Effect of NG-nitro-L-arginine methyl ester on testicular blood flow and serum steroid hormones during sepsis

Production of nitric oxide (NO) via NO synthase (NOS) has been implicated in the regulation of steroidogenesis in normal physiology and septic pathophysiology. The hypothesis that blockade of NOS by NG-nitro-L-arginine methyl ester (L-NAME) would affect testicular blood flow and circulating levels of steroid reproductive hormones was tested. Male Sprague-Dawley rats (350-450 g) were randomized to septic and nonseptic groups. Sepsis was induced with an intraperitoneal (i.p.) injection of a cecal slurry (200 mg/kg in 5 mL 5% dextrose in water (D5W)) in rats, while nonseptic rats received only sterile D5W. The rats (n = 6 per group) were catheterized in the jugular vein, left ventricle (via right carotid artery), and tail artery to determine blood flow and systemic hemodynamics and to collect blood at 24 h after induction of sepsis/sham sepsis. After baseline (24 h post-cecal slurry challenge) measurement, L-NAME (.50 mg/ kg·min) was infused through the jugular vein for 10 min, blood flow was determined using a radioactive microsphere technique, and blood samples were collected. The serum concentrations of corticosterone, progesterone, and testosterone were determined using radioimmunoassay. Plasma concentrations of NO byproducts (NOx) were determined using the Greiss reaction. After 24 h, heart rate, testicular blood flow, and NOx levels were significantly increased, whereas the serum concentration of testosterone was significantly decreased in the septic group as compared with the nonseptic group. However, serum concentrations of progesterone and corticosterone at 24 h after induction of sham-sepsis or sepsis were not statistically different. Infusion of L-NAME significantly reduced the testicular blood flow and serum NOx levels in septic rats as compared with their baseline values. The administration of L-NAME significantly increased the concentration of testosterone in nonseptic and septic rats as compared with their respective basal values. However, testosterone levels in septic rats were still significantly lower than in nonseptic rats. The results of this study indicate that the synthesis of NO through NO synthase may play a role in the regulation of testicular blood flow and the serum levels of testosterone, associated with chronic peritoneal sepsis in the rat