Effects of colostrum serum on the serotonergic system in the dorsal raphe nuclei of exercised rats

The central fatigue hypothesis suggests that exhaustion, or the maximum level of exercise, induces excessive stress and increases serotonin concentrations in the brain, which in turn decreases central nervous system (CNS) function and induces fatigue. Our aim was to determine the effects of colostrum serum on the serotonergic system in the dorsal raphe nuclei during exhaustive exercise. Animals were randomly divided into five groups: control, exercise, exercise and treatment with 50, 100, and 200 mg/kg of colostrum serum. The rats in the colostrum serum treatment groups were fed colostrum serum at three different doses of 50, 100, and 200 mg/kg per day for seven days. The rats in the control and exercise groups received water by oral gavage once per day for seven days. The time to exhaustion in response to treadmill running increased after treatment with colostrum serum. These results show that exhaustive exercise led to over activation of the serotonergic system in the dorsal raphe nuclei, and that treatment with colostrum serum suppressed of the exercise-induced expression of tryptophan hydroxylase (TPH) and serotonin (5-HT). The results also indicated that exhaustive exercise induced 5-HT1A autoreceptor and serotonin transporter (5-HTT) overexpression in the dorsal raphe nuclei, and that colostrum serum treatment suppressed exhaustive exercise-induced 5-HT1A and 5-HTT expression in the dorsal raphe nuclei. The most effective dose of colostrum serum was 100 mg/kg. Overall, our study suggests that colostrum serum has positive effects on exercise performance and recovery by increasing the resistance to fatigue.