Comparative pharmacological study of hydroethanol extracts of Passiflora alata and Passiflora edulis leaves.

Several species of the genus Passiflora, known in Brazil as "maracujá", have widespread use in folk medicine as sedatives and tranquillizers. The anxiolytic activity of hydroethanol extracts of P. alata and P. edulis leaves was evaluated using the elevated plus-maze test. The extracts presented anxiolytic activity in dosages around 50, 100 and 150 mg/kg.

Psychopharmacological screening of Pfaffia glomerata Spreng. (Amarathanceae) in rodents.

The alcoholic extract of Pfaffia glomerata roots (100, 500, 1000 mg/kg, intraperitoneally (i.p.), and 500, 1000, 1500 mg/kg, per os) was studied in several behavioral animal models for the evaluation of central activity: open field, barbiturate sleeping time, pentilenotetrazole (PTZ)-induced convulsions, elevated plus-maze, step-down inhibitory avoidance and forced swimming test. The acute treatment (500 mg/kg, i.p.) interfered with the open-field habituation, decreased sleep latency and increased barbiturate-induced sleeping time, protected partially the animals of PTZ-induced convulsions, decreased the memory retention in step-down inhibitory avoidance, and did not have an important effect in the elevated plus-maze test and forced swimming test. The same extract at 1000 mg/kg per os did not cause any effect in barbiturate sleeping time and pentilenotetrazole-induced convulsions models. Thus, the effect on the memory was deeper evaluated in the step-down inhibitory avoidance task. When administered by intraperitoneal route, the extract showed a dose-dependent effect causing full amnesia at 1000 mg/kg. On the other hand, when it was given by oral route at 500, 1000 and 1500 mg/kg, no influence on the memory retention was observed. These results suggest that the alcoholic extract of P. glomerata roots presents different effects depending on the route of administration: by i.p route, it seems to be a central nervous system depressant agent; by oral route, it seems to be ineffective, at least in the tested doses.

The anticonvulsant compound gabapentin possesses anxiolytic but not amnesic effects in rats.

This report describes the effects of the antiepileptic agent gabapentin on anxiety and memory. Male Wistar rats received intraperitoneal administrations of gabapentin (10, 30 and 100mg/kg), diazepam (1 mg/kg), saline or diazepam vehicle 30 minutes prior to experimental procedures. Animals were: (1) tested on step-down inhibitory avoidance (footshock 0.3 mA) and habituation to an open-field for memory assessment; and (2) submitted to the elevated plus-maze to evaluate the potential anxiolytic effects of gabapentin. Animals treated with gabapentin showed a reduction in anxiety similar to that observed in animals treated with diazepam. Memory was not affected by gabapentin in any of the tests, but was impaired by diazepam. The lack of effects of gabapentin on memory suggest a potential advantage of this drug over compounds with previously known anxiolytic property, which have amnesic effects at doses used for the treatment of anxiety disorders.

Anxiolytic natural and synthetic flavonoid ligands of the central benzodiazepine receptor have no effect on memory tasks in rats.

The naturally occurring flavonoids, chrysin (5,7-dihydroxyflavone) and apigenin (5,7,4'-trihydroxyflavone), and the synthetic compound, 6,3'-dinitroflavone have been recently reported to selectively bind with high affinity to the central benzodiazepine receptor, and to exert powerful anxiolytic and other benzodiazepine-like effects in rats. Their chemical analog, quercetin, shares none of these effects. In the present article we find that, in contrast to diazepam, chrysin, apigenin, and 6,3'-dinitroflavone have no amnestic effect on acquisition or retention of three different learning tasks (inhibitory avoidance, shuttle avoidance, and habituation to an open field), even when given at doses higher than those previously reported to be anxiolytic. Apigenin had a slight enhancing effect on training session performance and, when given posttraining, on test session retention, of crossing responses in the open field and hindered retention of inhibitory avoidance, and showed no anxiolytic action in an elevated plus maze. Unlike diazepam, none of these drugs had any analgesic effect in the tail-flick test. The data suggest that chrysin, apigenin, and 6,3'-dinitroflavoine, three flavonoids derivatives possessing anxioselective effects acting on central benzodiazepine receptors, may deserve clinical trials as anxiolytic agents.