This study assessed the effects of gonadectomy on stable metabolites of nitric oxide and major enzymes involved in antioxidant defense in various regions of male and female rat brain. Male and female Sprague Dawley rats were gonadectomized under anesthesia; 3 weeks following surgery rats were decapitated, brains rapidly removed and dissected (cortex, hippocampus, corpus striatum, midbrain and cerebellum); naïve animals of each sex were included as controls. Nitrite/nitrate ($NO_2$/$NO_3$) levels, and catalase (CAT) and superoxide dismutase (SOD) activities were determined in tissue homogenates. The results show that female sex hormones affect the parameters studied and indicate that the basal sex differences de-picted do not necessarily result from the primary effects of sexually dimorphic gonadal hormonal influences. The regional variation implies that the observed sex differences in $NO_2$/$NO_3$ levels may be secondary to differences in central neurotransmission systems such as the glutamatergic or the dopaminergic.