OR27-08 High-Fat Diet Induces Epigenetic and Metabolic Changes in Kisspeptin Neurons in Association with Obesity and Male Secondary Hypogonadism

Abstract Disclosure: R. Fang: None. R.S. Carroll: None. U.B. Kaiser: None. Background and Objective: The prevalence of male hypogonadism and infertility are increasing in association with the pandemic of obesity and type 2 diabetes (T2D). A bidirectional relationship between kisspeptin (Kiss1) neurons in the hypothalamic arcuate nucleus (ARC) and metabolism is emerging. Kiss1 neuron dysfunction has been reported in male mice fed a high-fat diet (HFD), a model of metabolic disorder-induced hypogonadism. However, the mechanism is not well understood. 5-hydroxymethylcytosine (5hmC), an oxidation product of 5-methylcytosine (5mC) generated by the Ten-Eleven Translocation (TET) family of α-ketoglutarate-dependent dioxygenases, is down-regulated by hyperglycemia via AMPK signaling and glucose oxidation intermediates such as succinate and fumarate. We hypothesize that the porous blood-brain barrier in the median eminence exposes Kiss1 neurons to metabolite changes in the peripheral blood that directly impact the Kiss1 neuron 5hmC methylome and metabolism. Methods: Six-week-old male C57BL6 mice were fed ad libitum standard chow (Purina 5053, 13.2% fat) or high-fat diet (HFD; Research Diets D12492, 60% fat) for 3 months. ARC tissue was collected from chow- and HFD-fed mice and analyzed by RNA-seq and hydroxymethylated DNA immunoprecipitation sequencing (hMeDIP-seq). Results: Mice fed HFD developed obesity (48.3 ± 0.8 vs 29.3 ± 0.7 g, p<0.001) and hyperglycemia (fasting glucose 186.4 ± 4.7 vs 125.8 ± 4.3 mg/dL, p<0.001). Glucose clearance was significantly slower in glucose tolerance and insulin tolerance tests, demonstrating glucose intolerance and insulin resistance. HFD mice had lower T levels (2.1 ± 0.6 vs 6.1 ± 2.0 ng/ml, p<0.05) and sperm counts (0.63 ± 0.04 vs 0.41 ± 0.03 million, p<0.05). LH secretion in response to ip senktide stimulation – but not to ip kisspeptin-10 – was significantly reduced (AUC 51.4 ± 3.3 vs 63.1 ± 7.2, p<0.05). Differentially expressed genes detected by RNA-seq in HFD ARC (676 in total, 1.5 fold change & p<0.05) were enriched in KEGG pathways important for fatty acid metabolism, neuron projection, and synapse formation and maintenance. hMeDIP-seq revealed widespread 5hmC alterations that correlated with gene expression changes. Ectopic TET expression in immortalized ARC Kiss1 neuron cell line restored 5hmC and expression of key metabolic and neuronal genes (Fabp7, Foxo1, Rxra, Dusp1, Fos) that were suppressed in HFD ARC, demonstrating functional importance. Conclusions: Our study demonstrates that Kiss1 neurons are sensitive to diet and metabolic changes, and are key targets of the effects of metabolic disorders. Hyperglycemia-induced 5hmC changes play a key role in regulating Kiss1 neuron metabolism and function, thereby affecting reproduction. These findings provide a new mechanism underlying the cross-talk of Kiss1 neurons and metabolism, independent of upstream inputs from POMC and AgRP neurons. Presentation: Monday, July 14, 2025