5-Hydroxytryptaminergic receptor agonists: effects on neuropeptide Y potentiation of feeding and respiratory quotient.
The objective of the present report was to characterize further the potential interactive effects of NPY and 5-HT on feeding and whole-body calorimetry. Specifically, several experiments examined the impact of various 5-HT receptor agonists on NPY stimulated eating and alterations in respiratory quotient (RQ). This included the 5-HT1A/1B receptor agonist RU 24969, the 5-HT1B/2C agonist TFMPP and the 5-HT2A/2C agonist DOI. In feeding tests conducted at the onset of the dark cycle, RU 24969, TFMPP and DOI were administered 5 min prior to PVN injection of NPY and food intake was measured 1 h postinjection. The metabolic effects of NPY following similar pretreatment were monitored using an open-circuit calorimeter measuring the volume of oxygen consumed (VO2), carbon dioxide produced (VCO2) and RQ (VCO2/VO2). PVN injection of NPY (50-100 pmol) potentiated feeding and evoked reliable increases in RQ. DOI (5-20 nmol), but not RU 24969 (5-20 nmol) or TFMPP (10-40 nmol), antagonized NPY induced eating and blocked the peptide's effects on RQ. These findings suggest that 5-HT2A receptors within the PVN modulate NPY's effect on feeding and energy substrate utilization at the start of the nocturnal period.
Currie
P J
PJ
Department of Psychology, 71 W. Warren Ave., Wayne State University, Detroit, MI 48202, USA.
Coscina
D V
DV
D000818:Animals; D004357:Drug Synergism; D004435:Eating / Q000187:drug effects*; D007211:Indoles / Q000008:administration & dosage; D008297:Male; D008845:Microinjections; D009478:Neuropeptide Y / Q000008:administration & dosage / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000187:drug effects*; D010879:Piperazines / Q000008:administration & dosage; D051381:Rats; D017207:Rats, Sprague-Dawley; D017366:Serotonin Receptor Agonists / Q000008:administration & dosage / Q000494:pharmacology*
D007211:Indoles; D009478:Neuropeptide Y; D010879:Piperazines; D017366:Serotonin Receptor Agonists; C018406:1-(3-trifluoromethylphenyl)piperazine; C025145:5-methoxy 3-(1,2,3,6-tetrahydro-4-pyridinyl)1H indole