Anticonvulsant Activity of Extracts ofPlectranthus barbatusLeaves in Mice

Plectranthus barbatusis a medicinal plant used to treat a wide range of disorders including seizure. However, the anticonvulsant activity of this plant has not been studied in depth. We therefore sought to evaluate the anticonvulsant activity of a hydroalcoholic extract ofP. barbatusleaves on seizures induced by strychnine sulphate (2.0 mg/kg) and pilocarpine (600 mg/kg) in mice. The extract was administered orally at 1, 10, 30, and 100 mg/kg. We report that theP. barbatusextract had marked anticonvulsant activity against strychnine-induced convulsions, but was quite ineffective against pilocarpine-induced convulsions. Further experiments will be required to identify the active molecules(s) and their mechanism(s) of action.

Attempts at Use of Strychnine Sulfate in the Treatment of Nonketotic Hyperglycinemia

In two cases of nonketotic hyperglycinemia treated from early ages with strychnine sulphate, the patients demonstrated persistent severe psychomotor retardation and seizures. Strychnine therapy improved tone and feeding, but did not seem to alter fundamentally the course of the disease in either patient.

Effects of Pre-Trial Strychnine on Maze Learning

The effects of pre-trial administration of strychnine sulphate on maze learning were assessed for both massed and distributed practice. Analysis of trials to criterion and errors to criterion confirmed strychnine's facilitation of learning under massed practice but showed no such facilitating effect under distributed practice.

Effect of Level of External Stimulation on Rate of Learning and Interaction of this Effect with Strychnine Treatment in Mice

In these studies an attempt was made to test for disruption of learning by general external stimulation delivered after training. In addition, in Exp. I only, strychnine sulphate was tested for effects on learning and for a possible interaction with stimulation treatment. Mice were trained on a spatial discrimination task, and stimulation was delivered after each day's block of trials. The general findings were that stimulation as tested did not disrupt learning. A facilitative effect of strychnine was obtained, but only when the stimulation was low. These were discussed in terms of perseveration-consolidation theory and of previous studies in which no facilitative effects of strychnine were obtained.

Note on Strychnine Sulphate, General Activity and Facilitation of Learning

Effects of three doses (.1, .3, and .7 mg/kg) of strychnine sulphate on the general activity of the rat were studied. None of the doses influenced exploration or any other aspect of spontaneous behavior. This finding restricts the generality of the view that attributes the facilitation of learning produced by strychnine to a decrease in the level of general activity.