Ethnomedicinal plants used for treating epilepsy by indigenous communities of sub-Himalayan region of Uttarakhand,India

Ethnopharmacological relevance

Although many plants are claimed to possess anticonvulsant/antiepileptic (AC/AE) properties, but there is very little information available about plants used by various ethnic communities in different parts of India to treat epilepsy, one of the most common disorders of central nervous system (CNS); this communication provides significant ethnomedicinal information on the plants used by indigenous communities: Bhoxa, Tharu and nomadic Gujjars of sub-Himalayan region, Uttarakhand, India to treat epilepsy, so that it could be used as a baseline data for studying chemical constituents and biological activities of these promising plants.

Aims of the study

To record herbal preparations used by the presently studied communities for treating epilepsy and discuss AC/AE properties of the recorded plants.

Research strategy and methods

Ninety one traditional healers (29 Bhoxa, 35 Tharu and 27 nomadic Gujjars) in sub-Himalayan region of Uttarakhand, India were interviewed to collect information on herbal preparations used by them for treating epilepsy. For each recorded species the use value (UV) and fidelity level (FL) was calculated.

Results

A total of 24 plants belonging to 24 genera and 22 families were used by the presently studied communities in 26 formulations to treat epilepsy. According to FL and UV values, most preferred species for the treatment of epilepsy by Bhoxa community are Ricinus communis L. and Datura stramonium L.; by nomadic Gujjar community are Martynia annua L., Bacopa monnieri (L.) Wettst. and Ricinus communis L.; and by Tharu community are Allium sativum L., Asparagus racemosus Willd. and Achyranthes aspera L. Eight plants viz., Allium sativum L., Boerhavia diffusa L., Cassia fistula L., Clerodendrum viscosum Vent., Datura stramonium L., Inula cappa DC., Oroxylum indicum (L.) Kurz and Pavetta indica L. recorded in the present survey have been reported for the first time in treatment of epilepsy by these indigenous communities in India. Five out of these eight newly reported plants viz., Cassia fistula L., Clerodendrum viscosum Vent., Inula cappa DC., Oroxylum indicum (L.) Kurz and Pavetta indica L. have not been pharmacologically evaluated yet for their possible AC/AE properties.

Conclusions

Detailed research on the listed plants and their derivatives may be undertaken to provide new alternative treatments and therapeutic uses for epilepsy or other diseases of CNS. We hope that this article will stimulate further investigations into natural products for new AC/AE agents from the recorded ethnomedicinal plants.     

Comparative immunohistochemistry of synaptic markers in the rodent hippocampus in pilocarpine epilepsy

Pilocarpine-induced epileptic state (Status epilepticus) generates an aberrant sprouting of hippocampal mossy fibers, which alter the intrahippocampal circuits. The mechanisms of the synaptic plasticity remain to be determined. In our studies in mice and rats, pilocarpine-induced seizures were done in order to gain information on the process of synaptogenesis. After a 2-month survival period, changes in the levels of synaptic markers (GAP-43 and Syn-I) were examined in the hippocampus by means of semi-quantitative immunohistochemistry. Mossy fiber sprouting (MFS) was examined in each brain using Timm's sulphide-silver method. Despite the marked behavioral manifestations caused by pilocarpine treatment, only 40% of the rats and 56% of the mice showed MFS. Pilocarpine treatment significantly reduced the GAP-43 immunoreactivity in the inner molecular layer in both species, with some minor differences in the staining pattern. Syn-I immunohistochemistry revealed species differences in the sprouting process. The strong immunoreactive band of the inner molecular layer in rats corresponded to the Timm-positive ectopic mossy fibers. The staining intensity in this layer, representing the ectopic mossy fibers, was weak in the mouse. The Syn-I immunoreactivity decreased significantly in the hilum, where Timm's method also demonstrated enhanced sprouting. This proved that, while sprouted axons displayed strong Syn-I staining in rats, ectopic mossy fibers in mice did not express this synaptic marker. The species variability in the expression of synaptic markers in sprouted axons following pilocarpine treatment indicated different synaptic mechanisms of epileptogenesis.     

Inhibition of pilocarpine‐induced saliva secretion by adrenergic agonists in ICR mice

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Effects of pilocarpine on the cortical and hippocampal theta rhythm in different vigilance states in rats

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Loss of input from the mossy cells blocks maturation of newly generated granule cells

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Neurobehavioral maturation of offspring from epileptic dams: Study in the rat lithium–pilocarpine model

In the present study, we explored the consequences of epilepsy on the neurobehavioral development of the offspring in a rat model of spontaneous epilepsy, the lithium–pilocarpine model of temporal lobe epilepsy not dependent on genetic factors and in animals not receiving any antiepileptic treatment. Status epilepticus was induced by lithium–pilocarpine in female rats. After the occurrence of spontaneous seizures the rats were mated and the neurobehavioral development of the offspring was explored. Rat pups were cross-fostered early after birth. We hence obtained pups born from or raised by epileptic or non-epileptic dams. On the dams, we performed a follow-up of maternal care during pregnancy. On the pups, we performed a follow-up of classical parameters of development such as body weight and eyelid opening, and subjected the pups to various tests representative of neurobehavioral maturation extending from postnatal day 4 (PD4) to PD30 (righting reflex, suspension time, negative geotaxis, open field, locomotor coordination and eight arm maze). Altogether our data show that rat pups born from or raised by epileptic dams develop as well as control pups raised by control dams. Intriguingly, pups born from lithium–pilocarpine exposed dams and raised by control mothers tend to have better scores than the two other groups in all tests. This indicates that the exposure to seizures during pregnancy is not harmful for the development of the fetus.     

Antiepileptic drugs combined with high‐frequency electrical stimulation in the ventral hippocampus modify pilocarpine‐induced status epilepticus in rats

Purpose: To evaluate the effects of high‐frequency electrical stimulation (HFS) in both ventral hippocampi, alone and combined with a subeffective dose of antiepileptic drugs, during the status epilepticus (SE) induced by lithium‐pilocarpine (LP). Methods: Male Wistar rats, stereotactically implanted in both ventral hippocampi, were injected with pilocarpine (30 mg/kg, i.p.) 24 h after lithium (3 mEq/kg) administration. One minute following pilocarpine injection, HFS (pulses of 60 μs width at 130 Hz at subthreshold intensities and applied during 3 h) was applied alone or combined with subeffective doses of antiepileptic drugs. Results: HFS alone reduced the incidence of severe generalized seizures. This effect was not evident when HFS was combined with phenytoin (33.3 mg/kg, i.p.). HFS combined with diazepam (0.41 mg/kg, i.p.) or phenobarbital (10 mg/kg, i.p.) reduced the incidence of severe generalized seizures and mortality rate, and augmented the latency to first forelimb clonus, generalized seizure, and status epilepticus (SE). When combined with gabapentin (46 mg/kg, i.p.), HFS reduced the incidence of severe generalized seizures, enhanced latency to SE, and decreased mortality rate. Discussion: Subeffective doses of antiepileptic drugs that increase the γ‐aminobutyric acid (GABA)ergic neurotransmission may represent a therapeutic tool to augment the HFS‐induced anticonvulsant effects.     

Ketogenic diet exhibits neuroprotective effects in hippocampus but fails to prevent epileptogenesis in the lithium‐pilocarpine model of mesial temporal lobe epilepsy in adult rats

Purpose: Although the number of antiepileptic drugs (AEDs) is increasing, none displays neuroprotective or antiepileptogenic properties that could prevent status epilepticus (SE)–induced drug‐resistant epilepsy. Ketogenic diet (KD) and calorie restriction (CR) are proposed as alternative treatments in epilepsy. Our goal was to assess the neuroprotective or antiepileptogenic effect of these diets in a well‐characterized model of mesial temporal lobe epilepsy following initial SE induced by lithium‐pilocarpine in adult rats. Methods: Seventy‐five P50 male Wistar rats were fed a specific diet: normocalorie carbohydrate (NC), hypocalorie carbohydrate (HC), normocalorie ketogenic (NK), or hypocalorie ketogenic (HK). Rats were subjected to lithium‐pilocarpine SE, except six NC to constitute a control group for histology (C). Four rats per group were implanted with epidural electrodes to record electroencephalography (EEG) during SE and the next six following days. From the seventh day, the animals were video‐recorded 10 h daily to determine latency to epilepsy onset. Neuronal loss in hippocampus and parahippocampal cortices was analyzed 1 month after the first spontaneous seizure. Results: After lithium‐pilocarpine injection, neither KD nor CR modified SE features or latency to epilepsy. In hippocampal layers, KD or CR exhibited a neuroprotective potential without cooperative effect. Parahippocampal cortices were not protected by the diets. Conclusion: The antiepileptic effect of KD and/or CR is overwhelmed by lithium‐pilocarpine injection. The isolated protection of hippocampal layers induced by KD or CR or their association failed to modify the course of epileptogenesis.     

Do proconvulsants modify or halt epileptogenesis? Pentylenetetrazole is ineffective in two rat models of temporal lobe epilepsy

In patients at risk of developing epilepsy after an initial precipitating injury to the brain, the epileptogenic latent period may offer a window of opportunity for initiating potential antiepileptogenic therapy in an attempt to prevent epilepsy from developing. One potential target for antiepileptogenesis is the development of neuronal hyperexcitability during the latent period. Surprisingly, some recent studies in models of temporal lobe epilepsy (TLE) have suggested that proconvulsant drugs could have favourable effects on epileptogenesis, resulting in the proposal of pursuing proconvulsant prophylaxis for epileptogenesis. In the present study, we evaluated this provocative hypothesis by experiments with the GABA(A) receptor antagonist pentylenetetrazole (PTZ) in two TLE models, the intrahippocampal kainate model and the lithium-pilocarpine model in rats. First, we repeatedly determined the PTZ seizure threshold by i.v. infusion of the convulsant during the latent period following intrahippocampal kainate. In line with recent experiments in the lithium-pilocarpine model, the PTZ seizure threshold was significantly decreased over several days following status epilepticus. We then studied whether prolonged infusion of a proconvulsant dose of PTZ at different times after kainate or pilocarpine affected the development of epilepsy. PTZ did not prevent the development of spontaneous recurrent seizures and did not decrease their frequency or severity, but exerted only a moderate disease-modifying effect in that spontaneous seizures in the kainate model were significantly shortened. These data indicate that administration of proconvulsant drugs such as PTZ during the latent period following SE is not a promising strategy for preventing epilepsy.