Social isolation induces behavioral and emotional changes in human beings and animals. Cho et al. (2017) conducted a study to determine the treadmill exercise effect on depression. This study used female and male Sprague-Dawley socially isolated rat pups. Researchers ensured that the procedures used aligned with the National Health Institute and Korean Medical Sciences Academy. The delivery day was designated day 0, and the rats were categorized into four. The groups included: the social isolation group, the control group, and the exercise and social isolation and exercise group (Cho et al., 2017). The social isolation group’s rat pups were housed individually. On the contrary, the exercise and the control groups’ rat pups were housed under standard conditions and with their mothers. Each day, every rat pup was injected with 5-Bromo-2′-deoxyuridine (50-mg/kg BrdU) (Cho et al., 2017). This was conducted sixty minutes from postnatal day 21 to 26 before starting the treadmill exercise.
The researchers used different methods and materials to conduct the study. In the treadmill exercise protocol, the rat pups ran on the treadmill once a day for half an hour from the 21 st to the 34 th day. Additionally, a forced swimming examination was conducted to determine the rat pups’ degree of depression. Tissue preparation happens by anesthetizing the animals with Zoletil 50 to start the sacrificial process (Cho et al., 2017).
A response absence prompted the researchers to use 50 mM phosphate-buffered saline (PBS) and 500 mM phosphate buffer. Cho et al. ( 2017) expound that the researchers also aimed to evaluate tryptophan hydroxylase (TPH)-positive and 5-hydroxytryptamine (5-HT)-positive cells in the dorsal raphe by conducting immunofluorescence. Moreover, BrdU immunohistochemistry was performed to identify the hippocampal dentate gyrus newly generated cells. Cho et al. (2017) explain that western blot analysis was performed using a tyrosine kinase B (TrkB) and BDNF. The transfer of proteins to nitrocellulose was performed, and an anti-BDNF rabbit polyclonal antibody helped to probe the blots. An enhanced chemiluminescence detection kit helped to detect immunoreactivity. One-way analysis and Duncan’s post hoc examination evaluated the groups’ differences.
The depression state evaluation was examined by forced swimming. The social isolation group’s resting time was longer than the control group. The treadmill exercise significantly decreased the resting time of the social isolation group rat pups. Additionally, the control group’s mobility time was longer than the social isolation. In addition, the treadmill activity helped increase the social isolation group rat pups’ mobility. Corresponding to Cho et al. (2017), this group’s 5-HT-positive and TPH-positive cell numbers were lower than the control group. Also, the social isolation and exercise groups’ TPH-positive cells were higher compared to the social isolation one.
Moreover, higher photomicrographs of BrdU-positive cells were witnessed in the control group compared to the social isolation one. This exercise played a crucial role in enhancing the social isolation group rat pups’ TrkB and BDNF expression (Cho et al., 2017). Therefore, the researchers concluded that treadmill exercise increases neuronal generation by ameliorating the symptoms of stress from social isolation.
In summary, physical activity is an essential behavioral intervention strategy because it enhances the generation of new cells. Additionally, exercise helps in hippocampal dentate gyrus survival. The Increased neurogenesis is closely related to a depressive state ameliorating effect. Physical activity plays a significant role in humans and animals because it has an antidepressant effect on them. There exists a close connection between hippocampal neurogenesis and antidepressant medications. As a result, hippocampal neurogenesis significantly impacts the effects of antidepressants.