Protective Effect of Environmental Enrichment on the Morphology of Neurons in the Motor Cortex of Diabetic and Stressed Rats

Author(s): Narendra Pamidi, Christina Gertrude Yap, Satheesha Nayak B

Background: The present study aimed to evaluate the effects of EE on the morphology of pyramidal neuron at the motor cortex of diabetic and stressed rats.

Methods and materials: Male Wistar rats were grouped into Normal Control (NC), Vehicle Control (VC), Diabetes (D), Diabetes + Stress (D+S), Diabetes + Environmental Enrichment (D+EE) and Diabetes + Stress +Environmental Enrichment (D+S+EE) (n=8). Hyperglycemia was induced in Westar rats using streptozotocin (40mg/kg; ip). Blood sugar levels and body weight was measured at regular intervals to monitor the development of hyperglycemia. All experimental groups were housed in standard cages throughout the experiment. Rats in groups D+S and D+S+EE were transferred into space restrained cages for 6 hours daily. D+S+EE group were transferred into EE cages immediately after the space restrained session for subsequent 6 hours daily. On day 30, all rats were sacrificed and brains were harvested and prepared for rapid Golgi staining protocol. Dendritic branchings and dendritic intersections of the motor cortex neurons were quantitated using a camera lucida attached to Biolux research microscope. Data was analyzed using ANOVA with Bonferroni’s test.

Result: Hyperglycemia was developed in all experimental groups (Blood glucose > 250 mg/dl, p<0.001) on Day 2 post STZ injection. Exposure to EE did not show any evidence in reducing blood sugar levels in D+EE and D+S+EE groups. EE treated groups (D+EE; D+S+EE) exhibited significant prevention (D+EE vs. D: p<0.001; D+S+EE vs. D+S: p<0.001) of body weight reduction on Day 30 in comparison to D and D+S groups. Overall, significantly lower numbers of total apical (p<0.001) and basal (p<0.001) dendritic branching points was observed in groups D and D+S relative to NC group. On the other hand, D+EE and D+S+EE groups demonstrated significantly higher numbers of total apical (p<0