GLUCOSE, INSULIN, AND OPEN-FIELD RESPONSES TO IMMOBILIZATION IN NONOBESE DIABETIC (NOD) MICE

Numerous studies have suggested that stress precipitates type I diabet es. Because stress-elicited hyperglycemia may play a role in this effe ct, we measured the influence of acute immobilization (90 min) upon pl asma glucose and insulin levels in nonobese diabetic (NOD) mice, a spo ntaneous model of type I diabetes. To this end, prediabetic 8-week-old mice of both sexes were compared to age- and sex-matched C57BL/6 cont rol mice. Baseline plasma glucose levels and immobilization-elicited h yperglycemia were both lower in male and female NOD mice compared to t heir C57BL/6 counterparts. However, the maximal effects of immobilizat ion upon plasma insulin (and corticosterone) levels were not different between NOD and C57BL/6 mice. When subjected to a metabolic stressor, such as 2-deoxyglucose-induced neuroglucopenia, both strains responde d with similar increases in plasma glucose levels. This change was ass ociated with hyperinsulinemia, whose amplitude was lower in NOD than i n C57BL/6 females. Lastly, administration of the alpha(2)-adrenergic a gonist, clonidine, elicited a marked increase in plasma glucose levels , whose amplitude was independent of the strain. The results from this study indicate that the two strains differed in their glycemic respon se to a psychological, but not to a metabolic, stressor. Because NOD m ice were found to exhibit increased locomotion when placed for the fir st time in an open field, it is suggested that behavioral differences contribute to this differential effect of immobilization upon circulat ing glucose levels in NOD and C57BL/6 mice.