Involvement of the hippocampus in central nervous system-mediated glucoregulation in rats.
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.
Uemura
K
K
Third Department of Internal Medicine, Nagoya University School of Medicine, Japan.
Iguchi
A
A
Yatomi
A
A
Miura
H
H
Honmura
A
A
Yanase
M
M
Sakamoto
N
N
D000315:Adrenalectomy; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D002490:Central Nervous System / Q000502:physiology*; D005947:Glucose / Q000378:metabolism*; D006624:Hippocampus / Q000502:physiology*; D006728:Hormones / Q000097:blood; D008102:Liver Circulation; D008297:Male; D009388:Neostigmine / Q000494:pharmacology; D018377:Neurotransmitter Agents / Q000494:pharmacology; D009994:Osmolar Concentration; D051381:Rats; D011919:Rats, Inbred Strains; D014680:Veins
D001786:Blood Glucose; D006728:Hormones; D018377:Neurotransmitter Agents; D009388:Neostigmine; D005947:Glucose