Neurotoxic effects of type II-diabetes mellitus and the possible preventive effects of olive leaves supplement in male rats.

Background: Diabetes mellitus (DM) is a common metabolic disorder with well-known serious secondary complications. It is also associated with central nervous system damage. This damage is characterized by impairments in brain functions, with neurochemical and structural abnormalities.

Aim: The study was conducted to clarify the neuroprotective effects of olive leaf supplements on the brain and brain histological structure of diabetic adult rats.

Methods: Thirty adult male rats were allocated into three groups, the first group (CC), received an oral supplement containing olive leaves supplements (OLS) and served as a control; in the other group , DM was induced in these animals and left for 40 days; and the third group was DM+OL, which induced DM, then treated with oral OLS for 40 days. The investigation included serum glycemic index measurements, in addition to the level of malondialdehyde (MDA), glutathione (GSH), dopamine (DOP), acetylcholinesterase (AchE) in brain tissue, and histopathology of brain and pancreas.

Results: We demonstrated a significant increase in glycemic index measurements in diabetic groups (DM, DM+OL) at the beginning of a trial; however, the same parameters were significantly decreased after treatment with OLS in only the DM+OL group after 40 days. The study also showed differences in the levels of MDA, and GSH, in the diabetic groups, which returned to normal levels after being treated with OLS. Moreover, AchE and DOP exhibited a significant decline in diabetic rats. However, OLS induced a considerable rise in these neurotransmitters after treatment with it in the DM+OL group. The histopathological section of the pancreas and brain showed histopathological changes in DM groups; whereas, the tissue was shielded from chemical damage from DM by the OLS treatment in DM+OL animals.

Conclusion: Overall, diabetes impairs glucose hemostasis by affecting glucose concentration, insulin level, and insulin resistance. However, olive leaf supplements restored the glucose hemostasis close to normal in diabetic rats. Furthermore, diabetes affects neurotransmitters by increasing the level of oxidative stress in brain tissue, and brain cell damage. Nevertheless, olive leaf supplements can ameliorate DM harmful effects by retrieving the normal oxidative environment in the brain.