Search results for "Picrotoxin"
showing 5 items of 15 documents
GABAC receptors are functionally expressed in the intermediate zone and regulate radial migration in the embryonic mouse neocortex
2010
Radial neuronal migration in the cerebral cortex depends on trophic factors and the activation of different voltage- and ligand-gated channels. To examine the func- tional role of GABAC receptors in radial migration we ana- lyzed the effects of specific GABAA and GABAC receptor antagonists on the migration of BrdU-labeled neurons in vitro using organotypic neocortical slice cultures. These experi- ments revealed that the GABAA specific inhibitor bicuculline methiodide facilitated neuronal migration, while the GABAC specific inhibitor (1,2,5,6-tetrahydropyridine-4-yl) methylphos- phinic-acid (TPMPA) impeded migration. Co-application of TPMPA and bicuculline methiodide or the unspecific ionot…
gamma-Aminobutyric acid and cholinergic transmission in the guinea-pig ileum.
1983
1. The effects of GABA on release of acetylcholine and on contractility of the smooth muscle were studied in the myenteric plexus-longitudinal muscle preparation of the guinea pig. Acetylcholine was determined as radiolabelled transmitter from strips preloaded with 3H-choline. 2. GABA (1–300 μM) caused an increase in resting tension of smooth muscle as well as an increase in release of acetylcholine that was considerably reduced by tetrodotoxin. The facilitation by GABA of acetylcholine release exhibited a marked tachyphylaxis. The increase in muscle tension was clearly related to the increase in acetylcholine release. Muscimol (0.1–10 μM) also enhanced the release of acetylcholine. The eff…
Intrinsic activation of GABAA receptors suppresses epileptiform activity in the cerebral cortex of immature mice
2010
SUMMARY Purpose: Activation of ionotropic c-aminobutyric acid type A (GABAA) receptors induces in immature neocortical neurons a membrane depolarization that may contribute to the higher epilepsy susceptibility in newborns. To elucidate whether depolarizing GABAergic responses enhance or attenuate epileptiform activity in the immature neocortex, we investigated the effect of agonists, antagonists, and positive modulators of GABAA receptors on epileptiform activity. Methods: We performed in vitro field potential recordings on isolated whole neocortex preparations and whole cell recordings of identified pyramidal neurons in 400-lm slices of immature (postnatal day 1–7) mice. Epileptiform acti…
Behavioural responsiveness to picrotoxin and desipramine in adult rats prenatally exposed to different benzodiazepine receptor agonists
1995
The behavioural responsiveness to picrotoxin and desipramine was investigated in adult rats prenatally exposed to different benzodiazepine receptor agonists such as diazepam, alprazolam and zolpidem. Prenatal exposure to diazepam and alprazolam similarly potentiated the anti-immobility effect on the forced swimming test and the inhibitory effect on spontaneous motor activity of picrotoxin and desipramine and increased the seizure sensitivity to picrotoxin. Prenatal zolpidem seems to be ineffective. These data suggest that, despite the differences in their pharmacodynamic profile, prenatal exposure to diazepam and alprazolam, but not zolpidem, may have similar permanent consequences on the b…
Prenatal exposure to diazepam and alprazolam, but not to zolpidem, affects behavioural stress reactivity in handling-naïve and handling-habituated ad…
2002
A gentle long-lasting handling produces persistent neurochemical and behavioural changes and attenuates the impairment in the behavioural reactivity to novelty induced by the prenatal exposure to diazepam (DZ) in adult male rat progeny. This study investigated the consequences of a late prenatal treatment with three GABA/BDZ R agonists (DZ) alprazolam (ALP) and zolpidem (ZOLP)), on different stress-related behavioural patterns, in non-handled (NH), short-lasting handled (SLH) and long-lasting handled (LLH) adult male rats exposed to forced swim test (FST), acoustic startle reflex (ASR) and Vogel test (VT). The effects on motor activity were evaluated in the open field and in the Skinner box…