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Fredriksson R, Hägglund M, Olszewski PK, Stephansson O, Jacobsson JA, Olszewska AM, Levine AS, Lindblom J, Schiöth HB. The obesity gene, FTO, is of ancient origin, up-regulated during food deprivation and expressed in neurons of feeding-related nuclei of the brain. Endocrinology 2008; 149:2062-71. [PMID: 18218688 DOI: 10.1210/en.2007-1457] [Citation(s) in RCA: 254] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Gene variants of the FTO (fatso) gene have recently been strongly associated with body mass index and obesity. The FTO gene is well conserved and found in a single copy in vertebrate species including fish and chicken, suggesting that the ancestor of this gene was present 450 million years ago. Surprisingly, the FTO gene is present in two species of algae but not in any other invertebrate species. This could indicate that this gene has undergone a horizontal gene transfer. Quantitative real-time PCR showed that the gene is expressed in many peripheral and central rat tissues. Detailed in situ hybridization analysis in the mouse brain showed abundant expression in feeding-related nuclei of the brainstem and hypothalamus, such as the nucleus of the solitary tract, area postrema, and arcuate, paraventricular, and supraoptic nuclei as well as in the bed nucleus of the stria terminalis. Colabeling showed that the FTO gene is predominantly expressed in neurons, whereas it was virtually not found in astrocytes or glia cells. The FTO was significantly up-regulated (41%) in the hypothalamus of rats after 48-h food deprivation. We also found a strong negative correlation of the FTO expression level with the expression of orexigenic galanin-like peptide, which is mainly synthesized in the arcuate nucleus. These results are consistent with the hypothesis that FTO could participate in the central control of energy homeostasis.
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Thompson DJ, Genovese G, Halvardson J, Ulirsch JC, Wright DJ, Terao C, Davidsson OB, Day FR, Sulem P, Jiang Y, Danielsson M, Davies H, Dennis J, Dunlop MG, Easton DF, Fisher VA, Zink F, Houlston RS, Ingelsson M, Kar S, Kerrison ND, Kinnersley B, Kristjansson RP, Law PJ, Li R, Loveday C, Mattisson J, McCarroll SA, Murakami Y, Murray A, Olszewski P, Rychlicka-Buniowska E, Scott RA, Thorsteinsdottir U, Tomlinson I, Moghadam BT, Turnbull C, Wareham NJ, Gudbjartsson DF, Kamatani Y, Hoffmann ER, Jackson SP, Stefansson K, Auton A, Ong KK, Machiela MJ, Loh PR, Dumanski JP, Chanock SJ, Forsberg LA, Perry JRB. Genetic predisposition to mosaic Y chromosome loss in blood. Nature 2019; 575:652-657. [PMID: 31748747 PMCID: PMC6887549 DOI: 10.1038/s41586-019-1765-3] [Citation(s) in RCA: 211] [Impact Index Per Article: 35.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 10/04/2019] [Indexed: 12/13/2022]
Abstract
Mosaic loss of chromosome Y (LOY) in circulating white blood cells is the most common form of clonal mosaicism1-5, yet our knowledge of the causes and consequences of this is limited. Here, using a computational approach, we estimate that 20% of the male population represented in the UK Biobank study (n = 205,011) has detectable LOY. We identify 156 autosomal genetic determinants of LOY, which we replicate in 757,114 men of European and Japanese ancestry. These loci highlight genes that are involved in cell-cycle regulation and cancer susceptibility, as well as somatic drivers of tumour growth and targets of cancer therapy. We demonstrate that genetic susceptibility to LOY is associated with non-haematological effects on health in both men and women, which supports the hypothesis that clonal haematopoiesis is a biomarker of genomic instability in other tissues. Single-cell RNA sequencing identifies dysregulated expression of autosomal genes in leukocytes with LOY and provides insights into why clonal expansion of these cells may occur. Collectively, these data highlight the value of studying clonal mosaicism to uncover fundamental mechanisms that underlie cancer and other ageing-related diseases.
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research-article |
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Klyucherev TO, Olszewski P, Shalimova AA, Chubarev VN, Tarasov VV, Attwood MM, Syvänen S, Schiöth HB. Advances in the development of new biomarkers for Alzheimer's disease. Transl Neurodegener 2022; 11:25. [PMID: 35449079 PMCID: PMC9027827 DOI: 10.1186/s40035-022-00296-z] [Citation(s) in RCA: 114] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 03/28/2022] [Indexed: 12/16/2022] Open
Abstract
Alzheimer's disease (AD) is a complex, heterogeneous, progressive disease and is the most common type of neurodegenerative dementia. The prevalence of AD is expected to increase as the population ages, placing an additional burden on national healthcare systems. There is a large need for new diagnostic tests that can detect AD at an early stage with high specificity at relatively low cost. The development of modern analytical diagnostic tools has made it possible to determine several biomarkers of AD with high specificity, including pathogenic proteins, markers of synaptic dysfunction, and markers of inflammation in the blood. There is a considerable potential in using microRNA (miRNA) as markers of AD, and diagnostic studies based on miRNA panels suggest that AD could potentially be determined with high accuracy for individual patients. Studies of the retina with improved methods of visualization of the fundus are also showing promising results for the potential diagnosis of the disease. This review focuses on the recent developments of blood, plasma, and ocular biomarkers for the diagnosis of AD.
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Review |
3 |
114 |
4
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Olszewski PK, Li D, Grace MK, Billington CJ, Kotz CM, Levine AS. Neural basis of orexigenic effects of ghrelin acting within lateral hypothalamus. Peptides 2003; 24:597-602. [PMID: 12860204 DOI: 10.1016/s0196-9781(03)00105-0] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ghrelin stimulates feeding when administered centrally and peripherally. The lateral hypothalamus (LH) is thought to mediate ghrelin-induced hyperphagia. Thus, we examined central mechanisms underlying feeding generated by LH ghrelin. We determined that 0.3nmol of LH-injected ghrelin was the lowest dose increasing food consumption and it induced Fos immunoreactivity (IR; a marker of neuronal activation) in feeding-related brain areas, including the hypothalamic paraventricular, arcuate, and dorsomedial nuclei, amygdala, and nucleus of the solitary tract. Also, LH ghrelin induced Fos IR in LH orexin neurons. We conclude that the LH, as part of larger central circuitry, integrates orexigenic properties of ghrelin.
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22 |
102 |
5
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Olszewski PK, Grace MK, Billington CJ, Levine AS. Hypothalamic paraventricular injections of ghrelin: effect on feeding and c-Fos immunoreactivity. Peptides 2003; 24:919-23. [PMID: 12948845 DOI: 10.1016/s0196-9781(03)00159-1] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The paraventricular hypothalamic nucleus (PVN) appears to integrate orexigenic properties of a novel peptide, ghrelin. Thus, we examined central mechanisms underlying feeding generated by intra-PVN ghrelin. We established that 0.03 nmol of PVN-injected ghrelin was the lowest dose increasing food consumption and it induced c-Fos immunoreactivity (a marker of neuronal activation) in the PVN itself, as well as in other feeding-related brain areas, including the hypothalamic arcuate and dorsomedial nuclei, central nucleus of the amygdala, and nucleus of the solitary tract. We conclude that the PVN, as part of larger central circuitry, mediates orexigenic properties of ghrelin.
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6
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Olszewski PK, Fredriksson R, Olszewska AM, Stephansson O, Alsiö J, Radomska KJ, Levine AS, Schiöth HB. Hypothalamic FTO is associated with the regulation of energy intake not feeding reward. BMC Neurosci 2009; 10:129. [PMID: 19860904 PMCID: PMC2774323 DOI: 10.1186/1471-2202-10-129] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Accepted: 10/27/2009] [Indexed: 11/10/2022] Open
Abstract
Background Polymorphism in the FTO gene is strongly associated with obesity, but little is known about the molecular bases of this relationship. We investigated whether hypothalamic FTO is involved in energy-dependent overconsumption of food. We determined FTO mRNA levels in rodent models of short- and long-term intake of palatable fat or sugar, deprivation, diet-induced increase in body weight, baseline preference for fat versus sugar as well as in same-weight animals differing in the inherent propensity to eat calories especially upon availability of diverse diets, using quantitative PCR. FTO gene expression was also studied in organotypic hypothalamic cultures treated with anorexigenic amino acid, leucine. In situ hybridization (ISH) was utilized to study FTO signal in reward- and hunger-related sites, colocalization with anorexigenic oxytocin, and c-Fos immunoreactivity in FTO cells at initiation and termination of a meal. Results Deprivation upregulated FTO mRNA, while leucine downregulated it. Consumption of palatable diets or macronutrient preference did not affect FTO expression. However, the propensity to ingest more energy without an effect on body weight was associated with lower FTO mRNA levels. We found that 4-fold higher number of FTO cells displayed c-Fos at meal termination as compared to initiation in the paraventricular and arcuate nuclei of re-fed mice. Moreover, ISH showed that FTO is present mainly in hunger-related sites and it shows a high degree of colocalization with anorexigenic oxytocin. Conclusion We conclude that FTO mRNA is present mainly in sites related to hunger/satiation control; changes in hypothalamic FTO expression are associated with cues related to energy intake rather than feeding reward. In line with that, neurons involved in feeding termination express FTO. Interestingly, baseline FTO expression appears linked not only with energy intake but also energy metabolism.
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Research Support, Non-U.S. Gov't |
16 |
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Wirth MM, Olszewski PK, Yu C, Levine AS, Giraudo SQ. Paraventricular hypothalamic alpha-melanocyte-stimulating hormone and MTII reduce feeding without causing aversive effects. Peptides 2001; 22:129-34. [PMID: 11179607 DOI: 10.1016/s0196-9781(00)00367-3] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
alpha-Melanocyte-stimulating hormone (alpha-MSH) appears to play a tonic inhibitory role in feeding and energy storage. MTII, a specific synthetic MC3-R/MC4-R agonist, has similar effects on feeding in rats. The current studies demonstrate that PVN administration of alpha-MSH or MTII decreases nocturnal and NPY-stimulated food intake without causing aversive effects. Co-administration with NPY of 600 pmol alpha-MSH or 1 pmol MTII into the PVN caused a significant decrease in NPY-induced feeding. PVN administration of MTII or alpha-MSH at doses effective to suppress feeding did not cause conditioned taste aversion (CTA). ICV administration of alpha-MSH, however, did cause weak CTA. These results indicate that the potent effects on feeding of MC3-R and MC4-R agonists when injected into the PVN are not due to aversive effects.
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Olszewski PK, Levine AS. Central opioids and consumption of sweet tastants: when reward outweighs homeostasis. Physiol Behav 2007; 91:506-12. [PMID: 17316713 DOI: 10.1016/j.physbeh.2007.01.011] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2006] [Revised: 01/21/2007] [Accepted: 01/22/2007] [Indexed: 11/25/2022]
Abstract
Numerous reports have described opioids as peptides involved in the regulation of food intake. The role of these endogenous substances appears to be linked with reward-dependent feeding, since injection of opioid receptor ligands alters consumption of palatable foods and solutions more readily than of non-palatable ones, and intake of such tastants affects the activity of the opioid system within the brain. Among a variety of available foods, those rich in sucrose and other sweet tastants, are extremely appealing to humans and laboratory animals. In the current review, we focus on the rewarding aspects of consummator behavior driven by opioids. We attempt to delineate opioid-dependent central mechanisms responsible for overconsumption of "rewarding" palatable diets, especially foods high in sugar that can potentially jeopardize homeostasis.
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Review |
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Olszewski PK, Klockars A, Olszewska AM, Fredriksson R, Schiöth HB, Levine AS. Molecular, immunohistochemical, and pharmacological evidence of oxytocin's role as inhibitor of carbohydrate but not fat intake. Endocrinology 2010; 151:4736-44. [PMID: 20685878 PMCID: PMC2946140 DOI: 10.1210/en.2010-0151] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Oxytocin (OT) facilitates feeding termination stemming from high osmolality, stomach distention, and malaise. Recent knockout (KO) studies suggested a crucial function for OT in carbohydrate intake: OT-/- mice had increased preference for carbohydrates, including sucrose, but not fat (Intralipid). In striking contrast, sugar appetite was unaffected in the OT receptor KO mouse; data from wild-type animals have been insufficient. Therefore, we examined the involvement of OT in the regulation of sucrose vs. fat intake in C57BL/6 mice that served as a background KO strain. We exposed mice to a meal of sucrose or Intralipid and determined that the percentage of c-Fos-immunoreactive paraventricular hypothalamic OT neurons was elevated at termination of intake of either of the tastants, but this increase was 2-fold higher in sucrose-fed mice. A 48-h exposure to sucrose compared with Intralipid caused up-regulation of OT mRNA, whereas inherent individual preferences for sucrose vs. fat were not associated with differences in baseline OT expression as established with quantitative PCR. We found that L-368,899, an OT receptor antagonist, increased sugar intake when sucrose was presented alone or concurrently with Intralipid; it had no effect on Intralipid or total calorie consumption. L-368,899 affected Fos immunoreactivity in the paraventricular hypothalamus, arcuate nucleus, amygdala, and nucleus of the solitary tract, areas involved in aversion, satiety, and reward. This pattern serves as neuroanatomical basis of OT's complex role in food intake, including sucrose intake. The current findings expand our knowledge on OT and suggest that it acts as a carbohydrate-specific inhibitor of feeding.
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Research Support, N.I.H., Extramural |
15 |
90 |
10
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Olszewski PK, Klockars A, Schiöth HB, Levine AS. Oxytocin as feeding inhibitor: maintaining homeostasis in consummatory behavior. Pharmacol Biochem Behav 2010; 97:47-54. [PMID: 20595062 DOI: 10.1016/j.pbb.2010.05.026] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 05/12/2010] [Accepted: 05/26/2010] [Indexed: 12/13/2022]
Abstract
Initial studies showed that the anorexigenic peptide oxytocin (OT) regulates gastric motility, responds to stomach distention and to elevated osmolality, and blocks consumption of toxic foods. Most recently, it has been proposed to act as a mediator of general and carbohydrate-specific satiety and regulator of body weight. In the current review, we discuss the function of OT as a homeostatic inhibitor of consumption, capable of mitigating multiple aspects of ingestive behavior and energy metabolism.
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Review |
15 |
78 |
11
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Herisson FM, Waas JR, Fredriksson R, Schiöth HB, Levine AS, Olszewski PK. Oxytocin Acting in the Nucleus Accumbens Core Decreases Food Intake. J Neuroendocrinol 2016; 28. [PMID: 27114001 DOI: 10.1111/jne.12381] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Revised: 01/29/2016] [Accepted: 02/24/2016] [Indexed: 01/15/2023]
Abstract
Central oxytocin (OT) promotes feeding termination in response to homeostatic challenges, such as excessive stomach distension, salt loading and toxicity. OT has also been proposed to affect feeding reward by decreasing the consumption of palatable carbohydrates and sweet tastants. Because the OT receptor (OTR) is expressed in the nucleus accumbens core (AcbC) and shell (AcbSh), a site regulating diverse aspects of eating behaviour, we investigated whether OT acts there to affect appetite in rats. First, we examined whether direct AcbC and AcbSh OT injections affect hunger- and palatability-driven consumption. We found that only AcbC OT infusions decrease deprivation-induced chow intake and reduce the consumption of palatable sucrose and saccharin solutions in nondeprived animals. These effects were abolished by pretreatment with an OTR antagonist, L-368,899, injected in the same site. AcbC OT at an anorexigenic dose did not induce a conditioned taste aversion, which indicates that AcbC OT-driven anorexia is not caused by sickness/malaise. The appetite-specific effect of AcbC OT is supported by the real-time polymerase chain reaction analysis of OTR mRNA in the AcbC, which revealed that food deprivation elevates OTR mRNA expression, whereas saccharin solution intake decreases OTR transcript levels. We also used c-Fos immunohistochemistry as a marker of neuronal activation and found that AcbC OT injection increases activation of the AcbC itself, as well as of two feeding-related sites: the hypothalamic paraventricular and supraoptic nuclei. Finally, considering the fact that OT plays a significant role in social behaviour, we examined whether offering animals a meal in a social setting would modify their hypophagic response to AcbC OT injections. We found that a social context abolishes the anorexigenic effects of AcbC OT. We conclude that OT acting via the AcbC decreases food intake driven by hunger and reward in rats offered a meal in a nonsocial setting.
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12
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Lawson EA, Olszewski PK, Weller A, Blevins JE. The role of oxytocin in regulation of appetitive behaviour, body weight and glucose homeostasis. J Neuroendocrinol 2020; 32:e12805. [PMID: 31657509 PMCID: PMC7186135 DOI: 10.1111/jne.12805] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 10/14/2019] [Accepted: 10/24/2019] [Indexed: 12/28/2022]
Abstract
Obesity and its associated complications have reached epidemic proportions in the USA and also worldwide, highlighting the need for new and more effective treatments. Although the neuropeptide oxytocin (OXT) is well recognised for its peripheral effects on reproductive behaviour, the release of OXT from somatodendrites and axonal terminals within the central nervous system (CNS) is also implicated in the control of energy balance. In this review, we summarise historical data highlighting the effects of exogenous OXT as a short-term regulator of food intake in a context-specific manner and the receptor populations that may mediate these effects. We also describe what is known about the physiological role of endogenous OXT in the control of energy balance and whether serum and brain levels of OXT relate to obesity on a consistent basis across animal models and humans with obesity. We describe recent data on the effectiveness of chronic CNS administration of OXT to decrease food intake and weight gain or to elicit weight loss in diet-induced obese (DIO) and genetically obese mice and rats. Of clinical importance is the finding that chronic central and peripheral OXT treatments both evoke weight loss in obese animal models with impaired leptin signalling at doses that are not associated with visceral illness, tachyphylaxis or adverse cardiovascular effects. Moreover, these results have been largely recapitulated following chronic s.c. or intranasal treatment in DIO non-human primates (rhesus monkeys) and obese humans, respectively. We also identify plausible mechanisms that contribute to the effects of OXT on body weight and glucose homeostasis in rodents, non-human primates and humans. We conclude by describing the ongoing challenges that remain before OXT-based therapeutics can be used as a long-term strategy to treat obesity in humans.
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Research Support, N.I.H., Extramural |
5 |
69 |
13
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Schmid M, Poulsen MB, Olszewski P, Pelechano V, Saguez C, Gupta I, Steinmetz LM, Moore C, Jensen TH. Rrp6p controls mRNA poly(A) tail length and its decoration with poly(A) binding proteins. Mol Cell 2012; 47:267-80. [PMID: 22683267 DOI: 10.1016/j.molcel.2012.05.005] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2011] [Revised: 03/30/2012] [Accepted: 05/01/2012] [Indexed: 11/17/2022]
Abstract
Poly(A) (pA) tail binding proteins (PABPs) control mRNA polyadenylation, stability, and translation. In a purified system, S. cerevisiae PABPs, Pab1p and Nab2p, are individually sufficient to provide normal pA tail length. However, it is unknown how this occurs in more complex environments. Here we find that the nuclear exosome subunit Rrp6p counteracts the in vitro and in vivo extension of mature pA tails by the noncanonical pA polymerase Trf4p. Moreover, PABP loading onto nascent pA tails is controlled by Rrp6p; while Pab1p is the major PABP, Nab2p only associates in the absence of Rrp6p. This is because Rrp6p can interact with Nab2p and displace it from pA tails, potentially leading to RNA turnover, as evidenced for certain pre-mRNAs. We suggest that a nuclear mRNP surveillance step involves targeting of Rrp6p by Nab2p-bound pA-tailed RNPs and that pre-mRNA abundance is regulated at this level.
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Research Support, Non-U.S. Gov't |
13 |
65 |
14
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Alsiö J, Olszewski PK, Levine AS, Schiöth HB. Feed-forward mechanisms: addiction-like behavioral and molecular adaptations in overeating. Front Neuroendocrinol 2012; 33:127-39. [PMID: 22305720 DOI: 10.1016/j.yfrne.2012.01.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2011] [Revised: 11/24/2011] [Accepted: 01/13/2012] [Indexed: 12/23/2022]
Abstract
Food reward, not hunger, is the main driving force behind eating in the modern obesogenic environment. Palatable foods, generally calorie-dense and rich in sugar/fat, are thus readily overconsumed despite the resulting health consequences. Important advances have been made to explain mechanisms underlying excessive consumption as an immediate response to presentation of rewarding tastants. However, our understanding of long-term neural adaptations to food reward that oftentimes persist during even a prolonged absence of palatable food and contribute to the reinstatement of compulsive overeating of high-fat high-sugar diets, is much more limited. Here we discuss the evidence from animal and human studies for neural and molecular adaptations in both homeostatic and non-homeostatic appetite regulation that may underlie the formation of a "feed-forward" system, sensitive to palatable food and propelling the individual from a basic preference for palatable diets to food craving and compulsive, addiction-like eating behavior.
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Review |
13 |
58 |
15
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Almén MS, Jacobsson JA, Shaik JHA, Olszewski PK, Cedernaes J, Alsiö J, Sreedharan S, Levine AS, Fredriksson R, Marcus C, Schiöth HB. The obesity gene, TMEM18, is of ancient origin, found in majority of neuronal cells in all major brain regions and associated with obesity in severely obese children. BMC MEDICAL GENETICS 2010; 11:58. [PMID: 20380707 PMCID: PMC2858727 DOI: 10.1186/1471-2350-11-58] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Accepted: 04/09/2010] [Indexed: 11/10/2022]
Abstract
BACKGROUND TMEM18 is a hypothalamic gene that has recently been linked to obesity and BMI in genome wide association studies. However, the functional properties of TMEM18 are obscure. METHODS The evolutionary history of TMEM18 was inferred using phylogenetic and bioinformatic methods. The gene's expression profile was investigated with real-time PCR in a panel of rat and mouse tissues and with immunohistochemistry in the mouse brain. Also, gene expression changes were analyzed in three feeding-related mouse models: food deprivation, reward and diet-induced increase in body weight. Finally, we genotyped 502 severely obese and 527 healthy Swedish children for two SNPs near TMEM18 (rs6548238 and rs756131). RESULTS TMEM18 was found to be remarkably conserved and present in species that diverged from the human lineage over 1500 million years ago. The TMEM18 gene was widely expressed and detected in the majority of cells in all major brain regions, but was more abundant in neurons than other cell types. We found no significant changes in the hypothalamic and brainstem expression in the feeding-related mouse models. There was a strong association for two SNPs (rs6548238 and rs756131) of the TMEM18 locus with an increased risk for obesity (p = 0.001 and p = 0.002). CONCLUSION We conclude that TMEM18 is involved in both adult and childhood obesity. It is one of the most conserved human obesity genes and it is found in the majority of all brain sites, including the hypothalamus and the brain stem, but it is not regulated in these regions in classical energy homeostatic models.
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Research Support, N.I.H., Extramural |
15 |
57 |
16
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Olszewski PK, Shaw TJ, Grace MK, Höglund CE, Fredriksson R, Schiöth HB, Levine AS. Complexity of neural mechanisms underlying overconsumption of sugar in scheduled feeding: involvement of opioids, orexin, oxytocin and NPY. Peptides 2009; 30:226-33. [PMID: 19022308 PMCID: PMC2657876 DOI: 10.1016/j.peptides.2008.10.011] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2008] [Revised: 10/19/2008] [Accepted: 10/20/2008] [Indexed: 11/23/2022]
Abstract
A regular daily meal regimen, as opposed to ad libitum consumption, enforces eating at a predefined time and within a short timeframe. Hence, it is important to study food intake regulation in animal feeding models that somewhat reflect this pattern. We investigated the effect of scheduled feeding on the intake of a palatable, high-sugar diet in rats and attempted to define central mechanisms - especially those related to opioid signaling--responsible for overeating sweet foods under such conditions. We found that scheduled access to food, even as challenging as 20 min per day, does not prevent overconsumption of a high-sucrose diet compared to a standard one. An opioid receptor antagonist, naloxone, at 0.3-1 mg/kg b. wt., decreased the intake of the sweet diet, whereas higher doses were required to reduce bland food consumption. Real-time PCR analysis revealed that expression of hypothalamic and brainstem genes encoding opioid peptides and receptors did not differ in sucrose versus regular diet-fed rats, which suggests that scheduled intake of sweet food produces only a transient change in the opioid tone. Intake of sugar was also associated with upregulation of orexin and oxytocin genes in the hypothalamus and NPY in the brainstem. We conclude that scheduled consumption of sugar diets is associated with activity of a complex network of neuroregulators involving opioids, orexin, oxytocin and NPY.
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Research Support, N.I.H., Extramural |
16 |
57 |
17
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Caruso V, Lagerström MC, Olszewski PK, Fredriksson R, Schiöth HB. Synaptic changes induced by melanocortin signalling. Nat Rev Neurosci 2014; 15:98-110. [PMID: 24588018 DOI: 10.1038/nrn3657] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The melanocortin system has a well-established role in the regulation of energy homeostasis, but there is growing evidence of its involvement in memory, nociception, mood disorders and addiction. In this Review, we focus on the role of the melanocortin 4 receptor and provide an integrative view of the molecular mechanisms that lead to melanocortin-induced changes in synaptic plasticity within these diverse physiological systems. We also highlight the importance of melanocortin peptides and receptors in chronic pain syndromes, memory impairments, depression and drug abuse, and the possibility of targeting them for therapeutic purposes.
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Review |
11 |
56 |
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Sreedharan S, Shaik JHA, Olszewski PK, Levine AS, Schiöth HB, Fredriksson R. Glutamate, aspartate and nucleotide transporters in the SLC17 family form four main phylogenetic clusters: evolution and tissue expression. BMC Genomics 2010; 11:17. [PMID: 20059771 PMCID: PMC2824716 DOI: 10.1186/1471-2164-11-17] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Accepted: 01/08/2010] [Indexed: 11/12/2022] Open
Abstract
Background The SLC17 family of transporters transports the amino acids: glutamate and aspartate, and, as shown recently, also nucleotides. Vesicular glutamate transporters are found in distinct species, such as C. elegans, but the evolutionary origin of most of the genes in this family has been obscure. Results Our phylogenetic analysis shows that the SLC17 family consists of four main phylogenetic clades which were all present before the divergence of the insect lineage. One of these clades has not been previously described and it is not found in vertebrates. The clade containing Slc17a9 had the most restricted evolutionary history with only one member in most species. We detected expression of Slc17a1-17a4 only in the peripheral tissues but not in the CNS, while Slc17a5- Slc17a9 are highly expressed in both the CNS and periphery. Conclusions The in situ hybridization studies on vesicular nucleotide transporter revealed high expression throughout the cerebral cortex, certain areas in the hippocampus and in specific nuclei of the hypothalamus and thalamus. Some of the regions with high expression, such as the medial habenula and the dentate gyrus of the hippocampus, are important sites for purinergic neurotransmission. Noteworthy, other areas relying on purine-mediated signaling, such as the molecular layer of the dentate gyrus and the periaqueductal gray, lack or have a very low expression of Slc17a9, suggesting that there could be another nucleotide transporter in these regions.
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Research Support, Non-U.S. Gov't |
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Mitra A, Gosnell BA, Schiöth HB, Grace MK, Klockars A, Olszewski PK, Levine AS. Chronic sugar intake dampens feeding-related activity of neurons synthesizing a satiety mediator, oxytocin. Peptides 2010; 31:1346-52. [PMID: 20399242 PMCID: PMC3175817 DOI: 10.1016/j.peptides.2010.04.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Revised: 04/06/2010] [Accepted: 04/07/2010] [Indexed: 01/08/2023]
Abstract
Increased tone of orexigens mediating reward occurs upon repeated consumption of sweet foods. Interestingly, some of these reward orexigens, such as opioids, diminish activity of neurons synthesizing oxytocin, a nonapeptide that promotes satiety and feeding termination. It is not known, however, whether consumption-related activity of the central oxytocin system is modified under chronic sugar feeding reward itself. Therefore, we examined how chronic consumption of a rewarding high-sucrose (HS) vs. bland cornstarch (CS) diet affected the activity of oxytocin cells in the hypothalamus at the time of meal termination. Schedule-fed (2h/day) rats received either a HS or CS powdered diet for 20 days. On the 21st day, they were given the same or the opposite diet, and food was removed after the main consummatory activity was completed. Animals were perfused 60 min after feeding termination and brains were immunostained for oxytocin and the marker of neuronal activity, c-Fos. The percentage of c-Fos-positive oxytocin cells in the hypothalamic paraventricular nucleus was significantly lower in rats chronically exposed to the HS than to the CS diet, regardless of which diet they received on the final day. A similar pattern was observed in the supraoptic nucleus. We conclude that the chronic rather than acute sucrose intake reduces activity of the anorexigenic oxytocin system. These findings indicate that chronic consumption of sugar blunts activity of pathways that mediate satiety. We speculate that a reduction in central satiety signaling precipitated by regular intake of foods high in sugar may lead to generalized overeating.
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Research Support, N.I.H., Extramural |
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Olszewski PK, Shi Q, Billington CJ, Levine AS. Opioids affect acquisition of LiCl-induced conditioned taste aversion: involvement of OT and VP systems. Am J Physiol Regul Integr Comp Physiol 2000; 279:R1504-11. [PMID: 11004021 DOI: 10.1152/ajpregu.2000.279.4.r1504] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Aversive properties of lithium chloride (LiCl) are mediated via pathways comprising neurons of the nucleus of the solitary tract (NTS) and oxytocin (OT) and vasopressin (VP) cells in the hypothalamic paraventricular (PVN) and supraoptic (SON) nuclei. Because opioids act on brain regions that mediate effects of LiCl, we evaluated whether administration of opioids shortly before LiCl in rats influences 1) development of conditioned taste aversion (CTA) and 2) activation of NTS neurons and OT/VP cells. Neuronal activation was assessed by applying c-Fos immunohistochemical staining. Three opioids were used: morphine (MOR), a mu-agonist, butorphanol tartrate (BT), a mixed mu/kappa-agonist, and nociceptin/orphanin FQ (N/OFQ), which binds to an ORL1 receptor. BT and N/OFQ completely blocked acquisition of CTA. MOR alleviated but did not eliminate the aversive effects. Each of the opioids decreased LiCl-induced activation of NTS neurons as well as OT and VP cells in the PVN and SON. We conclude that opioids antagonize aversive properties of LiCl, presumably by suppressing activation of pathways that encompass OT and VP cells and NTS neurons.
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Olszewski PK, Levine AS. Minireview: Characterization of influence of central nociceptin/orphanin FQ on consummatory behavior. Endocrinology 2004; 145:2627-32. [PMID: 15044361 DOI: 10.1210/en.2004-0016] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Nociceptin/orphanin FQ (N/OFQ), a peptide closely related to dynorphin A, is the endogenous agonist of the NOP receptor that moderately increases food intake under various conditions. Its orexigenic properties are mediated by the brain circuitry. In the present review, we focus on discussing the nature of hyperphagic effects of N/OFQ with special emphasis on its function within feeding-related neural networks. Although some of N/OFQ's orexigenic effects resemble those induced by opioids, reward-dependent feeding appears to be affected in a different manner by agonists of the NOP and classical opioid receptors. Also, data suggest that N/OFQ may not only promote feeding initiation, but rather its role may be to inhibit signaling responsible for inhibition of consummatory behavior. Central systems involved in termination of feeding that seem to be influenced by N/OFQ encompass oxytocin, alpha-MSH, and CRH.
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Review |
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Olszewski PK, Wirth MM, Shaw TJ, Grace MK, Billington CJ, Giraudo SQ, Levine AS. Role of alpha-MSH in the regulation of consummatory behavior: immunohistochemical evidence. Am J Physiol Regul Integr Comp Physiol 2001; 281:R673-80. [PMID: 11448874 DOI: 10.1152/ajpregu.2001.281.2.r673] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Central injection of alpha-melanocyte-stimulating hormone (alpha-MSH) decreases food intake, suggesting a role for this peptide in the mediation of satiety. Inasmuch as alpha-MSH also supports the development of taste aversions under certain conditions, the nature of its influence on ingestive behavior, i.e., whether it is related to satiety or aversion, remains unclear. In the present studies, we used immunostaining, including that for c-Fos as a marker of neuronal activation, to further substantiate the physiological role for alpha-MSH in the regulation of consummatory behavior. We found that an increase in activation of alpha-MSH neurons in the arcuate nucleus coincided with meal termination. Administration of powerful aversive agents, LiCl and CuSO(4), did not stimulate alpha-MSH cells but did induce pronounced activation of oxytocin (OT) and vasopressin (VP) neurons, the final components of circuitry mediating aversion. We observed fewer Fos-positive OT/VP neurons after alpha-MSH injection into the lateral ventricle or into the hypothalamic paraventricular nucleus, treatments that cause mild or no aversion, respectively. The degree of activation of OT/VP neurons paralleled the magnitude of aversive response to a given treatment. Our data support the hypothesis that, in the arcuate nucleus, alpha-MSH acts as a satiety mediator independent from aversion-related mechanisms.
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Olszewski PK, Klockars A, Levine AS. Oxytocin: A Conditional Anorexigen whose Effects on Appetite Depend on the Physiological, Behavioural and Social Contexts. J Neuroendocrinol 2016; 28. [PMID: 26918919 DOI: 10.1111/jne.12376] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Revised: 02/16/2016] [Accepted: 02/19/2016] [Indexed: 01/17/2023]
Abstract
Central oxytocin suppresses appetite. Neuronal activity and the release of oxytocin coincide with satiation, as well as with adverse events (e.g. hyperosmolality, toxicity or excessive stomach distension) that necessitate an immediate termination of eating behaviour. Oxytocin also decreases consumption driven by reward, especially as derived from ingesting carbohydrates and sweet tastants. This review summarises current knowledge of the role of oxytocin in food intake regulation and highlights a growing body of evidence showing that oxytocin is a conditional anorexigen [i.e. its effects on appetite differ significantly with respect to certain (patho)physiological, behavioural and social contexts].
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Review |
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Olszewski PK, Grace MK, Sanders JB, Billington CJ, Levine AS. Effect of nociceptin/orphanin FQ on food intake in rats that differ in diet preference. Pharmacol Biochem Behav 2002; 73:529-35. [PMID: 12151026 DOI: 10.1016/s0091-3057(02)00821-3] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Nociceptin/orphanin FQ (N/OFQ) is an agonist of the ORL1 receptor. Despite homology with opioids, it does not bind to opioid receptors. Recent studies have shown that centrally administered N/OFQ increases food intake in a manner similar to opioid peptides; its effect is naloxone-reversible. Opioids appear to mediate "palatability/reward"-dependent feeding: Opioid agonists increase, while antagonists decrease, the intake of preferred diets. The current project was designed to elucidate whether the effect of N/OFQ on the consumption of preferred foods resembles that of opioid peptides. Rats had a constant access for 2 weeks to two palatable (high sucrose and high fat) diets, and their baseline preferences were established. Based on these preferences, animals were divided into three groups: fat preferrers, sucrose preferrers, and "neutrals". On the experimental day, rats received an intracerebroventricular injection of N/OFQ. Intriguingly, in fat-preferring rats, N/OFQ stimulated the intake of each of the two diets. It had no effect, however, on the consumption of either diet or cumulative food intake in sucrose-preferring or "neutral" animals. Our results reveal that N/OFQ, unlike opioids, does not increase the intake of preferred diets. Thus, it does not seem to mediate "palatability/reward"-driven feeding. Noteworthy, N/OFQ appears to cause hyperphagia only in fat-preferring rats.
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Olszewski PK, Billington CJ, Levine AS. Fos expression in feeding-related brain areas following intracerebroventricular administration of orphanin FQ in rats. Brain Res 2000; 855:171-5. [PMID: 10650146 DOI: 10.1016/s0006-8993(99)02239-8] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
While the influence of orphanin FQ (OFQ) on the regulation of food intake has been substantiated, little is known about feeding-related brain regions that mediate OFQ-induced feeding. To further investigate this, we injected OFQ intracerebroventricularly and evaluated c-Fos immunoreactivity in brain areas thought to be involved in the regulation of food intake. Altered c-Fos expression as a consequence of OFQ injection was observed in the nucleus of the solitary tract, paraventricular nucleus of the hypothalamus, supraoptic nucleus, central nucleus of amygdala, lateral septal nucleus and lateral habenular nucleus. Presumably, OFQ modulates food ingestion through its action on these brain regions, most probably by activating feeding signals as well as suppressing satiety mechanisms.
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