Methyldopa potentiated hypnosis due to hexobarbitone in mice, as did reserpine, chlorpromazine and 5-hydroxytryptamine. Methyldopa antagonized the increase by reserpine of sleep due to hexobarbitone, but enhanced the potentiation by chlorpromazine and 5-hydroxytryptamine of hypnosis due to hexobarbitone. The sedative effect of reserpine in mice and the emetic effect in pigeons were also antagonized by methyldopa. However, the effects of reserpine on convulsions due to leptazol and in causing ptosis were not antagonized by methyldopa.
Seven structurally-related compounds consisting of three antidepressant drugs (imipramine, desmethylimipramine and amitriptyline), three tranquillizing agents (promazine, chlorpromazine and chlorprothixene) and a hybrid, desmethylpromazine, have been examined in a series of tests involving autonomic functions and antagonism of reserpine.
l-Tetrahydroberberine-d-camphor sulfonate (THB-CS) possessed an inhibitory effect on apomorphine-induced chewing movement in a similar manner to that of tetrahydroberberine (THB). Both compounds enhanced barbiturate-induced hypnosis. They did not have an anticonvulsant effect on convulsive seizures induced by bicuculline, pentetrazole or strychnine. THB and THB-CS blocked dopamine-stimulated adenylate cyclase activity.
Neuropharmacological studies have been conducted on the venom of V. russelli on experimental animals. The venom was found to produce alteration in general behaviour pattern, reduction in spontaneous motility, hypothermia, potentiation of pentobarbitone hypnosis, analgesia, reduction in exploratory behaviour pattern, muscle relaxant action, and suppression of aggressive behaviour. The venom caused a significant increase in brain GABA content in mice. The observations are suggestive of a potent CNS-depressant action of V. russelli venom.