Vestibular compensation is an important model for developing the prevention and intervention strategies of vestibular disorders, and investigating the plasticity of the adult central nervous system induced by peripheral injury. Medial vestibular nucleus (MVN) in brainstem is critical center for vestibular compensation. Its neuronal excitability and sensitivity have been implicated in normal function of vestibular system. Previous studies mainly focused on the changes in neuronal excitability of the MVN in lesional side of the rat model of vestibular compensation following the unilateral labyrinthectomy (UL). However, the plasticity of sensitivity of bilateral MVN neurons dynamically responding to input stimuli is still largely unknown. In the present study, by using qPCR, whole-cell patch clamp recording in acute brain slices and behavioral techniques, we observed that 6 h after UL, rats showed a significant deficit in spontaneous locomotion, and a decrease in excitability of type B neurons in the ipsilesional rather than contralesional MVN. By contrast, type B neurons in the contralesional rather than ipsilesional MVN exhibited an increase in response sensitivity to the ramp and step input current stimuli. One week after UL, both the neuronal excitability of the ipsilesional MVN and the neuronal sensitivity of the contralesional MVN recovered to the baseline, accompanied by a compensation of spontaneous locomotion. In addition, the data showed that the small conductance Ca²⁺-activated K⁺ (SK) channel involved in the regulation of type B MVN neuronal sensitivity, showed a selective decrease in expression in the contralesional MVN 6 h after UL, and returned to normal level 1 week later. Pharmacological blockage of SK channel in contralateral MVN to inhibit the UL-induced functional plasticity of SK channel significantly delayed the compensation of vestibular motor dysfunction. These results suggest that the changes in plasticity of the ipsilesional MVN neuronal excitability, together with changes in the contralesional MVN neuronal sensitivity, may both contribute to the development of vestibular symptoms as well as vestibular compensation, and SK channel may be an essential ionic mechanism responsible for the dynamic changes of MVN neuronal sensitivity during vestibular compensation.
Animals ; Locomotion ; Neurons/physiology* ; Patch-Clamp Techniques ; Rats ; Vestibular Nuclei/metabolism* ; Vestibule, Labyrinth

OBJECTIVES: To explore the effect of etomidate on the neuronal activity of ventral thalamic reuniens nucleus and the underlying mechanisms. METHODS: Whole-cell patch clamp method was used to explore the effect of etomidate on the activity of ventral thalamic reuniens neurons in the acute brain slices obtained from 4-5 weeks old C57BL/6J mice. The electrophysiological characteristics of ventral thalamic reuniens neurons were recorded in the current clamp mode, and then the effects of etomidate (0.5, 2.0, 8.0 μmol/L etomidate groups) and intralipid (intralipid group) on the discharge frequency and membrane potential of ventral thalamic reuniens neurons were recorded. During the experiment, the ventral thalamic reuniens neuron firing rates (RNFRs) were recorded as F RESULTS: In the intralipid group, there was no significant difference among the F CONCLUSIONS Etomidate can inhibit the activity of ventral thalamic reuniens neurons in concentration-dependent manner, and which is reversible. Etomidate with sub-anesthetic concentration inhibits the activity of ventral thalamic reuniens neurons via targeting the GABA
Animals ; Etomidate/pharmacology* ; Mice ; Mice, Inbred C57BL ; Neurons ; Patch-Clamp Techniques ; Receptors, GABA-A

As a noninvasive neuromodulation technique, transcranial magnetic stimulation (TMS) is widely used in the clinical treatment of neurological and psychiatric diseases, but the mechanism of its action is still unclear. The purpose of this paper is to investigate the effects of different frequencies of magnetic stimulation (MS) on neuronal excitability and voltage-gated potassium channels in the
Action Potentials ; Animals ; Magnetic Phenomena ; Mental Disorders ; Mice ; Neurons ; Patch-Clamp Techniques ; Potassium Channels, Voltage-Gated

Action Potentials ; Brain ; Neurons ; Patch-Clamp Techniques

Patch clamp is a technique that can measure weak current in the level of picoampere (pA). It has been widely used for cellular electrophysiological recording in fundamental medical researches, such as membrane potential and ion channel currents recording, etc. In order to obtain accurate measurement results, both the resistance and capacitance of the pipette are required to be compensated. Capacitance compensations are composed of slow and fast capacitance compensation. The slow compensation is determined by the lipid bilayer of cell membrane, and its magnitude usually ranges from a few picofarads (pF) to a few microfarads (μF), depending on the cell size. The fast capacitance is formed by the distributed capacitance of the glass pipette, wires and solution, mostly ranging in a few picofarads. After the pipette sucks the cells in the solution, the positions of the glass pipette and wire have been determined, and only taking once compensation for slow and fast capacitance will meet the recording requirements. However, when the study needs to deal with the temperature characteristics, it is still necessary to make a recognition on the temperature characteristic of the capacitance. We found that the time constant of fast capacitance discharge changed with increasing temperature of bath solution when we studied the photothermal effect on cell membrane by patch clamp. Based on this phenomenon, we proposed an equivalent circuit to calculate the temperature-dependent parameters. Experimental results showed that the fast capacitance increased in a positive rate of 0.04 pF/℃, while the pipette resistance decreased. The fine data analysis demonstrated that the temperature rises of bath solution determined the kinetics of the fast capacitance mainly by changing the inner solution resistance of the glass pipette. This result will provide a good reference for the fine temperature characteristic study related to cellular electrophysiology based on patch clamp technique.
Cell Membrane ; Electric Capacitance ; Membrane Potentials ; Patch-Clamp Techniques ; Temperature

Brain ; N-Methylaspartate ; Neurons ; Patch-Clamp Techniques

In vascular smooth muscle, K⁺ channels, such as voltage-gated K⁺ channels (Kv), inward-rectifier K⁺ channels (Kir), and big-conductance Ca²⁺-activated K⁺ channels (BK(Ca)), establish a hyperpolarized membrane potential and counterbalance the depolarizing vasoactive stimuli. Additionally, Kir mediates endothelium-dependent hyperpolarization and the active hyperemia response in various vessels, including the coronary artery. Pulmonary arterial hypertension (PAH) induces right ventricular hypertrophy (RVH), thereby elevating the risk of ischemia and right heart failure. Here, using the whole-cell patch-clamp technique, we compared Kv and Kir current densities (I(Kv) and I(Kir)) in the left (LCSMCs), right (RCSMCs), and septal branches of coronary smooth muscle cells (SCSMCs) from control and monocrotaline (MCT)-induced PAH rats exhibiting RVH. In control rats, (1) I(Kv) was larger in RCSMCs than that in SCSMCs and LCSMCs, (2) I(Kv) inactivation occurred at more negative voltages in SCSMCs than those in RCSMCs and LCSMCs, (3) I(Kir) was smaller in SCSMCs than that in RCSMCs and LCSMCs, and (4) I(BKCa) did not differ between branches. Moreover, in PAH rats, I(Kir) and I(Kv) decreased in SCSMCs, but not in RCSMCs or LCSMCs, and I(BKCa) did not change in any of the branches. These results demonstrated that SCSMC-specific decreases in I(Kv) and I(Kir) occur in an MCT-induced PAH model, thereby offering insights into the potential pathophysiological implications of coronary blood flow regulation in right heart disease. Furthermore, the relatively smaller I(Kir) in SCSMCs suggested a less effective vasodilatory response in the septal region to the moderate increase in extracellular K⁺ concentration under increased activity of the myocardium.
Animals ; Coronary Vessels ; Heart Diseases ; Heart Failure ; Hyperemia ; Hypertension ; Hypertrophy, Right Ventricular ; Ischemia ; Membrane Potentials ; Monocrotaline ; Muscle, Smooth ; Muscle, Smooth, Vascular ; Myocardium ; Myocytes, Smooth Muscle ; Patch-Clamp Techniques ; Potassium Channels ; Rats ; Septum of Brain

OBJECTIVE: To investigate the effects of etomidate on electrophysiological properties and nicotinic acetylcholine receptors (nAChRs) of ventral horn neurons in the spinal cord. METHODS: The spinal cord containing lumbosacral enlargement was isolated from 19 neonatal SD rats aged 7-12 days. The spinal cord were sliced and digested with papain (0.18 g/30 mL artificial cerebrospinal fluid) and incubated for 40 min. At the ventral horn, acute mechanical separation of neurons was performed with fire-polished Pasteur pipettes, and perforated patch-clamp recordings combined with pharmacological methods were employed on the adherent healthy neurons. In current-clamp mode, the spontaneous action potential (AP) of the ventral horn neurons in the spinal cord was recorded. The effects of pretreatment with different concentrations of etomidate on AP recorded in the ventral horn neurons were examined. In the voltage-clamp mode, nicotine was applied to induce inward currents in the ventral horn neurons, and the effect of pretreatment with etomidate on the inward currents induced by nicotine were examined with different etomidate concentrations, different holding potentials and different use time. RESULTS: The isolated ventral horn neurons were in good condition with large diverse somata and intact processes. The isolated spinal ventral horn neurons (=21) had spontaneous action potentials, and were continuously perfused for 2 min with 0.3, 3.0 and 30.0 μmol/L etomidate. Compared with those before administration, the AP amplitude, spike potential amplitude and overshoot were concentration-dependently suppressed ( < 0.01), and spontaneous discharge frequency was obviously reduced ( < 0.01, =12). The APs of the other 9 neurons were completely abolished by etomidate at 3.0 or 30 μmol/L. At the same holding potential (VH=-70 mV), pretreatment with 0.3, 3.0 or 30.0 μmol/L etomidate for 2 min concentration-dependently suppressed the current amplitude induced by 0.4 mmol/L nicotine ( < 0.01, =7). At the holding potentials of - 30, - 50, and - 70 mV, pretreatment with 30.0 μmol/L etomidate for 2 min voltage-dependently suppressed the current amplitude induced by 0.4 mmol/L nicotine ( < 0.01, =6 for each holding potential). During the 6 min of 30.0 μmol/L etomidate pretreatment, the clamped cells were exposed to 0.4 mmol/L nicotine for 4 times at 0, 2, 4, and 6 min (each exposure time was 2 s), and the nicotinic current amplitude decreased gradually as the number of exposures increased. But at the same concentration, two nicotine exposures (one at the beginning and the other at the end of the 6 min pretreatment) resulted in a significantly lower inhibition rate compared with 4 nicotine exposures ( < 0.01, =6). CONCLUSIONS etomidate reduces the excitability of the spinal ventral neurons in a concentration-dependent manner and suppresses the function of nAChR in a concentration-, voltage-, and use-dependent manner.
Animals ; Animals, Newborn ; Etomidate ; Neurons ; Patch-Clamp Techniques ; Rats ; Spinal Cord

The lamina II, also called the substantia gelatinosa (SG), of the trigeminal subnucleus caudalis (Vc), is thought to play an essential role in the control of orofacial nociception. Glycine and serotonin (5-hydroxytryptamine, 5-HT) are the important neurotransmitters that have the individual parts on the modulation of nociceptive transmission. However, the electrophysiological effects of 5-HT on the glycine receptors on SG neurons of the Vc have not been well studied yet. For this reason, we applied the whole-cell patch clamp technique to explore the interaction of intracellular signal transduction between 5-HT and the glycine receptors on SG neurons of the Vc in mice. In nine of 13 neurons tested (69.2%), pretreatment with 5-HT potentiated glycine-induced current (I(Gly)). Firstly, we examined with a 5-HT₁ receptor agonist (8-OH-DPAT, 5-HT(1/7) agonist, co-applied with SB-269970, 5-HT₇ antagonist) and antagonist (WAY-100635), but 5-HT₁ receptor agonist did not increase IGly and in the presence of 5-HT₁ antagonist, the potentiation of 5-HT on I(Gly) still happened. However, an agonist (α-methyl-5-HT) and antagonist (ketanserin) of the 5-HT₂ receptor mimicked and inhibited the enhancing effect of 5-HT on I(Gly) in the SG neurons, respectively. We also verified the role of the 5-HT₇ receptor by using a 5-HT₇ antagonist (SB-269970) but it also did not block the enhancement of 5-HT on I(Gly). Our study demonstrated that 5-HT facilitated I(Gly) in the SG neurons of the Vc through the 5-HT₂ receptor. The interaction between 5-HT and glycine appears to have a significant role in modulating the transmission of the nociceptive pathway.
Animals ; Glycine ; Mice ; Neurons ; Neurotransmitter Agents ; Nociception ; Patch-Clamp Techniques ; Receptors, Glycine ; Serotonin ; Signal Transduction ; Substantia Gelatinosa

Cordycepin exerts neuroprotective effects against excitotoxic neuronal death. However, its direct electrophysiological evidence in Alzheimer's disease (AD) remains unclear. This study aimed to explore the electrophysiological mechanisms underlying the protective effect of cordycepin against the excitotoxic neuronal insult in AD using whole-cell patch clamp techniques. β-Amyloid (Aβ) and ibotenic acid (IBO)-induced injury model in cultured hippocampal neurons was used for the purpose. The results revealed that cordycepin significantly delayed Aβ + IBO-induced excessive neuronal membrane depolarization. It increased the onset time/latency, extended the duration, and reduced the slope in both slow and rapid depolarization. Additionally, cordycepin reversed the neuronal hyperactivity in Aβ + IBO-induced evoked action potential (AP) firing, including increase in repetitive firing frequency, shortening of evoked AP latency, decrease in the amplitude of fast afterhyperpolarization, and increase in membrane depolarization. Further, the suppressive effect of cordycepin against Aβ + IBO-induced excessive neuronal membrane depolarization and neuronal hyperactivity was blocked by DPCPX (8-cyclopentyl-1,3-dipropylxanthine, an adenosine A₁ receptor-specific blocker). Collectively, these results revealed the suppressive effect of cordycepin against the Aβ + IBO-induced excitotoxic neuronal insult by attenuating excessive neuronal activity and membrane depolarization, and the mechanism through the activation of A₁R is strongly recommended, thus highlighting the therapeutic potential of cordycepin in AD.
Action Potentials ; Adenosine ; Alzheimer Disease ; Fires ; Ibotenic Acid ; Membranes ; Neurons ; Neuroprotection ; Neuroprotective Agents ; Patch-Clamp Techniques ; Pyramidal Cells