To investigate the testicular oxidative stress and apoptosis status, as well as the sperm functional parameters in streptozotocin (STZ) induced diabetic rats following treatment with rooibos (Aspalathus linearis), honeybush (Cyclopia intermedia) and sutherlandia (Lessertia frutescens) infusions.
Diabetes was induced by injecting fourteen-week-old adult male Wistar rats (250-300 g) with a single intraperitoneal injection of STZ (45 mg/kg body weight). Fifty rats were randomly divided into five groups: the vehicle group received 0.1 M citrate buffer, the diabetic control group received 45 mg/kg STZ, the diabetic+rooibos group received 45 mg/kg STZ + 2.0% rooibos, the diabetic+honeybush group received 45 mg/kg STZ + 4.0% honeybush, and the diabetic+sutherlandia group received 45 mg/kg STZ + 0.2% sutherlandia. Rats were sacrificed 7 weeks after induction of diabetes mellitus. The testes and epididymides were harvested and weighed after induction. Spermatozoa were retrieved from the cauda epididymis for motility, concentration, and morphology analysis, and the testis was used for all biochemical assays. Oxidative stress was determined by measuring malondialdehyde levels, catalase, and superoxide dismutase activities, while apoptotic biomarkers were evaluated by Western blotting assays.
After induction of diabetes, rats in the diabetic control group, diabetic+rooibos group, diabetic+honeybush group, and diabetic+sutherlandia group presented with significantly elevated blood glucose levels as compared with the vehicle group (P<0.001). Rats in the diabetic control group had a reduction in sperm progressive motility, while rats in the diabetic+rooibos group and the diabetic+sutherlandia group displayed an increase in progressive motility as compared with the diabetic control group. The diabetic control animals showed a 40.0% decrease in sperm concentration when compared to the vehicle group, and there were no significant differences in sperm kinematic and speed parameters between the groups. In addition, the percentage of morphologically normal spermatozoa was increased by 13.0%, 16.0%, and 15.0% after treatment with rooibos, honeybush, and sutherlandia, respectively and the rats in the diabetic+infusion groups also displayed an increase in superoxide dismutase activity when compared to the diabetic control group.
Rooibos, honeybush and sutherlandia infusions may partly alleviate diabetes-induced sperm function impairment by reducing oxidative stress.