Ovarian hormones and high‐fat diet duration distinctively modulate hypothalamic chemokine profile

Abstract

Excessive intake of saturated fats triggers inflammation in the hypothalamus, a key regulator of energy balance. In the chronic phase of this inflammatory response, bone marrow‐derived and lymphoid cells are chemoattracted to this region, partially mitigating high‐fat diet (HFD)‐induced metabolic impairments. In rodents, the onset and magnitude of this inflammation differ between males and females, reflecting sex‐specific patterns of metabolic regulation. However, how the hypothalamic chemokine profile evolves during HFD‐induced inflammation, and whether it is influenced by biological sex, remains unclear. Here, male and female C57BL/6J mice were fed a HFD for 1, 3, 14, or 28 days. To isolate the role of ovarian hormones in modulating hypothalamic chemokine profile, we also analyzed ovariectomized (OVX) females with or without estrogen replacement. Quantitative polymerase chain reaction‐based expression analysis revealed that most chemokines and their receptors were transiently modulated in the hypothalamus during the course of the HFD exposure, showing reduced levels in the acute phase and normalization during the chronic phase. Despite the modest sex‐dependent effects observed, messenger RNA expression of the chemokine receptor C–X–C motif chemokine receptor 3 (CXCR3) was significantly higher in females than in males after 14 and 28 days of HFD, suggesting faster recruitment of CXCR3 ⁺ immune cells that may contribute to female protection against metabolic dysfunction. Females lacking ovarian hormone production displayed increased hypothalamic expression of Cxcr3 and Ccl2 . Only Cxcr3 expression was partially normalized by estradiol treatment, suggesting that non‐estrogenic ovarian factors may play a role in modulating specific chemokine signaling pathways. Together, our findings show that hypothalamic chemokine signaling is dynamically and transiently regulated throughout the phases of HFD‐induced inflammation, with Cxcr3 modulation by HFD and ovarian hormones contributing to sex‐specific resilience against metabolic inflammation.