Protective effects of Polygala paniculata extract against methylmercury-induced neurotoxicity in mice

Abstract

We have examined the possible protective effects of Polygala paniculata extract against methylmercury (MeHg)-induced neurotoxicity in adult mice. MeHg was diluted in drinking water (40 mg L(-1), freely available) and the hydroalcoholic Polygala extract was diluted in a 150 mM NaCl solution and administered by gavage (100 mg kg(-1) b.w., twice a day). After a two-week treatment, MeHg exposure significantly inhibited glutathione peroxidase and increased glutathione reductase activity, while the levels of thiobarbituric acid reactive substances were increased in the cerebral cortex and cerebellum. These alterations were prevented by administration of Polygala extract, except for glutathione reductase activity, which remained elevated in the cerebral cortex. Behavioural interference in the MeHg-exposed animals was evident through a marked deficit in the motor performance in the rotarod task, which was completely recovered to control levels by Polygala extract co-administration. This study has shown, for the first time, the in-vivo protective effects of Polygala extract against MeHg-induced neurotoxicity. In addition, our findings encourage studies concerning the beneficial effects of P. paniculata on neurological conditions related to excitotoxicity and oxidative stress.

Simultaneous Effects of Green Tea Extracts and Fish Oil on Mercury Accumulation and Antioxidant Defenses in Methylmercury-exposed Adult Mice

“…Some reports indicate that dietary fat can influence oxidative DNA damage, nephrotoxicity, and steroidogenic enzyme activities after MeHg exposure (Grotto et al, 2011;Jin et al, 2008Jin et al, , 2009McVey et al, 2008). However, the human diet varies widely, and some reports have shown that foodstuffs other than seafood may also prevent MeHg toxicity and accumulation (Abdalla et al, 2010;Farina et al, 2005;Lee et al, 1999;Rowland et al, 1986;Sumathi et al, 2012). Therefore, daily fish consumption may alleviate relatively few health risks.…”

Antinociceptive Effect of the Polygala sabulosa Hydroalcoholic Extract in Mice: Evidence for the Involvement of Glutamatergic Receptors and Cytokine Pathways

“…Scientific studies in isolated cells and in animals have confirmed the biological activities of the plants from genus Polygala [2-10]. The chemical constituents of Polygala , coumarins, steroids, saponins, lignans, flavonoids and xanthones confer to these plants valuable pharmacological properties [7][8][9][10][11][12][13].Recently, we have demonstrated that Polygala sabulosa hydroalcoholic extract (HE) A. W. Bennett (Polygalaceae) produced antinociceptive action against the acetic acidinduced visceral nociception. The presence of styryl-2-pyrones, coumarin (scopoletin) and steroid ( α -spinasterol) gives to the plant a potent antinociceptive effect [9].…”

“…Scientific studies in isolated cells and in animals have confirmed the biological activities of the plants from genus Polygala [2-10]. The chemical constituents of Polygala , coumarins, steroids, saponins, lignans, flavonoids and xanthones confer to these plants valuable pharmacological properties [7][8][9][10][11][12][13].…”

Assessing the neurotoxicological risk of methylmercury exposure for beluga whales (delphinapterus leucas) harvested in the Mackenzie Delta Estuary.

“…Clinical symptoms o f Hg toxicity include cerebellar ataxia, constriction o f the visual field and damage to the auditory region o f the temporal lobe (Clarkson, 1997;Ekino et al, 2007). Clinical symptoms o f Hg intoxication include the loss o f motor coordination (Bellum et al, 2012), abnormal movements and convulsions (Takeuchi et al, 1977) and loss o f balance (Farina et al, 2005). Macaque monkeys had impaired high-frequency hearing and visual damage following postnatal MeHg exposure (Newland and Paletz, 2000).…”

“…We would expect clinical symptoms of Hg intoxication to include the loss o f motor coordination (Bellum et al, 2012), abnormal movements and convulsions (Takeuchi et al, 1977), loss of balance (Farina et al, 2005), and reduced passive avoidance. The harvesters did not observe any abnormal movements or behaviour in the beluga whales prior to harpooning, which suggests that Hg exposure in the eleven whales analyzed in this study were not exhibiting clinical symptoms of Hg intoxication.…”