Effect of Estrogen on Hyperprolactinemia-Induced Glucose Intolerance in SHN Mice

Abstract

The effects of prolactin (PRL) on circulating levels of glucose and insulin, and of estradiol on hyperprolactinemia-induced glucose intolerance of tissues were studied in pituitary-grafted SHN mice (PG mice) and sham-operated controls. Pituitary grafting (PG) decreased blood glucose levels in male mice at 1 and 3 months after the operation but did not alter those in females. PG had little effect on serum insulin levels in males, but increased those in females. In female mice at 2 months after PG, blood glucose levels were significantly higher at 1, 2, and 4 hr after glucose load when compared with those in controls. In contrast, there was no significant difference in blood glucose levels after glucose load between male PG and control mice. The rate at which blood glucose levels decreased was slower in female PG mice than in controls during the 30 min after insulin injection, whereas there was no difference in the rate after insulin injection between male PG and control mice. In ovariectomized (Ovx) mice, no significant difference was found in the blood glucose levels after a glucose load between PG and control groups at 2 months after PG. In Ovx mice treated daily with estrogen, however, a PG-dependent high level of blood glucose was observed after glucose load. These results suggest that hyperprolactinemia decreases glucose tolerance via an increase in insulin resistance in female SHN mice and that estrogen is essential to the expression of the PRL effect.

A Low Carbohydrate, High Protein Diet Slows Tumor Growth and Prevents Cancer Initiation

“…1A), in keeping with previous reports showing that BG drops within 7 days on a ketogenic diet (20). Interestingly, this drop was more pronounced in male mice, consistent with the reported BG buffering effects of estrogen (21). On the basis of these results, we carried out the majority of our studies with male mice.…”

Insulin secretion and GLUT-2 expression in undernourished neonate rats

“…Other hormones such as insulin-like growth factor (IGF) play an important role in the regulation of postnatal development, especially in ␤-cell growth, maturation and function [34], whereas hormones such as prolactin as well as estrogens act in a gender-dependent manner. The induction of an increased insulin secretion by prolactin is observed only in the female [35]. Also, estrogens in other tissues have been described as increasing the expression of GLUT-1 and GLUT-3, enhancing the insulin gene expression and thereby enabling insulin secretion through the blockage of K-ATP channels and modulating Akt (phospholipase B), a principal enzyme in the insulinsignaling process [36][37][38].…”

The antipsychotic drug sulpiride induces insulin intolerance but does not affect body weight in adult male mice

“…Hyperprolactinemia induction by other methods than antipsychotic administration impairs insulin effects on glucose metabolism in mice (Matsuda and Mori 1996), but it is unknown if the molecular mechanisms underlying insulin resistance with sulpiride are the same, so understanding sulpiride direct mechanisms on hyperglycemia and insulin resistance in male mice needs more studies.…”