OBJECTIVE: Insulin resistance is a common feature of both polycystic ovary syndrome (PCOS) and non-insulin-dependent diabetes mellitus (NIDDM); however, the persistent reproductive disturbances appear to be limited to the former, suggesting that insulin resistance in the ovary itself may confer this susceptibility. DESIGN: Prospective study. SETTING: University-affiliated department. PATIENT(S): Forty-four women undergoing IVF treatment, of whom 11 had polycystic ovaries and 33 had normal ovulation (NO). INTERVENTION(S): The various effects and signaling of insulin and insulin-like growth factor-1 (IGF-1) were examined in cultured ovarian granulosa cells treated with troglitazone (1 microg/mL) or with vehicle by reverse transcription-polymerase chain reaction, western blot, and in vitro functional analyses. MAIN OUTCOME MEASURE(S): Glycogen and DNA syntheses, mRNA and protein expression, and cellular localization of insulin/IGF-1 receptors and insulin receptor substrates (IRSs). RESULT(S): There were significant decreases in insulin-stimulated glucose incorporation into glycogen in PCOS cells, which is a metabolic action of insulin. However, IGF-1 stimulation was found to be greater in PCOS cells at all experimental concentrations with respect to thymidine incorporation compared with NO cells, which is a mitogenic action. Troglitazone increased the insulin-induced glycogen synthesis but reduced the IGF-1-augmented responses of DNA synthesis in PCOS cells to the range within those of NO granulosa cells. We then found that troglitazone treatment reversed the expression imbalance between IRS-1 and IRS-2 in PCOS cells. CONCLUSION(S): There is a selective defect in insulin actions in PCOS granulosa cells, which suggests ovarian insulin resistance, and this metabolic phenotype is associated with an enhanced IGF-1 mitogenic potential. Troglitazone could divergently alter expression of various IRS molecules and insulin actions and could be used as an ovarian insulin sensitizer and mitogen/steroidogenic inhibitor in PCOS.
OBJECTIVE:Insulin resistance is a common feature of both polycystic ovary syndrome (PCOS) and non-insulin-dependent diabetes mellitus (NIDDM); however, the persistent reproductive disturbances appear to be limited to the former, suggesting that insulin resistance in the ovary itself may confer this susceptibility. DESIGN: Prospective study. SETTING: University-affiliated department. PATIENT(S): Forty-four women undergoing IVF treatment, of whom 11 had polycystic ovaries and 33 had normal ovulation (NO). INTERVENTION(S): The various effects and signaling of insulin and insulin-like growth factor-1 (IGF-1) were examined in cultured ovarian granulosa cells treated with troglitazone (1 microg/mL) or with vehicle by reverse transcription-polymerase chain reaction, western blot, and in vitro functional analyses. MAIN OUTCOME MEASURE(S): Glycogen and DNA syntheses, mRNA and protein expression, and cellular localization of insulin/IGF-1 receptors and insulin receptor substrates (IRSs). RESULT(S): There were significant decreases in insulin-stimulated glucose incorporation into glycogen in PCOS cells, which is a metabolic action of insulin. However, IGF-1 stimulation was found to be greater in PCOS cells at all experimental concentrations with respect to thymidine incorporation compared with NO cells, which is a mitogenic action. Troglitazone increased the insulin-induced glycogen synthesis but reduced the IGF-1-augmented responses of DNA synthesis in PCOS cells to the range within those of NO granulosa cells. We then found that troglitazone treatment reversed the expression imbalance between IRS-1 and IRS-2 in PCOS cells. CONCLUSION(S): There is a selective defect in insulin actions in PCOS granulosa cells, which suggests ovarian insulin resistance, and this metabolic phenotype is associated with an enhanced IGF-1 mitogenic potential. Troglitazone could divergently alter expression of various IRS molecules and insulin actions and could be used as an ovarian insulin sensitizer and mitogen/steroidogenic inhibitor in PCOS.
Authors: Pradeep P Kayampilly; Brett L Wanamaker; James A Stewart; Carrie L Wagner; K M J Menon Journal: Endocrinology Date: 2010-09-01 Impact factor: 4.736
Authors: Kathryn J Brothers; Sheng Wu; Sara A DiVall; Marcus R Messmer; C Ronald Kahn; Ryan S Miller; Sally Radovick; Fredric E Wondisford; Andrew Wolfe Journal: Cell Metab Date: 2010-09-08 Impact factor: 27.287