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Hypothalamic Inflammation as a Critical Link Between Metabolic Dysfunction and Impaired Endometrial Receptivity in Obese Polycystic Ovary Syndrome

Sun C, Han Y, Pan Z, Li J, Cheng X, Sun M, Wang Y, Kuang H

Physiological research, 2026

Abstract

Obese polycystic ovary syndrome (PCOS) involves insulin resistance (IR) and impaired endometrial receptivity, potentially driven by hypothalamic inflammation. We investigated if inhibiting the hypothalamic Toll-like receptor 4 (TLR4)/IkappaB kinase beta (IKKbeta) pathway could ameliorate IR and improve endometrial receptivity in an obese PCOS rat model. An obese PCOS rat model was established using letrozole and high-fat diet. Rats were divided into control, PCOS, and three intervention groups: PCOS + intracerebroventricular (i.c.v.) TAK242 (central TLR4 inhibitor), PCOS + intraperitoneal (i.p.) TAK242 (systemic inhibitor), and PCOS + Metformin. We assessed hypothalamic inflammation (TLR4/IKKbeta pathway), metabolic parameters (body weight, OGTT, ITT, HOMA-IR), systemic inflammation, and reproductive phenotypes. Endometrial receptivity was evaluated at pregnancy day 6 by uterine morphology, histology, pinopode development (SEM), and receptivity markers (BMP2, VEGF, IGFBP-1). The obese PCOS model successfully induced hypothalamic inflammation (activated TLR4/IKKbeta pathway), systemic inflammation, profound IR, and impaired endometrial receptivity (poor decidualization, sparse pinopodes, suppressed receptivity markers). Central (i.c.v.) TAK242 administration was most effective, significantly suppressing the hypothalamic TLR4/IKKbeta pathway, attenuating weight gain, normalizing insulin sensitivity, and, critically, restoring endometrial receptivity. Metformin also improved IR…

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