Increased anxiety level induced by social crowding stress in rats is not related to changes in the nitrergic system of the brain

In our previous studies, we have shown that stress induced by early social deprivation or total isolation, increases nitric oxide synthase activity in the brain regions of laboratory animals, and possible links between this phenomenon and stress-induced psychoemotional disturbances have been discussed. In the present study, we studied the effects of chronic psychosocial stress (housing under crowding conditions for 6 weeks) on the anxiety behavior and the indices of nitrergic system and intensity of free radical-mediated processes. Stress significantly increased anxiety levels, primarily influencing the exploratory components of animal behavior. Nitric oxide synthase activity and the levels of nitric oxide stable metabolites did not differ in the cerebral cortex, hippocampus, striatum and cerebellum of the control and stressed rats. Stress moderately increased the content of lipid peroxidation products in the cerebellum, whereas the levels of protein- and nonprotein thiol groups remained unchanged. Thus, the increased anxiety level in rats subjected to a long-term crowding was not accompanied by changes in the nitrergic system in the brain.