AJP - Regulatory, Integrative and Comparative Physiology, Vol 266, Issue 1 87-R94, Copyright © 1994 by American Physiological Society
Metabolic and neurochemical profiles in insulin-treated diabetic rats
L. L. Bellush and S. G. Reid
Department of Psychology, Ohio University, Athens 45701.
Plasma glucose concentration was measured at 3-h intervals in
streptozotocin-induced diabetic rats placed on various insulin replacement
regimens using three different kinds of insulin. High insulin dosages
produced at least periodic hypoglycemia, even though there were no overt
signs of insulin overdose. Low- and single-dose regimens produced periods
of hyperglycemia. Both high and low doses of protamine zinc insulin
normalized diabetes-induced reductions in 5-hydroxyindole-3-acetic acid
[5-HIAA; the principal metabolite of 5-hydroxytryptamine (5-HT)] and 5-HT
turnover (5-HIAA/5-HT), despite the failure of the low-dose regimen to
normalize plasma glucose. Diabetic rats evidenced continued hyperphagia and
hyperdipsia during insulin treatment, and insulin treatment also induced
hyperphagia and excessive weight gain in nondiabetic rats. Insulin
treatment only partially normalized diabetes-induced adrenal hypertrophy.
Adrenal hypertrophy is an indication of a continued stresslike
physiological state in diabetes even during insulin therapy. This state may
be involved in the enhanced risk in diabetic humans for development of
anxiety disorders and clinical depression.
