Involvement of oxidative stress and pro-inflammatory cytokines in copper sulfate-induced depression-like disorders and abnormal neuronal morphology in mice.

Epidemiological studies have implicated copper as one of the key environmental risk factors for the pathogenesis of depression. However, the precise mechanism by which copper contribute to the genesis of depression particularly the involvement of oxidative stress-driven neuroinflammation is yet to be fully investigated. Thus, this study was designed to evaluate the effects of copper sulfate (CuSO) on depression-like behaviors and the role of oxidative stress and pro-inflammatory cytokines in mice. Forty male Swiss mice were distributed into control and three test groups (n = 10), and were treated orally with distilled water (10 mL/kg) or CuSO (25, 50 and 100 mg/kg) daily for 28 days. Afterwards, the tail suspension, forced swim, and sucrose splash tests were used for the detection of depression-like effects. The animals were then euthanized and the brains were processed for the estimation of biomarkers of oxidative stress and pro-inflammatory cytokines (tumor necrosis factor-alpha and interleukin-6). The histomorphological features and neuronal viability of the prefrontal cortex, hippocampus and striatum were also determined. Mice exposed to CuSO displayed depression-like features when compared with controls. The brain concentrations of malondialdehyde, nitrite and pro-inflammatory cytokines were elevated in CuSO-treated mice. Mice exposed to CuSO also had reduced brain antioxidant status (glutathione, glutathione-s-transferase, total thiols, superoxide-dismutase and catalase), as well as altered histomorphological features, and decreased population of viable neuronal cells. These findings suggest that CuSO increases oxidative stress and pro-inflammatory cytokines to elicit depression-like effects in mice.