Behavioral thermoregulation during vitamin B6 deficiency.

Abstract

Thermoregulatory behavior was studied in vitamin B6-deficient and control rats exposed to a temperature of 2–3 C. The animals were kept in an experimental chamber provided with a lever which, when pressed, turned on a heat lamp placed above the chamber. The B6-deficient rats turned on the heat lamp more frequently than did the controls. This difference was observed with both ad libitum and paired feeding. Furthermore, administration of vitamin B6 to the deficient rats and deoxypyridoxine, a B6 antagonist, to the controls brought about reversals in the relative frequency of heat reinforcements which were accompanied by changes in biochemical indices of vitamin B6 deficiency, i.e., increased xanthurenic acid excretion and decreased plasma glutamic-oxalacetic transaminase levels. Measurements of skin and rectal temperatures in the cold indicate that the body temperature of B6-deficient rats falls more rapidly than that of controls, a fact which would account for the difference in thermoregulatory behavior. Attempts to search for evidence of thyroid dysfunction in B6-deficient rats as the possible cause of such behavioral differences were unrevealing. These experiments indicate that behavioral studies are useful in assessing nutritional deficiency.