EXPERIMENTAL MYASTHENIA GRAVIS-LIKE NEUROMUSCULAR IMPAIRMENT WITH CLEISTHANTHUS-COLLINUS LEAF EXTRACT ADMINISTRATION IN RAT

Intraperitoneal administration of a sublethal dose (120 mg/kg body wt) of Cleistanthus collinus aqueous leaf extract (CCLE) was found to ind uce a neuromuscular disorder like myasthenia gravis in rats after 45 m in. The neuromuscular junction (NMJ) blockade was analysed in vivo in the sciatic nerve-anterior tibialis muscle prpearation. The pattern of nerve evoked compound muscle action potentials (NCMAP) at various fre quencies of supramaximal electrical stimulation from single to 100 Hz were recorded, Administration of CCLE showed a sequential decremental response in NCMAP resembling the established EMG patterns of myastheni a gravis (MG), The diagnostic tests, namely a transient improvement an d repair of the decremental response in NCAMPs after administration of 4-aminopyridine (1 mg/kg), a characteristic decrement in the 4th or 5 th potential on lower frequencies of stimulation, an increased sensiti vity to d-tubocurarine (120 mu g/kg) and with least or marginal effect on CMAPs on direct muscle stimulation suggested an MG-like neuromuscu lar disorder which occurs due to ACh receptor blockade, Further, with prior administration of antisnake venon serum (AVS) - an antiserum fac tor for krait alpha bungarotoxin, the NCMAP decremental response in bo th control and in CCLE administered rats was rectified transiently and also delayed the onset of NMJ blockade. It is suggested that the prol onged and irreversible effect of the leaf extract, unlike the reversib le effect of curare, confers a sustained NMJ blockade required for ind ucing a MG-like condition.