Role of 5-HT1A and 5-HT1B receptors in the hypophagic effect of 5-HT on the structure of feeding behavior.
BACKGROUND
Feeding behavior is deeply affected by serotonergic neurotransmission. This regulatory activity is mediated mainly by specific 5-HT1/2 receptors, and the paraventricular nucleus (PVN) plays a key role in this phenomena. In order to reveal the involvement of 5-HT1A and 5-HT1B receptors in the paraventricular nucleus of the hypothalamus (PVN) on serotonin-induced hypophagia, we examined the effects of intra-PVN injections of serotonin in WAY 100635 or SB 216641-pretreated rats on the structure of feeding behavior.


METHODS
Male Wistar rats were kept at 21+/-1 degrees C with a 12 h light /dark cycle on a self-selection feeding paradigm, provided with freely available and separate sources of protein, carbohydrate, fat and water. Blockade of 5-HT1A or 5-HT1B receptors in the paraventricular nucleus was effected by WAY 100635 (2 microg) or SB-216641 (2 microg) pretreatment; ten minutes later, 5-HT (2 microg) was applied into the same nucleus, then food intake and meal patterns were measured in a 30-minute period. The behavioral test was conducted at the beginning of the dark phase.


RESULTS
The suppressive effect of 5-HT on carbohydrate intake was blocked by both WAY 100635 and SB 216641 at the beginning of the active (dark) feeding period.


CONCLUSIONS
The hypophagic effect induced by 5-HT requires activation of 5-HT1A and 5-HT1B receptors, and the specific contribution of these subtype receptors is different, since the 5-HT1A subtype showed higher behavioral selectivity.
Mancilla-Diaz
Juan Manuel
JM
Laboratory of Alimentary Neurobiology, Universidad Nacional Autonoma de Mexico, FES Iztacala, Mexico. jmmd@servidor.unam.mx
Escartin-Perez
Rodrigo Erick
RE
Lopez-Alonso
Veronica Elsa
VE
Floran-Garduño
Benjamin
B
Romano-Camacho
Jose Bernardo
JB
D000818:Animals; D001549:Benzamides / Q000494:pharmacology; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D004435:Eating / Q000187:drug effects; D005247:Feeding Behavior / Q000187:drug effects*; D005518:Food Preferences / Q000187:drug effects; D007276:Injections, Intraventricular; D008297:Male; D010069:Oxadiazoles / Q000494:pharmacology; D010286:Paraventricular Hypothalamic Nucleus / Q000378:metabolism / Q000502:physiology; D010879:Piperazines / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011985:Receptors, Serotonin / Q000187:drug effects* / Q000502:physiology; D012701:Serotonin / Q000008:administration & dosage / Q000494:pharmacology* / Q000502:physiology; D012702:Serotonin Antagonists / Q000494:pharmacology; D014867:Water / Q000008:administration & dosage
D001549:Benzamides; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins; C108531:N-(3-(2-dimethylamino)ethoxy-4-methoxyphenyl)-2'-methyl-4'-(5-methyl-1,2,4-oxadiazol-3-yl)-(1,1'-biphenyl)-4-carboxamide; D010069:Oxadiazoles; D010879:Piperazines; D011725:Pyridines; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D014867:Water; D012701:Serotonin; C090413:N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide