Peripubertal hyperinsulinemia upregulates phosphatidylinositol 3-kinase/akt pathway in rat ovaries.

OBJECTIVE

Polycystic ovary syndrome (PCOS) usually develops during peripuberty and is often associated with hyperinsulinemia. Paradoxically, hyperinsulinemic patients with PCOS develop peripheral insulin resistance but retain ovarian insulin sensitivity. We investigated the effect of peripubertal hyperinsulinemia on insulin signaling pathways in rat ovaries.

METHODS

Hyperinsulinemia was induced in peripubertal female rats by infusing insulin (0.14 IU/day) for 4 weeks. Control animals received normal saline. At autopsy, trunk blood was collected for insulin assay; ovaries were collected for examining the effect of hyperinsulinemia on phosphatidylinositol 3-kinase/Akt (PI3-K/Akt) and mitogen-activated protein kinase (MAPK/ERK1/2) pathways.

RESULTS

Compared with control, ovarian protein levels of total Akt, phospho-Akt, and phospho-glycogen synthase kinase-3beta were upregulated and phospho-phosphatase and tensin homolog was downregulated in hyperinsulinemic animals. The MAPK/ERK1/2 pathway was unaffected.

CONCLUSIONS

Peripubertal hyperinsulinemia upregulates the PI3-K/Akt pathway in rat ovaries. Ovarian insulin sensitivity in hyperinsulinemic patients with PCOS is potentially retained by this mechanism.