AJP - Endocrinology and Metabolism, Vol 245, Issue 1 14-E18, Copyright © 1983 by American Physiological Society
Reciprocal changes in gluconeogenic enzyme activity in liver and kidney by VMH lesion
K. Nagai, S. Inoue and H. Nakagawa
The effects of bilateral lesions of the ventromedial hypothalamus (VMH) on
daily rhythms of the activity of a gluconeogenic enzyme,
phosphoenolpyruvate carboxykinase (PEPCK), in the liver and kidney of rats
were examined. PEPCK activity in the liver was considerably lowered by VMH
lesions, but its rhythm remained similar to that of control liver. In
contrast, PEPCK activity in the kidney was markedly elevated by the
lesions. From these findings, it is suggested that the VMH is not the site
of the master biological clock of the rhythm of PEPCK activity. Although
these results do not exclude the possibility that hyperphagia and
hyperinsulinemia associated with VMH lesions induce changes in the levels
of PEPCK activities, they support the hypothesis that suppression of the
sympathetic nervous system causes the changes in PEPCK activity through
direct or indirect mechanisms. These findings also suggest that the
reciprocal change in PEPCK activities in the liver and kidney after VMH
lesions is related to complementary functions of the two organs in
maintenance of homeostasis of blood glucose.
