Glycerol supplementation attenuates testicular inflammation and miRNA dysregulation in obese rats.

Obesity-associated male reproductive dysfunction is increasingly linked to metabolic imbalance, testicular inflammation, advanced glycation end-product/receptor (AGE/RAGE) activation, and microRNA dysregulation. This study investigated whether glycerol supplementation modulates these pathways in high-fat diet (HFD)-induced obese rats. Adult male rats were allocated into four groups (n = 6 per group): control, HFD (8-week induction), glycerol (800mg/kg, 45 days), and HFD + glycerol. Body weight, testis weight, gonadosomatic index and testicular histopathology (Johnsen score, tubular differentiation index, spermiogenesis index) were assessed, together with serum glucose and triglycerides, testicular mRNA expression of RAGE, nuclear factor kappa B (NF-κB), interleukin-1 beta (IL-1β), interleukin-8 (IL-8), miR-143, miR-155 and miR-146a by qRT-PCR, and protein expression of AGE, tumor necrosis factor alpha (TNF-α), IL-1β and NF-κB by immunohistochemistry. HFD feeding increased serum glucose and triglycerides, upregulated RAGE, NF-κB, IL-1β, IL-8, miR-143 and miR-155, reduced miR-146a expression, and increased AGE, TNF-α, IL-1β and NF-κB immunopositivity. HFD also markedly reduced testis weight, gonadosomatic index and all three histological indices. Glycerol alone produced no adverse metabolic, inflammatory or histological alterations. In HFD-fed rats, glycerol significantly reduced serum triglycerides, normalized RAGE, NF-κB, TNF-α, IL-1β and miR-146a transcript responses, decreased AGE accumulation and inflammatory protein immunopositivity, partially corrected miR-143, restored absolute testis weight to control-comparable values, and substantially improved testicular histoarchitecture. However, serum glucose improved only near-significantly, miR-155 was unchanged, and histological indices and inflammatory protein immunopositivity did not return to control levels. Glycerol supplementation therefore attenuates, but does not completely reverse, obesity-associated testicular inflammatory dysregulation and structural impairment.