AJP - Regulatory, Integrative and Comparative Physiology, Vol 265, Issue 1 117-R123, Copyright © 1993 by American Physiological Society
Responses to catecholamines in perfused livers of hypothalamic-lesioned rats
Y. Matsui, H. Ishibashi, K. Kimura, M. Shiota, M. Ohta and T. Sugano
Laboratory of Veterinary Physiology, University of Osaka Prefecture, Japan.
The responses of hepatic glycogenolysis to catecholamines in ventromedial
hypothalamus (VMH)-lesioned male rats were examined in perfused livers.
Seven days after bilateral electrical lesioning of the VMH, the livers were
perfused. Isoproterenol, a beta-agonist, stimulated greater glucose
production in VMH-lesioned rats than in controls (32.8 vs. 5.6 mumol
glucose.h-1.g liver-1), while responses to phenylephrine, an alpha-agonist,
decreased significantly compared with controls (44.4 vs. 69.8 mumol
glucose.h-1.g liver-1). There were no significant differences in responses
of livers to glucagon and vasopressin between control and VMH-lesioned
rats. Adrenodemedullation showed the same effect on beta-responses as
lesions in the VMH, but no effect on alpha-responses. Plasma epinephrine
levels were not detectable with the high-performance liquid chromatography
analysis in VMH-lesioned rats. The periodicity of plasma corticosterone
levels was observed in both VMH-lesioned and control rats, although daytime
increases in plasma corticosterone were blocked by VMH lesions. These
results suggest that the lesions in the VMH cause changes in the levels of
adrenergic receptor and that the increase in beta-responses is caused
mostly by the reduction of plasma epinephrine.
