Ca2+ toxicity due to reverse Na+/Ca2+ exchange contributes to degeneration of neurites of DRG neurons induced by a neuropathy-associated Nav1.7 mutation.

Gain-of-function missense mutations in voltage-gated sodium channel Nav1.7 have been linked to small-fiber neuropathy, which is characterized by burning pain, dysautonomia and a loss of intraepidermal nerve fibers. However, the mechanistic cascades linking Nav1.7 mutations to axonal degeneration are incompletely understood. The G856D mutation in Nav1.7 produces robust changes in channel biophysical properties, including hyperpolarized activation, depolarized inactivation, and enhanced ramp and persistent currents, which contribute to the hyperexcitability exhibited by neurons containing Nav1.8. We report here that cell bodies and neurites of dorsal root ganglion (DRG) neurons transfected with G856D display increased levels of intracellular Na(+) concentration ([Na(+)]) and intracellular [Ca(2+)] following stimulation with high [K(+)] compared with wild-type (WT) Nav1.7-expressing neurons. Blockade of reverse mode of the sodium/calcium exchanger (NCX) or of sodium channels attenuates [Ca(2+)] transients evoked by high [K(+)] in G856D-expressing DRG cell bodies and neurites. We also show that treatment of WT or G856D-expressing neurites with high [K(+)] or 2-deoxyglucose (2-DG) does not elicit degeneration of these neurites, but that high [K(+)] and 2-DG in combination evokes degeneration of G856D neurites but not WT neurites. Our results also demonstrate that 0 Ca(2+) or blockade of reverse mode of NCX protects G856D-expressing neurites from degeneration when exposed to high [K(+)] and 2-DG. These results point to [Na(+)] overload in DRG neurons expressing mutant G856D Nav1.7, which triggers reverse mode of NCX and contributes to Ca(2+) toxicity, and suggest subtype-specific blockade of Nav1.7 or inhibition of reverse NCX as strategies that might slow or prevent axon degeneration in small-fiber neuropathy.

Dark neurons in the ageing cerebellum: their mode of formation and effect of Maharishi Amrit Kalash.

Dark neurons are considered a manifestation of neuronal injury and although they cover various grades of damage their mode of formation is not yet clear. Age-dependent alterations in a dark purkinje neuronal population of guinea pigs (10 months and 32 months old) and rats (3 months, 6 months, 12 months, 15 months and 28 months) were studied. Light microscopical and electron microscopical observations revealed a significant increase (P < 0.05) in the number of dark purkinje neurons with age in both the guinea pigs and rats. Extraction of lipids from the cerebellum sections before processing for histochemical reaction resulted in a reduction of the dark neuronal population. In an other set of experiments, significant age-dependent increase in the cathepsin-D activity and lipid peroxidation was documented in the guinea pig cerebellum. Treatment of guinea pigs with Maharishi Amrit Kalash (MAK) (500 mg/kg body wt/day, for two months) significantly inhibited (P < 0.05) the activity of cathepsin-D and lipid peroxidation, and decreased the number of dark neurons. These findings suggest that the number of dark neurons increases with age and MAK prevents the conversion of light to dark purkinje neurons due to its inhibitory effects on cathepsin-D activity and antioxidant properties. We suggest that the conformational changes in the normal protein structure due to higher proteolytic activity and peroxidation of lipid in the aging cerebellum endangers a redundant capability for various staining agents and the Osimic acid molecules to react with proteins, lipids and other molecules, leading to an intensified cyto- and karyoplasms electron density.

Effect of Maharishi Amrit Kalash on age dependent variations in mitochondrial antioxidant enzymes, lipid peroxidation and mitochondrial population in different regions of the central nervous system of guinea-pigs.

Age related changes in the mitochondria of different regions of the CNS of two age groups of guinea-pigs (10 months and 32 months) were studied. The activities of glutathione peroxidase (GPx) and glutathione reductase (GRd) decreased significantly (p <0.05) with age in the mitochondrial fractions of cerebral cortex, hypothalamus, cerebellum and spinal cord. A significant (p <0.05) age related decrease in mitochondrial numerical density was observed in all regions studied. Electron microscopic observations revealed various degenerative changes in the mitochondria with age. Treatment of the animals with the Ayurvedic herbal mixture "Maharishi Amrit Kalash" (MAK), 500 mg/kg body wt. daily for 2 months, significantly induced the activity of antioxidant enzymes, and also reversed the pathological changes to a considerable extent. MAK increased the activity of GPx significantly only in the 32 month-old animals. This shows the specificity of the action of MAK.

Effect of Maharishi Amrit Kalash an ayurvedic herbal mixture on lipid peroxidation and neuronal lipofuscin accumulation in ageing guinea pig brain.

The effects of ayurvedic herbal mixture Maharishi Amrit Kalash(MAK) were studied on brain lipid peroxidation, oxygen consumption, and lipofuscin accumulation in 10 months and 32 months old guinea pigs. Brain regions studied were cerebral cortex, hypothalamus, cerebellum and spinal cord. Parameters assessed were lipid peroxidation, oxygen consumption, and lipofuscin accumulation. The endogenous lipid peroxide was found to be increased significantly (P < 0.05) in the 32-month-old animals. Neuronal lipofuscin accumulation in the neurons of cerebral motor cortex, cerebellum and cervical spinal cord was increased (P < 0.05) in the older animals. Oxygen consumption was found to be decreased significantly(P < 0.05) in the 32-month old guinea pigs. Treatment with MAK at a dose of 500 mg/kg body weight daily for two months reduced the lipid peroxidation and lipofuscin pigment accumulation significantly in brain regions and it also helped in restoring the normal oxygen consumption in the older animals. This indicates antioxidant properties of MAK.

Taurine protects against carbon tetrachloride toxicity in the cultured neurons and in vivo.

Carbon tetrachloride (CCl4) has been found to induce cellular damage by generating oxygen free radicals. A study was carried out to investigate the effects of taurine (extracted from Pegasus laternarius Cuvier) on CCl4 intoxicated cultured neurons. CCl4 application (0.4 mmol x l(-1), 0.8 mmol x l( -1), 1.2 mmol x l (-1) and 1.6 mmol x l(-1 )) increased the lipid peroxidation product and decreased glutathione peroxidase (GPx) activity significantly in a concentration dependent manner. Pretreatment of cultures with taurine (10 micromol x l(-1), 30 micromol x l(-1) and 60 micromol x l(-1)) prevented the loss of GPx activity and lipid peroxidation. The effects of three different dosages of taurine (10 mg/kg body wt., 20 mg/kg body wt. and 40 mg/ kg body wt.) for 45 days on the activities of superoxide dismutase and glutathione peroxidase were examined in the cerebrum, cerebellum and medulla of normal and CCl4 treated mice. Treatment of mice with taurine provided protection against CCl4 toxicity as was evident by lipid peroxide status. Taurine was not so successful at inducing the activity of SOD in normal animals except in the medulla where it could increase the activity of SOD (p < 0.05). Taurine induces the GPx activity in a dose dependent manner in all regions of the brain studied. Also in the CCl4 poisoned mice taurine could augment the status of GPx activity in a dose dependent manner. Hence it is concluded that taurine can protects neurons from the oxidative stress induced by CCl4.

Maharishi Amrit Kalash, an ayurvedic medicinal preparation, enhances cholinergic enzymes in aged guinea pig brain.

The effect of orally fed Maharishi Amrit Kalash was examined on the activities of cholinergic enzymes in the guinea pig brain. The activity of the cholinergic enzymes viz. choline-acetyltransferase and acetylcholinesterase enzymes was found to be reduced significantly (P<0.05) in the various regions of CNS of the aged guinea pigs. Oral administration of MAK(500 mg/kg body weight daily) for 2 months significantly increased (P<0.05) the activity of choline acetyltransferase and acetylcholinesterase in the older animals. The present study indicates that this food supplement can be helpful in alleviating the cholinergic deficits in the old age.

Age-dependent variations in mitochondrial and cytosolic antioxidant enzymes and lipid peroxidation in different regions of central nervous system of guinea pigs.

The age-related changes in the activities of antioxidant enzymes of mitochondrial and cytosolic fractions were measured in different regions of the central nervous system (CNS) in 10 and 32 months old guinea pigs. In old animals, the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) were reduced (p < 0.05) in all the regions of CNS studied but catalase (CAT) declined significantly only in the cerebral cortex, hypothalamus and cerebellum. Glutathione reductase (GRd) activity declined in cerebral cortex and hypothalamus in the cytosolic fractions and only in cerebellum in the mitochondrial fraction. It is concluded that age-related decline in the activities of antioxidant enzymes is both region and enzyme specific. The endogenous lipid peroxide was found to be significantly higher (p < 0.05) in the 32 month old animals whereas, lipid peroxidation after incubating the tissue homogenate in air was found to be lower (p < 0.05). The in vitro mitochondrial lipid peroxidation decreased with age. The results indicate that accumulation of lipid peroxides takes place with ageing but the susceptibility of lipid peroxidation decreases in the older animals.

Improvement of impaired memory in mice by taurine.

Taurine was extracted from Pegasus laternarius Cuvier to study its effects on learning and memory in mice. Mice were treated with different doses of taurine (10 mg/kg, 20 mg/kg, 40 mg/kg). The mice were treated with various chemical agents (pentobarbital, cycloheximide, sodium nitrite, alcohol) to disrupt the normal memory process. We measured the effect of taurine on step-down latency (SDL) and escape latency (EL) in a passive avoidance task after 10 or 30 days. Treatment with taurine alone did not change either SDL or EL. Taurine protected mice from the memory disruption induced by alcohol, pentobarbital, sodium nitrite, and cycloheximide but had no obvious effect on motor coordination, exploratory activity, or locomotor activity as measured using the rota-rod test and the hole board test. We conclude that taurine can be effective in attenuating the amnesia produced by alcohol, pentobarbital, cycloheximide, and sodium nitrite without compromising the behavioral aspects of the animals tested.

Maharishi Amrit Kalash rejuvenates ageing central nervous system's antioxidant defence system: an in vivo study.

The oxygen-free radical involvement in various deteriorative processes and in ageing is unquestionably established. In the present study age-related changes in antioxidant enzyme activity in the different regions of CNS of 10-month and 32-month-old guinea pigs were studied. Maharishi Amrit Kalash has shown promise in inhibiting the in vitro and in vivo lipid peroxidation. Therefore in the present study the effect of MAK on the activity of antioxidant enzymes was checked. Our results indicate that the activity of superoxide dismutase and glutathione peroxidase, was found to be reduced (P < 0.05) in all the regions of CNS studied, The activities of catalase declined significantly only in the cerebral cortex, hypothalamus and the cerebellum. Whereas glutathione reductase activity declined in the cerebral cortex and hypothalamus. It is concluded that the age-related decline in the activities of antioxidant enzymes is region-specific as well as enzyme-specific. The endogenous lipid peroxide was found to be increased significantly (P < 0.05) in the 32-month-old animals. Whereas the lipid peroxidation after incubating the tissue homogenate in the air was found to be decreased (P < 0.05) in the older animals. The results indicate that the accumulation of lipid peroxides take place with age but the susceptibility of lipid peroxidation decreases in the older animals. The treatment of MAK 500 mg kg-1 body wt. for 2 months could augment the activities of antioxidant enzymes (P < 0.05). The effect of MAK was more pronounced in older than younger animals. It is concluded that the MAK can be used in compensating the decline in the activities of antioxidant enzymes in CNS and thereby it reduces the risks of lipid peroxidation.