Taurine has a number of beneficial pharmacological actions in the brain such as anxiolytic and neuroprotective actions. We explored to test whether taurine could be transported to the central nervous system through the intranasal route. Following intranasal administration of taurine in mice, elevated plus maze test, activity cage test and rota rod test were carried out to verify taurine’s effect on anxiety. For the characterization of potential mechanism of taurine’s anti-anxiety action, mouse convulsion tests with strychnine, picrotoxin, yohimbine, and isoniazid were employed. A significant increase in the time spent in the open arms was observed when taurine was administered through the nasal route in the elevated plus maze test. In addition, vertical and horizontal activities of mice treated with taurine via intranasal route were considerably diminished. These results support the hypothesis that taurine can be transported to the brain through intranasal route, thereby inducing anti-anxiety activity. Taurine’s anti-anxiety action may be mediated by the strychnine-sensitive glycine receptor as evidenced by the inhibition of strychnine-induced convulsion.
Administration, Intranasal ; Animals ; Anxiety ; Arm ; Brain ; Central Nervous System ; Isoniazid ; Mice ; Picrotoxin ; Receptors, Glycine ; Seizures ; Strychnine ; Taurine ; Yohimbine

It has been reported that Korean red ginseng (KRG), a valuable and important traditional medicine, has varied effects on the central nervous system, suggesting its activities are complicated. The paraventricular nucleus (PVN) neurons of the hypothalamus has a critical role in stress responses and hormone secretions. Although the action mechanisms of KRG on various cells and systems have been reported, the direct membrane effects of KRG on PVN neurons have not been fully described. In this study, the direct membrane effects of KRG on PVN neuronal activity were investigated by using a perforated patch-clamp in ICR mice. In gramicidin perforated patch-clamp mode, KRG extract (KRGE) induced repeatable depolarization followed by hyperpolarization of PVN neurons. The KRGE-induced responses were concentration-dependent and persisted in the presence of tetrodotoxin, a voltage sensitive Na+ channel blocker. The KRGE-induced responses were suppressed by 6-cyano-7-nitroquinoxaline-2,3-dione (10 µM), a non-N-methyl-D-aspartate (NMDA) glutamate receptor antagonist, but not by picrotoxin, a type A gamma-aminobutyric acid receptor antagonist. The results indicate that KRG activates non-NMDA glutamate receptors of PVN neurons in mice, suggesting that KRG may be a candidate for use in regulation of stress responses by controlling autonomic nervous system and hormone secretion.
6-Cyano-7-nitroquinoxaline-2,3-dione ; Animals ; Autonomic Nervous System ; Central Nervous System ; Glutamic Acid ; Gramicidin ; Hypothalamus ; Medicine, Traditional ; Membranes ; Mice ; Mice, Inbred ICR ; Neurons ; Panax ; Paraventricular Hypothalamic Nucleus ; Patch-Clamp Techniques ; Picrotoxin ; Receptors, GABA ; Receptors, Glutamate ; Tetrodotoxin

Stress and emotion are associated with several illnesses from headaches to heart diseases and immune deficiencies to central nervous system. Terminalia arjuna has been referred as traditional Indian medicine for several ailments. The present study aimed to elucidate the effect of T. arjuna bark extract (TA) against picrotoxin-induced anxiety. Forty two male Balb/c mice were randomly divided into six experimental groups (n = 7): control, diazepam (1.5 mg·kg), picrotoxin (1 mg·kg) and three TA treatemt groups (25, 50, and 100 mg/kg). Behavioral paradigms and PCR studies were performed to determine the effect of TA against picrotoxin-induced anxiety. The results showed that TA supplementation increased locomotion towards open arm (EPM) and illuminated area (light-dark box test), and increased rearing frequency (open field test) in a dose dependent manner, compared to picrotoxin (P < 0.05). Furthermore, TA increased number of licks and shocks in Vogel's conflict. PCR studies showed an up-regulation of several genes, such as BDNF, IP, DL, CREB, GABA, SOD, GPx, and GR in TA administered groups. In conclusion, alcoholic extract of TA bark showed protective activity against picrotoxin in mice by modulation of genes related to synaptic plasticity, neurotransmitters, and antioxidant enzymes.
Animals ; Antioxidants ; metabolism ; Anxiety Disorders ; drug therapy ; genetics ; metabolism ; psychology ; Brain-Derived Neurotrophic Factor ; genetics ; metabolism ; Dopamine Agents ; administration & dosage ; GABA Agents ; administration & dosage ; Glutathione Peroxidase ; genetics ; metabolism ; Humans ; Male ; Mice ; Mice, Inbred BALB C ; Neuronal Plasticity ; drug effects ; Neurotransmitter Agents ; metabolism ; Phytotherapy ; Picrotoxin ; adverse effects ; Plant Bark ; chemistry ; Plant Extracts ; administration & dosage ; Serotonin Agents ; administration & dosage ; Superoxide Dismutase-1 ; genetics ; metabolism ; Terminalia ; chemistry

.This study is to investigate the analgesic effect produced by intrathecal injection (ith) of oxysophoridine (OSR) and the mechanism of GABAA receptor. Warm water tail-flick test was used to detect the analgesic effect of OSR (12.5, 6.25, and 3.13 mg.kg-1 ith) and to observe the influence of GABA (gamma aminobutyric acid) agonist or antagonist on the analgesic effect of OSR in mice. Immunohistochemistry method were used to detect the influence of OSR (12.5 mg.kg-1, ith) on the GABAARalpha1 protein expression in spinal cord. The results obtained covers that OSR (12.5 and 6.25 mg.kg-, ith) alleviates pain significantly with the warm water tail-flick test (P<0.05, P<0.01), the rate of pain threshold increases by 68.45%; GABA and muscimol (MUS) produces analgesic synergism together with the OSR, picrotoxin (PTX) and bicuculline (BIC) antagonize the analgesic effect of OSR; OSR (12.5 mg.kg-1, ith) significantly increase the positive number of GABAARalpha1 nerve cell in spinal cord (P<0.01) and significantly decrease the average grey levels (P<0.01). In conclusion, OSR intrathecal injection has significant analgesic effect. And GABAA receptor in spinal cord is involved in the analgesic mechanism.
Alkaloids ; administration & dosage ; pharmacology ; Analgesics ; administration & dosage ; pharmacology ; Animals ; Bicuculline ; pharmacology ; Female ; GABA-A Receptor Agonists ; pharmacology ; GABA-A Receptor Antagonists ; pharmacology ; Injections, Spinal ; Male ; Mice ; Muscimol ; pharmacology ; Pain Threshold ; drug effects ; Picrotoxin ; pharmacology ; Random Allocation ; Receptors, GABA-A ; metabolism ; Spinal Cord ; metabolism ; gamma-Aminobutyric Acid ; pharmacology

BACKGROUND: The gonadotropin releasing hormone (GnRH) neurons perform a pivotal function in the central regulation of fertility. Somatostatin (SST) is an important neuromodulatory peptide in the central nervous system and alters neuronal activities via G protein- coupled SST receptors. A number of studies have shown that SST modulates the reproductive axis at the hypothalamic level. However, the precise action mechanisms of SST and related receptor subtypes have yet to be fully understood. In this study, we evaluated the direct effects of SST on GnRH neurons in juvenile mice. METHODS: Juvenile (postnatal days, < PND 30) GnRH-GFP transgenic mice expressing green fluorescent protein were used in this study. Acute coronal brain slices containing the preoptic area were prepared and all identified GnRH neurons were recorded using the gramicidin perforated-patch clamp technique; type II SST receptor (SSTR2) mRNA expression was evaluated via single cell reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: SST caused membrane hyperpolarization, depolarization, no response, or membrane hyperpolarization with a reduction of action potential. Most (57.7%, 30/52) of the GnRH neurons tested were hyperpolarized by SST and this SST-induced hyperpolarization was found to be concentration-dependent. The percentage of responses, membrane potential changes (MPC), and resting membrane potential (RMP) by SST were not significantly different in juvenile male and female GnRH neurons. The SST-induced hyperpolarization was maintained in the presence of tetrodotoxin (TTX), a sodium channel blocker, and an amino acid blocking cocktail (AABC) containing AP-5 (NMDA receptor antagonist), CNQX (non-NMDA glutamate receptor antagonist), picrotoxin (GABAA receptor antagonist), and strychnine (glycine receptor antagonist). SSTR2 mRNA was expressed on 10 (38%) among 26 GnRH neurons. Seglitide, an SSTR2 agonist, mimicked this SST-induced hyperpolarization (11/23 47.8%) and this response was maintained in the presence of TTX and AABC. CONCLUSION: Our data show that SST can exert potent inhibitory action against GnRH neuronal excitability via SSTR2 activation in juvenile mice.
6-Cyano-7-nitroquinoxaline-2,3-dione ; Action Potentials ; Animals ; Brain ; Central Nervous System ; Female ; Fertility ; Gonadotropin-Releasing Hormone ; Gonadotropins ; Gramicidin ; Humans ; Male ; Membrane Potentials ; Membranes ; Mice ; Mice, Transgenic ; Neurons ; Peptides, Cyclic ; Picrotoxin ; Preoptic Area ; Receptors, Glutamate ; RNA, Messenger ; Sodium Channels ; Somatostatin ; Strychnine ; Tetrodotoxin ; Axis, Cervical Vertebra

Shilajit, a medicine herb commonly used in Ayurveda, has been reported to contain at least 85 minerals in ionic form that act on a variety of chemical, biological, and physical stressors. The substantia gelatinosa (SG) neurons of the trigeminal subnucleus caudalis (Vc) are involved in orofacial nociceptive processing. Shilajit has been reported to be an injury and muscular pain reliever but there have been few functional studies of the effect of Shilajit on the SG neurons of the Vc. Therefore, whole cell and gramicidin-perfotrated patch clamp studies were performed to examine the action mechanism of Shilajit on the SG neurons of Vc from mouse brainstem slices. In the whole cell patch clamp mode, Shilajit induced short-lived and repeatable inward currents under the condition of a high chloride pipette solution on all the SG neurons tested. The Shilajit-induced inward currents were concentration dependent and maintained in the presence of tetrodotoxin (TTX), a voltage gated Na+ channel blocker, CNQX, a non-NMDA glutamate receptor antagonist, and AP5, an NMDA receptor antagonist. The Shilajit-induced responses were partially suppressed by picrotoxin, a GABAA receptor antagonist, and totally blocked in the presence of strychnine, a glycine receptor antagonist, however not affected by mecamylamine hydrochloride (MCH), a nicotinic acetylcholine receptor antagonist. Under the potassium gluconate pipette solution at holding potential 0 mV, Shilajit induced repeatable outward current. These results show that Shilajit has inhibitory effects on the SG neurons of Vc through chloride ion channels by activation of the glycine receptor and GABAA receptor, indicating that Shilajit contains sedating ingredients for the central nervous system. These results also suggest that Shilajit may be a potential target for modulating orofacial pain processing.
6-Cyano-7-nitroquinoxaline-2,3-dione ; Animals ; Brain Stem ; Central Nervous System ; Chloride Channels ; Facial Pain ; Gluconates ; Mecamylamine ; Mice ; Minerals ; N-Methylaspartate ; Neurons ; Picrotoxin ; Potassium ; Receptors, Glutamate ; Receptors, Glycine ; Receptors, Nicotinic ; Resins, Plant ; Strychnine ; Substantia Gelatinosa ; Tetrodotoxin

PURPOSE: Flutamide (4-nitro-3-t-trifluoromethyl-isobutyranilide) is an androgen-receptor antagonist with typical antiandrogenic effect, used to treat androgen-dependent disorders such as prostate cancer. However, some reports noted that flutamide has direct effects to neuronal cells. It has been shown to retard the development of electrical kindling in rats. METHODS: We used the chemoconvulsant 4-aminopyridine (4-AP) and picrotoxin (PTX) in the in vitro hippocampal slice model to determine of flutamide for the suppression of epileptiform discharges. Extracellular field potential recordings were obtained from the CA3 pyramidal layer of hippocampus. RESULTS: The concentration of 30 and 100 micrometer flutamide suppressed the whole mean number of epileptiform discharges to 57.8% and 66.8% each compared with the 4-AP only slices. In 100 micrometer PTX, 10 and 30 micrometer flutamide suppressed the whole mean number of epileptiform discharges to 56.6% and 82.5% each. Intermixed with flumazenil, the anticonvulsant effect of flutamide was decreased. CONCLUSIONS: Flutamide suppressed epileptiform discharges induced by 4-AP and PTX in vitro seizure model. It suggests that flutamide influence to anti-epileptic activity by benzodiazepine site of the GABAA receptor.
4-Aminopyridine ; Benzodiazepines ; Flumazenil ; Flutamide ; Neurons ; Picrotoxin ; Prostatic Neoplasms ; Seizures

The effects of ethanol on corticostriatal synaptic transmission were examined, using extracellular recording and analysis of population spike amplitudes in rat brain slices, to study how acute ethanol intoxication impairs striatal function. Ethanol caused a decrease in population spike amplitudes in a dose dependent manner (50~200 mM). Pretreatment with picrotoxin, a gamma-amino butyric acid (GABA)A receptor antagonist, increased the population spikes but ethanol (100 mM) was still effective in decreasing the population spikes under this condition. In the presence of (DL)-2-amino-5-phosphonovaleric acid (APV), N-methyl-D-aspartate (NMDA) receptor antagonist, the inhibitory action of ethanol on population spikes was not shown. These results suggest that ethanol inhibits the glutamatergic corticostriatal synaptic transmission through blockade of NMDA receptors.
Animals ; Brain ; Butyric Acid ; Ethanol* ; N-Methylaspartate* ; Picrotoxin ; Rats* ; Receptors, Glutamate ; Receptors, N-Methyl-D-Aspartate ; Synaptic Transmission*

Previous studies showed that a mixture, Coriaria Lactone (CL), extracted from a traditional Chinese herb Loranthus Parasiticus Mer, had a great excitatory influence on the nervous system, resulting in seizure. But what component in CL causes seizure is unclear. Tutin is a pure chemical component derived from CL. The present experiments were carried out to test if tutin has any epileptogenic action and to preliminarily study the mechanism underlying that action in vitro. The electrical activity of CA1 pyramidal cells, population spikes (PS), evoked by stimulation of the Schaffer collaterals in rat hippocampal slices was recorded extracellularly. The effects of tutin on the PS and the antagonistic actions of CNQX and AP-5 on the tutin-induced effects were investigated. The results are as follows. (1) Superfusion with 40, 30 and 20 microg/ml tutin caused significant increase in the amplitude and number of PS waves evoked by stimulating the Schaffer collaterals. Thirty minutes after superfusion of tutin, the amplitude of the first wave of the PSs was increased by (388.7+/-0.1)%, (317.2+/-19.1)% and (180.9+/-11.6)% in each of the above three groups, respectively, compared with the control (for each group, n=5, P<0.05). (2) With increase in amplitude, the PS number was increased to 4~11 waves from a single wave in the control and manifested multiple epileptiform discharges 30 min superfusion with tutin. (3) Spontaneous epileptiform discharges of CA1 pyramidal cells were obtained in 9 out of 34 cases after tutin superfusion. (4) The tutin-induced multiple epileptiform discharges of the CA1 pyramidal cells were completely blocked by CNQX, in aspects of both amplitude and number of the PS. Following the application of AP-5, the increase in the wave number of the tutin-induced epileptiform discharges was inhibited but the increase in the amplitude of the discharges was not significantly affected. These results indicate that tutin can induce typical multiple epileptiform discharges of CA1 pyramidal cells in rat hippocampal slices and might be used as an efficient epileptogenic agent, and that the excitable glutamate receptors, especially the non-NMDA receptors, may participate in the genesis of tutin-induced epileptiform discharges.
Animals ; Electrophysiology ; Epilepsy ; chemically induced ; physiopathology ; Female ; Hippocampus ; physiopathology ; Male ; Picrotoxin ; analogs & derivatives ; Pyramidal Cells ; physiopathology ; Rats ; Rats, Sprague-Dawley ; Sesquiterpenes ; pharmacology

Background: Several studies have suggested that the spinal cord may be an important site of anesthetic action and have established that general anesthetics potentiate the effects of GABA at the GABAA receptor. It was, therefore, hypothesized that the suppression of nocifensive movements during anesthesia is due to an enhancement of GABAA receptor-mediated transmission. Therefore, the aim of this study was to determine behaviorally whether intrathecal GABA, glycine, or opioid receptor antagonists may change the anesthetic effect of isoflurane and enflurane. Methods: The minimal alveolar concentration (MAC) of isoflurane and enflurane was determined in Sprague-Dawley rats, by the tail-clamp technique. First, MAC was determined and then concentration of each inhalation agent was increased by 0.2% from the sub-MAC level. Moving latencies were observed after the intrathecal administration of each receptor antagonist. Rectal temperature was measured and maintained at a steady level during the experiment. Results: The spinal antinociceptive effects of isoflurane and enflurane were significantly reversed by the GABAA receptor antagonist bicuculline and picrotoxin (P < 0.05). The rectal temperature was well maintained within the range of 37-39 degrees C. Conclusions: Our results suggest that the general anesthesia induced by isoflurane and enflurane, which are similar in terms of their action mechanism, is likely to be related to the spinal GABAA receptor system.
Anesthesia ; Anesthesia, General ; Anesthetics ; Anesthetics, General ; Animals ; Bicuculline ; Enflurane* ; gamma-Aminobutyric Acid ; Glycine ; Inhalation ; Isoflurane* ; Picrotoxin ; Rats* ; Rats, Sprague-Dawley ; Receptors, Opioid ; Spinal Cord