Impact of high-fructose and high-fat diets on hypothalamic insulin signaling in hepatic PKCε heterozygous male mice

Introduction: High fat diets (HFD) have been associated with metabolic complications and obesity. However, increasing evidence shows that high fructose consumption significantly contributes to obesity and metabolic complications, including insulin resistance. Insulin resistance is strongly associated with the development of metabolic syndrome, affecting thousands of people globally. Hepatic Protein Kinase C Epsilon (PKCε) modulates systemic insulin signaling, and its deletion may influence hypothalamic insulin responses, particularly under basal and insulin-stimulated conditions, allowing us to test whether high-fat or high-fructose diets differentially affect these pathways.We aim to investigate the effect of 1-month HFD and high fructose diet (HFrD) on hypothalamic insulin signaling in hepatic PKCε heterozygous male mice. Hypothesis: We hypothesize that hepatic deletion of PKCε in male and female mice on HFrD and HFD will enhance insulin signaling under insulin-stimulated conditions. Methods: Heterozygous LivPKCε (PKCεfl/Δ) male mice were randomly fed either a control diet (Research Diets Inc, RDI D12450J), high fructose diet ( RDI D02022704) or high fat diet (Research Diets D12492) for a month (n=2-4/group). At one month, a subset of these mice was randomly injected with 0.5 U/kg of insulin before being sacrificed, and the hypothalamus tissues were harvested. Protein expression was assessed by western blot analysis in a blinded format for Actin, phosphorylated AKT (p-AKT), AKT, phosphorylated Insulin Receptor (p-IR), and IR. These experiments were replicated to strengthen rigor. Results: Total IR (IR/actin; p< 0.05), total AKT (AKT/actin; p< 0.05) and pAKT (< 0.05) were downregulated in the HFD group compared to the control. Despite this, insulin stimulated p-IR/IR elevation in control mice (p< 0.05). In contrast, AKT/actin was upregulated in the HFrD group compared to the male control mice, especially under insulin conditions. Notably, the HFrD group showed a marked increase in p-IR/IR compared to control male mice (p< 0.05), particularly in the insulin-stimulated state. IR/Actin was upregulated in the HFrD male mice, stronger under insulin conditions. Summary of Data: In the hypothalamus, HFD reduced insulin sensitivity, whereas HFrD showed stronger insulin receptor and AKT responses, especially after insulin stimulation. These findings are consistent with our hypothesis that reducing hepatic PKCε may improve insulin signaling under dietary stress, especially with high fructose rather than high fat.Conclusion: These data demonstrate that dietary modulation of insulin signaling in hepatic PKCε heterozygous mice is also reflected in the hypothalamus, suggesting effects beyond the liver. Ongoing studies in homozygous LivPKCε (Δ/Δ) mice will be important to confirm and extend these observations. Funding Information: This work was supported by the National Science Foundation (NSF #1931045) and the National Institutes of Health (NIH R01DK126892-01A1). This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.