The Ameliorative Impact of Centella asiatica on the Working Memory Deficit in Streptozotocin-induced Rat Model of Alzheimer Disease

Alzheimer disease (AD) is a complex neurodegenerative disorder with a progressive nature leading to neural damage and cognitive and memory deficit. The present study investigated the neuroprotective effects of Centella asiatica (CA) in Streptozotocin (STZ)-induced rat model of memory impairment and neuronal damage.

The intracerebroventricular infusion of STZ (3 mg/rat) or saline (as the vehicle) was performed on days 1 and 3. CA (150 and 300 mg/kg/d) was administered through oral gavage for 21 days after model induction. We used the Y-maze test to assess the working memory-related performances of animals. Rats were then sacrificed, and their hippocampi were harvested for evaluation of neuronal density in the cornu ammonis (CA1, CA2, CA3) and Dentate Gyrus (DG) regions using stereology technique.

The intracerebroventricular infusion of STZ caused significant working memory impairment demonstrated in the Y-maze apparatus, with a significant decrease in alternative behavior compared to control animals (40.67±2.04 vs 73.00±1.88, P<0.0001). Oral administration of CA (150 and 300 mg/kg each day) for 21 days significantly improved STZ-induced working memory deficit (55.33±3.34 and 57.17±3.81 vs 40.67±2.04, P<0.013, P<0.004, respectively). Furthermore, 21 days of consecutive administration of CA significantly ameliorated STZ-induced neuronal loss in the CA1, CA2, and DG subfields of the hippocampus. 

Overall, these data demonstrate that CA increases neuronal density and improves cognitive impairment in the STZ-induced rat model of AD, thereby having promising therapeutic potential for neurodegenerative disorders. Accordingly, further studies are needed to determine the exact molecular mechanism of CA protective effects in brain disorders, particularly AD.