Protective role of an Indian herb, Moringa oleifera in memory impairment by high altitude hypoxic exposure: Possible role of monoamines

The influence of medicinal plants on hypobaric hypoxia was assessed by behavioral, electroencephaloghaphic study and brain monoamines estimation. Holtzman strain rats were divided into 3 groups: Control, hypobaric hypoxia and Moringa oleifera (MO) treated hypobaric hypoxia. Rats exposed to hypobaric hypoxia 412.0mm Hg (18,000 ft) for 21 days showed loss of memory as evidenced by increase in latency period and decrease in number of correct choices in daily trials in radial maze learning task. Biochemical studies showed decrease in norepinephrine (NE) level in cerebral cortex (CC), cerebellum (CB), midbrain (MB) and increase in caudate nucleus (CN). Dopamine (DA) level was decreased in CC and CN but increased in CB and MB, while serotonin (5-HT) level was decreased in CC but increased in CB, MB, and CN. The EEG studies showed persistent, high voltage fast wave discharges with a few β waves. Pretreatment with MO leaf extract (250 mg/kg), hypobaric hypoxic group showed an increase in correct choices and decrease in latency period. The EEG studies showed abolition of high voltage fast wave discharges and increase in β and a waves. NE level was significantly increased in CB and MB and decreased in CN whereas 5-HT level was decreased in CB and MB while increased in CN. The results suggest that MO improves maze-learning task possibly by specific brain monoamines on exposure to hypobaric hypoxia simulating at high altitude.