Oral Supplementation of Indole-3-acetic Acid Alleviates High-Fat-Induced Obesity by Activating the Gpha2-Mediated Thyroid-Stimulating Hormone Pathway

further confirmed that IAA directly suppresses de novo fatty acid biosynthesis and triacylglycerol assembly. Mechanistically, IAA upregulated hepatic Gpha2 expression, thereby activating the TSH-THR-PGC-1α-PPARγ signaling cascade and concomitantly repressing key lipogenic genes (Fasn, Acaca, and Srebp-1c). Collectively, these findings position IAA as a promising microbiota-derived metabolite with substantial preventive and therapeutic potential for obesity and related metabolic disorders.