Evidence that neuropeptide Y and dopamine in the perifornical hypothalamus interact antagonistically in the control of food intake.
Mapping studies have revealed that the perifornical hypothalamus (PFH) is a primary locus for both the feeding-stimulatory effect of neuropeptide Y (NPY) and the anorectic effect of catecholamines (CAs), suggesting that NPY and CAs may interact antagonistically there. To investigate this, the CA-releasing agent amphetamine (AMPH) was injected through indwelling guide cannulas into the PFH of satiated adult male rats 5 min prior to injection of NPY (78 pmol/0.3 microliters) and food intake was measured 1, 2, and 4 h later. Amphetamine (50-200 nmol) dose-dependently reduced NPY feeding, usually eliminating it at the higher doses. The receptors mediating this effect were investigated by sequential injection of various CA antagonists, AMPH, and NPY into the PFH. Neither the alpha- nor beta-adrenergic receptor antagonists phentolamine (100 nmol) or propranolol (200 nmol) significantly affected AMPH suppression of NPY feeding. In contrast, the dopamine receptor antagonist haloperidol (5 nmol) abolished AMPH suppression of NPY feeding, suggesting that dopamine (DA) mediates the AMPH effect. To examine this, epinephrine (EPI, 50-200 nmol) and DA (25-200 nmol) were tested for suppression of NPY-induced feeding. While EPI had no significant effect, DA at the maximally effective dose (50 nmol) reduced the NPY feeding response by 36% or more. These findings provide convergent evidence for antagonistic interactions between endogenous DA and NPY in the control of eating behavior.
Gillard
E R
ER
Department of Neuroscience, University of California, Riverside 92521.
Dang
D Q
DQ
Stanley
B G
BG
D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D000855:Anorexia / Q000139:chemically induced; D002395:Catecholamines / Q000378:metabolism*; D004298:Dopamine / Q000494:pharmacology*; D004435:Eating / Q000187:drug effects*; D004837:Epinephrine / Q000494:pharmacology*; D007031:Hypothalamus / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D009478:Neuropeptide Y / Q000037:antagonists & inhibitors*; D051381:Rats; D017207:Rats, Sprague-Dawley
D002395:Catecholamines; D009478:Neuropeptide Y; D000661:Amphetamine; D004298:Dopamine; D004837:Epinephrine