Streptozotocin-diabetes impairs prolactin binding to Leydig cells in prepubertal and pubertal rats

Prolactin (PRL) binding to Leydig cells in prepubertal and pubertal strepto zotocin (STZ)-diabetic and insulin-treated rats was studied. Prepubertal (3 0-day-old) and pubertal (50-day-old) rats were made diabetic by single inje ction of STZ (120 and 100 mg/kg b.wt, respectively). After 3 days of STZ ad ministration, a group of rats was given insulin injections subcutaneously ( 3 U/100 g b.wt/day in 2 equally divided doses). Animals of prepubertal and pubertal groups were killed on postnatal days 51 and 71, respectively. Age- dependent increase in serum testosterone, PRL levels and PRL receptors on L eydig cells were prevented by STZ-diabetes. Insulin administration partly o r completely prevented these changes. These results suggest that steroidoge nic defects in Leydig cells of prepubertal and pubertal diabetic rats may b e associated with decrease in serum PRL levels and its receptors on Leydig cells. Insulin probably has a role in the maintenance of PRL receptor numbe rs on Leydig cells during pubertal maturation.