OBJECTIVETo investigate the effect of NG-nitro-L-arginine (L-NNA), a nitric oxide synthase (NOS) inhibitor, on the testis cell apoptosis in morphine-dependent rats induced by naloxone and the involved mechanisms.

METHODSForty-eight Wistar rats were randomly divided into a control group, withdrawal group and a therapeutic group. Morphine-dependent rats were given gradually increasing doses of morphine to produce morphine-dependent models, the abstinent syndrome precipitated by naloxone. The inhibiting effect of L-NNA on the abstinent syndrome, and the testis apoptosis, NOS positive cells, calmodulin (CaM) contents, superoxide dismutase (SOD) activity, and glutathione super oxidase (GSHPx) activity of the morphine-dependent rats induced by naloxone were observed and recorded by radioimmunoassay, atomic absorption spectrometry, in situ nick translation (ISNT) and NADPH-d histochemical technique.

RESULTSCompared with the control rats, the function of the somesthetic motor nerves and autonomic nerves was excessive, the apoptosis and NOS positive cells in the testis were significantly increased (P < 0.05 or P < 0.01), the content of CaM and the activity of SOD and GSHPx were obviously decreased in the morphine-dependent rats induced by naloxone. But L-NNA could significantly inhibit the abstinent syndrome, decrease NOS positive cells and apoptosis, and increase CaM content and the activity of SOD and GSHPx in the testis.

CONCLUSIONMorphine dependence can induce testis cell apoptosis, an increase in testis NOS positive cells, a decrease in CaM content and the activity of SOD and GSHPx in the testis. L-NNA has the curative effect on the morphine abstinent syndrome, protects testis cells against apoptosis and improves their involved biochemical indexes.