摘要:

LTP is often studied as a model of synaptic plasticity. Plasticity in pain control systems may involve mechanisms similar to those involved in learning. We recently reported LTP of both the Aβ and C-fibre evoked responses of single dorsal horn neurons after a tetanic stimulation of the sciatic nerve, lasting for at least 6 h. In the present paper we show that identical stimulation induced LTP only of the C-fibre evoked response after blockade of muscular contractions during the tetanus. The C-fibre evoked response increased significantly less after pretreatment with either the AMPA antagonist NBQX or the NMDA antagonist D-AP5 (mean increase 33%) than in untreated animals (105%,p< 0.001), indicating that both AMPA and NMDA receptor stimulation are involved in the induction of LTP.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE neuroprotective effects of a novel Group II metabotropic glutamate receptor (mGluR) agonist, LY354740, have been evaluated in a gerbil model of global ischaemia. When administered at 50 mg/kg, i.p., 30 min and 6 h after a 3 min period of bilateral carotid artery occlusion (BCAO), the compound reduced the damage to CA1 hippocampal neurones to a significant level. However, when the ischaemic insult was made more severe, by increasing the period of occlusion to 4 and 5 min, the neuroprotective effects of LY354740 were reduced. From these findings, it would appear that Group II mGluRs may play a role in ischaemic damage in the gerbil hippocampus and that agonists at these receptors are potential neuroprotective agents.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

WE infer the functional integration of the visual, auditory and proprioceptive spatial maps from the behaviour of a patient (G.A.) with left visual neglect, i.e. a derangement of visual space representation. G.A. was required to point manually to left, centre or right acoustic stimuli, under visual control or blindfolded, with the responding hand (left or right) located either on the left, centre or right space. G.A.'s manual pointing responses to left auditory stimuli were strongly influenced by the visual spatial information and by the proprioceptive spatial information related to the position of the responding effector. In the visual control condition, when the patient performed the task with the left effector located on the left, pointing responses to left auditory stimuli were shifted towards the right intact visual space. In contrast, when the visual spatial information was rendered less salient, i.e. in the blindfolded condition, and the effector was again located on the left, manual pointing responses were confined to the previously ignored left space. These findings are consistent with the view that the acoustic representation is modulated by the impaired visual representation and by the proprioceptive spatial map related to the position of the responding effector.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

METABOTROPIC glutamate receptors (mGluRs) have been shown to contribute to nociceptive processing in the spinal cord. We have investigated the pharmacology of the mGluR agonist (1S,3R)-ACPD during inflammatory hyperalgesia in anin vitropreparation of the juvenile rat hemisected spinal cord. Superfusion of (1S,3R)-ACPD produced a concentration-dependent ventral root depolarization in naive and hyperalgesic animals with no significant difference in EC50values (55.5 ± 6.36 μM and 51.0 ± 5.76 μM, respectively,n= 4). However, the amplitude of the maximum response was significantly enhanced by 23% in hyperalgesic compared with naive animals. The NMDA receptor antagonist D-AP5 reversed this effect, leaving the (1S,3R)-ACPD dose-response curve unchanged in naive animals. These results suggest a tonic NMDA component in the spinal cord during inflammatory hyperalgesia.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE purpose of the present study was to investigate patterns of circadian rhythmicity in the retina of a salmonid fish, the rainbow trout (Oncorhynchus mykiss). In a first attempt to show both morphological and neurochemical variations during light/dark conditions (LD) and during continuous darkness (DD), we investigated retinomotor movements and the associated regulatory transmitters, dopamine and melatonin. All parameters studied showed patterns of rhythmicity in LD and DD, clearly indicating the presence of an endogenous clock in the rainbow trout eye. The most salient variations of all parameters studied were found at the transitions from light to dark and vice versa in LD and from subjective day to subjective night and vice versa in DD. The amplitudes of rhythms compared between LD and DD were similar in pigment index, whereas a clear reduction was found for cone index, dopamine and melatonin.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE intrinsic membrane properties of giant neurons of the caudal pontine reticular nucleus (PnC) were evaluated in a rat brain slice preparation. These neurons show low RP levels, long membrane time constants, low membrane resistance, tonic AP firing, and a lack of rectification behavior. The results are compared to those measured in adjacent areas of the reticular formation and discussed for their impact on triggering and modulating the acoustic startle response.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE 5HT1Bagonists RU24969 (2.5-5.0 mg/kg) and anpirtoline (2.0 mg/kg) induced a striking increase in striatal Fos-like immunoreactivity in rats. In the rostral and dorsal regions of the striatum staining was dense and relatively homogeneous. In the ventral region of the striatum at more caudal levels, however, both drugs induced staining in patches which were in register with the opiate receptor rich striosomes. The effects of RU24969 could not be antagonized by the selective 5HT1Aantagonist p-MPPI and little or no striatal Fos expression could be observed after injections of the selective 5HT1Aagonist 8-OHDPAT or the selective 5HT3 antagonist MDL-72222.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

FUNCTIONAL magnetic resonance imaging was used to determine the activation of the amygdala while seven social phobics and five healthy controls were exposed to slides of neutral faces as well as aversive odor stimuli. The amygdala was selectively activated in the social phobics during presentation of the face stimuli. The data show for the first time that the amygdala is active in human phobics when they are exposed to potentially fear-relevant stimuli. Further research is needed to determine the extent to which overactivation of the amygdala precedes or is a consequence of phobia.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

THE role of intracellular Ca2+stores during depolarization-evoked Ca2+signals in cultured cerebellar granule neurones was assessed by depletion of the stores with a specific inhibitor of the endoplasmic reticulum Ca2+pump: thapsigargin (TG, 0.7 μM). The maximal rate of [Ca2+]iincrease, measured as the first-order differential of the [Ca2+]itrace, increased directly in proportion to the increasing KCl concentration (in the range 20–90 mM) or, for a given KCl concentration (50 mM), to the levels of pre-stimulation [Ca2+i(range 25–100 nM Ca2+). Both these relationships were unaffected by TG. In contrast, the amplitude of the KCl-evoked response for KCl concentrations > 30 mM (inducing an increase in [Ca2+]i> 400 nM) was increased in the presence of TG.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

IT is unclear whether the neural algorithm that underlies stereoscopic vision in birds incorporates both low level (camouflage breaking) and high level (depth ordering) comparisons of information available to each of the eyes. Both visual functions were successfully tested by examining transitive inference performance in two barn owls trained to discriminate static Julesz random dot stereograms, thus demonstrating a capacity to detect relative depth using fine retinal disparity as the sole cue for discrimination. Our behavioral tests provide strong evidence that the barn owl possesses global stereopsis comparable to that found in the macaque monkey - the owl's best stereoacuity was 2 min of arc.

ISSN:0959-4965    

出版商:OVID    

年代:1998

数据来源: OVID