Endocrinology, Vol 124, 2449-2455, Copyright © 1989 by Endocrine Society

ARTICLES

Involvement of the hippocampus in central nervous system-mediated glucoregulation in rats

K Uemura, A Iguchi, A Yatomi, H Miura, A Honmura, M Yanase and N Sakamoto
Third Department of Internal Medicine, Nagoya University School of Medicine, Japan.

To find out whether the hippocampus is involved in central nervous system-mediated glucoregulation, we injected saline, neostigmine, dopamine, norepinephrine, bombesin, beta-endorphin, somatostatin, and prostaglandin F2 alpha into the dorsal hippocampus in anesthetized fed rats. After injection of dopamine, norepinephrine, bombesin, beta- endorphin, somatostatin, or prostaglandin F2 alpha, the level of hepatic venous plasma glucose did not differ from that in saline- treated control rats. However, neostigmine, an inhibitor of acetylcholine esterase, caused a dose-dependent increase in the hepatic venous plasma glucose concentration. This neostigmine-induced hyperglycemia was dose-dependently suppressed by coadministration of atropine, but not by hexamethonium. Injection of neostigmine (5 X 10(- 8) mol) resulted in an increase not only in glucose but also in glucagon, epinephrine, and norepinephrine in hepatic venous plasma. In bilateral adrenalectomized rats, neostigmine-induced hyperglycemia was suppressed, but the hepatic venous plasma glucose concentration still increased significantly. These results indicate that the hippocampus is involved in central nervous system-mediated glucoregulation through cholinergic muscarinic activation, partly via epinephrine secretion.