A Novel Frameless Laser Stereotaxis System for Neurosurgical Interventions.

OBJECTIVE: The aim of the article is to introduce a novel laser-based frameless stereotactic device that can locate intracranial lesions quickly and with computed tomograph (CT)/magnetic resonance imaging (MRI) films. Preliminary experiences of application in 416 cases are also summarized. METHODS: From August in 2020 to October in 2022, a total of 416 cases of new minimalist laser stereotactic surgery have been performed on 415 patients. Of the 415 patients, 377 had intracranial hematomas, while the remaining cases were brain tumors or brain abscesses. Postoperative CT was used to evaluate the accuracy of catheterization of 405 patients according to the MISTIE study. The duration time of locating was recorded. Rebleeding refers to the definition: Compared with preoperative CT, the relative volume of postoperative hematoma increases by >33% or absolute volume increase >12.5 mL. RESULTS: According to postoperative CT, the accuracy of 405 stereotactic catheterization cases was good in 346 cases (85.4%) and suboptimal in 59 cases (14.6%), with no poor results. Postoperative rebleeding occurred in 4 spontaneous cerebral hemorrhage cases and 1 brain biopsy case. The average localization time of supratentorial lesions was 13.2 minutes in the supine position, 21.5 minutes in the lateral position, and 27.6 minutes in the prone position. CONCLUSIONS: The new laser-based frameless stereotactic device is simple in principle and convenient in positioning operation of brain hematoma and abscess puncture, brain biopsy and tumor surgery, and appropriate to the precision requirements in most craniocerebral surgery.

[Clinical features of mah-jong reflex epilepsy].

OBJECTIVE: To analyze clinical features of mah-jong reflex epilepsy, and to explore the underlying mechanisms.
 Methods: The clinical data of 15 patient (a study group), who visited in the outpatient department in the Third Xiangya Hospital, Central South University from 2016 to 2018, were collected and analyzed. The clinical data included disease history, 24 h- electroencephalography (EEG) and magnetic resonance imaging (MRI) scan. Next, previous 84 case (a literature group) reports published in the past 20 years were searched and compared.
 Results: Both groups of mah-jong reflex epilepsy were predominant in middle-aged men, with onset ages of (44.53±10.58) and (41.48±17.85) years old, respectively. In the study group, time interval usually lasted (4.00±2.45) h from starting play mah-jong to seizure attack, 73.3% patients complained mental fatigue before seizure attack, and 93.3% of the patients were described to have general tonic-clonic seizure. Few positive result was discovered in auxiliary examination, and the percentage was 9.3% in EEG, while no positive outcome was seen in head MRI. There were no significant differences in gender, age of onset, duration of playing mah-jong before attack, type of attack, and changes of head MRI between the 2 groups (all P>0.05).
 Conclusion: Mental fatigue after long-time mah-jong playing and cognitive dysfunction might be the potential triggers in mah-jong reflex epilepsy.

Effects of naftopidil on inhibitory transmission in substantia gelatinosa neurons of the rat spinal dorsal horn in vitro.

OBJECTIVE: Naftopidil is used clinically for the treatment of voiding disorders in benign prostatic hyperplasia. Previous in vivo experiments in which naftopidil was applied intrathecally abolished rhythmic bladder contraction, suggesting that naftopidil might inhibit a voiding reflex through interaction with spinal dorsal horn neurons. Here we aimed to clarify the mechanism of action of naftopidil on dorsal horn neurons. METHODS: Whole-cell patch-clamp recordings were performed using substantia gelatinosa neurons of adult rat spinal cord slices. Miniature or evoked inhibitor and excitatory postsynaptic currents (IPSCs and EPSCs, respectively) were analyzed. RESULTS: Bath-applied naftopidil increased the frequency but not the amplitude of miniature IPSCs (mIPSCs) in 38% of neurons tested; in contrast, the effect of naftopidil on miniature EPSCs (mEPSCs) were mild and observed in only 2 out of 19 neurons. Naftopidil enhanced the amplitude of both GABAergic and glycinergic evoked-IPSCs (eIPSCs) that were elicited by focal stimuli in the presence of either the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), or the NMDA receptor antagonist DL-2-amino-5-phosphonovaleric acid (APV). CONCLUSIONS: Although naftopidil was developed as an alpha-1 adrenoceptor antagonist, our previous spinal cord slice experiments showed that the activation of an alpha-1 adrenoceptor in substantia gelatinosa increases the frequency of mIPSCs. This result suggested that, under our conditions, naftopidil may interact with a receptor(s) other than an alpha-1 adrenoceptor in the spinal dorsal horn. The present results suggested that naftopidil enhances the release of GABA and glycine by activating inhibitory interneuron terminals in the spinal dorsal horn via a receptor other than an alpha-1 adrenoceptor, thereby modulating sensory transmission in the substantia gelatinosa.

The antiepileptic effect of the glycolytic inhibitor 2-deoxy-D-glucose is mediated by upregulation of K(ATP) channel subunits Kir6.1 and Kir6.2.

Metabolic modulation of neuronal excitability is becoming increasingly important as an antiepileptic therapy. It was reported that the glycolytic inhibitor 2-deoxy-D-glucose (2-DG) and the activation of the ATP-sensitive potassium ion channel (K(ATP) channel) had an antiepileptic effect in models of epilepsy. To explore whether 2-DG exerts an antiepileptic effect through upregulation of the K(ATP) channel subunits Kir6.1 and Kir6.2, the expression of these subunits in hippocampus of five groups of mice with pilocarpine-induced status epilepticus (SE) was evaluated. A seizure group with pilocarpine-kindling convulsions (EP) was compared to similar groups treated with high, medium, and low 2-DG concentrations (100-500 mg/kg) and a normal control group (Con). Kir6.1 and Kir6.2 mRNAs and proteins were analyzed at 4 h, 1 days (acute period), 7 days (latent period), 30, and 60 days (chronic period) following SE. In the seizure group (compared to the Con group), hippocampal expression of Kir6.1 and Kir6.2 increased dramatically at 1, 7, and 30 days, and was further increased after treatment with medium and high dose 2-DG (all P < 0.05). Our results suggest that 2-DG may exert an antiepileptic effect through up-regulation of mRNAs and protein levels of Kir6.1 and Kir6.2, which may therefore be used as molecular targets in the treatment of epilepsy with 2-DG.

Identification of 5-HT receptor subtypes enhancing inhibitory transmission in the rat spinal dorsal horn in vitro.

BACKGROUND: 5-hydroxytryptamine (5-HT) is one of the major neurotransmitters widely distributed in the CNS. Several 5-HT receptor subtypes have been identified in the spinal dorsal horn which act on both pre- and postsynaptic sites of excitatory and inhibitory neurons. However, the receptor subtypes and sites of actions as well as underlying mechanism are not clarified rigorously. Several electrophysiological studies have been performed to investigate the effects of 5-HT on excitatory transmission in substantia gelatinosa (SG) of the spinal cord. In the present study, to understand the effects of 5-HT on the inhibitory synaptic transmission and to identify receptor subtypes, the blind whole cell recordings were performed from SG neurons of rat spinal cord slices. RESULTS: Bath applied 5-HT (50 µM) increased the frequency but not amplitudes of spontaneous inhibitory postsynaptic currents (sIPSCs) in 58% of neurons, and both amplitude and frequency in 23% of neurons. The frequencies of GABAergic and glycinergic mIPSCs were both enhanced. TTX (0.5 µM) had no effect on the increasing frequency, while the enhancement of amplitude of IPSCs was eliminated. Evoked-IPSCs (eIPSCs) induced by focal stimulation near the recording neurons in the presence of CNQX and APV were enhanced in amplitude by 5-HT. In the presence of Ba(2+) (1 mM), a potassium channel blocker, 5-HT had no effect on both frequency and amplitude. A 5-HT(2A) receptor agonist, TCB-2 mimicked the 5-HT effect, and ketanserin, an antagonist of 5-HT(2A) receptor, inhibited the effect of 5-HT partially and TCB-2 almost completely. A 5-HT(2C) receptor agonist WAY 161503 mimicked the 5-HT effect and this effect was blocked by a 5-HT(2C) receptor antagonist, N-desmethylclozapine. The amplitudes of sIPSCs were unaffected by 5-HT(2A) or 5-HT(2C) agonists. A 5-HT(3) receptor agonist mCPBG enhanced both amplitude and frequency of sIPSCs. This effect was blocked by a 5-HT(3) receptor antagonist ICS-205,930. The perfusion of 5-HT(2B) receptor agonist had no effect on sIPSCs. CONCLUSIONS: Our results demonstrated that 5-HT modulated the inhibitory transmission in SG by the activation of 5-HT(2A) and 5-HT(2C) receptors subtypes located predominantly at inhibitory interneuron terminals, and 5-HT(3) receptors located at inhibitory interneuron terminals and soma-dendrites, consequently enhanced both frequency and amplitude of IPSCs.

Inhibition of Membrane Na+ Channels by A Type Botulinum Toxin at Femtomolar Concentrations in Central and Peripheral Neurons.

Recent studies have demonstrated that the botulinum neurotoxins inhibit the release of acetylcholine, glutamate, GABA, and glycine in central nerve system (CNS) neurons. The Na+ current (INa) is of major interest because it acts as the trigger for many cellular functions such as transmission, secretion, contraction, and sensation. Thus, these observations raise the possibility that A type neurotoxin might also alter the INa of neuronal excitable membrane. To test our idea, we examined the effects of A type neurotoxins on INa of central and peripheral neurons. The neurotoxins in femtomolar to picomolar concentrations produced substantial decreases of the neuronal INa, but interestingly the current inhibition was saturated at about maximum 50% level of control INa. The inhibitory pattern in the concentration-response curve for the neurotoxins differed from tetrodotoxin (TTX), local anesthetic, and antiepileptic drugs that completely inhibited INa in a concentration-dependent manner. We concluded that A type neurotoxins inhibited membrane Na+-channel activity in CNS neurons and that INa of both TTX-sensitive and-insensitive peripheral dorsal ganglion cells were also inhibited similarly to a maximum 40% of the control by the neurotoxins. The results suggest evidently that A2NTX could be also used as a powerful drug in treating epilepsy and several types of pain.

Inhibition of membrane Na+ channels by A type botulinum toxin at femtomolar concentrations in central and peripheral neurons.

Recent studies have demonstrated that the botulinum neurotoxins inhibit the release of acetylcholine, glutamate, GABA, and glycine in central nerve system (CNS) neurons. The Na(+) current (I(Na)) is of major interest because it acts as the trigger for many cellular functions such as transmission, secretion, contraction, and sensation. Thus, these observations raise the possibility that A type neurotoxin might also alter the I(Na) of neuronal excitable membrane. To test our idea, we examined the effects of A type neurotoxins on I(Na) of central and peripheral neurons. The neurotoxins in femtomolar to picomolar concentrations produced substantial decreases of the neuronal I(Na), but interestingly the current inhibition was saturated at about maximum 50% level of control I(Na). The inhibitory pattern in the concentration-response curve for the neurotoxins differed from tetrodotoxin (TTX), local anesthetic, and antiepileptic drugs that completely inhibited I(Na) in a concentration-dependent manner. We concluded that A type neurotoxins inhibited membrane Na(+)-channel activity in CNS neurons and that I(Na) of both TTX-sensitive and -insensitive peripheral dorsal ganglion cells were also inhibited similarly to a maximum 40% of the control by the neurotoxins. The results suggest evidently that A2NTX could be also used as a powerful drug in treating epilepsy and several types of pain.

Synergic effect of diazepam and muscimol via presynaptic GABA(A) receptors on glutamatergic evoked EPSCs.

We investigated the functional roles of diazepam (DZP) at presynaptic GABA(A) receptors on glutamatergic nerve terminals in contributing to glutamatergic transmission evoked by single and/or paired-pulse focal electrical stimulation. In mechanically dissociated rat hippocampal CA3 neurons with adherent glutamatergic nerve terminals (boutons), namely 'synaptic bouton' preparation, action potential-evoked excitatory postsynaptic currents (eEPSCs) were recorded using conventional whole-cell patch configuration under voltage-clamp condition. Selective activation of presynaptic GABA(A) receptors by muscimol (3-30µM) induced presynaptic inhibition: i.e. the decrease of amplitude and increase of failure rate (Rf) and paired-pulse ratio (PPR) of eEPSCs which are sensitive to bicuculline. DZP (10-100µM) also induced such presynaptic inhibition, but the bicuculline-insensitive effects were caused by inhibition of both voltage-dependent Na(+) and Ca(2+) channels. Muscimol (0.01-0.3µM) or DZP (0.1-3µM) itself did not induce any currents at the low concentration used. However, simultaneous application of muscimol and DZP at low concentrations induced a significant bicuculline-sensitive presynaptic inhibition. Marked desensitization of presynaptic inhibition was also caused by muscimol at higher concentrations than 10µM. The results suggest that in vivo conditions, activation of presynaptic GABA(A) receptors could be readily available with a tiny amount of DZP.