Preventive effect of ethanol extract of Phyllanthus rheedii Wight. on D-galactosamine induced hepatic damage in Wistar rats

AIM OF THE STUDY: Phyllanthus rheedii Wight. (Euphorbiaceae) has been used by Muthuvan tribes of Kerala for curing liver diseases. The present study was conducted to assess the hepatoprotective activity of this plant. The ethanol extract of Phyllanthus rheedii was pharmacologically analysed for its preventive effect in d-galactosamine (d-GalN) induced liver damage in rats. MATERIAL AND METHODS: The levels of hepatotoxicity in various groups were quantified by different parameters of liver damage viz. serum levels of ALT, AST, LDH, GGT, ALP and total bilirubin. The effect of extract on the expression levels of pro-inflammatory cytokines like TNF-alpha, and TGF-beta were analysed by RT-PCR. Histological changes in the liver were evaluated by hematoxylin and eosin staining of paraffin processed liver sections. The antioxidant and choleretic activity of the extract were also analysed. RESULTS: Comparison of serum values of control and extract treated groups have revealed that the d-GalN induced alterations in the serum and liver markers were normalized in extract treatment groups showing hepatoprotective activity of the extract. The extract also prevented the toxin induced histological changes in liver. The mRNA levels of TGF-beta and TNF-alpha in the liver were up regulated by the hepatotoxin. The extract treatment has normalized this change, giving light to the probable mechanism of action of the extract. It has showed marked antioxidant and choleretic activity. Preliminary phytochemical screening has revealed the presence of tannins, flavanoids and phenolics as major components. CONCLUSIONS: This study concluded the ethanol extract of P. rheedii could be a promissory candidate for drug development and validated the tribal claim.     

Age-related decline in the responsiveness of motor cortex to plastic forces reverses with levodopa or cerebellar stimulation

The plasticity of motor cortex is integral for motor memory and skills acquisition but it declines with aging. Forty healthy volunteers, across 6 decades, were tested to examine the (a) age-dependency of motor cortex responsiveness to plasticity induction, as measured from the response to paired associative stimulation (PAS) and the (b) effect of aging on the cerebellar modulation of motor cortex response to PAS. We examined if reduced dopaminergic transmission was involved in the age-related decline of response to PAS by retesting 10 of the older subjects after a single dose of levodopa. There was a substantial decline in the motor cortex response to PAS with aging, which was restored by levodopa in the older subjects. The cerebellar modulation of motor cortex response to PAS was less vulnerable to aging and a single session of cerebellar inhibition reinstated the cortical responsiveness in older subjects. Both levodopa and cerebellar inhibition can be tested for their ability to enhance motor skills acquisition and motor performance in the elderly individuals.     

Altered neurochemical parameters in the brains of mice (Frings) susceptible to audiogenic seizures

In this study, several biochemical aspects of serotonergic neurons were compared in mice susceptible to audiogenic seizures (Frings) and in mice not susceptible to audiogenic seizures (CF 1). Tryptophan hydroxylase (TPH) activity was significantly lower in brains of Frings mice compared to CF1 mice; however, brain levels of 5-HT were similar in both strains. The significantly lower TPH activity in Frings mice was due to the altered kinetic characteristics of TPH activity in this strain. TPH from Frings mice had a significantly lower apparent maximal velocity and a significantly higher affinity for the substrate, as indicated by a lower apparent Km for tryptophan. The uptake of tryptophan and accumulation of 5-HT (following pargyline) were similar in Frings and CF 1 mice. The levels of 5-HT in selected brain regions of Frings and CF 1 mice were also similar, but NE levels were higher in the cerebral cortex and DA levels were higher in the neostriatum of Frings mice. It is unclear at this point what role, if any, 5-HT plays in susceptibility to audiogenic seizures in brains of Frings mice.