Impaired induction of prolactin secretion from the anterior pituitary by suckling in streptozotocin-induced diabetic rat.

Prolactin (PRL) secretion in streptozotocin-induced diabetic rats postpartum was examined to elucidate the reason for the reduced milk secretion of diabetic mothers. Pregnant Wistar rats were given citrate buffer (control group) or streptozotocin only (DM group) or with insulin (insulin group). Growth of pups was significantly lower in the DM group than in the control group, but similar in the insulin and control groups. Suckling-induced PRL secretion was significantly lower in the DM group than in the control group, and intermediate in the insulin group. TRH-induced PRL secretion was significantly lower in the DM group than in the control group, but the same in the insulin and control groups. Histologically, the mammary glands in the DM group were relatively less developed than those in the control group. The results suggest that reduced milk secretion in diabetic mothers is due to impaired induction by suckling of PRL secretion from the anterior pituitary as well as poor development of the mammary gland.