Background and objective: Polycystic ovary syndrome (PCOS) can be induced in Wistar rats by over production of nitric oxide (NO). This study evaluated the efficacy of naloxone on the breeding characteristics of rats suffering from nitric oxide induced PCOS.

Objective: To evaluate the levels of estrogen, albumin and gonadotropins (luteinizing hormone, follicle-stimulating hormone) as well as the activity of dopamine beta hydroxylase (DAß H) in aged female rats treated with nitric oxide precursor L-arginine and neuronal nitric oxide synthase antagonist L-NAME. Methods: A total of 224 Wistar rats (36 weeks old, weighing 250 g) based on a random sampling were divided into the control and experimental groups after Pap smear test. The control group received only saline (1 mL/kg) intraperitoneally (i.p.). The experiential groups were treated with L-arginine (5, 25 and 50 mg/kg, i.p.) and L-NAME (5 and 25 mg/kg, i.p.) for 3 to 21 days, once a day. Blood samples were taken from the rats and the levels of estrogen and albumin and gonadotropins in the serum were monitored by enzyme-linked immunosorbent assay kit, and the ovaries were examined immunohistopathologically for DAßH activity. Results: L-arginine (5 mg/kg) significantly increased estrogen level (P<0.05), which was associated with DAßH activation in the ovaries. L-NAME reduced this effect when administered prior to L-arginine dose. L-arginine caused no significant change in the levels of luteinizing hormone and follicle-stimulating hormone. Except for the lowest dose of L-arginine in the shortest period, albumin levels significantly decreased in other treatments compared to the control group (P<0.05). Conclusions: L-arginine is likely to reduce postmenopausal problems due to an increased nitric oxide level.