Modulation of plasma glucose levels by thyrotropin-releasing hormone administered intracerebroventricularly in the rat.
Thyrotropin-releasing hormone (TRH), but not histidyl-proline diketopiperazine (cyclo[His-Pro]), induced transient hyperglycemia associated with hyperglucagonemia and marked hyperinsulinemia when placed intracerebroventricularly (i.c.v.) in anesthetized rats. This TRH-induced hyperglycemia was prevented by acute adrenalectomy. However, adrenalectomy did not prevent TRH-induced hyperinsulinemia or hyperglucagonemia. In streptozotocin-induced diabetic rats, i.c.v. administration of TRH caused progressive and pronounced hyperglycemia. i.c.v. TRH-induced hyperinsulinemia was abolished by vagotomy and by systemic administration of hexamethonium or atropine. These results suggest that TRH induces hyperglycemia mediated by stimulation of the sympathetico-adrenal system and hyperinsulinemia by stimulation of the vagus nerve, and that the rapid decline of plasma glucose levels following transient hyperglycemia is due to hyperinsulinemia.
Marubashi
S
S
Third Department of Internal Medicine, Yamagata University School of Medicine, Japan.
Kunii
Y
Y
Tominaga
M
M
Sasaki
H
H
D000315:Adrenalectomy; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D005934:Glucagon / Q000097:blood; D006943:Hyperglycemia / Q000097:blood / Q000139:chemically induced; D006946:Hyperinsulinism / Q000097:blood / Q000139:chemically induced; D007276:Injections, Intraventricular; D007328:Insulin / Q000097:blood; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013311:Streptozocin / Q000494:pharmacology; D013973:Thyrotropin-Releasing Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D014628:Vagotomy; D014630:Vagus Nerve / Q000187:drug effects
D001786:Blood Glucose; D007328:Insulin; D013311:Streptozocin; D013973:Thyrotropin-Releasing Hormone; D005934:Glucagon