The Effect of High Fructose Diet on Insulin Signaling in Pituitary Tissue of Liver Androgen Receptor Knockout in Female Mice

Abstract

Intro: Insulin resistance affects up to a third of the US adult population and polycystic ovary syndrome affects up to 10% of reproductive-age adult women. Hyperandrogenism in females can increase predisposition to insulin resistance. Andrisse et al 2021 (PMCID: PMC9097557) showed that deleting the liver androgen receptor (LivARKO) prevented female mice from developing hyperandrogenemia (HA)-induced insulin resistance. This study placed female LivARKO mice on a high fructose diet (HFrD) to determine if LivARKO mice demonstrate blunted insulin resistance on HFrD compared to control diet. Hypothesize: It was hypothesized that (unlike HA-LivARKO) HFrD LivARKO female mice would display impaired insulin action (lowered insulin-stimulated p-AKT) in PIT tissue in comparison to the Control diet fed LivARKO female mice, suggesting that liver AR does not play a significant role in regulating HFrD-induced insulin resistance in the pituitary. Methods: Female LivARKO mice were placed on two diets: Control (Con, Research Diets Inc, RDI D12450J) and High Fructose (HFrD, RDI D02022704). After 3 months on the diet, the mice were sacrificed. Half of the mice were given a dose of 0.5 U/kg insulin before sacrificing to investigate the effects of the diets on insulin signaling. Western blots were used to determine protein expression in tissue from the pituitary tissue (PIT). BCA assays were used to standardize the protein concentration in each sample. Insulin action can be measured molecularly by examining p-AKT Serine 473 (positive regulator, Santa Cruz sc-514032). If p-AKT S473 levels increase in the presence of insulin, this indicates that insulin is likely functioning properly in the sample. Results:LivARKO female mice on a control diet (Con) for 3-months administered with insulin displayed a 3-fold significant increase in p-AKT levels in the pituitary compared to LivARKO-Con female mice not injected with insulin (basal), suggesting that LivARKO-Con mice pituitaries were insulin sensitive. However, LivARKO female mice fed a high fructose diet (HFrD) for 3-months and then administered with insulin displayed significantly lowered p-AKT levels in the pituitary compared to basal LivARKO-HFrD female mice and compared to insulin LivARKO-Con, indicating that LivARKO-HFrD female mice were experiencing insulin resistance (lowered insulin sensitivity compared to LivARKO-Con). Interestingly, p-AKT was significantly increased by 2.5 fold in LivARKO-HFrD female mice compared to LivARKO-Con, suggesting that HFrD increased insulin sensitivity in the pituitary. Conclusion: In conclusion, these data suggest that LivARKO indirectly disrupted insulin-stimulated p-AKT in PIT possibly via altering metabolites in the blood. Additionally, HFrD is known to cause insulin resistance, however, it is not known to alter p-AKT levels. Thus, the change in p-AKT levels is presumably associated with the LivARKO. Further research is required on what components of the Control Diet are prompting this difference in insulin action and if it only takes place in the LivARKO mouse model. We would like to thank the National Science Foundation for award # NSF 1931045 and the National Institutes of Health 1R01DK126892-01A1. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.