Effects of pivagabine on psychophysical performance and behavioural response in experimental models of stress.

The effect of pivagabine (4-[(2,2-dimethyl-1-oxopropyl)amino]butanoic acid, CAS 69542-93-4, Tonerg), a synthetic molecule with neuromodulatory activity, was evaluated on a series of behavioural parameters in rats exposed to various stimuli, with the aim of evaluating the response to stress (open field exploration, water maze, psychic conflict), conditioning (active and passive avoidance and avoidance retention, aggressiveness, extinction of conditioned responses), learning and performing of specific psychophysical tests (rota-rod, ballasted swimming, taut thread). Pivagabine induced significant improvement of stress-related tests by reducing the anxiety-producing reactions related to the various experimental settings. In conditioning tests an improvement in learning of conditioned responses was observed at lower dosages (10 and 50 mg/kg); an opposite effect was obtained with higher dosages (100 and 200 mg/kg).

The block of central vasopressin V1 but not V2 receptors suppresses grooming behavior and hypothermia induced by intracerebroventricular vasopressin in male rats.

The role of central vasopressin V1 receptors in grooming behavior induced by vasopressin and oxytocin was studied in male rats of the Wistar strain. The intracerebroventricular (ICV) injection of vasopressin (3 micrograms/5 microliters) induced hypothermia and enhanced novelty-induced grooming behavior. Enhanced grooming but not hypothermia was also induced by ICV injection of oxytocin (3 micrograms/5 microliters).

Effects of acute or chronic administration of risperidone on motor and sexual behavior of male rats.

A number of experiments were carried out to explore the behavioral profile of a novel antipsychotic, risperidone, after acute or chronic administration, in a dose range of 0.1-10 mg kg-1. This drug did not affect the acquisition and retention of avoidance behaviors in a dose of 0.

Different responses of gonadotropin-releasing hormone (GnRH) release to glutamate receptor agonists during aging.

GnRH release from hypothalamic explants from young and aged male Wistar-Kyoto rats was evaluated following stimulation with glutamate receptor agonists. Glutamate stimulated GnRH release to a similar extent in hypothalami from young and old animals, whereas N-methyl-D-Aspartate (NMDA) and kainate appeared more efficacious in young and old rats, respectively. Old rats were unable to respond to a maximal stimulating concentration of glutamate when they had been previously exposed to a challenge with the same agent.

Effects of RGH 2202 on cognitive and motor behavior of the rat.

The behavioral activity of the thyrotropin-releasing hormone (TRH) analogue, L-6-ketopiperidine-2-carbonyl-leucyl-L-prolinamide (RGH 2202), has been studied in animal models of central neurotransmission disruption. In 24-month-old rats, repeated administration of the peptide (5 or 10 mg/kg/day, injected IP for 20 days) was followed by a facilitated acquisition of active avoidance behavior in the shuttle-box test and retention of passive avoidance reaction in a step-through passive avoidance task. Also, ambulation in an open field was increased and motor performance and co-ordination in the rotorod test was facilitated by the treatment.