Behavioral evidence of thermal hyperalgesia in non-obese diabetic mice with and without insulin-dependent diabetes.

The non-obese diabetic (NOD) mouse, a model of Type 1 diabetes in humans, has proven useful for the study of genetic, immunologic and epidemiologic aspects of inherited diabetes. Behavioral evidence of hyperalgesia may also be present in the NOD mouse but has not been described. This study examined NOD mice with (NOD+) and without (NOD-) insulin-dependent diabetes, and control strain (ILI) mice for evidence of hyperalgesia to a noxious thermal stimulus. Interestingly, both NOD+ and NOD- mice showed reduced mean hindpaw withdrawal latencies when compared with non-diabetic ILI mice. NOD+ and NOD- mice were also abnormal in their general appearance, activity level, posture, gait and muscle bulk when compared with ILI mice. These findings raise the possibility that hyperalgesia in insulin-dependent NOD mice, or insulin-dependent humans with Type 1 diabetes, may be independent of diabetes and due to a primary disturbance within sensory pathways.