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Abstract
AbstractThe dip in food intake, which starts in late pregnancy and continues into early lactation, has traditionally been interpreted as a depression in intake due to physical constraints. However, the rôle of physical constraints on intake has been overemphasized, particularly in early lactation. There is mounting evidence that the presence and mobilization of body reserves in early lactation play an important rôle in regulating intake at this time.Conceptually, the dip in intake in early lactation observed when cows have access to non-limiting foods can be accounted for by assuming that the cow has a desired level of body reserves. When the cow is not compromised, the changes with time in body reserves and the dip in intake represent the normal case and provide the basis against which to assess true depressions in intake which may occur when the cow is compromised by limiting nutrition or environment.The regulation of body reserves and intake in the periparturient cow is orchestrated through nervous and hormonal signals. Likely factors that are involved in intake regulation are reproductive hormones, neuropeptides, adrenergic signals, insulin and insulin resistance and leptin. Furthermore, oxidation of NEFA in the liver may result in feedback signals that reduce intake. The relative importance of these is discussed. A better understanding of the physiological signals involved in intake regulation and their interrelations with body weight regulation may provide important indicators of the degree of compromise that periparturient cows may experience.
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2
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Cabanac M, Michel C, Gosselin C. Corticotropin Releasing Hormone and Body Weight Regulation: The Behavioral Approach. Nutr Neurosci 2016; 2:385-401. [DOI: 10.1080/1028415x.1999.11747293] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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3
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Scott I, Asher G, Barrell G, Juan J. Voluntary food intake of pregnant and non-pregnant red deer hinds. Livest Sci 2013. [DOI: 10.1016/j.livsci.2013.04.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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4
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Rios M. BDNF and the central control of feeding: accidental bystander or essential player? Trends Neurosci 2013; 36:83-90. [PMID: 23333344 DOI: 10.1016/j.tins.2012.12.009] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Revised: 12/19/2012] [Accepted: 12/20/2012] [Indexed: 01/15/2023]
Abstract
A considerable body of evidence links diminished brain-derived neurotrophic factor (BDNF) signaling to energy balance dysregulation and severe obesity in humans and rodents. Because BDNF exhibits broad neurotrophic properties, the underpinnings of these effects and its true role in the central regulation of food intake remain topics of debate in the field. Here, I discuss recent evidence supporting a critical role for this neurotrophin in physiological mechanisms regulating nutrient intake and body weight in the mature brain. They include reports of functional interactions of BDNF with central anorexigenic and orexigenic signaling pathways and evidence of recognized appetite hormones exerting neurotrophic effects similar to those of BDNF.
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Affiliation(s)
- Maribel Rios
- Tufts University School of Medicine, Department of Neuroscience, Boston, MA 02111, USA.
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Devetzis V, Zarogoulidis P, Kakolyris S, Vargemezis V, Chatzaki E. The corticotropin releasing factor system in the kidney: perspectives for novel therapeutic intervention in nephrology. Med Res Rev 2012; 33:847-72. [PMID: 22622997 DOI: 10.1002/med.21268] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The adaptation to endogenous and exogenous stress stimuli is crucial for survival but also for the onset of various diseases in humans. Corticotropin releasing factor (CRF) system is the major regulator of stress response and homeostasis. The members of this family of peptides extend their actions also outside CNS to the periphery where they may affect various body systems independently, acting via vagal and/or autocrine/paracrine pathways. In search for peripheral targets, kidney has rarely been studied separately, regarding expression and action of CRF and CRF-related peptides. We reviewed the existing literature concerning expression and action of the CRF system in normal and pathological renal tissue and explored possible clinical implications in nephrology. CRF system components are expressed in the kidney of experimental animals and in humans. The intrarenal distribution is reported to be equally extensive, suggesting a physiological or pathophysiological role in renal function and in the occurrence of renal disease. Urocortins have given multiple interesting observations in experimental models of renal disease and clinical studies, showing robust effects in renal regulation mechanisms. We summarize the relevant data and put them in context, proposing applications with clinical significance in the field of hypertension, diabetic nephropathy, chronic kidney disease, cardiorenal syndrome, and peritoneal dialysis.
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Affiliation(s)
- Vassilis Devetzis
- Laboratory of Pharmacology, Faculty of Medicine, Democritus University of Thrace, Alexandroupolis, Greece
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6
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Raspopow K, Abizaid A, Matheson K, Anisman H. Psychosocial stressor effects on cortisol and ghrelin in emotional and non-emotional eaters: influence of anger and shame. Horm Behav 2010; 58:677-84. [PMID: 20540943 DOI: 10.1016/j.yhbeh.2010.06.003] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Revised: 06/02/2010] [Accepted: 06/02/2010] [Indexed: 10/19/2022]
Abstract
Food consumption in stressful situations vary as a function of individual difference factors (e.g., emotional vs. non-emotional eating), and may be related to hormonal responses elicited by the stressful event. These hormonal responses may be tied to specific emotions elicited by the stressful event. The present investigation examined the emotional and hormonal (cortisol, ghrelin) responses of high and low emotional eaters following a laboratory stressor (Trier Social Stress Test; TSST). Women (n=48) either high or low in emotional eating status were tested in a TSST or served as controls during which blood samples were taken for analysis of cortisol and ghrelin, both of which have been implicated in eating and in response to stressors. The TSST promoted elevated cortisol levels, being somewhat more pronounced in emotional than in non-emotional eaters. Both shame and anger were provoked by the TSST, and although both these emotions were correlated with cortisol levels, only anger significantly mediated the relationship between the stressor and cortisol levels. As well, baseline ghrelin levels in low emotional eaters exceeded that of high emotional eaters, and increased moderately in response to the stressor situation, irrespective of emotional eating status. Interestingly, when provided with food, ghrelin levels declined in the non-emotional eaters, but not in emotional eaters. The possibility is offered that the lack of a decline of ghrelin in emotional eaters may sustain eating in these individuals.
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Affiliation(s)
- Kate Raspopow
- Institute of Neuroscience, Carleton University, Ottawa, Ontario, Canada
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7
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Merali Z, Hayley S, Kent P, McIntosh J, Bédard T, Anisman H. Impact of repeated stressor exposure on the release of corticotropin-releasing hormone, arginine-vasopressin and bombesin-like peptides at the anterior pituitary. Behav Brain Res 2009; 198:105-12. [DOI: 10.1016/j.bbr.2008.10.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2008] [Revised: 10/08/2008] [Accepted: 10/18/2008] [Indexed: 10/21/2022]
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8
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Chaillou E, Baumont R, Tramu G, Tillet Y. Effect of feeding on Fos protein expression in sheep hypothalamus with special reference to the supraoptic and paraventricular nuclei: an immunohistochemical study. Eur J Neurosci 2008. [DOI: 10.1111/j.1460-9568.2000.01338.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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9
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Nishiyama M, Makino S, Iwasaki Y, Tanaka Y, Nazarloo HP, Kaneda T, Asaba K, Hashimoto K. CRH mRNA expression in the hypothalamic paraventricular nucleus is inhibited despite the activation of the hypothalamo-pituitary-adrenal axis during starvation. Brain Res 2008; 1228:107-12. [PMID: 18619422 DOI: 10.1016/j.brainres.2008.06.065] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2007] [Revised: 05/13/2008] [Accepted: 06/19/2008] [Indexed: 11/15/2022]
Abstract
Corticotropin-releasing hormone (CRH) is one of the anorexigenic neuropeptides, and indeed the expression of hypothalamic CRH is known to be inhibited by starvation. To clarify whether elevated plasma glucocorticoid during starvation is responsible for the CRH suppression, we examined the expression level of hypothalamic CRH mRNA after food deprivation in adrenalectomized, plasma corticosterone (B)-clamped animals. Male Wistar rats were divided into 2 groups: one group had adrenalectomy (ADX) and B pellet implantation (ADX+B, n=42), and the other group had only sham operation (sham, n=42). Rats were then treated with either ad libitum food supply or food deprivation for up to 96 h. The expression of CRH mRNA in the paraventricular nucleus (PVN) was estimated by in situ hybridization. After food deprivation, mean plasma B level was markedly elevated in sham group, but almost clamped in the ADX+B group. In this experimental condition, CRH mRNA in the PVN was significantly decreased in the sham group, whereas no change was obtained in the ADX+B group. Our data suggest the decrease in CRH mRNA seems to be related to the elevated glucocorticoid level during starvation. The status of hyperadrenocorticism without activation of CRH led us to speculate that adrenocortical function is predominant in the hypothalamic-pituitary-adrenal (HPA) axis during starvation.
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Affiliation(s)
- Mitsuru Nishiyama
- Department of Endocrinology, Metabolism and Nephrology, Kochi Medical School, Kohasu, Oko-cho, Nankoku, Kochi 783-8505, Japan.
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10
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Behan DP, Heinrichs SC, De Souza EB. Section Review: Central & Peripheral Nervous Systems: Corticotropin releasing factor and Alzheimer's disease: recent developments with implications for more effective therapies. Expert Opin Investig Drugs 2008. [DOI: 10.1517/13543784.5.10.1277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Abstract
Rhodiola rosea L. is one of the most popular adaptogen and anti-stress plants in European and Asiatic traditional medicine. Its pharmacological properties appear to depend on its ability to modulate the activation of several components of the complex stress-response system. Exposure to both physical and psychological stress reduces feeding in rodents. The aim of this work was thus to determine whether in rats an hydroalcoholic R. rosea extract standardized in 3% rosavin and 1% salidroside (RHO) reverses hypophagia induced by (1) physical stress due to 60 min immobilization; (2) intracerebroventricular injection of corticotrophin-releasing factor (CRF, 0.2 microg/rat), the major mediator of stress responses in mammals; (3) intraperitoneal injection of Escherichia coli Lipopolysaccharide (LPS, 100 microg/kg); (4) intraperitoneal administration of fluoxetine (FLU, 8 mg/kg). The effect of the same doses of the plant extract was also tested in freely-feeding and in 20 h food-deprived rats. RHO was administered acutely by gavage to male Wistar rats 1 h before the experiments. The results show that at 15 and 20 mg/kg, RHO reversed the anorectic effects induced both by immobilization and by intracerebroventricular CRF injection. Moreover, at the same doses, RHO failed to reduce the anorectic effect induced both by LPS and FLU, and did not modify food intake in both freely-feeding and food-deprived rats. These findings strongly demonstrated that RHO is able selectively to attenuate stress-induced anorexia, providing functional evidence of claimed adaptogen and anti-stress properties of Rhodiola rosea L.
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Affiliation(s)
- Laura Mattioli
- Department of Experimental Medicine and Public Health, University of Camerino, Camerino, Italy
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Yoshimura R, Omori H, Somekawa S, Osaka T, Ito R, Inoue S, Endo Y. Continuous carbachol infusion promotes peripheral cell proliferation and mimics vagus hyperactivity in a rat model of hypothalamic obesity. Biomed Res 2006; 27:81-8. [PMID: 16707847 DOI: 10.2220/biomedres.27.81] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Lesions of the ventromedial hypothalamus (VMH) result in obesity and enhanced cellular proliferation in various organs, including the pancreas, gastrointestinal tract, and liver. Previous studies have suggested that vagal hyperactivity, rather than overeating, induces the peripheral cell proliferation in VMH-lesioned rats. The goal of the present study was to investigate the mechanism of peripheral cell proliferation in VMH-lesion-induced obesity by infusing rats with the acetylcholine agonist, carbachol, and then measuring cellular proliferation in the pancreas and duodenum using immunohistochemistry. The ventromedial hypothalamus was bilaterally lesioned in five rats. In other rats, the bilateral vagus nerves were ligated (vagotomized), and saline or carbachol was continuously administered by an osmotic minipump (n = 5 in each group). Three days later, rats were killed, and cell proliferation was assessed in the pancreas and the duodenum using immunohistochemistry for proliferating cell nuclear antigen (PCNA). Additionally, cellular proliferation in the duodenum was more precisely examined by assessing incorporation of 5-bromo-2'-deoxyuridine (BrdU). Cellular proliferation was higher in rats that received carbachol infusions and in rats with VMH-lesions when compared with control rats (P < 0.05, respectively). The pancreatic PCNA-expressing cells were predominantly identified as the B-cells of the islets of Langerhans. These data demonstrate that carbachol infusion can induce pancreatic and duodenal cell proliferation to a degree that was comparable to that in vagal hyperactivity induced by VMH lesions.
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Affiliation(s)
- Ryoichi Yoshimura
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan.
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Chance WT, Dayal R, Friend LA, James JH. Elevated blood lactate is not a primary cause of anorexia in tumor-bearing rats. Nutr Cancer 2005; 48:174-81. [PMID: 15231452 DOI: 10.1207/s15327914nc4802_7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Tumor-bearing (TB) rats exhibit elevated concentrations of lactate in blood contiguous with the development of anorexia. Continuous intravenous infusion of lactate into non-TB rats reduced food intake at plasma concentrations lower than those observed in anorectic TB rats. Levels of neuropeptide Y (NPY) were elevated in the ventromedial (VMH) and dorsomedial hypothalamic regions of lactate-infused rats. The addition of the enhancer of pyruvate dehydrogenase activity, dichloroacetate (DCA), to the drinking water of TB rats (0.1-0.4%) normalized blood lactate concentration but had no significant effect on anorexia. However, the elevated concentration of NPY in the VMH of anorectic TB rats was also normalized by the DCA treatment. No alterations in regional hypothalamic levels of corticotropin-releasing factor were observed within any treatment conditions. These results suggest that, although hyperlactatemia may be involved in maintaining elevated NPY concentrations in anorectic TB rats, it does not appear to be a significant factor in the etiology of experimental cancer anorexia.
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Affiliation(s)
- William T Chance
- Medical Research Service, Veterans Affairs Medical Center, Cincinnati, OH, USA.
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Rollo CD, Lai M, Whitehead K, Perreault ML, Lemon J, Chaudhry AM. Thermoregulation of transgenic growth hormone mice. CAN J ZOOL 2004. [DOI: 10.1139/z04-052] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Transgenic growth hormone (TG) mice (Mus musculus L., 1758) obtain enhanced growth via compensatory feeding at intermediate sizes and via higher growth efficiency. The latter involves diverting resources from other functions such as locomotion and wakefulness. Thermogenesis is a major expense for small mammals, so we explored whether TG mice express a trade-off between growth and thermoregulation. TG mice are hypothermic and cannot maintain their body temperature under cold stress. TG mice showed initial enlargement of brown adipose tissue and subsequent age-related decreases not seen in controls. Some TG mice became torpid after fasting durations not known to affect other mice. On a high-calorie diet, TG mice had higher body temperatures even though controls did not. Our background strain developed obesity on a high-protein and high-fat diet, and on a diet supplemented with carbohydrates, whereas TG mice never developed obesity. White adipose tissue deposits of TG females were relatively larger, but those of TG males were relatively smaller, than those of controls fed standard food. We also found significant effects of the three experimental diets, as well as gender, age, body mass, ambient temperature, and behavioural activity, on rectal temperatures of TG mice and controls in a large breeding colony. Thermogenesis of TG mice fed standard food appears energetically constrained, likely contributing to enhanced growth efficiency.
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15
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Abstract
Research is reviewed on effects of neuropeptide Y (NPY) on energy substrate utilization and central interactions among NPY, serotonin and urocortin, particularly in neurons of the paraventricular nucleus of the hypothalamus.
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Affiliation(s)
- Paul J Currie
- Department of Psychology, Barnard College, Columbia University, 3009 Broadway, New York, NY 10027, USA.
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Li RS, Nakagawa Y, Nakanishi T, Fujisawa Y, Ohzeki T. Different responsiveness in body weight and hepatic 11beta-hydroxysteroid dehydrogenase (11beta-HSD) type 1 mrna to 11beta-HSD inhibition by glycyrrhetinic acid treatment in obese and lean zucker rats. Metabolism 2004; 53:600-6. [PMID: 15131764 DOI: 10.1016/j.metabol.2003.11.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Tissue-specific dysregulation of 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) activity in obese humans and animals may be associated with obesity and the metabolic syndrome. We investigated the effect of inhibition of 11beta-HSD with glycyrrhetinic acid (GE), an effective 11beta-HSD inhibitor, on body weight regulation in obese Zucker rats, which have a defect in the leptin receptor gene. GE (280 mg/kg/d) was administered in drinking water to 8-week-old male Zucker rats for 14 weeks. GE had no effect on food intake or weight gain, and did not affect hepatic 11beta-HSD1 and renal 11beta-HSD2 mRNA levels in obese rats. In contrast, average daily food intake and body weight on week 14 were significantly reduced by GE in lean rats (both P <.0001). Hepatic 11beta-HSD1 and renal 11beta-HSD2 mRNA levels were also significantly decreased by GE in lean rats (both P <.05). GE had no significant effect on plasma corticosterone levels in obese rats but lowered them in lean rats (P <.05). Plasma leptin levels declined in both GE-treated obese and lean rats (both P <.01). In conclusion, long-term GE treatment decreased weight gain in lean Zucker rats but not in obese Zucker rats. These findings suggest that the differing responses of 11beta-HSD1 to GE in obese and lean Zucker rats are closely associated with the different weight-gain responses. Furthermore, the weight-lowering effect of GE may require intact leptin receptors.
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Affiliation(s)
- Ren-Shan Li
- Department of Pediatrics, Hamamatsu University School of Medicine, Hamamatsu, Japan
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Campbell RE, Grove KL, Smith MS. Distribution of corticotropin releasing hormone receptor immunoreactivity in the rat hypothalamus: coexpression in neuropeptide Y and dopamine neurons in the arcuate nucleus. Brain Res 2003; 973:223-32. [PMID: 12738066 DOI: 10.1016/s0006-8993(03)02487-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
An abundance of physiological data suggests an interaction between neuropeptide Y (NPY) and corticotropin-releasing hormone (CRH) in the regulation of endocrine and autonomic functions. Previously, studies in our laboratory have indicated that NPY neurons in the arcuate nucleus of the hypothalamus (ARH) project to and come in close contact with CRH neurons in the paraventricular nucleus of the hypothalamus (PVH). Conversely, it has been demonstrated that the ventromedial portion of the ARH, an area containing NPY neurons, displays CRH receptor binding and CRH receptor mRNA. These data suggest a possible reciprocal feedback regulation between NPY and CRH neurons. The ARH also contains several other populations of neurons that may be targets of the CRH system and express CRH receptors; most notable are tuberoinfundibular dopaminergic neurons (TIDA). The PVH is an important component in the regulation of prolactin secretion and may play a role in the suppression of TIDA activity, which is a critical step in the prolactin stress response. The purpose of the present study was to characterize the distribution and cellular localization of CRH R(1) receptor-like immunoreactivity (CRH R(1)-ir) in the rat hypothalamus and to determine the phenotype of neurons in the ARH that contain CRH R(1)-ir. CRH R(1)-ir was present throughout the rat brain. Hypothalamic regions with the highest levels of immunostaining were the supraoptic nucleus, magnocellular PVH, ARH, and suprachiasmatic nucleus. Double label immunofluorescence was used to demonstrate that CRH R(1)-ir in the ARH was localized to NPY cell bodies. Furthermore, TIDA neurons in the ARH also displayed CRH R(1)-ir. However, despite an abundance of CRH R(1)-ir cells in the ARH, CRH-ir fiber innervation to the ARH was extremely sparse. Therefore, although this study provides neuroanatomical evidence for direct CRH R(1) regulation of ARH NPY and TIDA neurons in the rat, it is not consistent with the idea of a reciprocal feedback loop and suggests the involvement of other CRH-like ligands, such as urocortin.
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Affiliation(s)
- Rebecca E Campbell
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health & Science University, 505 NW 185th Avenue, Beaverton, OR 97006-3499, USA
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Richardson RD, Omachi K, Kermani R, Woods SC. Intraventricular insulin potentiates the anorexic effect of corticotropin releasing hormone in rats. Am J Physiol Regul Integr Comp Physiol 2002; 283:R1321-6. [PMID: 12429558 DOI: 10.1152/ajpregu.00521.2001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Intraventricular corticotropin releasing hormone (CRH) suppresses food intake and body weight as a stress response. Insulin, acting within the brain, also suppresses food intake and body weight, and this suppression is related to caloric homeostasis. We determined if increased insulin within the brain potentiates the anorexic effects of intraventricular CRH. Rats were food deprived for 17 h each day and then given 30-min access to Ensure. One-half received continuous third ventricular infusion of synthetic cerebrospinal fluid via osmotic minipumps, and one-half received insulin (0.6 mU/day). During the infusion, rats also received 0, 0.1, 1.0, or 5.0 microg of CRH into the lateral ventricle just before access to Ensure. Insulin alone had no effect on Ensure intake or body weight. CRH dose dependently reduced Ensure intake in both groups, and the reduction was greater in the insulin group. Hence, central insulin potentiated the ability of centrally administered CRH to suppress food intake. These findings suggest that stress-related influences over food intake, particularly those mediated via CRH, interact with relative adiposity as signaled to the brain by central insulin.
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Proulx K, Richard D, Walker CD. Leptin regulates appetite-related neuropeptides in the hypothalamus of developing rats without affecting food intake. Endocrinology 2002; 143:4683-92. [PMID: 12446596 DOI: 10.1210/en.2002-220593] [Citation(s) in RCA: 156] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Leptin regulates food intake in adult mammals by stimulating hypothalamic anorexigenic pathways and inhibiting orexigenic ones. In developing rodents, fat stores are low, yet circulating leptin levels are high and do not appear to regulate food intake. We determined whether two appetite-related neuropeptides [neuropeptide Y (NPY) and proopiomelanocortin (POMC)] and food intake behavior are sensitive to leptin [3 mg/kg body weight (BW), ip] in neonates. We measured the effects of 1) acute leptin administration (3 mg/kg BW, ip, 3 h before testing) on food intake on postnatal day (PND) 5, 8, and 10; and 2) chronic leptin treatment (3 mg/kg BW, ip, daily PND3-PND10) on BW gain and fat pads weight on PND10. In addition to hypothalamic POMC and NPY expression, we determined the expression of suppressor of cytokine signaling-3, all subtypes of leptin receptors, and corticotropin-releasing factor receptor-2 mRNA in PND10 pups receiving either an acute (PND10) or a chronic (PND 3-10) leptin (3 mg/kg BW, ip) or vehicle treatment. Brains were removed 30 or 120 min after the last injection. Acute leptin administration did not affect food intake at any age tested. Chronic leptin treatment did not change BW but decreased fat pad weight significantly. In the arcuate nucleus (ARC), acute leptin increased SOCS-3 and POMC mRNA levels, but decreased NPY mRNA levels in the rostral part of ARC. Chronic leptin down-regulated all subtypes of leptin receptors mRNA and decreased NPY mRNA levels in the caudal ARC but had no further effect on POMC expression. Chronic leptin increased corticotropin-releasing factor receptor-2 mRNA levels in the ventromedial hypothalamus. We conclude that despite adult-like effects of leptin on POMC, NPY, and CRFR-2 expression in neonates, leptin does not regulate food intake during early development.
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Affiliation(s)
- Karine Proulx
- McGill University, Department of Psychiatry, Douglas Hospital Research Center, Montréal, Québec, Canada H4H 1R3
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Dirks A, Groenink L, Bouwknecht JA, Hijzen TH, Van Der Gugten J, Ronken E, Verbeek JS, Veening JG, Dederen PJWC, Korosi A, Schoolderman LF, Roubos EW, Olivier B. Overexpression of corticotropin-releasing hormone in transgenic mice and chronic stress-like autonomic and physiological alterations. Eur J Neurosci 2002; 16:1751-60. [PMID: 12431228 DOI: 10.1046/j.1460-9568.2002.02245.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
To gain a greater insight into the relationship between hyperactivity of the corticotropin-releasing hormone (CRH) system and autonomic and physiological changes associated with chronic stress, we developed a transgenic mouse model of central CRH overproduction. The extent of central and peripheral CRH overexpression, and the amount of bioactive CRH in the hypothalamus were determined in two lines of CRH-overexpressing (CRH-OE) mice. Furthermore, 24 h patterns of body temperature, heart rate, and activity were assessed using radiotelemetry, as well as cumulative water and food consumption and body weight gain over a 7-day period. CRH-OE mice showed increased amounts of CRH peptide and mRNA only in the central nervous system. Despite the presence of the same CRH transgene in their genome, only in one of the two established lines of CRH-OE mice (line 2122, but not 2123) was overexpression of CRH associated with increased levels of bioactive CRH in the hypothalamus, increased body temperature and heart rate (predominantly during the light (inactive) phase of the diurnal cycle), decreased heart rate variability during the dark (active) phase, and increased food and water consumption, when compared with littermate wildtype mice. Because line 2122 of the CRH transgenic mice showed chronic stress-like neuroendocrine and autonomic changes, these mice appear to represent a valid animal model for chronic stress and might be valuable in the research on the consequences of CRH excess in situations of chronic stress.
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Affiliation(s)
- Anneloes Dirks
- Department of Psychopharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, the Netherlands.
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Abstract
The high incidence of obesity, its multifactorial nature, the complexity and lack of knowledge of the bodyweight control system, and the scarcity of adequate therapeutics have fuelled anti-obesity drug development during a considerable number of years. Irrespective of the efforts invested by researchers and companies, few products have reached a minimum level of effectiveness, and even fewer are available in medical practice. As a consequence of anti-obesity research, our knowledge of the bodyweight control system increased but, despite this, the pharmacological approaches to the treatment of obesity have not resulted yet in effective drugs. This review provides a panoramic of the multiple different approaches developed to obtain workable drugs. These approaches, however, rely in only four main lines of action: control of energy intake, mainly through modification of appetite;control of energy expenditure, essentially through the increase of thermogenesis;control of the availability of substrates to cells and tissues through hormonal and other metabolic factors controlling the fate of the available energy substrates; andcontrol of fat reserves through modulation of lipogenesis and lipolysis in white adipose tissue. A large proportion of current research is centred on neuropeptidic control of appetite, followed by the development of drugs controlling thermogenic mechanisms and analysis of the factors controlling adipocyte growth and fat storage. The adipocyte is also a fundamental source of metabolic signals, signals that can be intercepted, modulated and used to force the brain to adjust the mass of fat with the physiological means available. The large variety of different approaches used in the search for effective anti-obesity drugs show both the deep involvement of researchers on this field and the large amount of resources devoted to this problem by pharmaceutical companies. Future trends in anti-obesity drug research follow closely the approaches outlined; however, the increasing mass of information on the molecular basis of bodyweight control and obesity will in the end prevail in our search for effective and harmless anti-obesity drugs.
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Affiliation(s)
- José-Antonio Fernández-López
- Centre Especial de Recerca en Nutrició i Ciència dels Aliments, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
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Chaillou E, Baumont R, Tramu G, Tillet Y. Long-term undernutrition followed by short-term refeeding effects on the corticotropin-releasing hormone containing neurones in the paraventricular nucleus: an immunohistochemical study in sheep. J Neuroendocrinol 2002; 14:269-75. [PMID: 11963823 DOI: 10.1046/j.1365-2826.2002.00768.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The effect of nutritional level on the immunoreactivity of corticotropin-releasing hormone (CRH) in neurones of the hypothalamic paraventricular nucleus was described in sheep, a ruminant, whose feeding strategy differs from that of monogastric species. Two groups of ewes were underfed (40%), or fed at maintenance (100%) for 167 days, after which one-half of each group was killed or ad libitum refed (at least 150% of maintenance) for 4 days before killing. The presence of CRH in the paraventricular nucleus was examined by immunohistochemistry. The number of CRH immunoreactive neurones was increased in underfed ewes, but without modification of the plasma concentration of cortisol, indicating that the rise of CRH was not released in the portal blood nor linked to the pituitary-adrenal axis. Refeeding did not modify significantly the number of CRH immunoreactive neurones in the nucleus although these neurones were increased, only in refed ewes that were previously underfed. These data differ from those for rats and mice where CRH expression is decreased or not modified by underfeeding which could reflect different effects of undernutrition on CRH immunoreactive neurones in monogastric compared to ruminants species.
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Rosmond R, Bouchard C, Björntorp P. A C-1291G polymorphism in the alpha2A-adrenergic receptor gene (ADRA2A) promoter is associated with cortisol escape from dexamethasone and elevated glucose levels. J Intern Med 2002; 251:252-7. [PMID: 11886485 DOI: 10.1046/j.1365-2796.2002.00961.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVES The objective of the current study was to examine the potential impact of a C right arrow G substitution at position -1291 of the alpha2A-adrenergic receptor gene (ADRA2A) promoter on obesity and estimates of insulin, glucose, and lipid metabolism as well as circulating hormones, including salivary cortisol in 284 unrelated Swedish men born in 1944. MAIN OUTCOME MEASURES The subjects were genotyped by using PCR amplification of the promoter region of the ADRA2A gene followed by digestion with the restriction enzyme MspI. RESULTS The frequencies were 0.23 for allele C and 0.77 for allele G. The observed genotype frequencies were 45.8 and 54.2% for C/G and G/G, respectively. Heterozygotes (n=121) had significantly (P=0.009) higher salivary cortisol levels after 0.5 mg dexamethasone compared with G/G homozygotes (n=143). Fasting glucose was found to be significantly (P=0.017) higher in heterozygotes than in G/G homozygotes. The latter group had also a borderline significantly (P=0.080) higher mean diastolic blood pressure. These results were all adjusted for the potential confounding effect of body mass index (BMI) and waist-to-hip ratio (WHR). Other measurements such as BMI, WHR, abdominal sagittal diameter, total testosterone, insulin-like growth factor I, serum leptin, fasting insulin and serum lipids were not different across the ADRA2A genotype groups. CONCLUSIONS In conclusion, we have shown that an C --> G polymorphism at position -1291 of the ADRA2A gene is associated with a subnormal cortisol response to dexamethasone, elevated glucose levels and perhaps increased diastolic blood pressure. The pathophysiology could involve an altered density of the alpha2A-AR that destabilizes the sympathetic-hypothalamic-pituitary-adrenal systems in those with genetic vulnerability in the alpha2A-adrenergic receptor gene promoter.
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Affiliation(s)
- R Rosmond
- Department of Clinical Chemistry, Sahlgrenska University Hospital, Göteborg, Sweden
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24
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Heinrichs SC, Souza EB. Corticotropin‐Releasing Factor in Brain: Executive Gating of Neuroendocrine and Functional Outflow. Compr Physiol 2001. [DOI: 10.1002/cphy.cp070407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Ingvartsen KL, Boisclair YR. Leptin and the regulation of food intake, energy homeostasis and immunity with special focus on periparturient ruminants. Domest Anim Endocrinol 2001; 21:215-50. [PMID: 11872319 DOI: 10.1016/s0739-7240(02)00119-4] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The biology of leptin has been studied most extensively in rodents and in humans. Leptin is involved in the regulation of food intake, energy homeostasis and immunity. Leptin is primarily produced in white adipose tissue and acts via a family of membrane bound receptors, including an isoform with a long intracellular domain (OB-Rb), and many isoforms with short intracellular domains (Ob-Rs). OB-Rb is predominantly expressed in the hypothalamic regions involved in the regulation of food intake and energy homeostasis. The other isoforms are distributed ubiquitously and are found in most peripheral tissues in far greater abundance than OB-Rb. The effects of leptin on food intake and energy homeostasis are central and are mediated via a network of orexigenic neuropeptides (neuropeptide Y, galanin, galanin-like peptide, melanin-concentrating hormone, orexins, agouti-related peptide) and anorexigenic neuropeptides (corticotropin-releasing hormone, pro-opiomelanocortin, alpha-melanocyte stimulating hormone and cocaine- and amphetamine-regulated transcript). In addition, leptin acts directly on immune cells to stimulate hematopoesis, T-cell immunity, phagocytosis, cytokine production, and to attenuate susceptibility to infectious insults. Emerging data in ruminants suggest that leptin is dynamically regulated by many factors and physiological states. Thus, leptin is secreted in a pulsatile fashion, but without a marked diurnal rhythm. A positive relationship between adiposity and plasma leptin concentration exists in growing and lactating ruminants. The concentration of plasma leptin increases during pregnancy, starts to decline 1--2 wk before parturition, and reaches a nadir in early lactation. The reduction of plasma leptin at parturition is likely to promote centrally mediated adaptations required in periods of energy deficit, but could have negative effects on immune cell function. Future research is needed in ruminants to address the roles played by leptin and the central nervous system in orchestrating metabolism during the periparturient period and during infectious diseases.
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Affiliation(s)
- K L Ingvartsen
- Danish Institute of Agricultural Sciences, Department of Animal Health and Welfare, Research Centre Foulum, DK-8830, Tjele, Denmark.
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26
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Abstract
Knowledge of the genetic and molecular events underlying the neuroendocrine and behavioural sequelae of the response to stress has advanced rapidly over recent years. The response of an individual to a stressful experience is a polygenic trait, but also involves non-genetic sources of variance. Using a combination of top-down (quantitative trait locus [QTL] and microarray analysis) and bottom-up (gene targeting, transgenesis, antisense technology and random mutagenesis) strategies, we are beginning to dissect the molecular players in the mediation of the stress response. Given the wealth of the data obtained from mouse mutants, this review will primarily focus on the contributions made by transgenesis and knockout studies, but the relative contribution of QTL studies and microarray studies will also be briefly addressed. From these studies it is evident that several neuroendocrine and behavioural alterations induced by stress can be modelled in mouse mutants with alterations in hypothalamic-pituitary-adrenal axis activity or other, extrahypothalamic, neurotransmitter systems known to be involved in the stress response. The relative contribution of these models to understanding the stress response and their limitations will be discussed.
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Affiliation(s)
- T Steckler
- CNS Discovery, Janssen Research Foundation, Turnhioutseweg 30, B-2340 Beerse, Belgium.
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Currie PJ, Coscina DV, Bishop C, Coiro CD, Koob GF, Rivier J, Vale W. Hypothalamic paraventricular nucleus injections of urocortin alter food intake and respiratory quotient. Brain Res 2001; 916:222-8. [PMID: 11597609 DOI: 10.1016/s0006-8993(01)02851-7] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Corticotropin releasing hormone (CRH) acts on the central nervous system to alter energy balance and influence both food intake and sympathetically-mediated thermogenesis. CRH is also reported to inhibit food intake in several models of hyperphagia including neuropeptide Y (NPY)-induced eating. The recently identified CRH-related peptide, urocortin (UCN), also binds with high affinity to CRH receptor subtypes and decreases food intake in food-deprived and non-deprived rats. The present experiment characterized further the feeding and metabolic effects of UCN by examining its impact after direct injections into the paraventricular nucleus (PVN) of the hypothalamus. In feeding tests (n=8), UCN (50-200 pmol) was injected into the PVN at the onset of the dark cycle and food intake was measured 1, 2 and 4 h postinjection. In separate rats (n=8), the metabolic effects of UCN were monitored using an open circuit calorimeter which measured oxygen consumption (V(O2)) and carbon dioxide production (V(CO2)). Respiratory quotient (RQ) was calculated as V(CO2)/V(O2). UCN suppressed feeding at all times studied and reliably decreased RQ within 30 min of infusion. Additional work examined the effect of UCN (50-100 pmol) pretreatment on the feeding and metabolic effects of NPY. NPY, injected at the start of the dark period, reliably increased 2 h food intake. This effect was blocked by PVN UCN administration. Similarly, UCN blocked the increase in RQ elicited by NPY alone. These results suggest that UCN-sensitive mechanisms within the PVN may modulate food intake and energy substrate utilization, possibly through an interaction with hypothalamic NPY.
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Affiliation(s)
- P J Currie
- Department of Psychology, Barnard College, Columbia University, New York, NY 10027, USA.
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29
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Abstract
Since its discovery, leptin (a 167-amino acid product of the OB gene) has quickly moved to the forefront as an important hormone for regulation of energy balance. It closes a feedback loop from adipose tissue to hypothalamic neuropeptide-containing neural circuitry involved in regulation of food intake and neuroendocrine/autonomic outflow. While increased central leptin signalling reduces adiposity via a reduction in food intake, it also has remarkable metabolic effects that promote leanness, independent of food intake. These include: (i) increased energy expenditure, (ii) in-place degradation of fat, and (iii) increased thermogenesis. Hypothalamic neurones that synthesize corticotropin releasing hormone and melanocortins (i.e. alpha-melanocyte-stimulating hormone and agouti-related protein) are likely effector pathways that mediate the anorexigenic and metabolic effects of leptin. Activation of sympathetic outflow (via neuropeptidergic effector pathways of central leptin) to a number of tissues that store fat might be an important mechanism through which these peripheral metabolic effects are elicited. It is proposed that these peripheral metabolic effects contribute to the satiating properties of leptin.
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Affiliation(s)
- G van Dijk
- Department of Animal Physiology, Division Neuroendocrinology, School of Behavioural and Cognitive Neurosciences, University of Groningen, Haren, The Netherlands.
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30
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Heinrichs SC, Joppa M, Lapsansky J, Jeske K, Nelson R, De Souza E. Selective stimulatory actions of corticotropin-releasing factor ligands on correlates of energy balance. Physiol Behav 2001; 74:5-13. [PMID: 11564446 DOI: 10.1016/s0031-9384(01)00421-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Acute administration of corticotropin-releasing factor (CRF) results in anorexic and sympathomimetic effects that suggest efficacy in chronic models of energy balance. The present studies employed a broad spectrum energy balance indices in lean and genetically obese Zucker rats in order to fully characterize the pharmacological efficacy of CRF and a CRF binding protein (CRF-BP) ligand inhibitor, CRF(6-33), which is thought to liberate CRF from CRF-BP. Acute administration of CRF(6-33) significantly increased CRF(2) receptor density by 10% within the ventromedial hypothalamic (VMH) nucleus of Zucker lean rats and decreased density by 10% in Zucker obese rats. A single infusion of CRF(6-33) increased nonshivering thermogenesis by 25-30% as measured by proton conductance in brown adipose tissue of both lean and obese rats. Chronic CRF(6-33) infusion suppressed body weight gain and elevated core temperature irrespective of genotype while increasing motor activity in obese rats without altering heart rate or blood pressure. Taken together, these results document strain-dependent, long-term effects of a CRF-BP ligand inhibitor on a select subset of physiological and behavioral measures of increased energy expenditure.
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Affiliation(s)
- S C Heinrichs
- Neurocrine Biosciences, Inc., 10555 Science Center Drive, San Diego, CA 92121, USA.
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31
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Abstract
CRH is the key physiological mediator of the endocrine, autonomic, and behavioral responses to stress. The recent characterization of urocortin, a new mammalian CRH-like ligand, adds to the complexity of the CRH system. Both CRH and urocortin mediate their endocrine and/or synaptic effects via two classes of CRH receptors. Similarly, both CRH and urocortin bind to the CRH-binding protein (CRH-BP). This secreted binding protein is smaller than the CRH receptors, but binds CRH and urocortin with an affinity equal to or greater than that of the receptors, and blocks CRH-mediated ACTH release in vitro. Several regions of CRH-BP expression colocalize with sites of CRH synthesis or release, suggesting that this binding protein may have a profound impact on the biological activity of CRH (or urocortin). While in vitro and in vivo studies have characterized the biochemical properties and regulation of the CRH-BP, animal models of altered CRH-BP expression can provide additional information on the in vivo role of this important modulatory protein. This review focuses on three mouse models of CRH-BP overexpression or deficiency. These animal models show numerous physiological changes in the HPA axis and in energy balance, with additional alterations in anxiogenic behavior. These changes are consistent with the hypothesis that CRH-BP plays an important in vivo modulatory role by regulating levels of "free" CRH and other CRH-like peptides in the pituitary and central nervous system.
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Affiliation(s)
- A F Seasholtz
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, USA.
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32
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Chisari AN, Giovambattista A, Perello M, Spinedi E. Impact of maternal undernutrition on hypothalamo-pituitary-adrenal axis and adipocyte functions in male rat offspring. Endocrine 2001; 14:375-82. [PMID: 11444436 DOI: 10.1385/endo:14:3:375] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2000] [Revised: 01/15/2001] [Accepted: 02/09/2001] [Indexed: 11/11/2022]
Abstract
Malnutrition induces profound deleterious effects on several metabolic and neuroendocrine functions. In the present study, we examined the impact of maternal food restriction, during gestation and lactation, on the metabolic-neuroendocrine function of their male offspring at 21 and 60 d of age. Well-nourished (WN) and undernourished (UN) pregnant rats were used, during gestation and lactation, until pups were weaned. Twenty-one-day-old WN and UN male pups were studied in basal and postinsulin conditions. Additional groups of weaned (WN and UN) male rats were fed either ad libitum (WN-WN and UN-WN) or in a restricted fashion (WN-UN and UN-UN) until experimentation at age 60 d. Body weights of mothers and their male offspring were monitored. Basal and postinsulin plasma concentrations of several metabolic fuels were evaluated. Our results indicate that 21-d-old UN male rats exhibited (vs their WN counterparts), decreased body weights, similar basal and postinsulin glycemia, similar basal plasma adrenocorticotropic hormone (ACTH) and corticosterone levels but diminished ACTH response to insulin treatment, and basal hypoleptinemia and significant insulin-induced leptin release. Finally, at 60 d of age, long-term UN (WN-UN and UN-UN) rats showed lower plasma (basal and postinsulin) glucose, and basal triglyceride levels than their counterparts (WN-WN and UN-WN). Sixty-day-old rats submitted to either food restriction protocol also showed a reduced hypothalamo-pituitary-adrenal axis response to insulin-induced hypoglycemia and basal hypoleptinemia, in spite of restoration of normal body weights. These results further indicate a clear metabolic-neuroendocrine dysfunction in male pups of UN mothers, with the abnormality partially present at weaning and deteriorated by adulthood, even after the recovery of normal body weight. Our study strongly supports the importance of the irreversibility of a deleterious allostatic state resulting from fetal and early postnatal undernutrition.
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Affiliation(s)
- A N Chisari
- Neuroendocrine Unit, Multidisciplinary Institute on Cell Biology, CONICET-CIC, La Plata, Argentina
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33
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Stanley SA, Small CJ, Murphy KG, Rayes E, Abbott CR, Seal LJ, Morgan DG, Sunter D, Dakin CL, Kim MS, Hunter R, Kuhar M, Ghatei MA, Bloom SR. Actions of cocaine- and amphetamine-regulated transcript (CART) peptide on regulation of appetite and hypothalamo-pituitary axes in vitro and in vivo in male rats. Brain Res 2001; 893:186-94. [PMID: 11223006 DOI: 10.1016/s0006-8993(00)03312-6] [Citation(s) in RCA: 162] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cocaine- and amphetamine-regulated transcript (CART) and CART peptide are abundant in hypothalamic nuclei controlling anterior pituitary function. Intracerebroventricular (ICV) injection of CART peptide results in neuronal activation in the paraventricular nucleus (PVN), rich in corticotrophin-releasing factor (CRH) and thyrotrophin-releasing factor (TRH) immunoreactive neurons. The aims of this study were three-fold. Firstly, to examine the effects of CART peptide on hypothalamic releasing factors in vitro, secondly, to examine the effect of ICV injection of CART peptide on plasma pituitary hormones and finally to examine the effect of PVN injection of CART peptide on food intake and circulating pituitary hormones. CART(55-102) (100 nM) peptide significantly stimulated the release of CRH, TRH and neuropeptide Y from hypothalamic explants but significantly reduced alpha melanocyte stimulating hormone release in vitro. Following ICV injection of 0.2 nmol CART(55-102), a dose which significantly reduces food intake, plasma prolactin (PRL), growth hormone (GH) and adrenocorticotrophin hormone (ACTH) and corticosterone increased significantly. Following PVN injection of CART(55-102), food intake was significantly reduced only at 0.2 and 0.6 nmol. However, PVN injection of 0.02 nmol CART(55-102) produced a significant increase in plasma ACTH. ICV injection of CART peptide significantly reduces food intake. Unlike many anorexigenic peptides, there is no increased sensitivity to PVN injection of CART(55-102). In contrast, both ICV and PVN injection of CART(55-102) significantly increased plasma ACTH and release of hypothalamic CRH is significantly increased by CART peptide in vitro. This suggests that CART peptide may play a role in the control of pituitary function and in particular the hypothalamo-pituitary adrenal axis.
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Affiliation(s)
- S A Stanley
- Endocrine Unit, Imperial College School of Medicine, Hammersmith Hospital, Du Cane Road, London W12 ONN, UK
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34
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Abstract
In the adult cerebellum, corticotropin releasing factor (CRF), that is localized in climbing fibers, mossy fibers, and a fine varicose plexus along the Purkinje cell layer, modulates the responsiveness of Purkinje cells to excitatory amino acids. During development, CRF has been detected in the primitive cerebellar anlage as early as embryonic day (E)10, and is continuously expressed throughout embryonic and postnatal cerebellar ontogeny. To investigate a possible trophic role for CRF during cerebellar development, cerebellar culture studies using E18 mouse embryos were carried out. In our culture paradigm, that used serum-free defined medium to suppress cell proliferation, CRF induced proliferation of cells in a dose-dependent manner in a range of concentrations between 0.1-10 microM. The proliferating cells were identified as astrocytes based on their expression of vimentin and GFAP. BrdU incorporation studies supported the proposed mitogenic effect of CRF on developing astrocytes. The mitogenic effects of CRF seemed to be primarily on immature astrocytes determined by their differential expression of vimentin and GFAP. Astrocytes at more advanced stages of development, as determined by the extent of process outgrowth and GFAP expression, incorporated less BrdU compared to immature astrocytes. CRF receptors were localized in astrocytes, and the proliferation of astrocytes induced by CRF was inhibited by astressin, a competitive CRF receptor antagonist. In conclusion, CRF induces proliferation of astrocytes derived from the developing cerebellum, that suggests a gliotrophic role for CRF during cerebellar development.
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Affiliation(s)
- B K Ha
- Department of Neuroscience, Ohio State University, Columbus, Ohio 43210, USA
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Chaillou E, Baumont R, Tramu G, Tillet Y. Effect of feeding on Fos protein expression in sheep hypothalamus with special reference to the supraoptic and paraventricular nuclei: an immunohistochemical study. Eur J Neurosci 2000. [DOI: 10.1046/j.1460-9568.2000.01338.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Ingvartsen KL, Andersen JB. Integration of metabolism and intake regulation: a review focusing on periparturient animals. J Dairy Sci 2000; 83:1573-97. [PMID: 10908064 DOI: 10.3168/jds.s0022-0302(00)75029-6] [Citation(s) in RCA: 345] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
There has been great interest in dry matter intake regulation in lactating dairy cattle to enhance performance and improve animal health and welfare. Predicting voluntary dry matter intake (VDMI) is complex and influenced by numerous factors relating to the diet, management, housing, environment and the animal. The objective of this review is to identify and discuss important metabolic factors involved in the regulation of VDMI and their integration with metabolism. We have described the adaptations of intake and metabolism and discussed mechanisms of intake regulation. Furthermore we have reviewed selected metabolic signals involved in intake regulation. A substantial dip in VDMI is initiated in late pregnancy and continues into early lactation. This dip has traditionally been interpreted as caused by physical constraints, but this role is most likely overemphasized. The dip in intake coincides with changes in reproductive status, fat mass, and metabolic changes in support of lactation, and we have described metabolic signals that may play an equally important role in intake regulation. These signals include nutrients, metabolites, reproductive hormones, stress hormones, leptin, insulin, gut peptides, cytokines, and neuropeptides such as neuropeptide Y, galanin, and corticotrophin-releasing factor. The involvement of these signals in the periparturient dip in intake is discussed, and evidence supporting the integration of the regulation of intake and metabolism is presented. Still, much research is needed to clarify the complex regulation of VDMI in lactating dairy cows, particularly in the periparturient animal.
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Affiliation(s)
- K L Ingvartsen
- Danish Institute of Agricultural Sciences, Department of Animal Health and Welfare, Research Centre Foulum, Tjele.
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Ohata H, Suzuki K, Oki Y, Shibasaki T. Urocortin in the ventromedial hypothalamic nucleus acts as an inhibitor of feeding behavior in rats. Brain Res 2000; 861:1-7. [PMID: 10751559 DOI: 10.1016/s0006-8993(99)02378-1] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Urocortin (UCN), a member of the corticotropin-releasing factor (CRF) family, inhibits food intake when it is injected intracerebroventricularly in rats. To explore the site of action of UCN in feeding behavior, we examined the effects of injection of UCN into various hypothalamic nuclei on food and water intake in 24-h fasted rats. Injection of UCN into the ventromedial hypothalamic nucleus (VMH) significantly inhibited food and water intake over 3 h without sedative effect, but no significant effect was observed following injection either into the lateral hypothalamic area, or the paraventricular nucleus of the hypothalamus. To further explore the physiological significance of endogenous UCN of the VMH in feeding behavior, the effect of immunoneutralization of hypothalamic UCN on food intake was examined. Injection of anti-rat UCN rabbit gamma-globulin into the bilateral VMH in freely fed rats significantly potentiated food and water intake compared with rats that received normal rabbit gamma-globulin. These results suggest that endogenous UCN in the VMH exert inhibitory control on ingestive behavior.
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Affiliation(s)
- H Ohata
- Department of Physiology, Nippon Medical School, 1-1-5 Sendagi Bunkyo-ku, Tokyo, Japan. ohata_hisayuki/
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Benoit SC, Thiele TE, Heinrichs SC, Rushing PA, Blake KA, Steeley RJ. Comparison of central administration of corticotropin-releasing hormone and urocortin on food intake, conditioned taste aversion, and c-Fos expression. Peptides 2000; 21:345-51. [PMID: 10793215 DOI: 10.1016/s0196-9781(00)00153-4] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Corticotropin-releasing hormone (CRH) is a potent regulator of the hypothalamic-pituitary-adrenal axis, and reduces food intake when administered into the third cerebral ventricle (i3vt). However, CRH also promotes conditioned taste aversion (CTA) learning which indicates that its anorectic effects are accompanied by aversive consequences that would reduce food intake independently of energy regulation. Urocortin (Ucn) is a closely related mammalian peptide that binds to both identified CRH receptor subtypes and also reduces food intake when administered i3vt. The present experiments compared the aversive consequences of i3vt administration of CRH and Ucn at doses that produced comparable decrements in food intake. Experiment 1 found that 1.0 microg Ucn and 2.0 microg CRH produced similar reductions in food intake. Experiment 2 demonstrated that, at these doses, CRH but not Ucn promoted robust and reliable CTA learning. A third experiment showed comparable increased c-Fos-like immunoreactivity after Ucn and CRH in forebrain and hindbrain structures associated with food intake. It is concluded that Ucn, at doses that reduce food intake to levels like that observed after administration of CRH, do not produce similarly aversive consequences.
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Affiliation(s)
- S C Benoit
- Department of Psychiatry, University of Cincinnati, P.O. Box 670559, Cincinnati, OH 45267-0559, USA.
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Timofeeva E, Deshaies Y, Picard F, Richard D. Corticotropin-releasing hormone-binding protein in brain and pituitary of food-deprived obese (fa/fa) Zucker rats. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:R1749-59. [PMID: 10600923 DOI: 10.1152/ajpregu.1999.277.6.r1749] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study was conducted to verify whether experimental conditions such as obesity and food deprivation, which promote food intake and reduce thermogenesis, could modify the expression of the corticotropin-releasing hormone (CRH)-binding protein (BP) in the rat brain. In situ hybridization, histochemistry, and immunohistochemistry were used to assess the expression of CRH-BP in lean (Fa/?) and obese (fa/fa) Zucker rats that were fed ad libitum, food deprived for 24 h, or food deprived for 24 h and refed for 6 h. In both lean and obese rats, food deprivation led to a reduction in body weight that was accompanied by a reversible increase in plasma corticosterone levels. Food deprivation and, to a lesser degree, obesity induced the expression of CRH-BP mRNA in the dorsal part of the medial preoptic area (MPOA). This induction of the CRH-BP gene led to by food deprivation was confirmed by the appearance in the dorsal part of the MPOA of neurons immunoreactive to CRH-BP. Food deprivation (in particular) and obesity also increased the levels of CRH-BP mRNA in the basolateral amygdala (BLA). The enhanced CRH-BP expression in the MPOA and BLA in response to food deprivation was reversed by refeeding. In lean Fa/? rats, the CRH-BP mRNA level in the pituitary cells was significantly decreased after food deprivation and restored after refeeding. When food was provided ad libitum, the number of cells expressing CRH-BP in the anterior pituitary was significantly higher in lean rats than in obese animals. Food deprivation for 24 h decreased dramatically the number of pituitary cells expressing CRH-BP in lean rats. Altogether, the present results demonstrate that food deprivation and, to a lesser extent, obesity can selectively affect the expression of CRH-BP. Given both the inactivating effect of CRH-BP on the CRH system and the potential roles played by the MPOA and BLA in the thermogenic and anorectic effects of CRH, it can be argued that the induction of the CRH-BP gene in obesity and after food deprivation occurs as a mechanism to reduce energy expenditure and to stimulate food intake.
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Affiliation(s)
- E Timofeeva
- Département de Physiologie, Faculté de Médecine, Université Laval, Québec (Qué), Canada G1K 7P4
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Heinrichs SC, Richard D. The role of corticotropin-releasing factor and urocortin in the modulation of ingestive behavior. Neuropeptides 1999; 33:350-9. [PMID: 10657512 DOI: 10.1054/npep.1999.0047] [Citation(s) in RCA: 144] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Participation of the hypothalamo-pituitary-adrenocortical axis, and its primary brain trigger, corticotropin-releasing factor (CRF) in the control of ingestive behavior can be inferred from data suggesting that CRF and its homologue urocortin act in brain to limit appetite following administration in rodents. Moreover, levels of endogenous CRF, CRF(1)and CRF(2)receptors and CRF-binding protein, which sequesters CRF and urocortin, are altered by changes in nutritional status brought about by food restriction/repletion. Mediation of the anorexic effects of CRF and urocortin appear not to privilege CRF(1)receptors, unlike the anxiogenic effects of CRF which are primarily a consequence of CRF(1)receptor activation. Such fear-like consequences of CRF system activation constitute a non-specific mechanism whereby the emergence of behaviors incompatible with food intake may appear to suppress appetite without affecting hunger per se. However, enhanced appetite following administration of CRF receptor antagonists and the involvement of CRF systems in sexual appetite and drug-seeking behavior all suggest a role for CRF in ingestive behavior. In particular, available evidence suggests that physiologically relevant suppression of appetite may accompany CRF system activation occurring as a consequence of stressor exposure induced by nutrient imbalance, for example, or under conditions of excessive intake or consumption of unfamiliar foodstuffs.
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Affiliation(s)
- S C Heinrichs
- Department of Psychology, Boston College, Chestnut Hill, MA, 02467, USA.
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Abstract
Corticotropin-releasing factor (CRF) has been implicated in physiological processes associated with stress, including changes in feeding behavior. Intracerebroventricular (ICV) administration of CRF and urocortin have been shown to depress feeding, and antagonism of CRF receptors has been reported to attenuate hypophagic responses to many treatments, suggesting that brain CRF may mediate these responses. We have now studied feeding behavior of mice lacking the CRF gene (CRFko), comparing them to wild-type (CRFwt) mice. Feeding was assessed in nondeprived mice by measuring the intake of sweetened milk in a 30-min period and the food pellet intake over 24 h. ICV administration of CRF or urocortin (1 microg, but not lower doses) depressed milk and food pellet intake in normal mice. Physical restraint for 30 min, or administration of mouse interleukin-1beta (mIL-1beta, 100 ng, IP), lipopolysaccharide (LPS, 1 microg, IP), or the serotonergic agonist (d-fenfluramine, 4 mg/kg, IP) reliably reduced milk intake. LPS also reduced food pellet intake. The responses to restraint, IL-1, LPS, and fenfluramine were indistinguishable between the CRFwt and CRFko mice. These results suggest that CRF is not essential for the reduction in sweetened milk intake that occurs following restraint, LPS, IL-1, or d-fenfluramine administration to mice.
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Affiliation(s)
- A H Swiergiel
- Department of Pharmacology and Therapeutics, Louisiana State University Medical Center, Shreveport 71130-3932, USA
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Differential regulation of the expression of corticotropin-releasing factor receptor type 2 (CRF2) in hypothalamus and amygdala of the immature rat by sensory input and food intake. J Neurosci 1999. [PMID: 10234028 DOI: 10.1523/jneurosci.19-10-03982.1999] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The physiological consequences of activating corticotropin-releasing factor receptor type 2 (CRF2) are not fully understood. The neuroanatomic distribution of this CRF receptor family member is consistent with roles in mediating the actions of CRF and similar ligands on food intake control and integrative aspects of stress-related behaviors. However, CRF2 expression in the adult rat is not influenced by stress, corticosterone (CORT), or food intake. In immature rat we have demonstrated striking downregulation of CRF2mRNA in hypothalamic ventromedial nucleus (VMH) after 24 hr of maternal deprivation, a paradigm consisting of both physiological/psychological stress and food deprivation. The current study aimed to distinguish which element or elements of maternal deprivation govern CRF2mRNA expression by isolating the effects of food intake and discrete maternal sensory cues on CRF2mRNA levels in VMH and in reciprocally communicating amygdala nuclei. In maternally deprived pups, CRF2mRNA levels in VMH and basomedial (BMA) and medial (MEA) amygdala nuclei were 62, 72, and 102% of control levels, respectively. Sensory inputs of grooming and handling as well as of the pups' own suckling activity-but not food intake-fully restored CRF2mRNA expression in VMH. In contrast, all manipulations tended to increase CRF2mRNA levels in BMA of maternally deprived rats, and surrogate grooming increased CRF2mRNA expression significantly above that of nondeprived controls. CRF2mRNA expression was not influenced significantly by plasma adrenocorticotropic hormone (ACTH) and CORT levels. Thus, in the immature rat, (1) CRF2 expression is regulated differentially in hypothalamic and amygdala regions, and (2) CRF2mRNA levels in VMH are governed primarily by maternal or suckling-derived sensory input rather than food intake or peripheral stress hormones. These findings indicate a region-specific regulation of CRF2mRNA, supporting the participation of the receptor in neurochemically defined circuits integrating sensory cues to influence specific behavioral and visceral functions.
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van Dijk G, Seeley RJ, Thiele TE, Friedman MI, Ji H, Wilkinson CW, Burn P, Campfield LA, Tenenbaum R, Baskin DG, Woods SC, Schwartz MW. Metabolic, gastrointestinal, and CNS neuropeptide effects of brain leptin administration in the rat. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:R1425-33. [PMID: 10233036 DOI: 10.1152/ajpregu.1999.276.5.r1425] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To investigate whether brain leptin involves neuropeptidergic pathways influencing ingestion, metabolism, and gastrointestinal functioning, leptin (3.5 micrograms) was infused daily into the third cerebral ventricular of rats for 3 days. To distinguish between direct leptin effects and those secondary to leptin-induced anorexia, we studied vehicle-infused rats with food available ad libitum and those that were pair-fed to leptin-treated animals. Although body weight was comparably reduced (-8%) and plasma glycerol was comparably increased (142 and 17%, respectively) in leptin-treated and pair-fed animals relative to controls, increases in plasma fatty acids and ketones were only detected (132 and 234%, respectively) in pair-fed rats. Resting energy expenditure (-15%) and gastrointestinal fill (-50%) were reduced by pair-feeding relative to the ad libitum group, but they were not reduced by leptin treatment. Relative to controls, leptin increased hypothalamic mRNA for corticotropin-releasing hormone (CRH; 61%) and for proopiomelanocortin (POMC; 31%) but did not reduce mRNA for neuropeptide Y. These results suggest that CNS leptin prevents metabolic/gastrointestinal responses to caloric restriction by activating hypothalamic CRH- and POMC-containing pathways and raise the possibility that these peripheral responses to CNS leptin administration contribute to leptin's anorexigenic action.
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Affiliation(s)
- G van Dijk
- Department of Animal Physiology, University of Groningen, 9750 AA Haren, The Netherlands.
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Nishiyama M, Makino S, Asaba K, Hashimoto K. Leptin effects on the expression of type-2 CRH receptor mRNA in the ventromedial hypothalamus in the rat. J Neuroendocrinol 1999; 11:307-14. [PMID: 10223285 DOI: 10.1046/j.1365-2826.1999.00331.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The product of the ob gene, leptin, is thought to act in the hypothalamus to reduce food intake and body weight (b.w.) in rats and mice; however, the mechanisms of leptin action in the brain have not been fully elucidated. Corticotropin-releasing hormone (CRH) is a potent anorectic neuropeptide, and its type-2 receptor (CRHR-2) in the ventromedial hypothalamus (VMH) appears to play an important role in the expression of this anorectic effect. We explored here the impact of systemic leptin administration on CRH mRNA expression in the hypothalamic paraventricular nucleus (PVN) and CRHR-2 mRNA expression in the VMH in male rats, using in-situ hybridization histochemistry. The expression of CRH mRNA in the PVN and CRHR-2 mRNA in the VMH were increased at 2 h and 6 h, respectively, after a single intraperitoneal injection of leptin (1.0 mg/kg). Continuous subcutaneous infusion of leptin (1.2 mg/kg/day) via an osmotic minipump for 5 days increased the expression of CRHR-2 mRNA in the VMH, but not the expression of CRH mRNA in the PVN, compared with vehicle treatment. The rats that received the single or continuous administration of leptin showed reductions of food intake and b.w. compared with vehicle-treated rats. These results are consistent with our previous findings that the expression of CRHR-2 mRNA in the VMH is positively correlated with plasma leptin concentrations under various conditions, and highlight the importance of circulating leptin for the regulation of VMH CRHR-2 mRNA. The present results also raise the possibility that leptin reduces food intake and b.w. at least partially due to the enhancement of the anorectic effect of CRH via increased PVN CRH expression and/or VMH CRHR-2 expression.
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Affiliation(s)
- M Nishiyama
- Second Department of Internal Medicine, Kochi Medical School, Kohasu, Japan.
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McIntosh J, Anisman H, Merali Z. Short- and long-periods of neonatal maternal separation differentially affect anxiety and feeding in adult rats: gender-dependent effects. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1999; 113:97-106. [PMID: 10064879 DOI: 10.1016/s0165-3806(99)00005-x] [Citation(s) in RCA: 191] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Environmental manipulations during early development can induce permanent alterations in hypothalamic-pituitary-adrenal (HPA) and behavioral responses to stressors. However, little is known about the impact of early life experiences on appetitive responses. The present investigation assessed the effects of brief handling/separation or protracted separation from the dams, on feeding and anxiety responses during development. During the first 3 weeks post-partum, Sprague-Dawley rat pups were exposed daily to either brief (15 min) handling/isolation (H), a more protracted (3 h) period of maternal separation (MS), or were not handled (NH). When tested on the elevated plus-maze (at 5-6 weeks) H groups displayed less anxiety than NH gender-matched controls. Surprisingly, so did the MS females. At weaning (Day 22), the MS rats weighed significantly less than both the H and NH animals; the difference between the H and MS was more robust and persisted throughout the experiment (D 62). The H animals of both genders, and the females of the MS group, consumed more of the palatable 'snack' than their NH counterparts. The feeding suppressant response to the various satiety peptides (bombesin, cholecystokinin, and amylin) was not affected by the early life experience, with exception of cholecystokinin (CCK) effects, which were more pronounced in H and MS males. These results suggest that early life events may contribute to anxiety and/or ingestive disorders such as anorexia nervosa, bulimia and obesity.
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Affiliation(s)
- J McIntosh
- School of Psychology, University of Ottawa, 11 Marie Curie, Room 214 VNR, Ottawa, Ontario, Canada
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Javed A, Kamradt MC, Van de Kar LD, Gray TS. D-Fenfluramine induces serotonin-mediated Fos expression in corticotropin-releasing factor and oxytocin neurons of the hypothalamus, and serotonin-independent Fos expression in enkephalin and neurotensin neurons of the amygdala. Neuroscience 1999; 90:851-8. [PMID: 10218785 DOI: 10.1016/s0306-4522(98)00523-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The neurotransmitters expressed by neurons activated by D-fenfluramine (5 mg/kg, i.p.) were identified in the hypothalamus, amygdala and bed nucleus of the stria terminalis. Induction of Fos immunoreactivity following D-fenfluramine injection was used as an index of neuronal activation. To test whether D-fenfluramine activated neurons by releasing serotonin from the serotonergic nerve terminals, rats were pretreated with fluoxetine (10 mg/kg, i.p.), a serotonin reuptake inhibitor that prevents the release of serotonin stimulated by D-fenfluramine, 12 h before D-fenfluramine injection. The approximate percentages of peptidergic neurons that contained Fos immunoreactivity after D-fenfluramine administration were 94% of corticotropin-releasing factor and 22% of oxytocin cells in the paraventricular nucleus of the hypothalamus, 6% of oxytocin cells in the supraoptic nucleus of the hypothalamus, 36% of enkephalin and 15% of neurotensin cells in the central amygdaloid nucleus, and 19% of enkephalin and 9% of neurotensin cells in the bed nucleus of the stria terminalis. Fluoxetine pretreatment blocked Fos expression in corticotropin-releasing factor- and oxytocin-expressing cells in the hypothalamus, but not in enkephalin-and neurotensin-expressing cells located in the bed nucleus of the stria terminalis and central amygdaloid nucleus. D-Fenfluramine did not induce Fos immunoreactivity in vasopressin-, thyrotropin-releasing hormone-, somatostatin- and tyrosine hydroxylase-containing cells in the hypothalamus, and corticotropin-releasing factor-expressing cells in the central amygdaloid nucleus and bed nucleus of the stria terminalis. These results show that D-fenfluramine stimulates corticotropin-releasing factor- and oxytocin-expressing cells in the hypothalamus via serotonin release. The enkephalin- and neurotensin-expressing cells in the amygdala are activated by D-fenfluramine via non-serotonergic mechanisms. Induction of Fos expression by D-fenfluramine in restricted populations of cells suggests a selective activation of neuronal circuitry that is likely to be involved in the appetite suppressant effects of D-fenfluramine.
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Affiliation(s)
- A Javed
- Neuroscience program, Loyola University of Chicago School of Medicine, Maywood, IL 60153, USA
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Vrang N, Tang-Christensen M, Larsen PJ, Kristensen P. Recombinant CART peptide induces c-Fos expression in central areas involved in control of feeding behaviour. Brain Res 1999; 818:499-509. [PMID: 10082837 DOI: 10.1016/s0006-8993(98)01349-3] [Citation(s) in RCA: 163] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We have recently shown that the hypothalamic neuropeptide CART (cocaine-amphetamine-regulated-transcript) is a leptin dependent endogenous satiety factor in the rat. In the present study we confirm and extend our previous observations by showing that intracerebroventricular (i.c.v.) administered CART(42-89) dose-dependently inhibits 3-h food intake in food restricted rats with a lowest effective dose of 0.5 microgram. CART also potently inhibits NPY-induced food intake in satiated rats as well as nighttime food intake in free feeding animals. To identify brain areas potentially involved in mediating the anorectic effects of CART, the temporal expression pattern of the immediate early gene c-fos was examined in the central nervous system by immunohistochemistry in rats receiving recombinant CART. Compared to vehicle, CART induced c-Fos expression in several hypothalamic and brainstem structures implicated in the central control of food intake. In the hypothalamus, high numbers of c-Fos immunoreactive (-ir) cells were observed in the medial parvocellular part of the paraventricular nucleus and in the posterior part of the dorsomedial nucleus. Lower numbers of c-Fos positive nuclei were found in the supraoptic and arcuate nuclei. A relatively high number of c-Fos-ir cells was found in the central nucleus of the amygdala. In the brainstem, c-Fos-positive nuclei were found in the parabrachial nucleus, and in the nucleus of the solitary tract. Notably both the area postrema and the dorsal motor nucleus of the vagus were virtually devoid of c-Fos-ir cells. The present experiments suggest that CART peptide exerts its inhibitory effects on appetite by activating hypothalamic and brainstem neurones implicated in the central control of feeding behaviour and metabolism.
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Affiliation(s)
- N Vrang
- Institute of Medical Anatomy, Department B, The Panum Institute, University of Copenhagen, Blegdamsvej 3 DK-2200, Copenhagen, Denmark.
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Rosmond R, Björntorp P. Blood pressure in relation to obesity, insulin and the hypothalamic-pituitary-adrenal axis in Swedish men. J Hypertens 1998; 16:1721-6. [PMID: 9869004 DOI: 10.1097/00004872-199816120-00003] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Some studies have shown a clustering of obesity, insulin and hypertension. The present study was performed to further characterize these associations. SUBJECTS AND METHODS In a population of 51-year-old men (n=284), measurements of systolic and diastolic blood pressure were analyzed in relation to general obesity (body mass index) and central obesity (waist: hip circumference ratio and abdominal sagittal diameter), and to the fasting insulin and insulin: glucose ratio as an approximation of insulin sensitivity. The regulation of diurnal cortisol secretion was examined in repeated salivary samples. RESULTS Linear regression analysis showed that all three parameters of obesity were significantly and strongly related to both systolic and diastolic blood pressure, more powerfully than insulin, glucose and insulin sensitivity (insulin: glucose ratio). Stepwise multiple regression showed that only central obesity, measured as the abdominal sagittal diameter, remained significantly (P< 0.001), and independently of insulin and insulin sensitivity, associated with both systolic and diastolic blood pressure (beta=7.5 and 4.2, respectively). A diurnal cortisol curve with normal rhythm was associated with lower than average blood pressures (P< 0.001) but not with insulin levels or the heart rate. In contrast, a flattened diurnal cortisol curve, indicating perturbations in the activity of the hypothalamic-pituitary-adrenal axis, was directly related to blood pressures, heart rate and insulin (P<0.001), and has previously been found to be strongly associated with abdominal obesity. CONCLUSIONS These findings suggest that general and central obesity is independently related to blood pressure, and that insulin may account for only part of this association. The activity of the hypothalamic-pituitary-adrenal axis is apparently important for blood pressure regulation, suggesting that mechanisms of the central nervous system have an impact.
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Affiliation(s)
- R Rosmond
- Department of Heart and Lung Diseases, Sahlgrenska University Hospital, Göteborg, Sweden
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Rajakumar PA, He J, Simmons RA, Devaskar SU. Effect of uteroplacental insufficiency upon brain neuropeptide Y and corticotropin-releasing factor gene expression and concentrations. Pediatr Res 1998; 44:168-74. [PMID: 9702909 DOI: 10.1203/00006450-199808000-00005] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Various hypothalamic functions such as feeding behavior, energy expenditure, body weight gain, level of anxiety, and sexual maturation are mediated by a balance between the concentrations of neuropeptide Y (NPY) and corticotropin-releasing factor (CRF). To test the hypothesis that maternal uteroplacental insufficiency alters the offspring's brain NPY and/or CRF levels, we examined the effect of maternal uterine artery ligation with intrauterine growth restriction (IUGR) (p < 0.05) upon fetal (20 d) and postnatal (4, 14, and 21 d) brain NPY and CRF synthesis, concentrations, and regional distribution. An age-related increase in NPY (0.8 kb) and CRF (1.4 kb) mRNA levels with peak amounts at the 14-d postnatal age (p < 0.05) was observed. IUGR was associated with a 75% increase in fetal brain NPY mRNA levels (p < 0.05) with no change in NPY peptide, CRF mRNA and peptide amounts. Although the increase in NPY mRNA levels persisted postnatally (p < 0.05) at d 4 and 21, CRF mRNA amounts were 2.5-fold higher only in the 4-d IUGR (p < 0.05). Paralleling the mRNA changes, an age-related increase in RIA of NPY and CRF peptide concentrations was noted (p < 0.05). IUGR caused postnatal brain NPY and CRF peptide changes similar to corresponding mRNA levels (p < 0.05), despite normal postnatal circulating glucose, insulin, corticosterone, and leptin concentrations. The age-specific intergroup differences in the NPY and CRF peptide immunoreactivity appeared predominantly in the hypothalamic region. We conclude that maternal uteroplacental insufficiency causing IUGR leads to a pretranslational imbalance in the immediate (4 d) postnatal brain NPY and CRF peptide concentrations, thereby altering the developmental pattern. This alteration in NPY and CRF peptide concentrations, despite normalization of the metabolic milieu was associated with a persistent diminution in body weight. The IUGR-associated pretranslational increase in NPY and not CRF peptide levels at d 21, may herald changes in feeding behavior during the postsuckling phase.
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Affiliation(s)
- P A Rajakumar
- Department of Pediatrics, University of Pittsburgh, Magee-Women's Research Institute, PA 15213, USA
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