Serotoninergic activity has been linked to regulation of eating, Clin Neuropharmacol. 1988;11 Suppl 1:S51-71. with 5HT drugs reducing food intake. Although serotonin was initially thought to involved mainly with carbohydrate intake regulation, Brain Res. 1989 Nov 27;503(1):132-40. more recent studies seem to show a predominant effect on fat intake and the ability of serotonin administration to prevent fat intake-induced weight gain. Obes Res. 1995 Nov;3 Suppl 4:471S-476S.
Serotonin injection peripherally reduces food intake, specifically fat intake. Am J Physiol. 1972 Jul;223(1):176-9. Reduction of food intake with central injection of several serotonin agonists (quipazine, meta-chlorophenylpiperazine [mCPP] and d-norfenfluramine) have been demonstrated Am J Physiol. 1999 Sep;277(3 Pt 2):R802-11. with increased satiated behaviour in animals. Pharmacol Biochem Behav. 1997 Jan;56(1):41-6. The reduction of food intake induced by dexfenfluramine, Obes Res. 1995 Nov;3 Suppl 4:463S-470S. a drug that releases serotonin and partially inhibits its reuptake, is blocked by the broad spectrum serotonin antagonist metergoline, Clin Neuropharmacol. 1988;11 Suppl 1:S135-8. as well as by serotonin reuptake inhibitors suggesting the role of serotoninergic pathways in this drug's action on satiety induction. On the other hand, Fluoxetine which blocks serotonin reuptake, also reduces food intake, J Clin Psychiatry. 1985 Mar;46(3 Pt 2):7-13. although this effect is not antagonised by metergoline suggesting involvement of other pathways in fluoxetine's anorexigenic action. Fluoxetine at a daily dose of 60 mg seems to produce a weight loss of 0.23 kg/week compared to placebo, Am J Clin Nutr. 1992 Jan;55(1 Suppl):181S-184S. although weight regain is a limiting feature in clinical trials of SSRIs as Fluoxetine Int J Obes Relat Metab Disord. 1994 Mar;18(3):129-35. and Sertraline.
Several receptor subtypes have been described for the 5HT receptor family. Obes Res. 1995 Nov;3 Suppl 4:441S-447S Activation of the 5HT1A receptor in the dorsal raphe nucleus stimulates food intake acutely Obes Res. 1995 Nov;3 Suppl 4:449S-462S. while stimulation of the 5-HT1B receptor reduces food intake. Eur J Pharmacol. 1987 Sep 23;141(3):429-35. In fact, 5-HT1b receptor knock out prevents the fenfluramine induced reduction in food intake. J Neurosci. 1998 Jul 15;18(14):5537-44. The 5-HT1B induced satiety induction might be mediated through NPY reduction in the PVN. Peptides. 1996;17(6):943-9. A third serotonin receptor 5HT2C may also have a role in food intake regulation, as shown by weight gain in mice lacking this receptor. Nature. 1995 Apr 6;374(6522):542-6. Studies seem to suggest that 5HT1B and 5HT2A/2C receptors seem to be mainly involved with food intake regulation. Am J Physiol. 1995 Jan;268(1 Pt 2):R14-20. Serotonin receptors in the GIT may play a role in modulation of gastric motility/emptying and in turn regulation of food intake. Enterostatin, a gut hormone secreted following fat ingestion, seems to have effects on the serotoninergic system with increased serotonin turnover. Obes Res. 1997 Jul;5(4):360-72.
Serotonin injection peripherally reduces food intake, specifically fat intake. Am J Physiol. 1972 Jul;223(1):176-9. Reduction of food intake with central injection of several serotonin agonists (quipazine, meta-chlorophenylpiperazine [mCPP] and d-norfenfluramine) have been demonstrated Am J Physiol. 1999 Sep;277(3 Pt 2):R802-11. with increased satiated behaviour in animals. Pharmacol Biochem Behav. 1997 Jan;56(1):41-6. The reduction of food intake induced by dexfenfluramine, Obes Res. 1995 Nov;3 Suppl 4:463S-470S. a drug that releases serotonin and partially inhibits its reuptake, is blocked by the broad spectrum serotonin antagonist metergoline, Clin Neuropharmacol. 1988;11 Suppl 1:S135-8. as well as by serotonin reuptake inhibitors suggesting the role of serotoninergic pathways in this drug's action on satiety induction. On the other hand, Fluoxetine which blocks serotonin reuptake, also reduces food intake, J Clin Psychiatry. 1985 Mar;46(3 Pt 2):7-13. although this effect is not antagonised by metergoline suggesting involvement of other pathways in fluoxetine's anorexigenic action. Fluoxetine at a daily dose of 60 mg seems to produce a weight loss of 0.23 kg/week compared to placebo, Am J Clin Nutr. 1992 Jan;55(1 Suppl):181S-184S. although weight regain is a limiting feature in clinical trials of SSRIs as Fluoxetine Int J Obes Relat Metab Disord. 1994 Mar;18(3):129-35. and Sertraline.
Several receptor subtypes have been described for the 5HT receptor family. Obes Res. 1995 Nov;3 Suppl 4:441S-447S Activation of the 5HT1A receptor in the dorsal raphe nucleus stimulates food intake acutely Obes Res. 1995 Nov;3 Suppl 4:449S-462S. while stimulation of the 5-HT1B receptor reduces food intake. Eur J Pharmacol. 1987 Sep 23;141(3):429-35. In fact, 5-HT1b receptor knock out prevents the fenfluramine induced reduction in food intake. J Neurosci. 1998 Jul 15;18(14):5537-44. The 5-HT1B induced satiety induction might be mediated through NPY reduction in the PVN. Peptides. 1996;17(6):943-9. A third serotonin receptor 5HT2C may also have a role in food intake regulation, as shown by weight gain in mice lacking this receptor. Nature. 1995 Apr 6;374(6522):542-6. Studies seem to suggest that 5HT1B and 5HT2A/2C receptors seem to be mainly involved with food intake regulation. Am J Physiol. 1995 Jan;268(1 Pt 2):R14-20. Serotonin receptors in the GIT may play a role in modulation of gastric motility/emptying and in turn regulation of food intake. Enterostatin, a gut hormone secreted following fat ingestion, seems to have effects on the serotoninergic system with increased serotonin turnover. Obes Res. 1997 Jul;5(4):360-72.