The impact of amygdala glutamate receptors on cardiovascular function in rats with post-traumatic stress disorder / 生理学报

Post-traumatic stress disorder (PTSD) has been reported to be associated with a higher risk of cardiovascular disease. The amygdala may have an important role in regulating cardiovascular function. This study aims to explore the effect of amygdala glutamate receptors (GluRs) on cardiovascular activity in a rat model of PTSD. A compound stress method combining electrical stimulation and single prolonged stress was used to prepare the PTSD model, and the difference of weight gain before and after modeling and the elevated plus maze were used to assess the PTSD model. In addition, the distribution of retrogradely labeled neurons was observed using the FluoroGold (FG) retrograde tracking technique. Western blot was used to analyze the changes of amygdala GluRs content. To further investigate the effects, artificial cerebrospinal fluid (ACSF), non-selective GluR blocker kynurenic acid (KYN) and AMPA receptor blocker CNQX were microinjected into the central nucleus of the amygdala (CeA) in the PTSD rats, respectively. The changes in various indices following the injection were observed using in vivo multi-channel synchronous recording technology. The results indicated that, compared with the control group, the PTSD group exhibited significantly lower weight gain (P < 0.01) and significantly decreased ratio of open arm time (OT%) (P < 0.05). Retrograde labeling of neurons was observed in the CeA after microinjection of 0.5 µL FG in the rostral ventrolateral medulla (RVLM). The content of AMPA receptor in the PTSD group was lower than that in the control group (P < 0.05), while there was no significant differences in RVLM neuron firing frequency and heart rate (P > 0.05) following ACSF injection. However, increases in RVLM neuron firing frequency and heart rate were observed after the injection of KYN or CNQX into the CeA (P < 0.05) in the PTSD group. These findings suggest that AMPA receptors in the amygdala are engaged in the regulation of cardiovascular activity in PTSD rats, possibly by acting on inhibitory pathways.

Changes in cardiovascular function and related psychophysiological pathways in a rat model of post-traumatic stress disorder / 生理学报

This study was aimed to investigate the cardiovascular function in rats with post-traumatic stress disorder (PTSD) and the potential association with the activities of the rostral ventrolateral medulla (RVLM) and the medial habenular nucleus (MHb). Multi-channel in vivo recordings were used to simultaneously acquire spontaneous neuronal firing and peripheral physiological indices, and FluoroGold (FG) retrograde tracing technique was used to observe the projections of labeled neurons in the MHb. The results showed that the discharge frequency of RVLM and MHb neurons, the systolic blood pressure (SBP), and the mean arterial pressure (MAP) in the PTSD group were all increased significantly compared with those in control group (P < 0.05). MHb neurons were retrogradely labeled by FG through microinjection (4% FG, 0.5 μL) into the RVLM. In the control group, electrical stimulation in the MHb increased heart rate (HR) at 100-300 μA (P < 0.05), elevated SBP and MAP at 200-300 μA (P < 0.05), and remarkably increased the RVLM neuronal discharge frequency at 100-500 μA (P < 0.05 or P < 0.01). In the PTSD group, however, only the discharge frequency of RVLM neurons was increased by the electrical stimulation at 100-300 μA (P < 0.05). These results suggest that cardiovascular activities of the PTSD model rat are enhanced, and this change may be related to the activity changes of RVLM and MHb and the potential connection between the two nuclei.

Evaluation of Unilateral Masticatory Muscle Function by Comprehensive Intervention / 中山大学学报(医学科学版)

@#【Objective】 To compare the changes of electromyographic activity of masticatory muscles in unilateral chewers before and after comprehensive intervention，and to evaluate the effect of comprehensive intervention.【Methods】 Thirty patients with unilateral mastication were selected，aged（19.3±0.5）years old. There was no statistically significant difference in general conditions ，which met the selection criteria for unilateral mastication. Randomly divided into intervention group and control group，with 15 cases in each group. The control group did not undergo any treatment，and the intervention group was given comprehensive intervention treatment mainly by eliminating inducement and muscle function training. Six months later，the electromyogram of masseter（left：LMM，right：RMM）and anteriovent of digastric muscle（left：LDA，right：RDA） were recorded in the two groups during the maximum opening and closing movement（M1）and masticatory movement（M2）. Statistical analysis was performed for the above.【Results】① There were significant differences in the average electromyographic difference values of LDA［M1：-7.4（-12.98，-1.84）］and RMM［M2：-2.28（- 4.42，- 0.13）］before and after intervention in the intervention group（P < 0.05）；the average EMG values of RMM and RDA in M2 after intervention were 9.62（5.99，9.98），9.96（7.91，12.62），compared with RMM［4.88（3.87~5.88）］，RDA［5.05（3.07~8.12）］in control group，the difference was statistically significant（P < 0.01）. ② The peak electromyogram values of bilateral DA （M1） and MM （M2） in intervention group were higher than those before intervention （P < 0.05）；the peak electromyogram values of LDA（M1）after intervention was 760.24（322.34~953.81），compared with LDA［M1 ：317.41（186.17~474.81）］in the control group，the difference was statistically significant（P < 0.05）.③ The activity asymmetry index of MM and DA in intervention group was lower than that before intervention（P < 0.05）；the value of the MM index［M1（15.59 ± 10.52），M2（10.84 ± 7.35）］after the intervention was lower than that in control group［M（129.89 ± 20.56），M（222.39 ± 16.87）］（P < 0.05），the DA index value［M1：7.60（5.00~26.5）］was lower than that in control group［25.4（13.8~43.50）］（P < 0.05）.【Conclusions】After comprehensive intervention，the contractility and symmetry of masseter and anteriovent of digastric muscle were significantly improved ，and the function of masticatory muscles recovered well.

Electrophysiological phenotypes of synaptic transmission and neural network in hippocampal neurons of the α7-nAChR knockout mice / 生理学报

It was reported that α7 nicotinic acetylcholine receptor (α7-nAChR) knockout (α7 KO) mice showed few functional phenotypes. The purpose of this study was to investigate the effect of α7 KO on the electrophysiological characteristics of hippocampus in mice. The effect of α7 KO on hippocampal CA3-CA1 synaptic transmission in mice was evaluated by standard extracellular field potential recordings. The electrophysiological phenotype of γ-aminobutyrate A receptors (GABA-Rs) of single hippocampal neuron was detected by perforated patch-clamp recordings. The results showed that, the slope of field excitatory postsynaptic potential (fEPSP) and carbachol-induced theta oscillation were significantly decreased in the hippocampal CA1 neurons of α7 KO mice, compared with those of wild type mice. Under the treatment of GABA-R agonist muscimol, the I-V curves of both the hippocampal CA1 and CA3 neurons of α7 KO mice shifted towards depolarizing direction obviously, compared with those of wild type mice. These results suggest that the hippocampal CA3-CA1 synaptic transmission in α7 KO mice was significantly impaired and GABA-R maturation was significantly delayed, indicating that the deletion of α7-nAChR gene could significantly change the electrophysiological function of the hippocampus. The results may provide a new understanding of the role of α7-nAChR in hippocampal function and associated diseases.

Functional plasticity of trigeminal motor nucleus in unilateral mastication model rats / 生理学报

To observe the plasticity changes of trigeminal motor nucleus (Mo5) and masseter H-reflex in unilateral mastication model rats and explore the possible mechanism of functional plasticity in motor center involved in unilateral mastication, 54 adult male Wistar rats were randomly divided into 1-month (n = 10), 3-month (n = 10), and 16-month (n = 7) model groups and their corresponding control groups, respectively. Unilateral mastication model rats were prepared by intermittent removal of clinical crowns of left teeth (model side). Rats were anesthetized (20% urethane, i.p.), and bilateral Mo5 were chosen to conduct extracellular recordings, while bilateral electromyography (EMG) of masseter muscle and its H-reflex were simultaneously recorded by a polygraph. It was observed that the firing rate of Mo5 neurons in model sides was significantly lower than that of right sides in 3 model groups, and that of left sides in their control groups. The response latency of Mo5, which was evoked by electrical stimulation of masseter nerve in model sides of 1-month and 3-month model groups, was significantly longer than that of left sides in their control groups. Moreover, the amplitude of H-wave in model sides of 3-month and 16-month model groups was lower than that of left sides in their control groups when H-reflex was evoked by electrical stimulation of left masseter nerve. These results suggest that unilateral mastication in model rats decreases the Mo5 neuron excitability, and this may be one of the functional plasticity mechanisms in motor center involved in unilateral mastication.

Apelin in the hypothalamic paraventricular nucleus improves cardiac function in surgical trauma rats / 生理学报

Apelin is a novel endogenous active peptide. The aim of this study is to investigate whether apelin in the paraventricular nucleus (PVN) can improve the cardiac function in rats subjected to thoracic surgery trauma, and whether it is involved in the protective effect of electro-acupuncture (EA). Sprague-Dawley rats were randomly divided into non-stressed group (control), thoracic surgical trauma stressed group (trauma) and bilateral Neiguan EA applied on thoracic surgical trauma stressed group (trauma + EA-PC 6). The mRNA expressions of apelin receptor (APJR) and apelin in the PVN were detected by real time-PCR. The exogenous apelin-13 (6 mmol/L, 0.1 μL) was microinjected into the rat PVN in the thoracic trauma group, and the effects of apelin-13 on the blood pressure (BP), heart rate (HR) and the discharge of rostral ventrolateral medulla (RVLM) neurons were observed through the simultaneous recording technology by polygraph. The results showed that the APJR mRNA expression was significantly decreased in the rats of trauma group as compared with that in the control group (P < 0.05), and a decline trend of apelin mRNA expression was also observed. EA application at bilateral Neiguan acupoints partially recovered the decline of APJR and apelin mRNA expression by the treatment of thoracic trauma. Both mean arterial pressure and HR in the thoracic surgical trauma group were significantly increased by the microinjection of exogenous apelin-13 into the PVN (P < 0.05), and the single-unit discharge rate of RVLM neurons also had an increasing trend. These results suggest that apelin in the PVN can improve the cardiac function of thoracic surgical trauma rats, and may be involved in the protective effects of EA.

Inhibitory effects of propofol on excitatory synaptic transmission in supraoptic nucleus neurons in vitro / 生理学报

The present study was designed to investigate the inhibitory effects of intravenous general anesthetic propofol (0.1-3.0 mmol/L) on excitatory synaptic transmission in supraoptic nucleus (SON) neurons of rats, and to explore the underlying mechanisms by using intracellular recording technique and hypothalamic slice preparation. It was observed that stimulation of the dorsolateral region of SON could elicit the postsynaptic potentials (PSPs) in SON neurons. Of the 8 tested SON neurons, the PSPs of 7 (88%, 7/8) neurons were decreased by propofol in a concentration-dependent manner, in terms of the PSPs' amplitude (P < 0.01), area under curve, duration, half-width and 10%-90% decay time (P < 0.05). The PSPs were completely and reversibly abolished by 1.0 mmol/L propofol at 2 out of 7 tested cells. The depolarization responses induced by pressure ejection of exogenous glutamate were reversibly and concentration-dependently decreased by bath application of propofol. The PSPs and glutamate-induced responses recorded simultaneously were reversibly and concentration-dependently decreased by propofol, but 0.3 mmol/L propofol only abolished PSPs. The excitatory postsynaptic potentials (EPSPs) of 7 cells increased in the condition of picrotoxin (30 µmol/L, a GABA(A) receptor antagonist) pretreatment. On this basis, the inhibitory effects of propofol on EPSPs were decreased. These data indicate that the presynaptic and postsynaptic mechanisms may be both involved in the inhibitory effects of propofol on excitatory synaptic transmission in SON neurons. The inhibitory effects of propofol on excitatory synaptic transmission of SON neurons may be related to the activation of GABA(A) receptors, but at a high concentration, propofol may also act directly on glutamate receptors.

Changes of masseter muscle asymmetry due to unilateral mastication after intervention: a electromyographic analysis / 南方医科大学学报

<p><b>OBJECTIVE</b>To explore the effect of intervention with unilateral mastication on masseter muscle asymmetry.</p><p><b>METHODS</b>Forty-three subjects (19 males and 24 females, mean age 20.0∓0.5 years) with unilateral chewing were divided into group A0 with motivation and without intervention, group A1 with motivation and intervention, group B0 without motivation or intervention, and group B1 without motivation but with intervention. In groups A0 and A1, the motivation was removed and groups A1 and group B1 received interventions. Surface electromyography was recorded using surface electromyography in all the subjects in mandible postural position (MPP), with maximum clenching in intercuspal position (ICP) and during chewing. The sEMG of the left and right masseter muscle were separately recorded to assess the asymmetry index of the masseter muscles (ASMM) and its changes after intervention.</p><p><b>RESULTS</b>In groupA0, the ASMM at MPP, during maximum clenching and chewing had no obvious changes after removal of the motivation. In group A1, the ASMM at MPP, during maximum clenching and chewing were obviously decreased after intervention. In group B0, the ASMM at MPP and during maximum clenching showed no obvious changes but ASMM during chewing significantly increased after removal of the motivation. In group B1, the ASMM at MPP, during maximum clenching and chewing all decreased obviously after intervention.</p><p><b>CONCLUSION</b>Interventions can significantly improve the bilateral symmetry of the masseter muscles in subjects with unilateral chewing, and the motivation for unilateral chewing should be removed before intervention.</p>

Receptor kinetics analyses of long-term potentiation of synaptic transmission in spinal cord motoneurons in vitro / 生理学报

The aim of the present study is to observe the receptor kinetics property of long-term potentiation (LTP) of excitatory postsynaptic potential (EPSP) in spinal cord motoneurons (MNs) by descending activation. The intracellular recording techniques were conducted in spinal cord MNs of neonatal rats aged 8-14 days. The changes of EPSP induced by ipsilateral ventrolateral funiculus (iVLF) stimulation (iVLF-EPSPs) were observed, and receptor kinetics of iVLF-EPSPs were analyzed. The results showed that, the amplitude, area under curve and maximum left slope of EPSP were positively correlated with stimulus intensity (P < 0.05 or P < 0.01), while the apparent receptor kinetic parameters apparent dissociation rate constant (K(2)), apparent equilibrium dissociation constant (K(T)) of EPSP were negatively correlated with stimulus intensity (P < 0.01 or P < 0.05). The iVLF-EPSPs were persistently increased after tetanic stimulation (100 Hz, 50 pulses/train, duration 0.4-1.0 ms, 6 trains, main interval 10 s, 10-100 V) in 5 of 11 tested MNs. The amplitude of iVLF-EPSPs was potentiated to more than 120% of baseline and lasted at least 30 min, which could be referred to as iVLF-LTP. Meanwhile, the area under curve and maximum left slope of EPSPs were also increased to more than 120% of baseline. During iVLF-LTP, apparent receptor kinetics analyses of iVLF-EPSPs indicated that K(2) and KT were decreased significantly to less than 80% of the baseline within 10 min and gradually and partially recovered in 3 MNs. These results of receptor kinetics analyses of iVLF-EPSPs suggest a possible enhancement in affinity of postsynaptic receptors in the early stage of iVLF-LTP in some MNs.

Effects of etomidate on descending activation of motoneurons in neonatal rat spinal cord in vitro / 生理学报

Descending activation pathways in spinal cord are essential for inducing and modulating autokinesis, but whether the effects of general anesthetic agents on the descending pathways are involved in initiation of skeletal muscle relaxation or not, as well as the underlying mechanisms on excitatory amino acid receptors still remain unclear. In order to explore the mechanisms underlying etomidate's effects on descending activation of spinal cord motoneurons (MNs), the conventional intracellular recording techniques in MNs of spinal cord slices isolated from neonatal rats (7-14 days old) were performed to observe and analyze the actions of etomidate on excitatory postsynaptic potential (EPSP) elicited by electrical stimulation of the ipsilateral ventrolateral funiculus (VLF), which was named VLF-EPSP. Etomidate at 0.3, 3.0 (correspond to clinical concentration) and 30.0 µmol/L were in turn perfused to MN with steadily recorded VLF-EPSPs. At low concentration (0.3 µmol/L), etomidate increased duration, area under curve and/or half-width of VLF-EPSP and N-methyl-D-aspartate (NMDA) receptor-mediated VLF-EPSP component (all P < 0.05), as well as amplitude, area under curve and half-width of non-NMDA receptor-mediated VLF-EPSP component (all P < 0.05), or decreased amplitude and area under curve of VLF-EPSP, its NMDA receptor component, and non-NMDA receptor component (all P < 0.05). However, at 3.0 and 30.0 µmol/L, it was only observed that etomidate exerted inhibitory effects on amplitude and/or duration and/or area under curve of VLF-EPSP (P < 0.05 or P < 0.01) with concentration- and time-dependent properties. Moreover, NMDA receptor-mediated VLF-EPSP component was more sensitive to etomidate at ≥ 3.0 µmol/L than non-NMDA receptor-mediated VLF-EPSP component did. As a conclusion, etomidate, at different concentrations, exerts differential effects on VLF-EPSP and glutamate receptors mediating the synaptic transmission of descending activation of MNs in neonatal rat spinal cord in vitro.

Inhibitory effects of propofol on supraoptic nucleus neurons of rat hypothalamus in vitro / 生理学报

To investigate the effects of novel intravenous general anesthetic propofol on membrane electrophysiological characteristics and action potential (AP) of the supraoptic nucleus (SON) neurons and possible ionic mechanisms, intracellular recordings were conducted in SON neurons from the coronal hypothalamic slice preparation of adult male Sprague Dawley (SD) rats. The results showed that bath application of 0.1 mmol/L propofol induced a significant decline in resting potential (P < 0.01), and higher concentrations of propofol (0.3 and 1.0 mmol/L) decreased time constant and slope resistance of cell membrane (P < 0.01). Under the hyperpolarizing current pulses exceeding 0.5 nA, an anomalous rectification was induced by hyperpolarization-activated cation channel (I(h) channel) in 11 out of 18 tested SON neurons. Bath of propofol reversibly decreased the anomalous rectification. Moreover, 0.1 mmol/L propofol elevated threshold level (P < 0.01) and decreased Max L. slope (P < 0.05) of the spike potential in SON neurons. Interestingly, 0.3 and 1.0 mmol/L propofol nullified APs in 6% (1/18) and 71% (12/17) tested SON neurons, respectively. In the SON neurons where APs were not nullified, propofol (0.3 mmol/L) decreased the amplitude of spike potential (P < 0.05). The higher concentrations of propofol (0.3 and 1.0 mmol/L) decreased firing frequencies evoked by depolarizing current pulses (0.1-0.7 nA), and shifted the current intensity-firing frequency relation curves downward and to the right. These results suggest that propofol decreases the excitability of SON neurons by inhibiting I(h) and sodium channels.

Intracellular recordings and multi-parameter analysis of long-term potentiation of synaptic responses in chick brain slices / 生理学报

Day-old chick is unique animal model in brain development and behavior study. The intermediate medial mesopallium (IMM), a region of the chick forebrain, is intimately involved in the early learning processes, which offers the ideal opportunity to study the neural changes that underlie behavioral plasticity. In this paper, the intracellular recordings were conducted from IMM neurons in chick forebrain slices, in which electrophysiological properties, synaptic responses and long-term potentiation (LTP) were observed. Coronal sections of left forebrains (500 mum thick), containing IMM, were prepared from domestic chicks, aged 2-10 days. In 69 IMM neurons, the resting membrane potential was measured to be (-59.4+/-5.3) mV, slope membrane resistance (70.8+/-27.2) MΩ, and time constant (10.2+/-4.3) ms. The amplitude, threshold, overshoot, half-width, max rise slope and max decay slope of action potential evoked by intracellular current injection were (85.2+/-9.4) mV, (-38.7+/-7.6) mV, (25.6+/-8.9) mV, (2.1+/-0.5) ms, (150.5+/-41.2) mV/ms and (-64.3+/-14.0) mV/ms, respectively. Spike-firing frequency was increased with depolarizing current intensity in 32 of 69 tested cells [linear regression slope was (21.5+/-10.9) Hz/nA, P<0.05 in all cells]. The depolarizing synaptic responses (i.e. EPSPs), with stimulus intensity- and membrane potential-dependent properties, were elicited by dorsal (n=25) or ventral (n=62) focal electrical stimuli at 0.1 Hz in all tested IMM neurons and could be nullified reversibly by perfusion with 100 mumol/L AP5 (NMDA receptor antagonist) and 3 mumol/L DNQX (non-NMDA receptor antagonist), but enlarged by 6 mumol/L bicuculline (GABA(A) receptor antagonist). The EPSPs evoked by ventral stimulation were persistently increased after tetanic stimulation (5 Hz, 300 pulses/train, 2 trains, train interval 10 min) in 6 of 12 tested IMM neurons. The amplitude of EPSPs was potentiated to more than 120% of control level (when analyzed at 45 min of enhancement, P<0.05, n=5), which lasted at least 30 min and then could be referred to as LTP. Moreover, area under curve, duration and max rise slope of EPSPs were also enhanced (P<0.05), while no significant changes were observed in the electrophysiological parameters of IMM neurons following induction of LTP (P>0.05). These results suggest that the intracellular recording techniques in the chick brain slices can be used to perform multi-parameter analysis of synaptic responses and their LTP.

Inhibitory and excitatory effects of sodium nitroprusside on supraopticnucleus neurons in vitro / 中国临床药理学与治疗学

Aim To realize the regulatory actions of nitric oxide(NO) on supraoptic nucleus (SON)neurons by observing the effects of NO donor sodium nitroprusside(SNP) on SON neurons.Methods The cell electrophysioloical properties were obtained by the intracellular recording techniques from the SON neurons in adult rat hypothalamic slices.Results In 11 silent cells, superfusion of SNP(1 mmol?L-1) for 3～5 min resulted in the depolarization response with a decrease of membrane resistance and time constant(P