Search results for "Inhibitory postsynaptic potential"
showing 10 items of 243 documents
Unit study in cat claustrum of the effects of iontophoretic neurotransmitters and correlations with the effects of activation of some afferent pathwa…
1982
Glutamate (Glut), acetylcholine (ACh) and dopamine (DA) were iontophoretically applied on cat claustral neurons. Glut did not affect all the neurons; ACh had both excitatory and inhibitory effects, while DA was prevalently inhibitory. An analysis was made of the time-course of excitatory and inhibitory responses on the basis of the mean firing rate variations during and after ACh and DA release. Three types of responses are described for each drug: short lasting inhibition, long lasting inhibition and long lasting excitation. The experimental data were statistically elaborated. The effects of ACh and of DA were compared with those of activation obtained by sensorial peripheric and thalamic …
Pharmacological heterogeneity of γ-aminobutyric acid receptors during development suggests distinct classes of rat cerebellar granule cells in situ
2001
The gamma-aminobutyric acid receptor (GABA(A)R) represents a ligand-gated Cl(-)-channel assembling as heteropentamere from 19 known subunits. Cerebellar granule cells contain a unique subset, namely the alpha1-, alpha6-, beta2-, gamma2- and delta-subunits. We studied their GABAergic pharmacology in situ using whole-cell patch-clamp recordings in brain slices and a modified Y-tube application system. The distribution of the EC50s for GABA in young (P8-P14) and medium aged animals (P15-P28) could be fitted with the sum of two Gaussian distributions with means of 60 and 185 microM and 27 and 214 microM, respectively. In older animals (P29-P48) the observed homogeneous range of sensitivities fi…
Involvement of tachykinin NK2 receptors in the modulation of spontaneous motility in rat proximal colon.
2000
The role of endogenous tachykinins and the mechanisms whereby they act on NK2 receptors, modulating spontaneous motility, were investigated in rat isolated proximal colon. The mechanical activity was detected as changes in intraluminal pressure. The NK2 receptor antagonist, MEN 10627, produced a concentration-dependent reduction of the contraction amplitude. [beta-Ala8]-neurokinin A(4-10), an NK2 receptor agonist, and [Sar9, Met(O2)11]-Substance P ([Sar9, Met(O2)11]-SP), an NK1 receptor agonist, induced a concentration-dependent contractile response, characterized by an increase in basal tone with superimposed phasic contractions. MEN 10627 antagonized the response to [beta-Ala8]-neurokinin…
Modulatory effects of the novel TrkB receptor agonist 7,8-dihydroxyflavone on synaptic transmission and intrinsic neuronal excitability in mouse visu…
2013
7,8-Dihydroxyflavone (7,8 DHF) is a new recently identified TrkB receptor agonist, which possesses a potent neurotrophic activity and shares many physiological properties with the neurotrophin "Brain Derived Neurotrophic Factor" (BDNF). However, its precise mechanism of action at the cellular level has not been clarified yet. In the present study we explored the effects of this agent on synaptic and intrinsic neuronal properties by performing whole-cell patch clamp recordings from layer 2/3 pyramidal neurons. Incubation of acute cortical slices with 7,8-DHF (20 µM) for 30 min caused a selective reduction in the strength of GABAergic inhibition. The amplitude of evoked inhibitory postsynapti…
Postnatal alterations of the inhibitory synaptic responses recorded from cortical pyramidal neurons in the Lis1/sLis1 mutant mouse
2006
Mutations in the mouse Lis1 gene produce severe alterations in the developing cortex. We have examined some electrophysiological responses of cortical pyramidal neurons during the early postnatal development of Lis/sLis1 mutant mice. In P7 and P30 Lis1/sLis1 neurons we detected a lower frequency and slower decay phase of mIPSCs, and at P30 the mIPSCs amplitude and the action potential duration were reduced. Zolpidem (an agonist of GABAA receptors containing the alpha1 subunit) neither modified the amplitude nor the decay time of mIPSCs at P7 in Lis1/sLis1 neurons, whereas it increased the decay time at P30. The levels of GABAA receptor alpha1 subunit mRNA were reduced in the Lis1/sLis1 brai…
GABAA agonist muscimol ameliorates learning/memory deficits in streptozocin-induced Alzheimer’s disease non-transgenic rat model
2015
Background: GABAergic inhibitory action regulates learning/memory processes and contributes to neurotransmission (Gong et al., 2009). Existing evidence suggests GABAergic system is involved in pathophysiology of Alzheimer’s disease (AD) via inhibitory interneuron deficits (Verret et al., 2012) and decrease in functional GABAA receptors (Limon et al., 2012). In vitro, GABA and muscimol (GABAA receptor agonist) blocked neuronal death induced by Aβ in rat hippocampal and cortical neurons (Paula-Lima et al., 2005). Our concept: low doses of muscimol may prevent learning/memory deficits in intracerebroventricular (icv) streptozocin (STZ)-induced AD non-transgenic rat model. Methods. Wistar male …
Involvement of purinergic nerves in the NANC inhibitory junction potentials in pigeon oesophageal smooth muscle.
2004
1. Electrical field stimulation (EFS) (0.5 ms in train of 2-32 Hz for 300 ms) in smooth muscle of pigeon oesophagus, in the presence of atropine (1 microm) and guanethidine (1 microm), elicited an inhibitory response consisting of a transient hyperpolarization (inhibitory junction potential, IJP) associated with muscle relaxation. 2. Sodium nitroprusside (SNP, 100 microm) induced hyperpolarization correlated to mechanical relaxation. 3. The nitric oxide (NO) synthase inhibitor N(omega)-nitro-l-arginine (from 0.1 to 100 microm) caused a concentration-dependent reduction of electromechanical response to EFS indicating a role for NO in this response. 4. Apamin (1 microm) reduced both IJP and r…
Non-adrenergic non-cholinergic nerve-mediated inhibitory control of pigeon oesophageal muscle.
1996
Pigeon oesophageal smooth muscle in vitro has spontaneous electromechanical activity. In the presence of atropine and guanethidine, electrical field stimulation evokes a transient TTX-sensitive response comprising inhibition of electric bursting activity and muscular relaxation. This NANC inhibitory response was analysed using the K+ channel blockers TEA and apamin, TEA perfusion (0.1-5 mM) induced a concentration-dependent reduction in amplitude of EFS-evoked relaxation. Responses to higher stimulation frequencies were more sensitive to TEA than those to lower ones. The maximum reduction in amplitude (29% of control) was obtained on 30 Hz EFS evoked responses during 5 mM TEA perfusion. In …
Short- and long-latency muscarinic inhibition of noradrenaline release from rabbit atria induced by vagal stimulation.
1988
1. The influence of the time interval between vagal and sympathetic nerve stimuli on the magnitude of muscarinic inhibition of noradrenaline release was studied in the isolated perfused rabbit atria preparation. The transmitter stores were labelled with [14C]choline and [3H]noradrenaline. 2. The right cardiac postganglionic sympathetic nerves were stimulated at 3 Hz for 3 min three times at intervals of 10 min. The [3H]noradrenaline outflow evoked by the second stimulation equalled the averaged means of the log values of amine outflows evoked by the first and third stimulations. 3. During the second sympathetic stimulation the right vagus nerve was stimulated (3 Hz, 3 min) in such a way tha…
Electrical stimulation of glossopharyngeal nerve and oesophageal EMG response in the pigeon
1985
The effects of the efferent glossopharyngeal nerve stimulation, on EMG activity of the pigeon cervical oesophagus, were studied. In control animals, stimulation caused a biphasic response characterized by an intra-stimulus excitatory component followed by a post-stimulus inhibitory one. The EMG response to glossopharyngeal stimulation appeared simultaneously throughout the cervical oesophagus. A bell-shaped mechanical wave was detected relating to the electrical excitatory component. Atropine administration antagonized the excitatory component, while the inhibitory one persisted. It occurs intra-stimulus, and its duration is increased, compared to control ones. A reduction in the oesophagea…