Assessment of L-Carnitine's effect on semen quality in an experimental varicocele animal model

Introduction . Varicocele is a well-characterized cause of spermatogenic impairment with established mechanisms of testicular tissue damage. Among antioxidants, L-carnitine is the most extensively studied agent for mitigating oxidative stress, optimizing sperm metabolism, maturation, and motility. However, available clinical literature presents conflicting data on the effects of carnitine supplementation on semen parameters. Objective . To evaluate the impact of L-carnitine on semen analysis parameters in an experimental chronic varicocele model. Materials & methods . Fifteen male rabbits were randomized into three groups: Group 1 (intact controls, n = 5); Group 2 (varicocele model without treatment, sacrificed at one-month post-induction, n = 5); Group 3 (varicocele model with L-carnitine treatment for one-month post-induction, n = 5). Varicocele was induced by partial ligation (50 – 67% narrowing) of the left renal vein, combined with daily gonadotropin (300 IU/kg) and 0.2 mL of 1% progesterone solution for 10 days starting 24 hours prior to ligation. L-carnitine was administered intragastrically at 26.15 mg/day (adjusted for rabbit metabolic differences) in Group 3. Semen was analyzed by light microscopy, assessing sperm count and quality. Results . At 14 days post-induction, seminal veins were visible (up to 1.8 mm diameter, no intergroup differences) with confirmed reflux. Mean vein diameter reached 2.1 mm by day 30. Left testis volume progressively declined by 0.6 cm³ (from 0.77 to 0.71 cm³) over 30 days (p > 0.05 across groups). Baseline semen parameters in Group 1 were significantly superior to Groups 2 and 3 (p < 0.05 – 0.01). Total sperm count was 310.2 million (Group 1), 199.3 million (Group 2), and 247.6 million (Group 3). Group 2 parameters were significantly inferior to Group 3: total sperm count (199.3 vs 247.6 million), live forms (68.3% vs 80.6%), PR+NP (61.5% vs 73.4%), PR (48.7% vs 65.4%), and sperm velocity (4 vs 8 μm/s) (p < 0.01). Conclusions . In a chronic varicocele model with persistent injurious stimulus, L-carnitine supplementation significantly improved both quantitative and qualitative semen parameters.