Insulin-induced gastric ulcers in the rat

The effects of long-lasting hypoglycemia on male reproductive organs in rats

Glucose has an important role in spermatogenesis. Nevertheless there are few reports in which the effects of long-lasting hypoglycemia on male reproductive organs have been evaluated. Therefore, insulin was administered subcutaneously at 100, 200, and 400 IU/kg to male rats twice a day for one month. This treatment regimen produced plasma glucose levels that rapidly decreased after treatment, with decreased glucose levels lasting for several hours after each administration on the first and final treatment days. During the treatment period, no abnormalities in clinical signs or body weight were observed. No statistically significant differences were noted in the weights of testes, epididymides, prostates and seminal vesicles, or pituitary glands. Histopathological examination revealed that the insulin-treated animals exhibited degeneration of seminiferous tubules in the testes and exfoliation of germ cells in the lumens of epididymides as a secondary change related to the testicular lesions. The incidences of the histopathological findings were found to be proportional to insulin dose. Sperm analysis of the group receiving the highest dosage indicated that the sperm concentration tended to decrease and the incidences of sperm malformations tended to increase. Our results suggest that long-lasting hypoglycemia affects male reproductive organs in rats.

Localization of insulin to gastroenteropancreatic cells in the turtle gastrointestinal tract

Insulin has been localized immunocytochemically to open-type gastroenteropancreatic endocrine cells in sections of Bouin's-fixed upper, middle, and lower intestine from Chrysemys picta, Pseudemys scripta scripta, P. scripta elegans, P. floridana, Sternotherus odoratus, and Trionyx spinifer asper. Radioimmunoassay of extracts of mucosal scrapings from Chrysemys intestine indicates differential amounts of insulin-like immunoreactivity within the intestine (higher amounts in the lower intestine) and in concentrations approximately one-tenth to one-fifth that found in extracts of Chrysemys pancreas. The presence of insulin in the gastrointestinal tract of chelonians represents a major departure from the typical vertebrate condition which is characterized by an absence of insulin from the spectrum of regulatory peptides in the gut.