The effect of chronic stress and obesity on sperm quality and testis histology in male rats; a morphometric and immunohistochemical study.

Abstract

Stress and obesity lead structural and functional abnormalities in many organs. This research investigated the effect of these two risk factors on sperm parameters and histologic structure of testis in rat model. Twenty-four male rats were divided into four groups with six rats in each group as control, stress, obesity, and stress-obesity groups. The rats of obesity and stress-obesity groups were fed high-fat diet for 12-week and obesity was created. Control and stress groups were given standard rat chow for the same time. Through last 4-week, stress and stress-obesity groups were applied to chronic mild stress procedure. At the end of the experiment, epididymal sperm was collected from vas deferens and testes were harvested from sacrificed animals. Sperm samples were evaluated in terms of concentration and motility by using Makler Chamber. Sperm smears were stained with Eosin-Y stain for morphological evaluation, and also histochemically for GABA transporter-1 (GAT1) expression assessment. Testis sections were dyed with Hematoxylin-Eosin and Johnsen scores were assessed. GAT1 expression was detected in testis sections by immunohistochemistry, and TUNEL method was used for determining apoptosis in testis. In comparison with the control samples in stress, obesity, and stress-obesity groups sperm concentration and motility decreased, and also the number of sperm with abnormal morphology increased. Stress, obesity, and stress-obesity groups showed a significantly decreased in sperm concentration and motility in comparison with the control group, and also in these groups had significantly increased number of abnormal sperm compared to control. Additionally, the testicular structure was deteriorated, and Johnsen scores decreased. And also GAT1 expression and apoptosis were prominent. These negative results, especially, testicular weight, sperm concentration, and Johnsen score were more observed in the stress-obesity group. Stress and obesity may induce male infertility by disrupting both sperm quality and testis histology. When stress and obesity are coexisting, these adverse effects are more severe. And also, increased GAT1 expression may be associated with these effects.