| Objective： Neurons in deep layer of entorhinal cortex play a key rolein spatial memory and consolidation.In our present research, we firstinvestigated how OrexinA regulated deep layer neurons of entorhinalcortex, approaching its ionic mechanism and physiological functions.Method： Deep layer neurons of medial entorhinal cortex were chosento do the whole-cell patch clamp recording.Application of TTX (ljxM)，CNQX (lOjxM) and AP-V (50fiM) inhibited presynaptic effect,to primarilyinvestigate postsynaptic ionic mechanism.Results： Our results show as follow:1.38.7%neurons were sensitive to OrexinA,while54.8%neuronswere insensitive;6.5%neurons were restrained by OrexinAWhole-cell recordings were obtained from a total of93neurons in deep layer of MEC.OrexinA triggers a burst of action potentials(Aps)accompanied by a depolarizion of membrane potential in deeper layerneurons of medial entorhinal cortex.In total of93neurons,36neurons havea significant excitability (38.7%).51of93neurons have no response(54.8%),and the other6neurons represent inhibition by OrexinA(6.5%).2.OrexinA suppresses the whole-cell potassium currentWe used whole-cell voltage-clamp techniques to test whether theeffects of OrexinA on the peak of whole-cell K+current which evoked inresponse to a20-mV increments steps(duration=0.5s,steps=6) from aholding potential-60mv to+40mV.In the presence of TTX,CNQX andAP-V+,the whole-cell K current was significantly suppressed after thetreatment of OrexinA(/?<0.05,n=6)3.OrexinA simultaneously suppresses the sustained K+currentwe also use4-AP (5mM) to pharmacologically isolated sustained K+conductance f+rom net-K conductance.After bathing4-AP (in the presenceof TTX,CNQX and AP-V) for at least2min,until the sustained potassiumcurrents were absolutely isolated while applying the same protocol.In thisstudy,sustained potassium currents (measured in peak value) weredefinitely decreased during OrexinA was puffed and recovered afterwashout.4. I2nlfux of C+a partially participates in the OrexinA-induceddepolarization C2+a-free ACSF added in TTX,CNQX,AP-V were perfused for at leastlOmin.While the neurons recorded were steady,we first tested changes ofmembrane potential.The average of the depolarization significantlyd2+ecreased in the Ca-freewith control level (20.11士8.38mV,n=15).5. OrexinA directly depolairzes the neurons through OXjreceptors.Neurons that have been showed to be excited by OrexinA in thepresence of TTX, CNQX and AP-V are chosen to carry out the nextstudy.After OrexinA was washed out,the whole brain slice was perfusedwith SB334867for at least10minutes.In the some condition, PuffingOrexinA (100jxM) induced no significantly depolarization (4士.0661.08mV,n=5) compared with control levels (20.1士8.4mV,n=15).Conclusion： Deep layer neurons of medial entorhinal cortex havediverse reactions to OrexinA.A large part of neurons were mainly withinsensitive effect to OrexinA,others were insensitive. OrexinA excitedneurons primarily by activating the Orexin receptor1,and then suppressingsustained potassium current and triggering calcium-influx. Objective： To investigate whether the effect of OrexinA excitingneurons in layer V of prefrontal cortex is mediated by p38-MAPK or not.Methods: Whole-cell patch clamp recording was used to do theresearch.Results: our results show as follow:1.OrexinA could excited layer V neurons of prefrontal cortex throughsuppressing HCN channels2.Suppressing p38-MAPK weaked the Ih current,and excited neurons.3.The effect of OrexinA on HCN channels did not involve p38-MAPKConclusion： We have identified that OrexinA could excited layer Vneurons of prefrontal cortex through suppressing HCN channels.We firstdemonstrated that suppressing p38-MAPK could directly enhance neuronsexcitability. However,p38-MAPK was not participated in the regulation ofOrexinA on HCN channels.In addition,the direct effect of p38-MAPK onHCN suggested that other signal molecules may involved in，andcooperated with OrexinA to enhance neurons excitability. |
PDF Full Text Request