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Facilitatory Effect (facilitatory + effect)
Selected AbstractsInterleukin-10 is associated with resistance to febrile seizures: Genetic association and experimental animal studiesEPILEPSIA, Issue 4 2009Yoshito Ishizaki Summary Purpose:, Febrile seizures (FS) are the most common form of childhood convulsions. Many reports have shown that a proinflammatory cytokine, interleukin-1 (IL-1) ,, may have a facilitatory effect on the development of FS. We have previously shown that the IL1B -511C/T single nucleotide polymorphism (SNP) is associated with simple FS of sporadic occurrence. The balance between pro- and antiinflammatory cytokines influences the regulation of infections and could, therefore, play a role in the pathogenesis of FS. Here, to determine whether pro- and antiinflammatory cytokine genes are responsible for the susceptibility to FS, we have performed an association study on functional SNPs of cytokine genes in FS patients and controls. Methods:, The promoter SNPs of four inflammatory cytokine genes (IL6 -572C/G, IL8 -251A/T, IL10 -592A/C and TNFA -1037C/T) were examined in 249 patients with FS (186 simple and 63 complex FS) and 225 controls. Because the IL10 -592 SNP showed a positive association with FS, two additional SNPs (IL10 -1082A/G and -819T/C) were subjected to haplotype analysis. Furthermore, we examined the in vivo role of IL-10 in hyperthermia-induced seizures using immature animal models. Results:, The frequencies of the IL10 -592C allele and -1082A/-819C/-592C haplotype were significantly decreased in FS as compared with in controls (p = 0.014 and 0.013, respectively). The seizure threshold temperature in the IL-10,administered rats was significantly higher than that in the saline-treated control ones (p = 0.027). Conclusions:, The present study suggests that IL-10 is genetically associated with FS and, contrary to IL-1,, confers resistance to FS. [source] Afferent-induced facilitation of primary motor cortex excitability in the region controlling hand muscles in humansEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2009H. Devanne Abstract Sensory inputs from cutaneous and limb receptors are known to influence motor cortex network excitability. Although most recent studies have focused on the inhibitory influences of afferent inputs on arm motor responses evoked by transcranial magnetic stimulation (TMS), facilitatory effects are rarely considered. In the present work, we sought to establish how proprioceptive sensory inputs modulate the excitability of the primary motor cortex region controlling certain hand and wrist muscles. Suprathreshold TMS pulses were preceded either by median nerve stimulation (MNS) or index finger stimulation with interstimulus intervals (ISIs) ranging from 20 to 200 ms (with particular focus on 40,80 ms). Motor-evoked potentials recorded in the abductor pollicis brevis (APB), first dorsalis interosseus and extensor carpi radialis muscles were strongly facilitated (by up to 150%) by MNS with ISIs of around 60 ms, whereas digit stimulation had only a weak effect. When MNS was delivered at the interval that evoked the optimal facilitatory effect, the H-reflex amplitude remained unchanged and APB motor responses evoked with transcranial electric stimulation were not increased as compared with TMS. Afferent-induced facilitation and short-latency intracortical inhibition (SICI) and intracortical facilitation (ICF) mechanisms are likely to interact in cortical circuits, as suggested by the strong facilitation observed when MNS was delivered concurrently with ICF and the reduction of SICI following MNS. We conclude that afferent-induced facilitation is a mechanism which probably involves muscle spindle afferents and should be considered when studying sensorimotor integration mechanisms in healthy and disease situations. [source] IP3 receptor in the hair cells of frog semicircular canal and its possible functional roleEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2006Maria Lisa Rossi Abstract The presence and functional role of inositol trisphosphate receptors (IP3R) was investigated by electrophysiology and immunohistochemistry in hair cells from the frog semicircular canal. Intracellular recordings were performed from single fibres of the posterior canal in the isolated, intact frog labyrinth, at rest and during rotation, in the presence of IP3 receptor inhibitors and drugs known to produce Ca2+ release from the internal stores or to increase IP3 production. Hair cell immunolabelling for IP3 receptor was performed by standard procedures. The drug 2-aminoethoxydiphenyl borate (2APB), an IP3 receptor inhibitor, produced a marked decrease of mEPSP and spike frequency at low concentration (0.1 mm), without affecting mEPSP size or time course. At high concentration (1 mm), 2APB is reported to block the sarcoplasmic-endoplasmic reticulum Ca2+ -ATPase (SERCA pump) and increase [Ca2+]i; at the labyrinthine cytoneural junction, it greatly enhanced the resting and mechanically evoked sensory discharge frequency. The selective agonist of group I metabotropic glutamate receptors (RS)-3,5-dihydroxyphenylglycine (DHPG, 0.6 mm), produced a transient increase in resting mEPSP and spike frequency at the cytoneural junction, with no effects on mEPSP shape or amplitude. Pretreatment with cyclopiazonic acid (CPA, 0.1 mm), a SERCA pump inhibitor, prevented the facilitatory effect of both 2APB and DHPG, suggesting a link between Ca2+ release from intracellular stores and quantal emission. Consistently, diffuse immunoreactivity for IP3 receptors was observed in posterior canal hair cells. Our results indicate the presence and a possibly relevant functional role of IP3-sensitive stores in controlling [Ca2+]i and modulating the vestibular discharge. [source] Interaction between genioglossus and diaphragm responses to transcranial magnetic stimulation in awake humansEXPERIMENTAL PHYSIOLOGY, Issue 4 2007Wei Wang The modulation of activity of the upper airway dilator and respiratory muscles plays a key role in the regulation of ventilation, but little is known about the link between their neuromuscular activation processes in vivo. This study investigated genioglossus and diaphragm responses to transcranial magnetic stimulation applied in different facilitatory conditions. The amplitude and latency of motor-evoked potential responses and the stimulation intensity threshold leading to a motor response (motor threshold) were recorded with stimulation applied at the vertex and anterolateral area in 13 awake normal subjects. Stimuli were applied during inspiration with and without resistance, during expiration with and without maximal tongue protrusion and during deep inspiration. In each stimulation location and condition, no diaphragmatic response was obtained without previous genioglossus activity (diaphragmatic and genioglossus responses latencies during expiration: 18.1 ± 2.9 and 6.3 ± 2.6 ms, respectively, mean ±s.d., P < 0.01). Genioglossus motor-evoked potential amplitude, latency and motor threshold were significantly modified with tongue protrusion with a maximal effect observed for stimulation in the anterolateral area. Deep inspiration was associated with a significant facilitatory effect on both genioglossus and diaphragm motor responses. The facilitatory effects of respiratory and non-respiratory manoeuvres were also observed during focal stimulation where isolated genioglossus responses were observed. Genioglossus and diaphragm differed in their motor threshold both at baseline and following facilitatory manoeuvres. Conclusions: (1) transcranial magnetic stimulation-induced genioglossus response systematically precedes that of diaphragm; (2) this sequence of activation is not modified by respiratory and non-respiratory manoeuvres; and (3) the genioglossus and diaphragm are differently influenced by these manoeuvres in terms of latency of the motor response and of motor threshold. [source] Involvement of ,, Subunits of Gq/11 in Muscarinic M1 Receptor Potentiation of Corticotropin-Releasing Hormone-Stimulated Adenylyl Cyclase Activity in Rat Frontal CortexJOURNAL OF NEUROCHEMISTRY, Issue 1 2000Maria C. Olianas Abstract : In the present study, we investigated the involvement of ,, subunits of Gq/11 in the muscarinic M1 receptor-induced potentiation of corticotropin-releasing hormone (CRH)-stimulated adenylyl cyclase activity in membranes of rat frontal cortex. Tissue exposure to either one of two ,, scavengers, the QEHA fragment type II adenylyl cyclase and the GDP-bound form of the , subunit of transducin, inhibited the muscarinic M1 facilitatory effect. Moreover, like acetylcholine (ACh), exogenously added ,, subunits of transducin potentiated the CRH-stimulated adenylyl cyclase activity, and this effect was not additive with that elicited by ACh. Western blot analysis indicated the expression in frontal cortex of both type II and type IV adenylyl cyclases, two isoforms stimulated by ,, subunits in synergism with activated Gs. The M1 receptor-induced enhancement of the adenylyl cyclase response to CRH was counteracted by the Gq/11 antagonist GpAnt-2A but not by GpAnt-2, a preferential Gi/o antagonist. In addition, the muscarinic facilitatory effect was inhibited by membrane preincubation with antiserum directed against the C terminus of the , subunit of Gq/11, whereas the same treatment with antiserum against either Gi1/2 or Go was without effect. These data indicate that in membranes of rat frontal cortex, activation of muscarinic M1 receptors potentiates CRH-stimulated adenylyl cyclase activity through ,, subunits of Gq/11. [source] A2A Adenosine Receptor Facilitation of Neuromuscular TransmissionJOURNAL OF NEUROCHEMISTRY, Issue 6 2000Influence of Stimulus Paradigm on Calcium Mobilization Abstract: The influence of stimulus pulse duration on calcium mobilization triggering facilitation of evoked [3H]acetylcholine ([3H]ACh) release by the A2A adenosine receptor agonist CGS 21680C was studied in the rat phrenic nerve-hemidiaphragm. The P-type calcium channel blocker ,-agatoxin IVA (100 nM) decreased [3H]ACh release evoked with pulses of 0.04-ms duration, whereas nifedipine (1 ,M) inhibited transmitter release with pulses of 1-ms duration. Depletion of intracellular calcium stores by thapsigargin (2 ,M) decreased [3H]ACh release evoked by pulses of 1 ms, an effect observed even in the absence of extracellular calcium. With short (0.04-ms) stimulation pulses, when P-type calcium influx triggered transmitter release, facilitation of [3H]ACh release by CGS 21680C (3 nM) was attenuated by both thapsigargin (2 ,M) and nifedipine (1 ,M). With longer stimuli (1 ms), a situation in which both thapsigargin-sensitive internal stores and L-type channels are involved in ACh release, pretreatment with either ,-agatoxin IVA (100 nM) or nifedipine (1 ,M) reduced the facilitatory effect of CGS 21680C (3 nM). The results suggest that A2A receptor activation facilitates ACh release from motor nerve endings through alternatively mobilizing the available calcium pools (thapsigargin-sensitive internal stores and/or P- or L-type channels) that are not committed to the release process in each stimulation condition. [source] Brain neurotransmitter receptor binding and nootropic studies on Indian Hypericum perforatum Linn.PHYTOTHERAPY RESEARCH, Issue 3 2002Vikas Kumar Abstract The high affinity binding sites for serotonin and benzodiazepine in the frontal cortex, for dopamine in the striatum and muscarinic cholinergic receptors in the hippocampus were investigated in the brains of Charles Foster rats treated for 3 days. Transfer latency on elevated plus maze (TL), passive and active avoidance behaviour (PA and AA) and electroconvulsive shock (ECS) induced amnesia were also studied. Pilot studies indicated that single dose administration of Indian Hypericum perforatum (IHp) had little or no acute behavioural effects and hence the extract of IHp was administered orally at two dose levels (100 and 200,mg/kg, p.o.) once daily for 3 consecutive days, while piracetam (500,mg/kg, i.p.), a clinically used nootropic agent, was administered acutely to rats as the standard nootropic agent. Control rats were treated with an equal volume of vehicle (0.3%,carboxymethyl cellulose). The results indicate that IHp treatment caused a significant decrease in the binding of [3H] spiroperone (DA-D2 receptor) to the striatum and an increase in the binding of [3H] ketanserin (5-HT2A receptor) and [3H] flunitrazepam (BDZ receptor) to the frontal cortex in rats. Preliminary pharmacological studies with IHp extract indicate the presence of two major behavioural actions, namely, antidepressant and anxiolytic. The present findings tend to elucidate the mechanism of earlier observations, the downregulation of the dopamine D2 receptor being consonant with anxiolytic and the upregulation of 5-HT2A and BDZ receptors being consonant with antidepressant activity. Piracetam when given alone, shortened the TL on days 1, 2 and 9 day and also antagonized the amnesic effects of ECS on the TL significantly, whereas IHp antagonized the amnesia produced by ECS. IHp had no significant effect per se on the retention of the PA in rats but produced a significant reversal of ECS induced PA retention deficit. Piracetam showed a significant facilitatory effect per se on PA retention and also reversed the ECS induced impaired PA retention. In the AA test, piracetam facilitated the acquisition and retention of AA in rats but IHp had no effect per se. Both the doses of IHp and piracetam significantly attenuated the ECS induced impaired retention of AA. These results indicate a possible nootropic action of IHp in amnesic animals, which was comparable qualitatively to piracetam. Copyright © 2002 John Wiley & Sons, Ltd. [source] | |||||||||||||