AJP - Regulatory, Integrative and Comparative Physiology, Vol 250, Issue 1 83-R88, Copyright © 1986 by American Physiological Society
Alpha 2-noradrenergic feeding rhythm in paraventricular nucleus: relation to corticosterone
P. Bhakthavatsalam and S. F. Leibowitz
The feeding response induced by the paraventricular nucleus (PVN) injection
of norepinephrine (NE) in rats has been shown to correlate positively in
magnitude with the level of circulating corticosterone. The present study
examined the feeding responses induced by NE and clonidine (CLON) injected
into the PVN and CLON injected intraperitoneally, as a function of diurnal
cycle and also in adrenalectomized animals with and without peripheral
corticosterone replacement. A periodicity in the effectiveness of
PVN-injected NE and CLON, as well as intraperitoneal CLON, was observed,
with a significantly stronger eating response occurring near the onset of
dark period compared with the response produced in the early light period.
Adrenalectomy abolished the feeding induced by each of these
alpha-noradrenergic agonists, and acute corticosterone replacement restored
the response. The feeding induced by intraperitoneally injected
2-deoxy-D-glucose was unaffected. These findings indicate the importance of
corticosterone to the action of peripherally and centrally administered
alpha-noradrenergic agonists and also suggest that the diurnal rhythm of
corticosterone plays an important role in determining the rhythm for the
feeding response induced by PVN alpha 2-noradrenergic activation.
