Hypoglycemia in mice exposed to an environment of high temperature and humidity

Changes in blood glucose levels in mice under an environment of a high temperature and humidity similar to summers in Japan were studied. When mice were exposed to a high temperature (30 ± 1 °C) and humidity (70 ± 2%), the blood glucose level increased with a short-term exposure and decreased with a long-term exposure compared to control mice housed at room temperature (23 ± 1 °C) and humidity (55 ± 2%). The liver glycogen level in the stress group also decreased in contrast to that of the control group. Mice were exposed to high temperature and humidity 8 hr/day for 6 days. The blood glucose level in the stress group at 8 hr after exposure significantly decreased on the first day; however, the level increased on the second and third day compared to the control group. Thereafter no significant difference in the glucose level was observed between the two groups. The circadian rhythm of blood glucose level in mice after exposure to stressful conditions for 8 hr/day for 7 days was not altered. From these results it appears that mice can adapt to these environmental conditions. Stress-induced hypoglycemia was improved by the following drugs which affect the adrenal function; pantotenic acid (250 mg/kg/day x 5, p.o.), ascorbic acid (1000 mg/kg or 500 mg/kg day x 5, p.o.), taurine (1000 mg/kg/day x 5, p.o.), aspartic acid (1000 or 2000 mg/kg, p.o.), glutamic acid (250-1000 mg/kg, p.o.) and baclofen (5-40 mg/kg, p.o.). Under normal conditions, aspartic acid (1000 or 2000 mg/kg, p.o.), glutamic acid (250 mg/kg, p.o.) and baclofen increased blood glucose level; but ascorbic acid, taurine and pantotenic acid did not. These results suggest that the stress-induced hypoglycemia may be due to the decrease in the adrenal cortical function.