Thaxter, K.A.; Young, Lauriann E.; Parshad, Omkar; Young, Ronald E.; Addae, J.
Author Affiliation, Ana.
Department of Basic Medical Sciences
Effects of neem as revealed by somatosensory evoked potentials and the elevated x maze
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Date of Publication
We previously reported significant decreases in spontaneous motor activity in rats treated with neem (Azadirachta indica). We further studied this sedative action of neem using intracortical somatosensory evoked potentials (SEPs) and behaviour in an elevated X maze to differentiate an anxiogenic effect from motor deficiency. In SEP studies, urethane anesthetized Wistar rats (200-250g) were given a steriodal extract of neem leaf (0.07 or 7 mg/kg i.p.), vehicle (1% DMSO/saline), diazepam (1 mg/kg) or no treatment (baseline). Amplitude of wave N1 increased (p<0.05) in neem versus (vs) vehicle treated rats and decreased (p<0.05) in diazepam treated rats vs baseline. For behavioral studies, rats (100-150g) received neem, vehicle, diazepam (2mg/kg i.p.), sham injection or no treatment (baseline) 1 hr before a 5-min exploration of the X maze. Open arm entries (%) indicated anxiogenesis after high dose (p<0.05; 7mg/kg vs 0.07mg/kg neem), and anxiolysis after low dose (0.07 mg/kg). The high-dose rats deposited more fecal boli in the maze (p<0.05) vs the vehicle group. Measures of total and closed arm entries showed that neem treatment did not significantly affect ability to explore the maze. Both doses of neem also increased rearing (p<0.05 vs vehicle). Sham injected rats performed more stretched-attended postures in closed areas of the maze than baseline rats (p<0.05), indicating anxiogenesis due to the injections. Diazepam vs sham injection reduced both rearing and closed arm entries (p<0.05), but increased both % open arm entries and residence time (p<0.05) without affecting total entries. Results suggest that the neem extract has a dose-related effect on anxiety and locomotory/orienting activity of rats in an elevated X maze. At high dose, 7mg/kg neem has cortical stimulatory and anxiogenic effects. CNS correlates may include serotonin and noradrenaline.....