Melatonin prevents sleep deprivation-associated anxiety-like behavior in rats: role of oxidative stress and balance between GABAergic and glutamatergic transmission.

Sleep deprivation (SD) has been shown to induce anxiety-like behavior. Melatonin, an endogenous potent antioxidant, protects neurons from oxidative stress in many disease models. Here we investigated the effect of melatonin against SD-induced anxiety-like behavior and attempted to define the possible mechanisms involved. SD was induced in rats using modified multiple platform model. Melatonin (15 mg/kg) was administered to the rats via intraperitoneal injection. The elevated plus maze test, open field test and light-dark exploration were used to evaluate anxiety-like behavior. Serum corticosterone was measured to determine stress level. Malondialdehyde (MDA) level and superoxide dismutase (SOD) enzyme activity of amygdala and serum were performed to determine the level of oxidative stress. Levels of protein were detected by means of Western blot. The results showed that SD induces anxiety-like behavior, while melatonin treatment prevented these changes. Serum corticosterone also increased with SD but its levels were normalized by melatonin. In addition, melatonin reversed SD-induced changes in MDA and SOD in both of amygdala and serum. The results of Western blot showed that melatonin attenuated the up-regulation of NR2B-containing N-methyl-D-aspartate receptors, GluR1 subunit of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor as well as phosphorylation of GluR1 at Ser831, and Ca/calmodulin-dependent protein kinase II-alpha in SD rats. Meanwhile, melatonin blocked the down-regulation of γ-aminobutyric acid A-alpha-2 receptor. In conclusion, our results suggest that melatonin prevents anxiety-like behavior induced by SD. The possible mechanism may be attributed to its ability to reduce oxidative stress and maintain balance between GABAergic and glutamatergic transmission.