Investigation of Effects of Two Chronic Stress Protocols on Depression-Like Behaviors and Brain Mineral Levels in Female Rats: an Evaluation of 7-Day Immobilization Stress

Abstract

We aimed to investigate the effects of two different chronic immobilization stress protocols on depression-related behaviors and brain mineral levels. Adult female Wistar albino rats were divided into 3 groups as follows (n = 10/group): control, immobilization stress-1 (45 min daily for 7 days), and immobilization stress-2 (45 min twice a day for 7 day). Stress-related behavior was evaluated by means of the forced swimming test (FST) and open field test (OFT). Minerals were analyzed using an inductively coupled plasma mass spectrometer. In the FST, swimming and immobility were significantly lower in the immobilization stress-1 and immobilization stress-2 groups. The climbing duration of the immobilization stress-2 group was higher than the control group. In the OFT, percentage of time spent in the central area was significantly lower in the immobilization stress-1 and immobilization stress-2 groups. Values of latency to center area, rearing, and grooming did not significantly differ between groups. In the immobilization stress-1 group, zinc was lower, and iron, copper, and manganese were higher than the control group. In the immobilization stress-2 group, copper and manganese were higher, and phosphate was lower than the control group. Our results showed that depression-related behaviors were more dominant in the immobilization stress-1 group. A decrease in the brain zinc level was valid only for the immobilization stress-1 group. These results point to the role of low brain zinc levels in the pathophysiology of depression.