Age-related changes of neurites in Meissner corpuscles of diabetic mice

Light touch and low-frequency vibration sense deteriorate during the development of diabetic neuropathy. As Meissner corpuscles are mechanoreceptors that respond to these sensations, this study explored the structural changes of neurites in Meissner corpuscles of diabetic mice C57BL/Ks(db/db). We evaluated silver impregnated neurites from forepaw digital pads from 46 diabetic and 46 nondiabetic female mice which ranged in age from 2.5 to 17 months. Light microscopically, neurites from diabetic mice were less coarse, less tortuous, and exhibited decreased varicosity and decreased corpuscle size compared with those from nondiabetic mice. Number of corpuscles per area and neurite intraepidermal continuations showed a statistically significant decrease with age and with diabetes. Projected area and width of neurites, measured within a fixed interval on camera lucida tracings, showed both a statistically significant increase with age and a decrease with diabetes. Neurite complexity was unchanged between diabetics and nondiabetics. These findings suggest that axonal dwindling, a characteristic of peripheral nerves in diabetes, extends to the receptors and occurs throughout the lifespan of the mouse.