Behavioral and neurochemical profile of the spontaneously diabetic Wistar BB rat

The overall objective of the present investigation was to examine the behavioral and neurochemical profile of long-term diabetes (2-4 months), in the spontaneously diabetic Wistar BB rat (SDR). This animal model mimics the salient symptomatology of Type-I diabetes in man and circumvents confounds attributed to non-specific effects encountered in the chemically-induced models of diabetes. The first set of experiments were designed to investigate the effects of dopamine (DA) agonists and circadian cycle on the following spontaneous behaviors: locomotion, floor activity, rearing frequency and rearing duration. The results demonstrated that the SDR manifests (1) a blunted response to d-amphetamine (0.5-3.0 mg/kg; i.p.), and (2) lower levels of spontaneous locomotor and rearing activity in the latter part of the dark cycle, particularly at the transition of the cycle from dark to light. The next set of experiments assessed the status of brain catecholamine and metabolite levels in the insulin maintained and deprived SDR. The regional catecholamine and metabolite levels of the insulin-maintained SDR were not significantly different from those of the non-diabetic or the genetically distinct controls. However, the cessation of insulin administration to the SDR for 4 days resulted in significant increases in the levels of norepinephrine in the cortex and the hypothalamus, DA in the hippocampus, and homovanillic acid in the striatum.