51. Urocortin1-induced anorexia is regulated by activation of the serotonin 2C receptor in the brain.
- Author
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Harada Y, Takayama K, Ro S, Ochiai M, Noguchi M, Iizuka S, Hattori T, and Yakabi K
- Subjects
- Aminopyridines pharmacology, Animals, Anorexia chemically induced, Energy Intake drug effects, Feeding Behavior, Gene Expression, Indoles pharmacology, Male, Medulla Oblongata metabolism, Pro-Opiomelanocortin genetics, Pro-Opiomelanocortin metabolism, Proto-Oncogene Proteins c-fos metabolism, Quinolines pharmacology, Rats, Rats, Sprague-Dawley, Serotonin 5-HT2 Receptor Agonists pharmacology, Serotonin 5-HT2 Receptor Antagonists pharmacology, Urocortins, Anorexia metabolism, Hypothalamus metabolism, Receptor, Serotonin, 5-HT2C metabolism
- Abstract
This study was conducted to determine the mechanisms by which serotonin (5-hydroxytryptamine, 5-HT) receptors are involved in the suppression of food intake in a rat stress model and to observe the degree of activation in the areas of the brain involved in feeding. In the stress model, male Sprague-Dawley rats (8 weeks old) were given intracerebroventricular injections of urocortin (UCN) 1. To determine the role of the 5-HT2c receptor (5-HT2cR) in the decreased food intake in UCN1-treated rats, specific 5-HT2cR or 5-HT2b receptor (5-HT2bR) antagonists were administered. Food intake was markedly reduced in UCN1-injected rats compared with phosphate buffered saline treated control rats. Intraperitoneal administration of a 5-HT2cR antagonist, but not a 5-HT2bR antagonist, significantly inhibited the decreased food intake. To assess the involvement of neural activation, we tracked the expression of c-fos mRNA as a neuronal activation marker. Expression of the c-fos mRNA in the arcuate nucleus, ventromedial hypothalamic nucleus (VMH) and rostral ventrolateral medulla (RVLM) in UNC1-injected rats showed significantly higher expression than in the PBS-injected rats. Increased c-fos mRNA was also observed in the paraventricular nucleus (PVN), the nucleus of the solitary tract (NTS), and the amygdala (AMG) after injection of UCN1. Increased 5-HT2cR protein expression was also observed in several areas. However, increased coexpression of 5-HT2cR and c-fos was observed in the PVN, VMH, NTS, RVLM and AMG. Whereas, pro-opiomelanocortin mRNA expression was not changed. In an UNC1-induced stress model, 5-HT2cR expression and activation was found in brain areas involved in feeding control., (Copyright © 2013 Elsevier Inc. All rights reserved.)
- Published
- 2014
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