Effects Of Nicotine On The Sensory Stinulation-Evolced Field Potential Responses In Mouse Cerebellar Molecular Layer

Objective:N acetylcholine receptor(nAChRs)exists in the mammalian cerebellar cortical nerve loop,and nicotine can activate nAChRs to affect the activity of various neurons in the cerebellar cortex by regulating other receptors and transmitters,but the effect of nicotine on the sensory information transmission of the molecular layer of the cerebellar layer of mammalian cerebellum is not clear.Therefore,the effect of different doses of nicotine on the field potential activity of cerebellar molecular layer induced by sensory stimulation and the mechanism of nicotine on the sensory information transmission of molecular layer in the cerebellar cortex will be investigated in vivo.Methods:6-8 weeks-old ICR mice were selected,then anesthetized by intraperitoneal injection of urethane at a body weight of 1.3 g/kg.After tracheal intubation,the INR mice were fixed on the experimental cradle.Drill a 1-1.5mm craniotomy at the site of the cerebellar cortex Crus ?,the dura mater was carefully removed and the exposed site was continuously superfused with oxygenated artificial cerebrospinal fluid(ACSF)by a peristaltic pump.By using the air-puff(30-60 ms,50-60 psi)of ipsilateral whisker pad,the sensory stimuli can be performed.The air-puff stimuliwere synchrinized with electrophysiological recording and were controled by a computer.Recording the sensory stimuli evoked potential changes in cerebellar cortical molecular layer field,the recording electrodes were filled with ACSF(20-30ul),with the resistance of 4-6 M?.The peristaltic pump was used to perfuse nicotine on the surface of the cerebellar cortex.Sensory stimulation evoked molecular layer field potential responses were revorded by an Axopatch-1D amplifier and acquired using Clampfit 10.3 software.Electrophysiological experimental data analysis using Clampfit 10.3 software,using Student's paired T-test SPSS software 17.0 to evaluate the differences between the mean values recorded under control and test conditions.Differences were considered statistically significant at P<0.05.Results:1.Air-puff stimulation on the ipsilateral whisker pad can induce the field potential response in the mouse cerebellar molecular layer,expressing an excitatory negative wave N1 and an inhibitory positive wave P1.After perfusion of nicotine(1mM)on the surface of the cerebellum,the amplitude of the inhibitory component and the area under the curve(AUC)of the facial stimulation-evoked field potential responses in the cerebellar cortical molecular layer decreased significantly(P<0.05).2.Nicotine inhibited the facial stimulation-evoked amplitude of P1 in the cerebellar molecular was concentration dependent.The concentration response curve showed that the decrease of amplitude of P1 was correspondence with the increase of the concentration of nicotine,the minimum concentration for inducing the change of the sensory response was 10 ?M,the maximum concentration was 2 mM,and the half effective concentration(EC50)was 1.62 mM.3.Administration of nicotine did not change the latency of the sensory stimulation evoked response in the cerebellar molecular layer,but the onset time of the positive wave P1 was earlier,the rising time was obviously prolonged,and the delay time was significantly shortened.4.In addition,compare with control conditions,the cerebellar surface perfusion of nicotine(1mM)decreased significantly the amplitude and AUC of excitatory negative wave N1.Conclusion:Nicotine inhibits sensory information transmission and integration in cerebellar cortex.