Yusra Ahmad

Metformin is a widely prescribed antidiabetic agent with pleiotropic effects extending beyond glycemic control, including anti-inflammatory and antioxidant actions. However, its impact on cytokine signaling and ferroptosis-related pathways in brown adipose tissue (BAT) remains poorly characterized. Here, we examined the transcriptional and metabolic responses to metformin in brown adipocytes and in a diet-induced obesity model. Differentiated brown adipocytes were treated with metformin and analyzed by RNA sequencing and RT-qPCR. C57BL/6 male mice fed a high-fat diet (HFD) were administered metformin to assess systemic metabolic parameters and BAT-specific responses, with validation by histology, RT-qPCR, and Western blot. Transcriptomic profiling identified differentially expressed genes enriched in cytokine–cytokine receptor interaction and ferroptosis-related KEGG pathways. Metformin modulated the expression of multiple inflammatory cytokine genes and upregulated antioxidant and ferroptosis defense-related genes, including the glutathione biosynthesis genes Gclc and Gclm, together with Hmox1, Gpx4, Nfe2l2 (Nrf2), and Slc7a11. Among these, Gpx4 showed the most consistent upregulation across mRNA and protein levels in BAT. In HFD-fed mice, metformin improved glucose tolerance and elevated the expression of antioxidant and ferroptosis-related genes in BAT, consistent with the in vitro findings. Together, these results indicate that metformin coordinately modulates antioxidant and ferroptosis defense-related gene expression in BAT, suggesting a tissue-protective transcriptional program under metabolic stress. Our findings identify candidate immunometabolic and ferroptosis-related targets of metformin in BAT and provide a basis for further mechanistic investigation of its tissue-specific actions beyond glycemic control.

The ketogenic diet (KD) is characterized by minimal carbohydrate, moderate protein, and high fat intake, leading to ketosis. It is recognized for its efficiency in weight loss, metabolic health improvement, and various therapeutic interventions. The KD enhances glucose and lipid metabolism, reducing triglycerides and total cholesterol while increasing high-density lipoprotein levels and alleviating dyslipidemia. It significantly influences adipose tissue hormones, key contributors to systemic metabolism. Brown adipose tissue, essential for thermogenesis and lipid combustion, encounters modified UCP1 levels due to dietary factors, including the KD. UCP1 generates heat by uncoupling electron transport during ATP synthesis. Browning of the white adipose tissue elevates UCP1 levels in both white and brown adipose tissues, a phenomenon encouraged by the KD. Ketone oxidation depletes intermediates in the Krebs cycle, requiring anaplerotic substances, including glucose, glycogen, or amino acids, for metabolic efficiency. Methylation is essential in adipogenesis and the body’s dietary responses, with DNA methylation of several genes linked to weight loss and ketosis. The KD stimulates FGF21, influencing metabolic stability via the UCP1 pathways. The KD induces a reduction in muscle mass, potentially involving anti-lipolytic effects and attenuating proteolysis in skeletal muscles. Additionally, the KD contributes to neuroprotection, possesses anti-inflammatory properties, and alters epigenetics. This review encapsulates the metabolic effects and signaling induced by the KD in adipose tissue and major metabolic organs.