Effects Of GW405833 And Lamotrigine On Electrophysiological Characteristics Of Neurons In Lateral Habenular Nucleus Of Mice

Background and objectiveThe habenular nucleus belongs to the epithalamus and is located in the habenular triangle at the head of the pineal gland and the inner side of the thalamus.It is divided into the medial habenular nucleus(MHb)and the lateral habenular nucleus(LHb).The main physiological function of habenula is to regulate the body's circadian rhythm and terror response.Recent studies have shown that the lateral habenula is related to the encoding of negative emotions and the pathophysiology of depression.The latest evidence shows that ketamine can block the bursting of lateral habenular nucleus neurons to quickly relieve depression.Therefore,cluster firing neurons in the lateral habenula may be an important target for the treatment of depression.Existing evidence shows that the cannabinoid type2 receptor(CB₂R)agonist GW405833(GW)and the antiepileptic drug lamotrigine(LTG)are both effective in treating depression.However,the regulation of these two drugs on lateral habenular nucleus neurons and their mechanism of action are still unclear.This subject studied the effects of GW and LTG on the discharge of different subtypes of neurons in the lateral habenula,and provided experimental evidence for revealing the targets and mechanisms of their antidepressant effects.Materials and Methods1.Animals:2-6 weeks old C57BL/J6 mice,wild-type(WT)mice.2.Lateral habenular nucleus slice preparation:prepare coronal slices containing 300?m of lateral habenular nucleus for patch clamp recording.3.Patch-clamp whole-cell recording:Under the infrared phase contrast interference microscope,use patch clamp to perform patch-clamp whole-cell recording of the electrophysiological data of lateral habenular nucleus neurons and VTA dopamine neurons,and detect lamotrigine And GW affects it.4.Data and statistical analysis:p Clamp 10.7 is used for patch clamp data collection,and Clampfit 10.7 is used for data analysis.In addition,other data uses Excel,SPSS,Graph Pad Prism7 and other software.A paired t test was used to compare data between two groups,and one-way analysis of variance was used to compare data from more than two groups.Data is expressed as mean±standard error(mean±S.E.M).Results1.In this experiment,a total of 188 cells were recorded in the lateral habenular nucleus.According to their discharge mode and membrane potential,they can be divided into three categories:resting neurons(Silent),whose membrane potential is about-55 m V,with tonic discharge Type neurons(Tonic),w hose membrane potential is about-43m V,and clustered firing nerves(Burst),whose membrane potential is about-60 m V,their ratio is about 45%:46%:9%.2.Lamotrigine 30?M can increase the excitability of Tonic neurons in the lateral habenular nucleus,ma inly by depolarizing the membrane potential of the neuron to make the absolute value smaller(P=0.0001,n=28).However,the effect of lamotrigine 10?M on the electrophysiological characteristics of neurons was not statistically significant(P=0.3419,n=12).3.Lamotrigine 10?M can inhibit the excitability of Silent neurons in the lateral habenular nucleus,mainly prolonging the time of triggering action potentials and increasing the adaptation index of action potentials(P=0.001,n=14).4.Lamotrigine 30?M can reduce the number of bursting induced by the lateral habenular nucleus(P=0.0015,n=6),and the inhibitory effect increases with the increase of the perfusion administration time,and reaches the maximum at 9 min after administration.Good results.Increase the absolute value of the post-hyperpolarization potential(P=0.0015,n=6),thereby inhibiting neuronal bursting.However,the effect of lamotrigine 10?M on bursting was not statistically significant(P=0.0549,n=8).5.CB₂R agonist GW 10?M can inhibit the excitability of Tonic neurons in the lateral habenular nucleus.After perfusion administration,the absolute value of neuronal excitation threshold intensity increases(P=0.0003,n=16)and the absolute value of resting membrane potential Becomes larger(P=0.039,n=16),and the firing frequency of neurons decreases(P=0.0141,n=16).6.GW 50?M can inhibit the excitability of Silent neurons in the lateral habenular nucleus by reducing the firing frequency of neurons(P=0.0063,n=4)and prolonging the trigger action potential(P=0.0012,n=4).7.GW 10?M has a significant inhibitory effect on the bursting induced by the lateral habenular nucleus,including reducing the absolute value of the subsequent hyperpolarization potential(P=0.0092,n=12)a nd making the intra-peak signal of the bursting The number is reduced(P=0.0092,n=12).8.GW 10?M can inhibit NMDA-induced bursting of dopamine neurons.GW 10?M can enhance SK current,and SK channel blocker(Apamine)can almost completely block SK curr ent.CB₂R blocker AM630can remove the enhancement effect of GW,and AM630's own control has no effect on SK current.ConclusionOur experimental results show that lamotrigine can inhibit the cluster firing of lateral habenular nucleus neurons,enhance the activity of Tonic neurons,and inhibit the activity of Silent neurons.In addition,GW can inhibit the bursting induced by lateral habenular nucleus neurons,and has an inhibitory effect on Tonic neurons and Silent neurons.GW can enhance SK current,and CB ₂R blocker AM630 can remove the enhancement effect of GW.AM630 self-control has no effect on SK current,but SK current can be almost completely blocked by Apamine.Therefore,activation of CB ₂Rs can inhibit NMDA-induced SK enhancement,which may be one of the important mechanisms of CB ₂R-mediated inhibition of neuronal bursting.