AJP - Regulatory, Integrative and Comparative Physiology, Vol 242, Issue 5 596-R603, Copyright © 1982 by American Physiological Society
2-Deoxy-D-glucose and insulin modify release of norepinephrine from rat hypothalamus
M. L. McCaleb and R. D. Myers
Both 2-deoxy-D-glucose (2-DG) and insulin, administered systemically, evoke
spontaneous feeding in the satiated animal. To determine whether
hypothalamic norepinephrine (NE) could be involved in this eating response,
we examined the effect of the two compounds on the kinetics of NE release
from this structure in the unrestrained rat. An individual site in the
hypothalamus of the rat was radiolabeled by 1.0-2.0 microCi of [14C]NE
microinjected in a volume of 0.5-1.0 microliters through a permanently
implanted guide cannula. Then 30 min later, the NE-labeled tissue was
perfused, by means of push-pull cannulas, with an artificial cerebrospinal
fluid at a rate of 25 microliters/min. The duration of each perfusion was
5.0 min with a 5.0-min interval between successive perfusions. After two
base-line samples were collected, a saline control injection or either 40
mg/kg 2-DG or 20 U/kg insulin was given intraperitoneally; then the
perfusion sequence was continued for an additional 1-h period. Aliquots of
the collected samples of perfusate were analyzed by combined scintillation
spectrometry and high-pressure liquid chromatography. 2-DG enhanced the
release of NE at sites in the medial hypothalamus, whereas insulin
generally caused a suppression of catecholamine efflux particularly at
sites within the lateral hypothalamic area. The changes in NE efflux were
morphologically specific. Taken together with the differences in amine
release, these results suggest that 2-DG and insulin modify feeding by
independent neurochemical mechanisms that may involve noradrenergic neurons
at the hypothalamic level.
