The impacts of L-citrulline and sildenafil on penile and testicular vascular perfusion pattern, advanced testicular analysis, steroids, and semen picture in normospermic dogs.

This study aimed for the first time to demonstrate the effects of combination of L-citrulline and sildenafil (L-Cit + S) on penile and testicular vascular perfusions in dogs regarding the semen quality and hormonal profile. Normospermic German Shepherd dogs were subdivided into three groups (n = 6/each); control group that injected 1 ml saline, second group subjected to L-Citrulline intravenous injection (L-Cit), and third one administrated oral dose of sildenafil with injected L-Cit (L-Cit + S). Dogs were examined at time points of assessment by hours. Semen collection, blood sampling, hormonal assaying, Doppler evaluation and testicular echo-texture analysis were performed. Testicular colored area (TCA) elevated significantly (P = 0.03) in L-Cit group at 8-120 h compared to other groups. While volume, echogenicity, and heterogeneity were not changed (P ≥ 0.05) among groups. Testicular and penile arteries Doppler indices were decreased (P = 0.01) in L-Cit group from 1 to 48 h with a sharp decrease (P = 0.01) was observed in L-Cit + S group within 1-8 h with a significant (P = 0.01) elevation of peak velocity and blood flow rate within the same hours in the same group. Motility % and sperm concentrations were increased (P = 0.02) at 4 h in third group. Circulating L-Cit levels were increased in second and third groups from 4 to 24 h, while S levels were (P = 0.01) increased from 1 to 4 h only in third group. An elevation of nitric oxide and estradiol levels was observed (P = 0.01) form 1 h in L-Cit + S group compared to other groups, while testosterone levels were increased (P = 0.01) from 1 h but rapidly declined till reach a lowest value at 48 h compared to other groups. Addition of L-citrulline to sildenafil demonstrated a more efficiency in improvement of blood flow, hormonal profile, and semen quality than using sildenafil alone due to the action of L-Cit on nitric oxide.