Alpha 2-adrenoceptor blockade does not block feeding induced by neuropeptide Y in sheep.
We tested the hypothesis that blockade of central alpha 2-adrenergic receptors would prevent neuropeptide Y (NPY)-induced feeding. Nine young female sheep were fitted with lateral ventricula cannulas. Bolus intracerebroventricular (ICV) injection of 3 nmol of NPY increased feed intake after 30 min between 45 and 153% in three experiments. A bolus ICV injection of 400 or 100 nmol of the alpha 2-antagonist, yohimbine, either 5 or 30 min before NPY injection, did not attenuate this response. Instead, yohimbine increased feed intake over NPY-induced feeding by 52 to 55%. We interpret these data as evidence that the putative NPY feeding pathway in feed-sated sheep is not dependent on the type of alpha 2-adrenergic mechanism which can be blocked by ICV injection of yohimbine.
Miner
J L
JL
Department of Animal Science, University of Missouri-Columbia 65211.
Della-Fera
M A
MA
Paterson
J A
JA
Baile
C A
CA
D000818:Animals; D001921:Brain / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004326:Drinking / Q000187:drug effects; D004435:Eating / Q000187:drug effects*; D005260:Female; D007276:Injections, Intraventricular; D009478:Neuropeptide Y / Q000494:pharmacology*; D011941:Receptors, Adrenergic / Q000187:drug effects; D012756:Sheep; D015016:Yohimbine / Q000494:pharmacology*
D009478:Neuropeptide Y; D011941:Receptors, Adrenergic; D015016:Yohimbine