA
| | - Virginia L Brooks
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR, USA
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14
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Sáenz de Miera C. Maternal photoperiodic programming enlightens the internal regulation of thyroid-hormone deiodinases in tanycytes. J Neuroendocrinol 2019; 31:e12679. [PMID: 30585670 DOI: 10.1111/jne.12679] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Revised: 12/09/2018] [Accepted: 12/20/2018] [Indexed: 12/15/2022]
Abstract
Seasonal rhythms in physiology are widespread among mammals living in temperate zones. These rhythms rely on the external photoperiodic signal being entrained to the seasons, although they persist under constant conditions, revealing their endogenous origin. Internal long-term timing (circannual cycles) can be revealed in the laboratory as photoperiodic history-dependent responses, comprising the ability to respond differently to similar photoperiodic cues based on prior photoperiodic experience. In juveniles, history-dependence relies on the photoperiod transmitted by the mother to the fetus in utero, a phenomenon known as "maternal photoperiodic programming" (MPP). The response to photoperiod in mammals involves the nocturnal pineal hormone melatonin, which regulates a neuroendocrine network including thyrotrophin in the pars tuberalis and deiodinases in tanycytes, resulting in changes in thyroid hormone in the mediobasal hypothalamus. This review addresses MPP and discusses the latest findings on its impact on the thyrotrophin/deiodinase network. Finally, commonalities between MPP and other instances of endogenous seasonal timing are considered, and a unifying scheme is suggested in which timing arises from a long-term communication between the pars tuberalis and the hypothalamus and resultant spontaneous changes in local thyroid hormone status, independently of the pineal melatonin signal.
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Affiliation(s)
- Cristina Sáenz de Miera
- Department Neurobiology of Rhythms, Institute for Cellular and Integrative Neuroscience, University of Strasbourg, Strasbourg, France
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15
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Abstract
While there is a growing consensus that insulin has diverse and important regulatory actions on the brain, seemingly important aspects of brain insulin physiology are poorly understood. Examples include: what is the insulin concentration within brain interstitial fluid under normal physiologic conditions; whether insulin is made in the brain and acts locally; does insulin from the circulation cross the blood-brain barrier or the blood-CSF barrier in a fashion that facilitates its signaling in brain; is insulin degraded within the brain; do privileged areas with a "leaky" blood-brain barrier serve as signaling nodes for transmitting peripheral insulin signaling; does insulin action in the brain include regulation of amyloid peptides; whether insulin resistance is a cause or consequence of processes involved in cognitive decline. Heretofore, nearly all of the studies examining brain insulin physiology have employed techniques and methodologies that do not appreciate the complex fluid compartmentation and flow throughout the brain. This review attempts to provide a status report on historical and recent work that begins to address some of these issues. It is undertaken in an effort to suggest a framework for studies going forward. Such studies are inevitably influenced by recent physiologic and genetic studies of insulin accessing and acting in brain, discoveries relating to brain fluid dynamics and the interplay of cerebrospinal fluid, brain interstitial fluid, and brain lymphatics, and advances in clinical neuroimaging that underscore the dynamic role of neurovascular coupling.
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Affiliation(s)
- Sarah M Gray
- Department of Pharmacology, Department of Medicine, University of Virginia, School of Medicine , Charlottesville, Virginia
| | - Eugene J Barrett
- Department of Pharmacology, Department of Medicine, University of Virginia, School of Medicine , Charlottesville, Virginia.,Division of Endocrinology, Department of Medicine, University of Virginia, School of Medicine , Charlottesville, Virginia
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16
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Kleinert M, Clemmensen C, Hofmann SM, Moore MC, Renner S, Woods SC, Huypens P, Beckers J, de Angelis MH, Schürmann A, Bakhti M, Klingenspor M, Heiman M, Cherrington AD, Ristow M, Lickert H, Wolf E, Havel PJ, Müller TD, Tschöp MH. Animal models of obesity and diabetes mellitus. Nat Rev Endocrinol 2018; 14:140-162. [PMID: 29348476 DOI: 10.1038/nrendo.2017.161] [Citation(s) in RCA: 527] [Impact Index Per Article: 87.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
More than one-third of the worldwide population is overweight or obese and therefore at risk of developing type 2 diabetes mellitus. In order to mitigate this pandemic, safer and more potent therapeutics are urgently required. This necessitates the continued use of animal models to discover, validate and optimize novel therapeutics for their safe use in humans. In order to improve the transition from bench to bedside, researchers must not only carefully select the appropriate model but also draw the right conclusions. In this Review, we consolidate the key information on the currently available animal models of obesity and diabetes and highlight the advantages, limitations and important caveats of each of these models.
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Affiliation(s)
- Maximilian Kleinert
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Division of Metabolic Diseases, Department of Medicine, Technische Universität München, D-80333 Munich, Germany
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Section of Molecular Physiology, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, DK-2200 Copenhagen, Denmark
| | - Christoffer Clemmensen
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Division of Metabolic Diseases, Department of Medicine, Technische Universität München, D-80333 Munich, Germany
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
| | - Susanna M Hofmann
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Institute for Diabetes and Regeneration Research, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Medizinische Klinik und Poliklinik IV, Klinikum der Ludwig-Maximilians-Universität München, Ziemssenstr. 1, D-80336 Munich, Germany
| | - Mary C Moore
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37212, USA
| | - Simone Renner
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Chair for Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilan University München, Feodor-Lynen-Str. 25, D-81377 Munich, Germany
| | - Stephen C Woods
- University of Cincinnati College of Medicine, Department of Psychiatry and Behavioral Neuroscience, Metabolic Diseases Institute, 2170 East Galbraith Road, Cincinnati, Ohio 45237, USA
| | - Peter Huypens
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
| | - Johannes Beckers
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Technische Universität München, Chair of Experimental Genetics, D-85354 Freising, Germany
| | - Martin Hrabe de Angelis
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Technische Universität München, Chair of Experimental Genetics, D-85354 Freising, Germany
| | - Annette Schürmann
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Department of Experimental Diabetology, German Institute of Human Nutrition (DIfE), Arthur-Scheunert-Allee 114-116, D-14558 Nuthetal, Germany
| | - Mostafa Bakhti
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Institute for Diabetes and Regeneration Research, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Institute of Stem Cell Research, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
| | - Martin Klingenspor
- Chair of Molecular Nutritional Medicine, Technische Universität München, TUM School of Life Sciences Weihenstephan, Gregor-Mendel-Str. 2, D-85354 Freising, Germany
- Else Kröner-Fresenius Center for Nutritional Medicine, Technische Universität München, D-85354 Freising, Germany
- Institute for Food & Health, Technische Universität München, D-85354 Freising, Germany
| | - Mark Heiman
- MicroBiome Therapeutics, 1316 Jefferson Ave, New Orleans, Louisiana 70115, USA
| | - Alan D Cherrington
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37212, USA
| | - Michael Ristow
- Energy Metabolism Laboratory, Institute of Translational Medicine, Swiss Federal Institute of Technology (ETH) Zurich, CH-8603 Zurich-Schwerzenbach, Switzerland
| | - Heiko Lickert
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Institute for Diabetes and Regeneration Research, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Institute of Stem Cell Research, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
| | - Eckhard Wolf
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Chair for Molecular Animal Breeding and Biotechnology, Gene Center, Ludwig-Maximilan University München, Feodor-Lynen-Str. 25, D-81377 Munich, Germany
| | - Peter J Havel
- Department of Molecular Biosciences, School of Veterinary Medicine and Department of Nutrition, 3135 Meyer Hall, University of California, Davis, California 95616-5270, USA
| | - Timo D Müller
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Division of Metabolic Diseases, Department of Medicine, Technische Universität München, D-80333 Munich, Germany
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
| | - Matthias H Tschöp
- Institute for Diabetes and Obesity, Helmholtz Diabetes Center at Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
- Division of Metabolic Diseases, Department of Medicine, Technische Universität München, D-80333 Munich, Germany
- German Center for Diabetes Research (DZD), Ingolstädter Landstr. 1, D-85764 Neuherberg, Germany
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17
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Vasselli JR, Pi-Sunyer FX, Wall DG, John CS, Chapman CD, Currie PJ. Central effects of insulin detemir on feeding, body weight, and metabolism in rats. Am J Physiol Endocrinol Metab 2017; 313:E613-E621. [PMID: 28720583 PMCID: PMC5792141 DOI: 10.1152/ajpendo.00111.2016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 07/11/2017] [Accepted: 07/11/2017] [Indexed: 12/20/2022]
Abstract
Insulin detemir (DET) is a basal insulin analog that, in contrast to other long-acting forms of insulin, has significant weight-gain-sparing effects in diabetic patients. We hypothesized that this effect of DET may be due to its enhanced catabolic action in the central nervous system. We investigated the long-term effects of single third ventricular (3V) microinjections of equimolar doses of DET and regular insulin in normal male rats on feeding, body weight, energy expenditure (EE), and respiratory quotient (RQ). Also, in acute testing, we assessed the ability of lower doses of DET to alter feeding, EE, and RQ when microinjected directly into the paraventricular nucleus (PVN). The anabolic peptide ghrelin served as a positive control in acute testing. 3V administration of both DET (0.5-2.0 mU) and regular insulin (2.0-8.0 mU) significantly reduced feeding and body weight over 48 and 120 h, respectively, with DET yielding greater inhibitory effects. DET also stimulated greater elevations of EE and reductions of RQ over 72 and 48 h postinjection, respectively. In acute (4 h) testing, microinjections of DET (0.5 mU) into the PVN reduced feeding, increased EE, and reduced RQ, while ghrelin (100 pmol) had the opposite effects. When administered sequentially into the PVN, DET (0.25 and 0.5 mU) reversed ghrelin-induced feeding, EE, and RQ effects. These data support the notion that the weight-sparing effect of DET is at least in part based on its central catabolic action and that enhanced EE and reduced RQ may participate in this effect.
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Affiliation(s)
- Joseph R Vasselli
- Obesity Nutrition Research Center, Department of Medicine, Columbia University, New York, New York; and
| | - F Xavier Pi-Sunyer
- Obesity Nutrition Research Center, Department of Medicine, Columbia University, New York, New York; and
| | - Daniel G Wall
- Department of Psychology, Reed College, Portland, Oregon
| | | | | | - Paul J Currie
- Department of Psychology, Reed College, Portland, Oregon
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18
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Cooney KA, Molden BM, Kowalczyk NS, Russell S, Baldini G. Lipid stress inhibits endocytosis of melanocortin-4 receptor from modified clathrin-enriched sites and impairs receptor desensitization. J Biol Chem 2017; 292:17731-17745. [PMID: 28878020 DOI: 10.1074/jbc.m117.785758] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 08/12/2017] [Indexed: 11/06/2022] Open
Abstract
Melanocortin-4 receptor (MC4R) is a G-protein-coupled receptor expressed in the brain's hypothalamus where it regulates energy homeostasis. MC4R agonists function to lower food intake and weight. In this respect, although obesity promotes hyperlipidemia and hypothalamic injury, MC4R agonists are nevertheless more effective to reduce food intake within hours of administration in overweight, rather than lean, mice. MC4R undergoes constitutive internalization and recycling to the plasma membrane with agonist binding inducing receptor retention along the intracellular route and, under prolonged exposure, desensitization. Here, we found that, in neuronal cells, lipid stress by exposure to elevated palmitate leaves unchanged the rate by which MC4R and transferrin receptor are constitutively excluded from the cell surface. However, lipid stress disrupted later steps of MC4R and transferrin receptor internalization to endosomes as well as traffic of agonist-occupied MC4R to lysosomes and MC4R desensitization. In the lipid-stressed cells, MC4R and clathrin were redistributed to the plasma membrane where they colocalized to sites that appeared by super-resolution microscopy to be modified and to have higher clathrin content than those of cells not exposed to elevated palmitate. The data suggest that lipid stress disrupts steps of endocytosis following MC4R localization to clathrin-coated sites and exclusion of the receptor from the extracellular medium. We conclude that increased effectiveness of MC4R agonists in obesity may be an unexpected outcome of neuronal injury with disrupted clathrin-dependent endocytosis and impaired receptor desensitization.
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Affiliation(s)
- Kimberly A Cooney
- From the Department of Biochemistry and Molecular Biology University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199
| | - Brent M Molden
- From the Department of Biochemistry and Molecular Biology University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199
| | - Nicholas S Kowalczyk
- From the Department of Biochemistry and Molecular Biology University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199
| | - Susan Russell
- From the Department of Biochemistry and Molecular Biology University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199
| | - Giulia Baldini
- From the Department of Biochemistry and Molecular Biology University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199
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19
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Gheibi S, Kashfi K, Ghasemi A. A practical guide for induction of type-2 diabetes in rat: Incorporating a high-fat diet and streptozotocin. Biomed Pharmacother 2017; 95:605-613. [PMID: 28881291 DOI: 10.1016/j.biopha.2017.08.098] [Citation(s) in RCA: 179] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 08/12/2017] [Accepted: 08/23/2017] [Indexed: 02/06/2023] Open
Abstract
Prevalence of diabetes, a serious public health problem is rapidly increasing worldwide. Type-2 diabetes is the common form of diabetes characterized by insulin resistance and abnormalities in insulin production. Despite the current development of therapeutic agents, there is no effective treatment without side effects; it is therefore necessary to find new prevention strategies and better treatments. For this purpose animal models of diabetes are appropriate tools, of which rodents due to the short generation time and economic considerations are the first choice. The aim of this review is to present features of a frequently used model of type-2 diabetes in rat, induced by a high fat diet and streptozotocin, taking into account its advantages/disadvantages and presenting a practical guide.
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Affiliation(s)
- Sevda Gheibi
- Endocrine Physiology Research Center, Research institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran; Neurophysiology Research Center and Department of Physiology, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Khosrow Kashfi
- Department of Molecular, Cellular and Biomedical Sciences, Sophie Davis School of Biomedical Education, City University of New York School of Medicine, New York, USA
| | - Asghar Ghasemi
- Endocrine Physiology Research Center, Research institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
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20
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Woods SC, May AA, Liu M, Tso P, Begg DP. Using the cerebrospinal fluid to understand ingestive behavior. Physiol Behav 2017; 178:172-178. [PMID: 27923718 PMCID: PMC5944842 DOI: 10.1016/j.physbeh.2016.11.037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 11/22/2016] [Accepted: 11/28/2016] [Indexed: 01/08/2023]
Abstract
The cerebrospinal fluid (CSF) offers a window into the workings of the brain and blood-brain barrier (BBB). Molecules that enter into the central nervous system (CNS) by passive diffusion or receptor-mediated transport through the choroid plexus often appear in the CSF prior to acting within the brain. Other molecules enter the CNS by passing through the BBB into the brain's interstitial fluid prior to appearing in the CSF. This pattern is also often observed for molecules synthesized by neurons or glia within the CNS. The CSF is therefore an important conduit for the entry and clearance of molecules into/from the CNS and thereby constitutes an important window onto brain activity and barrier function. Assessing the CSF basally, under experimental conditions, or in the context of challenges or metabolic diseases can provide powerful insights about brain function. Here, we review important findings made by our labs, as influenced by the late Randall Sakai, by interrogating the CSF.
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Affiliation(s)
- Stephen C Woods
- Department of Psychiatry and Behavioral Neuroscience, Metabolic Diseases Institute, University of Cincinnati College of Medicine, Cincinnati, OH, USA.
| | - Aaron A May
- Department of Pathology and Molecular Medicine, Metabolic Diseases Institute, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Min Liu
- Department of Pathology and Molecular Medicine, Metabolic Diseases Institute, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Patrick Tso
- Department of Pathology and Molecular Medicine, Metabolic Diseases Institute, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Denovan P Begg
- School of Psychology, University of New South Wales, Sydney, NSW 2052, Australia
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21
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Gray SM, Aylor KW, Barrett EJ. Unravelling the regulation of insulin transport across the brain endothelial cell. Diabetologia 2017; 60:1512-1521. [PMID: 28601906 PMCID: PMC5534844 DOI: 10.1007/s00125-017-4285-4] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 03/23/2017] [Indexed: 11/28/2022]
Abstract
AIMS/HYPOTHESIS For circulating insulin to act on the brain it must cross the blood-brain barrier (BBB). Remarkably little is known about how circulating insulin crosses the BBB's highly restrictive brain endothelial cells (BECs). Therefore, we examined potential mechanisms regulating BEC insulin uptake, signalling and degradation during BEC transcytosis, and how transport is affected by a high-fat diet (HFD) and by astrocyte activity. METHODS 125I-TyrA14-insulin uptake and transcytosis, and the effects of insulin receptor (IR) blockade, inhibition of insulin signalling, astrocyte stimulation and an HFD were tested using purified isolated BECs (iBECs) in monoculture and co-cultured with astrocytes. RESULTS At physiological insulin concentrations, the IR, not the IGF-1 receptor, facilitated BEC insulin uptake, which required lipid raft-mediated endocytosis, but did not require insulin action on phosphoinositide-3-kinase (PI3K) or mitogen-activated protein kinase kinase (MEK). Feeding rats an HFD for 4 weeks decreased iBEC insulin uptake and increased NF-κB binding activity without affecting insulin PI3K signalling, IR expression or content, or insulin degrading enzyme expression. Using an in vitro BBB (co-culture of iBECs and astrocytes), we found insulin was not degraded during transcytosis, and that stimulating astrocytes with L-glutamate increased transcytosis, while inhibiting nitric oxide synthase decreased insulin transcytosis. CONCLUSIONS/INTERPRETATION Insulin crosses the BBB intact via an IR-specific, vesicle-mediated transport process in the BECs. HFD feeding, nitric oxide inhibition and astrocyte stimulation can regulate BEC insulin uptake and transcytosis.
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Affiliation(s)
- Sarah M Gray
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA
| | - Kevin W Aylor
- Division of Endocrinology & Metabolism, Department of Medicine, University of Virginia, 450 Ray C. Hunt Drive, P.O. Box 801410, Charlottesville, VA, 22908, USA
| | - Eugene J Barrett
- Department of Pharmacology, University of Virginia, Charlottesville, VA, USA.
- Division of Endocrinology & Metabolism, Department of Medicine, University of Virginia, 450 Ray C. Hunt Drive, P.O. Box 801410, Charlottesville, VA, 22908, USA.
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22
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Levin BE. 10 lessons learned by a misguided physician. Physiol Behav 2017; 176:217-222. [PMID: 28034577 DOI: 10.1016/j.physbeh.2016.12.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 12/23/2016] [Accepted: 12/23/2016] [Indexed: 10/20/2022]
Abstract
It was a great and humbling honor to receive the 2016 Distinguished Career Award from my SSIB colleagues. This paper summarizes the major points of my DCA talk at the 2016 annual meeting. It is a reflection on my 50year medical and research career and 10 lessons I have learned over those years which might be of help to young investigators near the beginning of their own research careers. These lessons include: the value of being receptive to the opportunities provided you; how clinician-scientists can serve as critical role models for young investigators like me and a history of how my career developed as a result of their influence; the importance of carefully examining your own data, particularly when it doesn't agree with your preconceived ideas; the critical role that students, postdocs and PhD (and even veterinarian) colleagues can play in developing one's career; the likelihood that your career path will have many interesting twists and turns determined by changes in your own scientific interests and how rewarding various areas of research focus are to you; the importance of building a close-knit laboratory staff family; the fact that science and romance can mix. Finally, I offer 3 somewhat self-evident free pieces of advice for building and maintaining a rewarding career.
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Affiliation(s)
- Barry E Levin
- Department of Neurology, Rutgers New Jersey Medical School, 185 South Orange Avenue, MSB H506, Newark, NJ 07107, USA.
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23
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Brown RM, Kupchik YM, Spencer S, Garcia-Keller C, Spanswick DC, Lawrence AJ, Simonds SE, Schwartz DJ, Jordan KA, Jhou TC, Kalivas PW. Addiction-like Synaptic Impairments in Diet-Induced Obesity. Biol Psychiatry 2017; 81:797-806. [PMID: 26826876 PMCID: PMC4889544 DOI: 10.1016/j.biopsych.2015.11.019] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2014] [Revised: 11/20/2015] [Accepted: 11/24/2015] [Indexed: 10/22/2022]
Abstract
BACKGROUND There is increasing evidence that the pathological overeating underlying some forms of obesity is compulsive in nature and therefore contains elements of an addictive disorder. However, direct physiological evidence linking obesity to synaptic plasticity akin to that occurring in addiction is lacking. We sought to establish whether the propensity to diet-induced obesity (DIO) is associated with addictive-like behavior, as well as synaptic impairments in the nucleus accumbens core considered hallmarks of addiction. METHODS Sprague Dawley rats were allowed free access to a palatable diet for 8 weeks then separated by weight gain into DIO-prone and DIO-resistant subgroups. Access to palatable food was then restricted to daily operant self-administration sessions using fixed ratio 1, 3, and 5 and progressive ratio schedules. Subsequently, nucleus accumbens brain slices were prepared, and we tested for changes in the ratio between α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) and N-methyl-D-aspartate currents and the ability to exhibit long-term depression. RESULTS We found that propensity to develop DIO is linked to deficits in the ability to induce long-term depression in the nucleus accumbens, as well as increased potentiation at these synapses as measured by AMPA/N-methyl-D-aspartate currents. Consistent with these impairments, we observed addictive-like behavior in DIO-prone rats, including 1) heightened motivation for palatable food; 2) excessive intake; and 3) increased food seeking when food was unavailable. CONCLUSIONS Our results show overlap between the propensity for DIO and the synaptic changes associated with facets of addictive behavior, supporting partial coincident neurological underpinnings for compulsive overeating and drug addiction.
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Affiliation(s)
- Robyn Mary Brown
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425,Florey Institute of Neuroscience & Mental Health, University of Melbourne, Parkville, Australia,correspondence: Dr Robyn M Brown, Department of Neurosciences, Medical University of South Carolina, Charleston, SC, 29425, USA., Florey Institute of Neuroscience & Mental Health, University of Melbourne, Parkville, Vic, 3052, Australia, Ph: +61 3 9035 6592, Fax: +61 3 9035 3107,
| | - Yonatan Michael Kupchik
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425,Department of Medical Neurobiology, The Hebrew University, Jerusalem, Israel
| | - Sade Spencer
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425
| | - Constanza Garcia-Keller
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425,Departamento de Farmacología, Universidad Nacional de Córdoba, Córdoba, Argentina
| | | | - Andrew John Lawrence
- Florey Institute of Neuroscience & Mental Health, University of Melbourne, Parkville, Australia
| | | | - Danielle Joy Schwartz
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425
| | - Kelsey Ann Jordan
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425
| | - Thomas Clayton Jhou
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425
| | - Peter William Kalivas
- Department of Neurosciences, Medical University of South Carolina, Charleston, SC 29425
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Egedigwe CA, Ijeh II, Okafor PN, Ejike CECC. Aqueous and methanol extracts of Vernonia amygdalina leaves exert their anti-obesity effects through the modulation of appetite-regulatory hormones. PHARMACEUTICAL BIOLOGY 2016; 54:3232-3236. [PMID: 27569644 DOI: 10.1080/13880209.2016.1216135] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 07/19/2016] [Indexed: 06/06/2023]
Abstract
CONTEXT Aqueous and methanol extracts of Vernonia amygdalina Del. (Asteraceae) (AEVA and MEVA, respectively) leaves are reported to possess anti-obesity properties, exerted through unknown mechanisms. OBJECTIVE This study investigated the effects of AEVA and MEVA on relevant hormones and enzymes in high-fat diet (HFD)-induced obese rats. MATERIALS AND METHODS Forty-two Wistar rats were placed into seven groups. The test groups received 100 mg/kg.bw AEVA (AEVA100), 500 mg/kg.bw AEVA (AEVA500), 50 mg/kg.bw MEVA (MEVA50) and 200 mg/kg.bw MEVA (MEVA200), respectively. The positive control (PC) group received 20 mg/kg.bw Orlistat, while the negative control (NeC) and normal control (NoC) groups received distilled water. The extracts were given orally daily for 12 weeks. Thereafter, the concentrations/activities of relevant hormones/enzymes in their sera were determined. RESULTS Insulin concentrations (ng/ml) in the test groups ranged from 1.08 ± 0.01 (AEVA100) to 1.09 ± 0.01 (AEVA500). They were all similar (p > .05) to the NoC and PC controls. Leptin concentrations (pg/ml) in the test rats ranged from 0.02 ± 0.01 (AEVA500) to 0.03 ± 0.00 (MEVA50), and were all similar to the NoC group. The ghrelin concentrations of only the AEVA500 and MEVA200 groups were similar to those of the PC group (0.10 ± 0.01 pg/ml). AEVA100 and MEVA200 resulted in adiponectin concentrations (ng/ml) of the rats (0.27 ± 0.04 and 0.28 ± 0.04 respectively) that were similar to the PC group. The activities of lipoprotein lipase and the concentrations of intestinal amylase in the test rats were similar to values obtained for the control groups. CONCLUSION Appetite regulation may be the mechanism through which the weight-loss properties of AEVA and MEVA are expressed.
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Affiliation(s)
- Chima A Egedigwe
- a Department of Biochemistry , College of Natural Sciences, Michael Okpara University of Agriculture , Umudike , Abia State , Nigeria
- b Department of Chemistry/Biochemistry/Molecular Biology, Faculty of Science and Technology , Federal University Ndufu-Alike , Ikwo , Ebonyi State , Nigeria
| | - Ifeoma I Ijeh
- a Department of Biochemistry , College of Natural Sciences, Michael Okpara University of Agriculture , Umudike , Abia State , Nigeria
| | - Polycarp N Okafor
- a Department of Biochemistry , College of Natural Sciences, Michael Okpara University of Agriculture , Umudike , Abia State , Nigeria
| | - Chukwunonso E C C Ejike
- a Department of Biochemistry , College of Natural Sciences, Michael Okpara University of Agriculture , Umudike , Abia State , Nigeria
- c Department of Medical Biochemistry, Faculty of Basic Medical Sciences , Federal University Ndufu-Alike , Ikwo , Ebonyi State , Nigeria
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Giles ED, Jackman MR, MacLean PS. Modeling Diet-Induced Obesity with Obesity-Prone Rats: Implications for Studies in Females. Front Nutr 2016; 3:50. [PMID: 27933296 PMCID: PMC5121240 DOI: 10.3389/fnut.2016.00050] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 10/28/2016] [Indexed: 12/03/2022] Open
Abstract
Obesity is a worldwide epidemic, and the comorbidities associated with obesity are numerous. Over the last two decades, we and others have employed an outbred rat model to study the development and persistence of obesity, as well as the metabolic complications that accompany excess weight. In this review, we summarize the strengths and limitations of this model and how it has been applied to further our understanding of human physiology in the context of weight loss and weight regain. We also discuss how the approach has been adapted over time for studies in females and female-specific physiological conditions, such as menopause and breast cancer. As excess weight and the accompanying metabolic complications have become common place in our society, we expect that this model will continue to provide a valuable translational tool to establish physiologically relevant connections to the basic science studies of obesity and body weight regulation.
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Affiliation(s)
- Erin D Giles
- Department of Nutrition and Food Science, Texas A&M University , College Station, TX , USA
| | - Matthew R Jackman
- Anschutz Health and Wellness Center, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Paul S MacLean
- Anschutz Health and Wellness Center, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
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Boakes RA, Martire SI, Rooney KB, Kendig MD. Individual differences in saccharin acceptance predict rats' food intake. Physiol Behav 2016; 164:151-6. [DOI: 10.1016/j.physbeh.2016.05.050] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 05/26/2016] [Accepted: 05/28/2016] [Indexed: 01/05/2023]
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Sladek CD, Stevens W, Song Z, Johnson GC, MacLean PS. The "metabolic sensor" function of rat supraoptic oxytocin and vasopressin neurons is attenuated during lactation but not in diet-induced obesity. Am J Physiol Regul Integr Comp Physiol 2015; 310:R337-45. [PMID: 26661099 DOI: 10.1152/ajpregu.00422.2015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 12/07/2015] [Indexed: 12/14/2022]
Abstract
The oxytocin (OT) and vasopressin (VP) neurons of the supraoptic nucleus (SON) demonstrate characteristics of "metabolic sensors". They express insulin receptors and glucokinase (GK). They respond to an increase in glucose and insulin with an increase in intracellular [Ca(2+)] and increased OT and VP release that is GK dependent. Although this is consistent with the established role of OT as an anorectic agent, how these molecules function relative to the important role of OT during lactation and whether deficits in this metabolic sensor function contribute to obesity remain to be examined. Thus, we evaluated whether insulin and glucose-induced OT and VP secretion from perifused explants of the hypothalamo-neurohypophyseal system are altered during lactation and by diet-induced obesity (DIO). In explants from female day 8 lactating rats, increasing glucose (Glu, 5 mM) did not alter OT or VP release. However, insulin (Ins; 3 ng/ml) increased OT release, and increasing the glucose concentration in the presence of insulin (Ins+Glu) resulted in a sustained elevation in both OT and VP release that was not prevented by alloxan, a GK inhibitor. Explants from male DIO rats also responded to Ins+Glu with an increase in OT and VP regardless of whether obesity had been induced by feeding a high-fat diet (HFD). The HFD-DIO rats had elevated body weight, plasma Ins, Glu, leptin, and triglycerides. These findings suggest that the role of SON neurons as metabolic sensors is diminished during lactation, but not in this animal model of obesity.
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Affiliation(s)
- Celia D Sladek
- Department of Physiology and Biophysics and Medicine, University of Colorado School of Medicine, Aurora, Colorado
| | - Wanida Stevens
- Department of Physiology and Biophysics and Medicine, University of Colorado School of Medicine, Aurora, Colorado
| | - Zhilin Song
- Department of Physiology and Biophysics and Medicine, University of Colorado School of Medicine, Aurora, Colorado
| | - Ginger C Johnson
- Department of Physiology and Biophysics and Medicine, University of Colorado School of Medicine, Aurora, Colorado
| | - Paul S MacLean
- Department of Physiology and Biophysics and Medicine, University of Colorado School of Medicine, Aurora, Colorado
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Diet-induced obesity and diet-resistant rats: differences in the rewarding and anorectic effects of D-amphetamine. Psychopharmacology (Berl) 2015; 232:3215-26. [PMID: 26047964 PMCID: PMC4536171 DOI: 10.1007/s00213-015-3981-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Accepted: 05/19/2015] [Indexed: 10/23/2022]
Abstract
RATIONALE Obesity is a leading public health problem worldwide. Multiple lines of evidence associate deficits in the brain reward circuit with obesity. OBJECTIVE Whether alterations in brain reward sensitivity precede or are a consequence of obesity is unknown. This study aimed to investigate both innate and obesity-induced differences in the sensitivity to the effects of an indirect dopaminergic agonist. METHODS Rats genetically prone to diet-induced obesity (DIO) and their counterpart diet-resistant (DR) were fed a chow diet, and their response to D-amphetamine on intracranial self-stimulation and food intake were assessed. The same variables were then evaluated after exposing the rats to a high-fat diet, after DIO rats selectively developed obesity. Finally, gene expression levels of dopamine receptors 1 and 2 as well as tyrosine hydroxylase were measured in reward-related brain regions. RESULTS In a pre-obesity state, DIO rats showed innate decreased sensitivity to the reward-enhancing and anorectic effects of D-amphetamine, as compared to DR rats. In a diet-induced obese state, the insensitivity to the potentiating effects of D-amphetamine on intracranial self-stimulation (ICSS) threshold persisted and became more marked in DIO rats, while the anorectic effects were comparable between genotypes. Finally, innate and obesity-induced differences in the gene expression of dopamine receptors were observed. CONCLUSIONS Our results demonstrate that brain reward deficits antedate the development of obesity and worsen after obesity is fully developed, suggesting that these alterations represent vulnerability factors for its development. Moreover, our data suggests that the reward-enhancing and anorectic effects of D-amphetamine are dissociable in the context of obesity.
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Robinson MJF, Burghardt PR, Patterson CM, Nobile CW, Akil H, Watson SJ, Berridge KC, Ferrario CR. Individual Differences in Cue-Induced Motivation and Striatal Systems in Rats Susceptible to Diet-Induced Obesity. Neuropsychopharmacology 2015; 40:2113-23. [PMID: 25761571 PMCID: PMC4613617 DOI: 10.1038/npp.2015.71] [Citation(s) in RCA: 149] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2014] [Revised: 01/29/2015] [Accepted: 02/23/2015] [Indexed: 12/16/2022]
Abstract
Pavlovian cues associated with junk-foods (caloric, highly sweet, and/or fatty foods), like the smell of brownies, can elicit craving to eat and increase the amount of food consumed. People who are more susceptible to these motivational effects of food cues may have a higher risk for becoming obese. Further, overconsumption of junk-foods leading to the development of obesity may itself heighten attraction to food cues. Here, we used a model of individual susceptibility to junk-foods diet-induced obesity to determine whether there are pre-existing and/or diet-induced increases in attraction to and motivation for sucrose-paired cues (ie, incentive salience or 'wanting'). We also assessed diet- vs obesity-associated alterations in mesolimbic function and receptor expression. We found that rats susceptible to diet-induced obesity displayed heightened conditioned approach prior to the development of obesity. In addition, after junk-food diet exposure, those rats that developed obesity also showed increased willingness to gain access to a sucrose cue. Heightened 'wanting' was not due to individual differences in the hedonic impact ('liking') of sucrose. Neurobiologically, Mu opioid receptor mRNA expression was lower in striatal 'hot-spots' that generate eating or hedonic impact only in those rats that became obese. In contrast, prolonged exposure to junk-food resulted in cross-sensitization to amphetamine-induced locomotion and downregulation of striatal D2R mRNA regardless of the development of obesity. Together these data shed light on individual differences in behavioral and neurobiological consequences of exposure to junk-food diets and the potential contribution of incentive sensitization in susceptible individuals to greater food cue-triggered motivation.
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Affiliation(s)
- Mike JF Robinson
- Department of Psychology, University of Michigan, Ann Arbor, MI, USA,Department of Psychology, Wesleyan University, Middletown, CT, USA
| | - Paul R Burghardt
- Molecular and Behavioral Neuroscience Institute, The University of Michigan School of Medicine, Ann Arbor, MI, USA,Department of Psychiatry, University of Michigan School of Medicine, Ann Arbor, MI, USA
| | - Christa M Patterson
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Cameron W Nobile
- Department of Pharmacology, University of Michigan School of Medicine, Ann Arbor, MI, USA
| | - Huda Akil
- Molecular and Behavioral Neuroscience Institute, The University of Michigan School of Medicine, Ann Arbor, MI, USA
| | - Stanley J Watson
- Molecular and Behavioral Neuroscience Institute, The University of Michigan School of Medicine, Ann Arbor, MI, USA
| | - Kent C Berridge
- Department of Psychology, University of Michigan, Ann Arbor, MI, USA
| | - Carrie R Ferrario
- Department of Pharmacology, University of Michigan School of Medicine, Ann Arbor, MI, USA,Department of Pharmacology, University of Michigan, 1150 W. Medical Center Drive, MSRB III 1301, Ann Arbor, MI 48109, USA, Tel: +1 734 945 9887, Fax: +847 578 8515, E-mail:
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Ratner C, Madsen AN, Kristensen LV, Skov LJ, Pedersen KS, Mortensen OH, Knudsen GM, Raun K, Holst B. Impaired oxidative capacity due to decreased CPT1b levels as a contributing factor to fat accumulation in obesity. Am J Physiol Regul Integr Comp Physiol 2015; 308:R973-82. [DOI: 10.1152/ajpregu.00219.2014] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Accepted: 03/09/2015] [Indexed: 02/05/2023]
Abstract
To characterize mechanisms responsible for fat accumulation we used a selectively bred obesity-prone (OP) and obesity-resistant (OR) rat model where the rats were fed a Western diet for 76 days. Body composition was assessed by magnetic resonance imaging scans, and as expected, the OP rats developed a higher degree of fat accumulation compared with OR rats. Indirect calorimetry showed that the OP rats had higher respiratory exchange ratio (RER) compared with OR rats, indicating an impaired ability to oxidize fat. The OP rats had lower expression of carnitine palmitoyltransferase 1b in intra-abdominal fat, and higher expression of stearoyl-CoA desaturase 1 in subcutaneous fat compared with OR rats, which could explain the higher fat accumulation and RER values. Basal metabolic parameters were also examined in juvenile OP and OR rats before and during the introduction of the Western diet. Juvenile OP rats likewise had higher RER values, indicating that this trait may be a primary and contributing factor to their obese phenotype. When the adult obese rats were exposed to the orexigenic and adipogenic hormone ghrelin, we observed increased RER values in both OP and OR rats, while OR rats were more sensitive to the orexigenic effects of ghrelin as well as ghrelin-induced attenuation of activity and energy expenditure. Thus increased fat accumulation characterizing obesity may be caused by impaired oxidative capacity due to decreased carnitine palmitoyltransferase 1b levels in the white adipose tissue, whereas ghrelin sensitivity did not seem to be a contributing factor.
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Affiliation(s)
- Cecilia Ratner
- Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
- Section for Metabolic Receptology and Enteroendocrinology, The Novo Nordisk Foundation Center for basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Andreas Nygaard Madsen
- Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
- Section for Metabolic Receptology and Enteroendocrinology, The Novo Nordisk Foundation Center for basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Line Vildbrad Kristensen
- Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
- Section for Metabolic Receptology and Enteroendocrinology, The Novo Nordisk Foundation Center for basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Louise Julie Skov
- Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
- Section for Metabolic Receptology and Enteroendocrinology, The Novo Nordisk Foundation Center for basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Katrine Seide Pedersen
- Department of Biomedical Sciences, Cellular and Metabolic Research Section, Symbion, Copenhagen, Denmark
| | - Ole Hartvig Mortensen
- Department of Biomedical Sciences, Cellular and Metabolic Research Section, Symbion, Copenhagen, Denmark
| | - Gitte Moos Knudsen
- Neurobiology Research Unit and Center for Integrated Molecular Brain Imaging, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark; and
| | - Kirsten Raun
- Novo Nordisk Diabetes Research Unit, Novo Nordisk A/S, Maaloev, Denmark
| | - Birgitte Holst
- Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark
- Section for Metabolic Receptology and Enteroendocrinology, The Novo Nordisk Foundation Center for basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
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Gawałek M, Sliwowska JH. Neuronal basis of reproductive dysfunctions associated with diet and alcohol: From the womb to adulthood. Reprod Biol 2015; 15:69-78. [PMID: 26051454 DOI: 10.1016/j.repbio.2015.04.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2015] [Revised: 04/08/2015] [Accepted: 04/14/2015] [Indexed: 12/19/2022]
Abstract
The theory that individuals are born as tabula rasa and that their knowledge comes from experience and perception is no longer true. Studies suggest that experience is gained as early as in the mother's womb. Moreover, environmental stressors like alcohol or inadequate diet can affect physiological systems such as the hypothalmic-pituitary-gonadal (HPG) axis. The effects of these stressors can manifest as alterations in sexual development and adult reproductive functions. In this review, we consider and compare evidence from animal models and human studies demonstrating the role of environmental stressors (alcohol and under- or overnutrition) on the HPG axis. We review the role of alcohol and inadequate diet in prenatal reproductive system programming and consider specific candidate neurons in the adult hypothalamus through which reproductive function is being regulated. Finally, we review evidence from animal studies on the role that alcohol and diet play in fertility and reproductive disorders. We conclude that in order to better understand reproductive failure in animals and humans we need to consider in utero development and pay more attention to early life experience when searching for the origins of reproductive diseases.
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Affiliation(s)
- Monika Gawałek
- Laboratory of Neurobiology, Institute of Zoology, Poznań University of Life Sciences, Wojska Polskiego 71C, 60-625 Poznań, Poland.
| | - Joanna H Sliwowska
- Laboratory of Neurobiology, Institute of Zoology, Poznań University of Life Sciences, Wojska Polskiego 71C, 60-625 Poznań, Poland.
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Sasaki T. Age-Associated Weight Gain, Leptin, and SIRT1: A Possible Role for Hypothalamic SIRT1 in the Prevention of Weight Gain and Aging through Modulation of Leptin Sensitivity. Front Endocrinol (Lausanne) 2015; 6:109. [PMID: 26236282 PMCID: PMC4504171 DOI: 10.3389/fendo.2015.00109] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2015] [Accepted: 07/01/2015] [Indexed: 12/14/2022] Open
Abstract
The hypothalamus is the principal regulator of body weight and energy balance. It modulates both energy intake and energy expenditure by sensing the energy status of the body through neural inputs from the periphery as well as direct humoral inputs. Leptin, an adipokine, is one of the humoral factors responsible for alerting the hypothalamus that enough energy is stored in the periphery. Plasma leptin levels are positively linked to adiposity; leptin suppress energy intake and stimulates energy expenditure. However, prolonged increases in plasma leptin levels due to obesity cause leptin resistance, affecting both leptin access to hypothalamic neurons and leptin signal transduction within hypothalamic neurons. Decreased sensing of peripheral energy status through leptin may lead to a positive energy balance and gradual gains in weight and adiposity, further worsening leptin resistance. Leptin resistance, increased adiposity, and weight gain are all associated with aging in both humans and animals. Central insulin resistance is associated with similar observations. Therefore, improving the action of humoral factors in the hypothalamus may prevent gradual weight gain, especially during middle age. SIRT1 is a NAD(+)-dependent protein deacetylase with numerous substrates, including histones, transcription factors, co-factors, and various enzymes. SIRT1 improves both leptin sensitivity and insulin sensitivity by decreasing the levels of several molecules that impair leptin and insulin signal transduction. SIRT1 and NAD(+) levels decrease with age in the hypothalamus; increased hypothalamic SIRT1 levels prevent age-associated weight gain and improve leptin sensitivity in mice. Therefore, preventing the age-dependent loss of SIRT1 function in the hypothalamus could improve the action of humoral factors in the hypothalamus as well as central regulation of energy balance.
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Affiliation(s)
- Tsutomu Sasaki
- Laboratory for Metabolic Signaling, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
- *Correspondence: Tsutomu Sasaki, Laboratory for Metabolic Signaling, Institute for Molecular and Cellular Regulation, Gunma University, 3-39-15 Showa-machi, Maebashi, Gunma 371-8512, Japan,
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Steculorum SM, Solas M, Brüning JC. The paradox of neuronal insulin action and resistance in the development of aging-associated diseases. Alzheimers Dement 2014; 10:S3-11. [PMID: 24529522 DOI: 10.1016/j.jalz.2013.12.008] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Accepted: 12/05/2013] [Indexed: 02/08/2023]
Abstract
During past decades, ever-increasing life expectancy, despite the development of a sedentary lifestyle and altered eating habits, has led to a dramatic parallel increase in the prevalence of age-related diseases such as type 2 diabetes mellitus (T2DM) and neurodegenerative disorders. Converging evidence from animal and human studies has indicated that insulin resistance in the central nervous system (CNS) is observed in both T2DM and neurodegenerative disorders such as Alzheimer's disease (AD), leading to the hypothesis that impaired neuronal insulin action might be a unifying pathomechanism in the development of both diseases. This assumption, however, is in striking contrast to the evolutionary conserved, protective role of impaired insulin/insulin-like growth factor 1 signaling (IIS) in aging and in protein aggregation-associated diseases, such as AD. Thus, this review summarizes our current understanding of the physiological role of insulin action in various regions of the CNS to regulate neuronal function, learning, and memory, and to control peripheral metabolism. We also discuss mechanisms and clinical outcomes of neuronal insulin resistance and address the seeming paradox of how impaired neuronal IIS can protect from the development of neurodegenerative disorders.
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Affiliation(s)
- Sophie M Steculorum
- Department of Mouse Genetics and Metabolism, Institute for Genetics, University of Cologne, Köln, Germany; Center for Endocrinology, Diabetes and Preventive Medicine, University Hospital Cologne, Köln, Germany; Center for Molecular Medicine Cologne, Köln, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Ageing Associated Diseases, Köln, Germany; Max-Planck-Institute for Neurological Research, Köln, Germany
| | - Maite Solas
- Department of Mouse Genetics and Metabolism, Institute for Genetics, University of Cologne, Köln, Germany; Center for Endocrinology, Diabetes and Preventive Medicine, University Hospital Cologne, Köln, Germany; Center for Molecular Medicine Cologne, Köln, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Ageing Associated Diseases, Köln, Germany; Max-Planck-Institute for Neurological Research, Köln, Germany
| | - Jens C Brüning
- Department of Mouse Genetics and Metabolism, Institute for Genetics, University of Cologne, Köln, Germany; Center for Endocrinology, Diabetes and Preventive Medicine, University Hospital Cologne, Köln, Germany; Center for Molecular Medicine Cologne, Köln, Germany; Cologne Excellence Cluster on Cellular Stress Responses in Ageing Associated Diseases, Köln, Germany; Max-Planck-Institute for Neurological Research, Köln, Germany.
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Abraham MA, Filippi BM, Kang GM, Kim MS, Lam TKT. Insulin action in the hypothalamus and dorsal vagal complex. Exp Physiol 2014; 99:1104-9. [DOI: 10.1113/expphysiol.2014.079962] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Mona A. Abraham
- Toronto General Research Institute and Department of Medicine; University Health Network; Toronto Ontario Canada
- Department of Physiology; University of Toronto; Toronto Ontario Canada
| | - Beatrice M. Filippi
- Toronto General Research Institute and Department of Medicine; University Health Network; Toronto Ontario Canada
| | - Gil Myoung Kang
- Asan Medical Center; University of Ulsan College of Medicine; Seoul Republic of Korea
| | - Min-Seon Kim
- Asan Medical Center; University of Ulsan College of Medicine; Seoul Republic of Korea
| | - Tony K. T. Lam
- Toronto General Research Institute and Department of Medicine; University Health Network; Toronto Ontario Canada
- Department of Physiology; University of Toronto; Toronto Ontario Canada
- Asan Medical Center; University of Ulsan College of Medicine; Seoul Republic of Korea
- Department of Medicine; University of Toronto; Toronto Ontario Canada
- Banting and Best Diabetes Centre; University of Toronto; Toronto Ontario Canada
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Sliwowska JH, Fergani C, Gawałek M, Skowronska B, Fichna P, Lehman MN. Insulin: its role in the central control of reproduction. Physiol Behav 2014; 133:197-206. [PMID: 24874777 DOI: 10.1016/j.physbeh.2014.05.021] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 05/13/2014] [Accepted: 05/19/2014] [Indexed: 12/11/2022]
Abstract
Insulin has long been recognized as a key regulator of energy homeostasis via its actions at the level of the brain, but in addition, plays a role in regulating neural control of reproduction. In this review, we consider and compare evidence from animal models demonstrating a role for insulin for physiological control of reproduction by effects on GnRH/LH secretion. We also review the role that insulin plays in prenatal programming of adult reproduction, and consider specific candidate neurons in the adult hypothalamus by which insulin may act to regulate reproductive function. Finally, we review clinical evidence of the role that insulin may play in adult human fertility and reproductive disorders. Overall, while insulin appears to have a significant impact on reproductive neuroendocrine function, there are many unanswered questions regarding its precise sites and mechanisms of action, and their impact on developing and adult reproductive neuroendocrine function.
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Affiliation(s)
- Joanna H Sliwowska
- Laboratory of Neurobiology, Institute of Zoology, Poznan University of Life Sciences, ul. Wojska Polskiego 71 C, 60-625 Poznan, Poland.
| | - Chrysanthi Fergani
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, MS 39232, USA.
| | - Monika Gawałek
- Laboratory of Neurobiology, Institute of Zoology, Poznan University of Life Sciences, ul. Wojska Polskiego 71 C, 60-625 Poznan, Poland.
| | - Bogda Skowronska
- Department of Pediatric Diabetes and Obesity, Poznan University of Medical Sciences, Szpitalna Str. 27/33, 60-572 Poznan, Poland.
| | - Piotr Fichna
- Department of Pediatric Diabetes and Obesity, Poznan University of Medical Sciences, Szpitalna Str. 27/33, 60-572 Poznan, Poland.
| | - Michael N Lehman
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, MS 39232, USA.
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Jensen VFH, Bøgh IB, Lykkesfeldt J. Effect of insulin-induced hypoglycaemia on the central nervous system: evidence from experimental studies. J Neuroendocrinol 2014; 26:123-50. [PMID: 24428753 DOI: 10.1111/jne.12133] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 12/13/2013] [Accepted: 01/08/2014] [Indexed: 12/12/2022]
Abstract
Insulin-induced hypoglycaemia (IIH) is a major acute complication in type 1 as well as in type 2 diabetes, particularly during intensive insulin therapy. The brain plays a central role in the counter-regulatory response by eliciting parasympathetic and sympathetic hormone responses to restore normoglycaemia. Brain glucose concentrations, being approximately 15-20% of the blood glucose concentration in humans, are rigorously maintained during hypoglycaemia through adaptions such as increased cerebral glucose transport, decreased cerebral glucose utilisation and, possibly, by using central nervous system glycogen as a glucose reserve. However, during sustained hypoglycaemia, the brain cannot maintain a sufficient glucose influx and, as the cerebral hypoglycaemia becomes severe, electroencephalogram changes, oxidative stress and regional neuronal death ensues. With particular focus on evidence from experimental studies on nondiabetic IIH, this review outlines the central mechanisms behind the counter-regulatory response to IIH, as well as cerebral adaption to avoid sequelae of cerebral neuroglycopaenia, including seizures and coma.
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Affiliation(s)
- V F H Jensen
- Department of Veterinary Disease Biology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Department of Diabetes Toxicology and Safety Pharmacology, Novo Nordisk A/S, Maaloev, Denmark
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Cragle FK, Baldini G. Mild lipid stress induces profound loss of MC4R protein abundance and function. Mol Endocrinol 2014; 28:357-67. [PMID: 24506538 DOI: 10.1210/me.2013-1357] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Food intake is controlled at the central level by the melanocortin pathway in which the agonist α-MSH binds to melanocortin 4 receptor (MC4R), a Gs-coupled G protein-coupled receptor expressed by neurons in the paraventricular nuclei of the hypothalamus, which signals to reduce appetite. Consumption of a high-fat diet induces hypothalamic accumulation of palmitate, endoplasmic reticulum (ER) stress, apoptosis, and unresponsiveness to prolonged treatment with MC4R agonists. Here we have modeled effects of lipid stress on MC4R by using mHypoE-42 immortalized hypothalamic neurons expressing endogenous MC4R and Neuro2A cells expressing a tagged MC4R reporter, HA-MC4R-GFP. In the hypothalamic neurons, exposure to elevated palmitate in the physiological range induced splicing of X-box binding protein 1, but it did not activate C/EBP-homologous protein or induce increased levels of cleaved caspase-3, indicating mild ER stress. Such mild ER stress coexisted with a minimal loss of MC4R mRNA and yet a profound loss of cAMP signaling in response to incubation with the agonist. These findings were mirrored in the Neuro2A cells expressing HA-MC4R-GFP, in which protein abundance of the tagged receptor was decreased, whereas the activity per receptor number was maintained. The loss of cAMP signaling in response to α-MSH by elevated palmitate was corrected by treatment with a chemical chaperone, 4-phenylbutyrate in both mHypoE-42 hypothalamic neurons and in Neuro2A cells in which protein abundance of HA-MC4R-GFP was increased. The data indicate that posttranscriptional decrease of MC4R protein contribute to lower the response to α-MSH in hypothalamic neurons exposed to even a mild level of lipid stress and that a chemical chaperone corrects such a defect.
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Affiliation(s)
- Faith K Cragle
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205
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Song Z, Levin BE, Stevens W, Sladek CD. Supraoptic oxytocin and vasopressin neurons function as glucose and metabolic sensors. Am J Physiol Regul Integr Comp Physiol 2014; 306:R447-56. [PMID: 24477542 DOI: 10.1152/ajpregu.00520.2013] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Neurons in the supraoptic nuclei (SON) produce oxytocin and vasopressin and express insulin receptors (InsR) and glucokinase. Since oxytocin is an anorexigenic agent and glucokinase and InsR are hallmarks of cells that function as glucose and/or metabolic sensors, we evaluated the effect of glucose, insulin, and their downstream effector ATP-sensitive potassium (KATP) channels on calcium signaling in SON neurons and on oxytocin and vasopressin release from explants of the rat hypothalamo-neurohypophyseal system. We also evaluated the effect of blocking glucokinase and phosphatidylinositol 3 kinase (PI3K; mediates insulin-induced mobilization of glucose transporter, GLUT4) on responses to glucose and insulin. Glucose and insulin increased intracellular calcium ([Ca(2+)]i). The responses were glucokinase and PI3K dependent, respectively. Insulin and glucose alone increased vasopressin release (P < 0.002). Oxytocin release was increased by glucose in the presence of insulin. The oxytocin (OT) and vasopressin (VP) responses to insulin+glucose were blocked by the glucokinase inhibitor alloxan (4 mM; P ≤ 0.002) and the PI3K inhibitor wortmannin (50 nM; OT: P = 0.03; VP: P ≤ 0.002). Inactivating K ATP channels with 200 nM glibenclamide increased oxytocin and vasopressin release (OT: P < 0.003; VP: P < 0.05). These results suggest that insulin activation of PI3K increases glucokinase-mediated ATP production inducing closure of K ATP channels, opening of voltage-sensitive calcium channels, and stimulation of oxytocin and vasopressin release. The findings are consistent with SON oxytocin and vasopressin neurons functioning as glucose and "metabolic" sensors to participate in appetite regulation.
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Affiliation(s)
- Zhilin Song
- Department of Physiology, University of Colorado School of Medicine, Aurora, Colorado
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Ross MG, Desai M. Developmental Programming of Appetite/Satiety. ANNALS OF NUTRITION AND METABOLISM 2014; 64 Suppl 1:36-44. [DOI: 10.1159/000360508] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Rangel A. Regulation of dietary choice by the decision-making circuitry. Nat Neurosci 2013; 16:1717-24. [PMID: 24270272 DOI: 10.1038/nn.3561] [Citation(s) in RCA: 148] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2013] [Accepted: 10/01/2013] [Indexed: 12/11/2022]
Abstract
To advance our understanding of how the brain makes food decisions, it is essential to combine knowledge from two fields that have not yet been well integrated: the neuro-computational basis of decision-making and the homeostatic regulators of feeding. This Review integrates these two literatures from a neuro-computational perspective, with an emphasis in describing the variables computed by different neural systems and how they affect dietary choice. We highlight what is unique about feeding decisions, the mechanisms through which metabolic and endocrine factors affect the decision-making circuitry, why making healthy food choices is difficult for many people, and key processes at work in the obesity epidemic.
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Affiliation(s)
- Antonio Rangel
- 1] Humanities and Social Sciences, Caltech, Pasadena, California, USA. [2] Computational and Neural Systems, Caltech, Pasadena, California, USA
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McCully BH, Hasan W, Streiff CT, Houle JC, Woodward WR, Giraud GD, Brooks VL, Habecker BA. Sympathetic cardiac hyperinnervation and atrial autonomic imbalance in diet-induced obesity promote cardiac arrhythmias. Am J Physiol Heart Circ Physiol 2013; 305:H1530-7. [PMID: 24014675 DOI: 10.1152/ajpheart.00196.2013] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Obesity increases the risk of arrhythmias and sudden cardiac death, but the mechanisms are unknown. This study tested the hypothesis that obesity-induced cardiac sympathetic outgrowth and hyperinnervation promotes the development of arrhythmic events. Male Sprague-Dawley rats (250-275 g), fed a high-fat diet (33% kcal/fat), diverged into obesity-resistant (OR) and obesity-prone (OP) groups and were compared with rats fed normal chow (13% kcal/fat; CON). In vitro experiments showed that both OR and OP rats exhibited hyperinnervation of the heart and high sympathetic outgrowth compared with CON rats, even though OR rats are not obese. Despite the hyperinnervation and outgrowth, we showed that, in vivo, OR rats were less susceptible to arrhythmic events after an intravenous epinephrine challenge compared with OP rats. On examining total and stimulus-evoked neurotransmitter levels in an ex vivo system, we demonstrate that atrial acetylcholine content and release were attenuated in OP compared with OR and CON groups. OP rats also expressed elevated atrial norepinephrine content, while norepinephrine release was suppressed. These findings suggest that the consumption of a high-fat diet, even in the absence of overt obesity, stimulates sympathetic outgrowth and hyperinnervation of the heart. However, normalized cardiac parasympathetic nervous system control may protect the heart from arrhythmic events.
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Affiliation(s)
- Belinda H McCully
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, Oregon; and
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Cottone P, Sabino V, Nagy TR, Coscina DV, Levin BE, Zorrilla EP. Centrally administered urocortin 2 decreases gorging on high-fat diet in both diet-induced obesity-prone and -resistant rats. Int J Obes (Lond) 2013; 37:1515-23. [PMID: 23478425 PMCID: PMC3706508 DOI: 10.1038/ijo.2013.22] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2012] [Revised: 01/03/2013] [Accepted: 01/27/2013] [Indexed: 01/01/2023]
Abstract
Objective Obesity is a costly, deadly public health problem for which new treatments are needed. Individual differences in meal pattern have been proposed to play a role in obesity risk. The present study tested the hypothesis that i) the microstructure of chronic high-fat diet intake differs between genetically selected Diet-Induced Obesity (DIO) and Diet Resistant (DR) rats, and ii) central administration of urocortin 2 (Ucn 2), a corticotropin-releasing factor type 2 (CRF2) agonist, decreases high-fat diet intake not only in lean DR rats, but also in obese DIO rats. Design Male, selectively bred DIO and DR rats (n=10/genotype) were chronically fed a high-fat diet. Food and water intake as well as ingestion microstructure were then compared under baseline conditions and following third intracerebroventricular injection of Ucn 2 (0, 0.1, 0.3, 1, 3 µg). Results Irrespective of genotype, Ucn 2 reduced nocturnal food intake with a minimum effective dose of 0.3 µg, suppressing high-fat diet intake by ~40% at the 3 µg dose. Ucn 2 also made rats of both genotypes eat smaller and briefer meals, including at doses that did not reduce drinking. Obese DIO rats ate fewer but larger meals than DR rats, which they ate more quickly and consumed with 2/3rd less water. Conclusions Unlike leptin and insulin, Ucn 2 retains its full central anorectic efficacy to reduce high-fat diet intake even in obese, genetically-prone DIO rats, which otherwise show a “gorging” meal pattern. These results open new opportunities of investigation towards treating some forms of diet-induced obesity.
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Affiliation(s)
- P Cottone
- 1] Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, La Jolla, CA, USA [2] Laboratory of Addictive Disorders, Departments of Pharmacology and Psychiatry, Boston University School of Medicine, Boston, MA, USA [3] Harold L. Dorris Neurological Research Institute, The Scripps Research Institute, La Jolla, CA, USA
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Begg DP, Mul JD, Liu M, Reedy BM, D'Alessio DA, Seeley RJ, Woods SC. Reversal of diet-induced obesity increases insulin transport into cerebrospinal fluid and restores sensitivity to the anorexic action of central insulin in male rats. Endocrinology 2013; 154:1047-54. [PMID: 23337529 PMCID: PMC3578991 DOI: 10.1210/en.2012-1929] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Diet-induced obesity (DIO) reduces the ability of centrally administered insulin to reduce feeding behavior and also reduces the transport of insulin from the periphery to the central nervous system (CNS). The current study was designed to determine whether reversal of high-fat DIO restores the anorexic efficacy of central insulin and whether this is accompanied by restoration of the compromised insulin transport. Adult male Long-Evans rats were initially maintained on either a low-fat chow diet (LFD) or a high-fat diet (HFD). After 22 weeks, half of the animals on the HFD were changed to the LFD, whereas the other half continued on the HFD for an additional 8 weeks, such that there were 3 groups: 1) a LFD control group (Con; n = 18), 2) a HFD-fed, DIO group (n = 17), and 3) a HFD to LFD, DIO-reversal group (DIO-rev; n = 18). The DIO reversal resulted in a significant reduction of body weight and epididymal fat weight relative to the DIO group. Acute central insulin administration (8 mU) reduced food intake and caused weight loss in Con and DIO-rev but not DIO rats. Fasting cerebrospinal fluid insulin was higher in DIO than Con animals. However, after a peripheral bolus injection of insulin, cerebrospinal fluid insulin increased in Con and DIO-rev rats but not in the DIO group. These data provide support for previous reports that DIO inhibits both the central effects of insulin and insulin's transport to the CNS. Importantly, DIO-rev restored sensitivity to the effects of central insulin on food intake and insulin transport into the CNS.
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Affiliation(s)
- Denovan P Begg
- Departments of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, OH 45237, USA.
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Begg DP, Woods SC. Interactions between the central nervous system and pancreatic islet secretions: a historical perspective. ADVANCES IN PHYSIOLOGY EDUCATION 2013; 37:53-60. [PMID: 23471249 PMCID: PMC3776474 DOI: 10.1152/advan.00167.2012] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 01/14/2013] [Indexed: 05/10/2023]
Abstract
The endocrine pancreas is richly innervated with sympathetic and parasympathetic projections from the brain. In the mid-20th century, it was established that α-adrenergic activation inhibits, whereas cholinergic stimulation promotes, insulin secretion; this demonstrated the importance of the sympathetic and parasympathetic systems in pancreatic endocrine function. It was later established that insulin injected peripherally could act within the brain, leading to the discovery of insulin and insulin receptors within the brain and the receptor-mediated transport of insulin into the central nervous system from endothelial cells. The insulin receptor within the central nervous system is widely distributed, reflecting insulin's diverse range of actions, including acting as an adiposity signal to reduce food intake and increase energy expenditure, regulation of systemic glucose responses, altering sympathetic activity, and involvement in cognitive function. As observed with central insulin administration, the pancreatic hormones glucagon, somatostatin, pancreatic polypeptide, and amylin can each also reduce food intake. Pancreatic and also gut hormones are released cephalically, in what is an important mechanism to prepare the body for a meal and prevent excessive postprandial hyperglycemia.
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Affiliation(s)
- Denovan P Begg
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati, Cincinnati, OH 45237, USA
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Grayson BE, Seeley RJ, Sandoval DA. Wired on sugar: the role of the CNS in the regulation of glucose homeostasis. Nat Rev Neurosci 2013; 14:24-37. [PMID: 23232606 PMCID: PMC4231433 DOI: 10.1038/nrn3409] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Obesity and type 2 diabetes mellitus (T2DM)--disorders of energy homeostasis and glucose homeostasis, respectively--are tightly linked and the incidences of both conditions are increasing in parallel. The CNS integrates information regarding peripheral nutrient and hormonal changes and processes this information to regulate energy homeostasis. Recent findings indicate that some of the neural circuits and mechanisms underlying energy balance are also essential for the regulation of glucose homeostasis. We propose that disruption of these overlapping pathways links the metabolic disturbances associated with obesity and T2DM. A better understanding of these converging mechanisms may lead to therapeutic strategies that target both T2DM and obesity.
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Affiliation(s)
- Bernadette E Grayson
- Metabolic Diseases Institute, University of Cincinnati, Cincinnati, Ohio 45237, USA
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Aimé P, Hegoburu C, Jaillard T, Degletagne C, Garcia S, Messaoudi B, Thevenet M, Lorsignol A, Duchamp C, Mouly AM, Julliard AK. A physiological increase of insulin in the olfactory bulb decreases detection of a learned aversive odor and abolishes food odor-induced sniffing behavior in rats. PLoS One 2012; 7:e51227. [PMID: 23251461 PMCID: PMC3522659 DOI: 10.1371/journal.pone.0051227] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 10/30/2012] [Indexed: 11/19/2022] Open
Abstract
Insulin is involved in multiple regulatory mechanisms, including body weight and food intake, and plays a critical role in metabolic disorders such as obesity and diabetes. An increasing body of evidence indicates that insulin is also involved in the modulation of olfactory function. The olfactory bulb (OB) contains the highest level of insulin and insulin receptors (IRs) in the brain. However, a role for insulin in odor detection and sniffing behavior remains to be elucidated. Using a behavioral paradigm based on conditioned olfactory aversion (COA) to isoamyl-acetate odor, we demonstrated that an intracerebroventricular (ICV) injection of 14 mU insulin acutely decreased olfactory detection of fasted rats to the level observed in satiated animals. In addition, whereas fasted animals demonstrated an increase in respiratory frequency upon food odor detection, this effect was absent in fasted animals receiving a 14 mU insulin ICV injection as well as in satiated animals. In parallel, we showed that the OB and plasma insulin levels were increased in satiated rats compared to fasted rats, and that a 14 mU insulin ICV injection elevated the OB insulin level of fasted rats to that of satiated rats. We further quantified insulin receptors (IRs) distribution and showed that IRs are preferentially expressed in the caudal and lateral parts of the main OB, with the highest labeling found in the mitral cells, the main OB projection neurons. Together, these data suggest that insulin acts on the OB network to modulate olfactory processing and demonstrate that olfactory function is under the control of signals involved in energy homeostasis regulation and feeding behaviors.
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Affiliation(s)
- Pascaline Aimé
- Centre de Recherche en Neurosciences de Lyon (CRNL), Team Olfaction: From Coding to Memory, CNRS UMR 5292 - INSERM U1028- Université Lyon1 - Université de Lyon, Lyon, France
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, New York, United States of America
| | - Chloé Hegoburu
- Centre de Recherche en Neurosciences de Lyon (CRNL), Team Olfaction: From Coding to Memory, CNRS UMR 5292 - INSERM U1028- Université Lyon1 - Université de Lyon, Lyon, France
| | - Tristan Jaillard
- Métabolisme Plasticité Mitochondrie, CNRS UMR 5241 - Université Paul Sabatier, Toulouse, France
- STROMALab, CNRS UMR 5273 - EFS - INSERM U1031- Université Paul Sabatier, Toulouse, France
| | - Cyril Degletagne
- Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés (LEHNA), CNRS UMR 5023 - Université Lyon 1 – Université de Lyon, Villeurbanne, France
| | - Samuel Garcia
- Centre de Recherche en Neurosciences de Lyon (CRNL), Team Olfaction: From Coding to Memory, CNRS UMR 5292 - INSERM U1028- Université Lyon1 - Université de Lyon, Lyon, France
| | - Belkacem Messaoudi
- Centre de Recherche en Neurosciences de Lyon (CRNL), Team Olfaction: From Coding to Memory, CNRS UMR 5292 - INSERM U1028- Université Lyon1 - Université de Lyon, Lyon, France
| | - Marc Thevenet
- Centre de Recherche en Neurosciences de Lyon (CRNL), Team Olfaction: From Coding to Memory, CNRS UMR 5292 - INSERM U1028- Université Lyon1 - Université de Lyon, Lyon, France
| | - Anne Lorsignol
- Métabolisme Plasticité Mitochondrie, CNRS UMR 5241 - Université Paul Sabatier, Toulouse, France
- STROMALab, CNRS UMR 5273 - EFS - INSERM U1031- Université Paul Sabatier, Toulouse, France
| | - Claude Duchamp
- Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés (LEHNA), CNRS UMR 5023 - Université Lyon 1 – Université de Lyon, Villeurbanne, France
| | - Anne-Marie Mouly
- Centre de Recherche en Neurosciences de Lyon (CRNL), Team Olfaction: From Coding to Memory, CNRS UMR 5292 - INSERM U1028- Université Lyon1 - Université de Lyon, Lyon, France
| | - Andrée Karyn Julliard
- Centre de Recherche en Neurosciences de Lyon (CRNL), Team Olfaction: From Coding to Memory, CNRS UMR 5292 - INSERM U1028- Université Lyon1 - Université de Lyon, Lyon, France
- * E-mail:
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Moy GA, McNay EC. Caffeine prevents weight gain and cognitive impairment caused by a high-fat diet while elevating hippocampal BDNF. Physiol Behav 2012; 109:69-74. [PMID: 23220362 DOI: 10.1016/j.physbeh.2012.11.008] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Revised: 11/14/2012] [Accepted: 11/28/2012] [Indexed: 01/21/2023]
Abstract
Obesity, high-fat diets, and subsequent type 2 diabetes (T2DM) are associated with cognitive impairment. Moreover, T2DM increases the risk of Alzheimer's disease (AD) and leads to abnormal elevation of brain beta-amyloid levels, one of the hallmarks of AD. The psychoactive alkaloid caffeine has been shown to have therapeutic potential in AD but the central impact of caffeine has not been well-studied in the context of a high-fat diet. Here we investigated the impact of caffeine administration on metabolism and cognitive performance, both in control rats and in rats placed on a high-fat diet. The effects of caffeine were significant: caffeine both (i) prevented the weight-gain associated with the high-fat diet and (ii) prevented cognitive impairment. Caffeine did not alter hippocampal metabolism or insulin signaling, likely because the high-fat-fed animals did not develop full-blown diabetes; however, caffeine did prevent or reverse a decrease in hippocampal brain-derived neurotrophic factor (BDNF) seen in high-fat-fed animals. These data confirm that caffeine may serve as a neuroprotective agent against cognitive impairment caused by obesity and/or a high-fat diet. Increased hippocampal BDNF following caffeine administration could explain, at least in part, the effects of caffeine on cognition and metabolism.
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Diet-induced obesity: dopamine transporter function, impulsivity and motivation. Int J Obes (Lond) 2012; 37:1095-103. [PMID: 23164701 DOI: 10.1038/ijo.2012.178] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2012] [Revised: 09/26/2012] [Accepted: 10/06/2012] [Indexed: 12/28/2022]
Abstract
OBJECTIVE A rat model of diet-induced obesity (DIO) was used to determine dopamine transporter (DAT) function, impulsivity and motivation as neurobehavioral outcomes and predictors of obesity. DESIGN To evaluate neurobehavioral alterations following the development of DIO induced by an 8-week high-fat diet (HF) exposure, striatal D2-receptor density, DAT function and expression, extracellular dopamine concentrations, impulsivity, and motivation for high- and low-fat reinforcers were determined. To determine predictors of DIO, neurobehavioral antecedents including impulsivity, motivation for high-fat reinforcers, DAT function and extracellular dopamine were evaluated before the 8-week HF exposure. METHODS Striatal D2-receptor density was determined by in vitro kinetic analysis of [(3)H]raclopride binding. DAT function was determined using in vitro kinetic analysis of [(3)H]dopamine uptake, methamphetamine-evoked [(3)H]dopamine overflow and no-net flux in vivo microdialysis. DAT cell-surface expression was determined using biotinylation and western blotting. Impulsivity and food-motivated behavior were determined using a delay discounting task and progressive ratio schedule, respectively. RESULTS Relative to obesity-resistant (OR) rats, obesity-prone (OP) rats exhibited 18% greater body weight following an 8-week HF-diet exposure, 42% lower striatal D2-receptor density, 30% lower total DAT expression, 40% lower in vitro and in vivo DAT function, 45% greater extracellular dopamine and twofold greater methamphetamine-evoked [(3)H]dopamine overflow. OP rats exhibited higher motivation for food, and surprisingly, were less impulsive relative to OR rats. Impulsivity, in vivo DAT function and extracellular dopamine concentration did not predict DIO. Importantly, motivation for high-fat reinforcers predicted the development of DIO. CONCLUSION Human studies are limited by their ability to determine if impulsivity, motivation and DAT function are causes or consequences of DIO. The current animal model shows that motivation for high-fat food, but not impulsive behavior, predicts the development of obesity, whereas decreases in striatal DAT function are exhibited only after the development of obesity.
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Banks WA, Owen JB, Erickson MA. Insulin in the brain: there and back again. Pharmacol Ther 2012; 136:82-93. [PMID: 22820012 PMCID: PMC4134675 DOI: 10.1016/j.pharmthera.2012.07.006] [Citation(s) in RCA: 395] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 07/03/2012] [Indexed: 12/12/2022]
Abstract
Insulin performs unique functions within the CNS. Produced nearly exclusively by the pancreas, insulin crosses the blood-brain barrier (BBB) using a saturable transporter, affecting feeding and cognition through CNS mechanisms largely independent of glucose utilization. Whereas peripheral insulin acts primarily as a metabolic regulatory hormone, CNS insulin has an array of effects on brain that may more closely resemble the actions of the ancestral insulin molecule. Brain endothelial cells (BECs), the cells that form the vascular BBB and contain the transporter that translocates insulin from blood to brain, are themselves regulated by insulin. The insulin transporter is altered by physiological and pathological factors including hyperglycemia and the diabetic state. The latter can lead to BBB disruption. Pericytes, pluripotent cells in intimate contact with the BECs, protect the integrity of the BBB and its ability to transport insulin. Most of insulin's known actions within the CNS are mediated through two canonical pathways, the phosphoinositide-3 kinase (PI3)/Akt and Ras/mitogen activated kinase (MAPK) cascades. Resistance to insulin action within the CNS, sometimes referred to as diabetes mellitus type III, is associated with peripheral insulin resistance, but it is possible that variable hormonal resistance syndromes exist so that resistance at one tissue bed may be independent of that at others. CNS insulin resistance is associated with Alzheimer's disease, depression, and impaired baroreceptor gain in pregnancy. These aspects of CNS insulin action and the control of its entry by the BBB are likely only a small part of the story of insulin within the brain.
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Affiliation(s)
- William A Banks
- Geriatrics Research Education and Clinical Center, Veterans Affairs Puget Sound Health Care Center, Seattle, WA, USA.
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Cerf ME, Chapman CS, Louw J. High-fat programming of hyperglycemia, hyperinsulinemia, insulin resistance, hyperleptinemia, and altered islet architecture in 3-month-old wistar rats. ISRN ENDOCRINOLOGY 2012; 2012:627270. [PMID: 22988521 PMCID: PMC3440883 DOI: 10.5402/2012/627270] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Accepted: 07/10/2012] [Indexed: 12/31/2022]
Abstract
High-fat programming, by exposure to a high-saturated-fat diet in utero and/or during lactation, compromises beta-cell development and function in neonatal and weanling offspring. Therefore, high-fat programming effects were investigated on metabolism and islet architecture in young adult rats. Three-month-old male and female Wistar rat offspring were studied: HFG (maintained on a high-fat diet throughout fetal life), HFP (high-fat diet maintenance from birth to 3 months), and HFGP (high-fat diet maintenance throughout fetal and postnatal life). Control rats were maintained on a standard laboratory diet. Pancreata were double immunolabeled for insulin and glucagon to assess islet morphology and with Ki-67 to determine islet and acinar cell proliferation. HFP and HFGP males were heavier, hyperleptinemic, and hyperinsulinemic. Hyperglycemia presented in HFP males, HFP females, and HFGP males. HFGP males and HFP females were insulin resistant. HFP males displayed beta- and alpha-cell hyperplasia with alpha-cell hypertrophy evident in HFP females. Acinar cell proliferation rates were increased in HFP males. Postnatal high-fat programming induced the most diabetogenic phenotype with high-fat maintenance throughout fetal and postnatal life resulting in a severely obese phenotype. Fetal and postnatal nutrition shapes offspring health outcomes.
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Affiliation(s)
- Marlon E Cerf
- Diabetes Discovery Platform, South African Medical Research Council, P.O. Box 7505, Tygerberg, Cape Town 7505, South Africa
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