Efffects Of CRF On The Sensory Stimulation-evoked Field Potential Rfsponses In Mouse Cerebellar Molecular Layer

ObjectiveCorticotropin releasing factor(CRF)is an important neuropeptide that regulates stress response and visceral activity.CRF can affect the neuronal activity and external infermation transmission and integration in the cerebellar cortex through the distribution of afferent fibers in the mammalian cerebellar circuits?but the effective mechanism of its effects is not clear.Therefore,the present study will use in vivo electrophysiological recording and neuropharmacological methods to study the mechanism of the effect of CRF on the sensory stimulation-evoked field potential response in mouse cerebellar cortical molecular layer.MethodsSix to eight 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 ICR mice were fixed on the experimental cradle.Drill a 1-1.5mm craniotomy at the site of the cerebellar cortex Crus II,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(50-60 ms,50-60 psi)of ipsilateral whisker pad,the sensory stimuli can be performed.The air-puff stimuli were synchrinized with electrophysiological recording and were controlled by a computer.Recording the sensory stimuli evoked potential changes in cerebellar cortical molecular layer.The recording electrodes were filled with ACSF,with the resistance of 4-6 MΩ.Sensory stimulation evoked molecular layer field potential responses were recorded by an Axopatch-200B amplifier and acquired using Clampfit 10.3 software.The electrophysiological data were analyzed using Clampfit 10.3 software.Values are expressed as the mean ± S.E.M.Differences were evaluated with the One-way ANOVA using SPSS software.P values below 0.05 were considered to indicate a statistically significant difference between experimental groups.Results(1)Air puff stimulation on the whicker pad of anaesthetized mice evoked the field potential response in the molecular layer of the cerebellum,which expressing a larger positive wave(N1)after the transient negative wave(P1).Perfusion of CRF(300 nM)on the brain surface,the amplitude and the half-width of the tactile-stimulation-evoked inhibitory component,PI,were increased significantly than control conditions.(2)The cerebral surface perfusion CRF affects the waveform dynamics of P1,which leads to the shortening of the rising time and the increase of the delay time.There is a significant difference between CRF and control(P<0.05).(3)CRF increased the amplitude of P1 of the air puff stimulation-evoked cerebellar molecular field potential response was in a concentration dependent manner.The concentration response curve showed that the amplitude of P1 increased significantly with the increase of CRF concentration.The minimum concentration of sensory stimulation is 10 nM,the maximum concentration is 2μM,and the median effective concentration(EC50)is 234 nM.(4)In the presence of an non-selective CRF-R blockers,the effect of CRF on the amplitude of the inhibitory component of the tactile stimulation-evoked field potential in the cerebellar molecular layer was abolished,without the amplitude and half width of P1 increase,indicating that CRF induced the amplitude and half width of the field potential P1 in the cerebellar molecular layer of the mouse through the activation of the CRF receptor.(5)In the presence of CRP-R blockers,the cerebral surface perfusion CRF had no significant effect on the waveform dynamics of P1,and the increase time and the delay time were similar with control conditions.ConclusionsThe results of this study showed that CRF enhanced the inhibitory component P1 and influenced the waveform dynamics of tactile stimulation-evoked field potential response in mouse cerebellar cortical molecular layer via activation of CRF-R,suggesting that stress stimulation could affect the external information integration and transmission through the action of CRF receptor in the molecular layer of the cerebellar cortex.