Alterations of pancreatic islet size and growth following substantia nigra lesions in the rat.

Lesions of certain autonomic centers in the brain are known to alter feeding behavior, body weight, and influence the morphology and function of the pancreatic islets. Because marked reductions of food intake and body weight have been reported following damage to the substantia nigra (SN), we investigated the role of this brain area as a potential regulator of the endocrine pancreas. Rats were given bilateral SN lesions using the neurotoxin 6-hydroxydopamine (6-OHDA) at a dose of either 6 or 12 micrograms/hemisphere. Animals given sham lesions served as controls. Both the control and experimental rats were placed on a high-fat diet to minimize lesion-induced reductions of food intake and body weight. Eleven weeks following lesion placement, pancreatic tissues were collected and islet size and volume density were determined using point-counting stereological analyses. At the time of tissue collection, the body weights of control and experimental rats were comparable. Rats with SN lesions exhibited a reduction of pancreatic islet size and volume density, when compared with that of sham-lesioned controls. Moreover, the islets of SN-lesioned rats were comparable in size and volume density to that of younger animals. Hence, these observations suggest that damage to the SN produces an overall impairment of islet growth independently of changes in body weight.