The effects of pre-training and post-training administration of endosulfan on retention of a step-down passive avoidance task was studied in mice. Endosulfan at doses of 1.0 mg/kg(ip) and 2.0 mg/kg(ip) enhanced memory acquisition and retention. This effect of endosulfan was possibly mediated by interaction with cholinergic neurotransmission, as scopolamine (0.5 mg/kg, ip) significantly antagonized the memory enhancing effects of endosulfan. Clonidine (0.05 mg/kg, ip) did not have any effect on enhancement of memory produced by endosulfan, thus indicating possibly no role of noradrenergic system.

In the present study, the effect of single dose administration of 4 mg lorazepam on psychomotor performance was demonstrated in 6 volunteers. Performance was measured using a battery of paper and pencil tests which included B-letter cancellation test, digit symbol substitution test, symbol copying test, serial addition and serial subtraction tests, All the tests were sensitive to detect the lorazepam induced impairment of psychomotor function. This can be used as a model experiment to demonstrate to the undergraduate medical students the effects of CNS depressant drugs in humans. The student can also become acquainted with the concepts of clinical pharmacology during the demonstration.

Experimental evidence suggests that potassium channel openers play an important role in convulsions. In this study, the anticonvulsant activity of BRL 38227, a new potassium channel opener against digoxin-induced convulsions, is reported. Intraventricular administration of digoxin (7.5 micrograms), included "popcorn-type" convulsions in rats. BRL 38227, injected centrally increased the onset time of convulsions and decreased the mortality rate in a dose-dependent manner. Pretreatment with 4-aminopyridine, a potassium channel blocker antagonized the protective effect of BRL 38227. These findings show the involvement of potassium channels in digoxin-induced convulsions. Further these results indicate that in the future potassium channels might be a target for new anticonvulsant drugs.

Some reports suggest that addition of an H2 antagonist increases the efficacy of H1 antagonist but the influence on the side effect profile of antihistamines are largely unknown. The effects of ranitidine, chlorpheniramine, their combination and placebo on histamine induced wheal and flare, psychomotor performance and subjective symptoms were studied in 6 healthy male volunteers in a double blind randomized and cross-over (Latin square) study. Ranitidine significantly reduced the histamine induced wheal at 4 hrs (P < 0.05). Chlorpheniramine and the combination significantly reduced both histamine induced wheal and flare at 2 hrs and at 4 hrs (P < 0.05). Addition of ranitidine reduced the feeling of sleepiness produced by chlorpheniramine, though other subjective symptoms were not affected. None of the treatment schedules produced any consistent change in the psychomotor performance of the volunteers.