No abstract

The antistress effect of bacosides of Brahmi (Bacopa monnieri, BBM), dissolved in distilled water, was -studied in adult male Sprague Dawley rats by administering oral doses of 20 and 40 mg/kg for 7 consecutive days. In half of the animals treated with 20 or 40 mg/kg of BBM, stress was given 2 h after the last dose. Stress was also administered to the animals treated with distilled water alone. BBM, at both doses, did not induce a significant change in the expression of Hsp70 in any brain region studied while stress alone produced a significant increase in the Hsp70 expression in all the brain regions. A significant decrease in the activity of superoxide dismutase (SOD) was evident in the hippocampus with the lower dose of BBM and in animals given stress alone, while an increase in the activity of SOD was observed in the brain regions with the higher dose of BBM. An increase in the activity of cytochrome P450 (P450) dependent 7-pentoxyresorufin-o-dealkylase (PROD) and 7-ethoxyresorufin-o-deethylase (EROD) was observed in all the brain regions after exposure to stress alone and with both doses of BBM although the magnitude of induction of P450 expression was less with a higher dose of BBM. Interestingly, stress when given to the animals pretreated with BBM for 7 days resulted in a decrease in Hsp70 expression in all the brain regions with a significant decrease occurring only in the hippocampus. Likewise the activity of SOD was found to be further reduced in all the brain regions in the animals treated with the lower dose of BBM followed by stress. However, when stress was given to the animals pretreated with the higher dose of BBM, a significant increase in the enzyme activity was observed in the cerebral cortex and in the rest of the brain while the activity of SOD was reduced to a much greater extent in the cerebellum and in the hippocampus. Likewise, the activity of P450 enzymes was found to be restored to almost control levels in the animals given stress and pretreated with the higher dose of BBM, while a lesser degree of induction, compared with animals treated with BBM or stress alone, was observed in the animals pretreated with the lower dose of BBM and given stress. The data indicate that BBM has potential to modulate the activities of Hsp70, P450 and SOD thereby possibly allowing the brain to be prepared to act under adverse conditions such as stress.

No abstract

Heat shock proteins (Hsps) are a ubiquitous feature of cells in which these proteins cope with stress-induced denaturation of other proteins. Among the different families of Hsps, the 70 kDa family (hsp70) is the most highly conserved and has been most extensively studied. Apart from their primary role in cellular defense under stress condition, a number of studies in recent years have shown the immense potential of hsp70 in pollution monitoring using even transgenic approach both in vivo and in vitro. This article reviews the recent developments in the widespread application of hsp70 in environmental risk assessment. C

The single cell gel electrophoresis (SCGE) assay, also known as the Comet assay, is one of the most promising genotoxicity tests developed in recent years to measure and analyse DNA damage in single cells. The present study was undertaken to assess the in vivo genotoxicity of the synthetic pyrethroid cypermethrin in brain ganglia and anterior mid gut of Drosophila melanogaster. Freshly emerged first instar larvae (22 +/- 2 h) were placed in different concentrations of cypermethrin (0.0004, 0.0008, 0.002, 0.2 and 0.5 p.p.m.) mixed in standard Drosophila food and allowed to grow. At 96 +/- 2 h, brain ganglia and anterior midgut from control and treated larvae were dissected out, single cell suspensions were prepared and a Comet assay was performed. Our results revealed a significant dose-dependent increase in DNA damage in the cells of brain ganglia and anterior midgut of D.melanogaster exposed to cypermethrin as compared with controls (P < 0.05 at 0.002 p.p.m.; P < 0.001 at 0.2 and 0.5 p.p.m.). The present study shows in vivo genotoxicity of cypermethrin even at very low concentrations, which proves D.melanogaster as a model for in vivo genotoxicity assessment using the Comet assay.