Objective To investigate the effects of ATP, suramin, ivermectin (IVM) and low pH value on pyramidal cells of rat hippocampus. Methods Pyramidal cells were rapidly dissociated from the hippocampus of 7-day postnatal rats by mechanical and enzymatic methods. Effects of ATP, suramin, IVM and low pH value on P2X receptor of neurons were studied by the technique of whole cell patch clamp. Results The transmembrane current was affected by ATP and suramin. There were different effects of IVM and low pH value on ATP induced current on different neurons. Conclusion There is extensive expression of P2X receptor on hippocampus pyramidal cells of rats. The expression of P2X receptors subunits are different among neurons.

Objective　To study the effects of hypoxia and glutamic acid on the kinetic properties of NMDA receptor channel of the hypothalamic neurons in rats. Methods　Cell-attached mode patch clamp technique was employed to record the single channel current of the NMDA receptor. Results　The open probability of NMDA receptor channel was increased after acute hypoxia compared with that of normal state, the open time τ1,τ2 was changed from (0.33±0.10)ms，(4.36±0.26)ms to (0.93±0.22)ms，(7.64±0.72)ms, and the close time τ1,τ2 was from (18.03±3.50)ms，(171.50±19.10)ms to (3.42±1.02)ms，(19.39±3.07)ms. The mean open probability was changed from 0.12±0.05 in normal state to 0.66±0.36 in hypoxia state. Furthermore, glutamic acid can increase open time and open probability of NMDA receptor channel,decrease close time. Conclusion　The excitability and the open probability of NMDA receptor channel of hypothalamic neurons increased by hypoxia is related to glutamate.

Objective To investigate the expression change of P2X3 receptor in spinal dorsal horn and dorsal root ganglion(DRG) in rats with experimental inflammatory pain.Methods Totally 30 SD rats received a subcutaneous injection of carrageenan in the right paw to establish inflammatory pain model,and then divided randomly and equally into 5 groups,that is 6,12,24,72 and 168 h after injection.Another 6 rats undergoing a subcutaneous injection of normal saline in the right paw served as control.Pain threshold was assayed by thermal radiation and von Frey filament in 2,4,6,12,24,72 and 168 h after injection.Expression of P2X3 receptor in spinal dorsal horn and DRG of every group was measured by immunohistochemical staining(IHC).Results After injection of carrageenan,thermal hyperalgesia and mechanical allodynia appeared in the rats.The thermal withdrawl latency(TWL) and 50% paw withdrawl threshold(PWT) were decreased obviously from 2 h,descended to the lowest at 12 h,then returned to the normal level after 72 h.The expression of P2X3 receptor in spinal dorsal horn was increased obviously from 24 h,while that at DRG was increased obviously from 12 h.Both of the expressions lasted for 72 h,and returned to the normal level at 168 h after injection.Conclusion Thermal hyperalgesia and mechanical allodynia appear in the rats after carrageenan injection,and the P2X3 receptor is activated and up-regulated in the DRG and spinal cord,suggesting that P2X3 receptor may play an important role in the incidence and development of inflammatory pain.

Objective Glucocorticoid hormone may nongenomically affect cell functions in addition to its classic effects on gene expression. The purpose of present study was to explore whether dexamethasone, a synthetical glucocorticoid hormone, has a rapid nongenomic effect on ATP-induced currents in rat dorsal root ganglion (DRG) neurons and the related signal transduction pathway. Methods The effects of dexamethasone on ATP-induced currents were studied on cultured DRG neurons using patch clamp technique. Results Three types of currents (transient, sustained and biphasic) were evoked by ATP (100 ?mol/L) in cultured DRG neurons. When DRG neurons were pretreated with dexamethasone (0.01-10?mol/L) for 30s, inhibition of the transient current and the transient component of the biphasic current evoked by ATP in DRG neurons was observed. The inhibitory effect of dexamethasone was dose-dependent. However, dexamethasone did not seem to affect the sustained current and the sustained component of the biphasic current induced by ATP. The inhibitory effect of dexamethasone on ATP-induced currents was blocked by glucocorticoid receptor antagonist RU38486 (10?mol/L) and protein kinase A inhibitor H-89 (10?mol/L), but not by G protein inhibitor GDP-?-S (0.2mmol/L) and protein kinase C inhibitor chelerythrine chloride (10?mol/L). Conclusions Dexamethasone can selectively inhibit the transient current mediated by P2X3 receptors in DRG neurons. The inhibitory effect of dexamethasone might be mediated by glucocorticoid receptor through activating PKA signal pathway. These results suggest that glucocorticoid hormone might participate in the control of pain by modulating the actions of extracellular ATP in sensory neurons.

Objective To observe the expression and phosphorylation of N-methyl-D-aspartate (NMDA) receptor NR1 subunit in rat cortex and hippocampus under high altitude hypoxia. Methods The adult SD rats were exposed to hypobaric hypoxia imitating 5 500-meter high altitude for 8 h daily for 3, 7, 14, 21 d. Immunohistochemical staining, Western blotting and co-immunoprecipitation were used to detect the expression and phosphorylation of NR1 in rat cortex and hippocampus. Results Both immunohistochemistry and Western blotting showed NR1 expression in rat cortex and hippocampus was increased under hypoxia in a time-dependent manner. The tyrosine phosphorylation of hypoxia groups was increased, and reached the peak on day 14 after hypoxia, then decreased, still higher than that of control groups till day 21 (P

Objective To observe the time course of the changes in nitric oxide (NO) content and the activity of NO synthase (NOS) during hippocampal long term potentiation (LTP) in vitro . Methods The production and maintenance of LTP were detected by using extracelluar electrophysiological recording. NO content and NOS activity were determined by biochemical reaction. The expression of NOS mRNA was detected by in situ hybridization. Results Conditioning stimulation for 10 min induced LTP production and significant increases in NO content, NOS activity and expression of NOS mRNA. However, at 60 min after conditioning stimulation, LTP remained stably but NO content and NOS activity returned to the pre conditioning stimulation level. Moreover, the NOS mRNA was overexpressed at the early stage of LTP production. Conclusion Significant NO changes may occur at the early stage of LTP formation.

Objective To investigate the expression of P2X receptors in CA1 subfield of rat hippocampus and the effect of hypoxia on the expression. Methods We set up the hypoxia animal model of high altitude and observed the expression of P2X receptors by using immunohistochemical staining before and after hypoxia. Results Immunohistochemistry showed that there were several sub-type of P2X receptors expressed in hippocampus CA1 neurons. After long term hypoxia, the expression of these receptors was increased. Conclusion there were abundant of P2X receptors expressed on the hippocampus CA1 neurons. Hypoxia affects the expression P2X receptors.

Objective To investigate the effects of chitin on the functional recovery after sciatic nerve axotomy. Methods Upon silicone-tubulization of the transected sciatic nerve in the adult rats, either 0.9% saline or 1% chitin solution was injected into the silicone chamber. The status of functional recovery of the injured sciatic nerve was observed by electrophysiological analysis, hydrogen-peroxide oxidoreductase (HRP) retrograde trace method, and axon morphometric analysis at 30 and 90 d respectively after sciatic nerve transection. Results ① Chitin shortened the latent period of CMAP by 1.79 ms and 1.29 ms, promoted the nerve conduction velocity by 16.00 m/s and 22.00 m/s, enhanced the amplitude by 8.17 mv and 12.42 mv, respectively, at 30 and 90 d after sciatic nerve transection (P

Objective To investigate the P2X3 receptor expression and electrophysiological characteristics in dorsal root ganglion (DRG) in rat with neuropathic pain caused by chronic constriction injury of sciatic nerve (CCI) Methods P2X3 receptor expressions in L4,L5 and L6 DRG following CCI were observed by using a polyclonal antibody to label the P2X3 receptor ATP-activated currents in corresponding DRG neurons following CCI were observed by using electrophysiological technique Results A significant increase in P2X3 immunoreactivity was observed in the ipsilateral (injured) L4,L5 and L6 DRG and spinal cord on 7,14 d after CCI In small diameter neurons,a significant increase in the number of cells exhibiting a transient current to ATP was observed on 7,14 d after CCI Moreover,amplitude of these currents was increased Conclusion After CCI,the expression and function of P2X3 receptor in corresponding DRG are increased

AIM:To observe the effect of altitude hypoxia on ?-aminobutyric (GABA) content and prepro-somatostatin mRNA (PPS-mRNA) in the rat hypothalamus. METHODS: Using altitude hypoxia model,in situ hybridization and amino acid analyzer, the number of PPS-mRNA and GABA content in rat hypothalamus was determined. RESULTS:After altitude hypoxia, the contents of GABA in hypothalamus and the number of PPS-mRNA neurons in periventricular nucleus (PeVN), paraventricular nucleus (PaVN) and arcuate nucleus (ArcN) increased significiantly. Bicuculline, a GABA receptor antagonits, could enhance PPS-mRNA expression evoked by altitude hypoxia, but had no effect on GABA content. CONCLUSION: Altitude hypoxia can induce neurotransmitter imbalance of hypothalamus.