Enhancement of basolateral amygdaloid neuronal dendritic arborization following Bacopa monniera extract treatment in adult rats

Abstract

OBJECTIVE:In the ancient Indian system of medicine, Ayurveda, Bacopa monniera is classified as Medhya rasayana, which includes medicinal plants that rejuvenate intellect and memory. Here, we investigated the effect of a standardized extract of Bacopa monniera on the dendritic morphology of neurons in the basolateral amygdala, a region that is concerned with learning and memory.METHODS:The present study was conducted on 2½-month-old Wistar rats. The rats were divided into 2-, 4- and 6-week treatment groups. Rats in each of these groups were further divided into 20 mg/kg, 40 mg/kg and 80 mg/kg dose groups (n = 8 for each dose). After the treatment period, treated rats and age-matched control rats were subjected to spatial learning (T-maze) and passive avoidance tests. Subsequently, these rats were killed by decapitation, the brains were removed, and the amygdaloid neurons were impregnated with silver nitrate (Golgi staining). Basolateral amygdaloid neurons were traced using camera lucida, and dendritic branching points (a measure of dendritic arborization) and dendritic intersections (a measure of dendritic length) were quantified. These data were compared with the data from the age-matched control rats.RESULTS:The results showed an improvement in spatial learning performance and enhanced memory retention in rats treated with Bacopa monniera extract. Furthermore, a significant increase in dendritic length and the number of dendritic branching points was observed along the length of the dendrites of the basolateral amygdaloid neurons of rats treated with 40 mg/kg and 80 mg/kg of Bacopa monniera (BM) for longer periods of time (i.e., 4 and 6 weeks).CONCLUSION:We conclude that constituents present in Bacopa monniera extract have neuronal dendritic growth-stimulating properties.

A bacosides containing Bacopa monnieri extract alleviates allodynia and hyperalgesia in the chronic constriction injury model of neuropathic pain in rats

“…This study has demonstrated that treatment with Bacopa monnieri significantly suppressed the evoked nociceptive responses when orally administered daily in doses of 40 and 80 mg/kg, which were tolerable and benign based on the toxicity profile [31, 80]. Similar doses of Bacopa monnieri have been shown to possess significant neuroprotective effects including its ability to protect the cerebral cortex [81], enhance dendritic length and arborization of amygdala [71] and hippocampal CA 3 neurons [72]. Moreover, these doses also have significant anti-stress and anti-depressant activities [38, 82] and neuropathic pain is often associated with comorbidities such as anxiety and depression, resulting in a low health-related quality of life [83].…”

“…Bacopa monnieri extract was orally administered daily in doses of 40 and 80 mg/kg [71, 72]. Gabapentin, used as a positive control, was intraperitoneally administered once daily at a dose of 75 mg/kg [73].…”

The effect of Bacopa monnieri on gene expression levels in SH-SY5Y human neuroblastoma cells

“…These traditional claims have recently been supported by several animal and clinical studies. Animals treated chronically with Bacopa showed better acquisition and improved retention in learning tasks [ 3 – 11 ]. Similarly, clinical studies and a meta-analysis of randomized control trials also demonstrated that chronic oral administration of Bacopa (over a period of more than 12 weeks) to healthy subjects resulted in improvements in the subjects’ information processing speed, free recall, verbal memory and learning.…”

Neuropharmacological Review of the Nootropic HerbBacopa monnieri

“…Vollala et al 126 studied the effect of BM on the dendritic morphology of neurons in the basolateral amygdala, a region implicated in learning and memory. Twenty-four rats were divided into 2-, 4-, and 6-week treatment groups, and then further divided into 20, 40, and 80 mg/kg per os (p.o.)…”

“…Camera lucida tracings of basolateral amygdaloid neurons from control rats (A) and rats treated with Bacopa monniera for 6 weeks at doses of 20 mg/kg (B), 40 mg/kg (C), and 80 mg/kg (D). (Reprinted, with permission, from Vollala et al126 …”