Hemamalini and Muddanna S Rao
Introduction: Centella asiatica (CeA) is an herbaceous perennial creeper, growing in moist soil belonging to the umbelliferae family. Centella asiatica is used as brain tonic in ayurvedic medicine to enhance the neural function, learning and memory. This was correlated with improved dendritic arborization in normal animals. But CeA leaves extract protecting the neurons from neurodegeneration induced by stress was not reported. So in the present study the neuroprotective effect of CeA leaves extract on hippocampal CA3 neurons in restraint stressed mice was investigated first and then the effect of rehabilitation in stress and stress + CeA extract treated mice.
Materials and Methods: Experiment I: Three months old albino mice were divided into four groups. Group (i) was normal control, Group (ii) was saline control, Group (iii) was stress group, Group (iv) was stress + CeA treated group. Group (iii) mice were stressed in a wire mesh restrainer for 6 hours/day for 6 weeks. Group (iv) mice were also stressed like group (iii) but they received orally CeA leaves extract throughout the stress period. After 6 weeks, brain was removed, hippocampus was dissected and processed for Golgi staining. Hippocampal neurons were traced using camera lucida focused at high magnification. The concentric circle method of Sholl was used to quantify the dendrites.
Experiment II - Rehabilitation experiment - done in the same manner as mentioned above followed by 30 days of rehabilitation in the normal laboratory conditions after the last dose of extract.
Result: There was significant decrease in the number of dendritic spines, dendritic branching points and dendritic intersections in the hippocampal CA3 neurons in group (iii) both in experiment I and experiment II even after 30 days after rehabilitation. However, there was significant increase in group (iv) which was subjected to restraint stress and treated with CeA leaves extract both in experiment I and after 30 days of rehabilitation (Experiment II).
Conclusion: CeA protected the hippocampus CA3 neurons against the stress induced neurodegeneration. CeA leaves extract caused permanent changes in the dendritic morphology of hippocampal CA3 neurons (Experiment II)..