Intramuscular administration of L-arginine boosts testicular hemodynamics, plasma concentrations of testosterone and nitric oxide in heat-stressed rams

The current study aimed to assess, for the first time, the effects of intramuscular injection of L-arginine (L-arg) on testicular hemodynamics, echogenicity, and plasma concentrations of testosterone, total antioxidant capacity, and nitric oxide (NO) in Ossimi rams. Twelve sexually matured heat-stressed rams were randomly assigned to one of two groups: the L-arg group (n = 6) received 5 mg/kg L-arg dissolved in 2 ml normal saline 0.9%, or the control group (n = 6) received merely 2 ml of normal saline 0.9%. Blood sampling, B-mode ultrasound assessment of the testicular parenchyma, and pulsed-wave Doppler ul-trasound of the testicular artery for both right and left testis were performed immediately before 0 min and 1, 4, 24, 48, 72, and 168 h after L-arg or saline administration. In the L-arg group, resistive index (RI) and pulsatility index (PI) means were significantly lower compared to the control group at 4-168 h post-treatment. Plasma testosterone concentrations were higher (P < 0.05) at 4 h and onward in the L-arg treated compared to the control rams, the same for NO levels however its increase (P < 0.05) was observed as soon as 1 h post-treatment. In L-arg treated rams, NO concentrations were positively correlated to plasma testosterone concentrations (r = 0.7, p < .01), but negatively correlated to both RI and PI (r =-0.8 and-0.6, respectively, p < .01). In conclusion, L-arginine administration enhanced testicular blood flow and increased plasma testosterone and nitric oxide concentrations in heat-stressed rams. (c) 2022 Elsevier Inc. All rights reserved.

Automated summary

This study aimed to investigate the effects of L-arginine administration on testicular hemodynamics, echogenicity, and hormone levels in heat-stressed rams. The results showed that L-arginine treatment significantly improved testicular blood flow, increased testosterone and nitric oxide concentrations in the rams. These findings suggest that L-arginine has potential benefits for improving reproductive function in heat-stressed animals.