• BMB Reports
• /
• v.47 no.6
• /
• pp.324-329
• /
• 2014

Regulators of G-protein signaling (RGS) proteins regulate certain G-protein-coupled receptor (GPCR)-mediated signaling pathways. The GABAB receptor ($GABA_BR$) is a GPCR that plays a role in the stress response. Previous studies indicate that acute immobilization stress (AIS) decreases RGS4 in the prefrontal cortex (PFC) and hypothalamus (HY) and suggest the possibility of a signal complex composed of RGS4 and $GABA_BR$. Therefore, in the present study, we tested whether RGS4 associates with $GABA_BR$ in these brain regions. We found the co-localization of RGS4 and $GABA_BR$ subtypes in the PFC and HY using double immunohistochemistry and confirmed a direct association between $GABA_{B2}R$ and RGS4 proteins using co-immunoprecipitation. Furthermore, we found that AIS decreased the amount of RGS4 bound to $GABA_{B2}R$ and the number of double-positive cells. These results indicate that $GABA_BR$ forms a signal complex with RGS4 and suggests that RGS4 is a regulator of $GABA_BR$.

• Journal of Pharmacopuncture
• /
• v.19 no.2
• /
• pp.163-166
• /
• 2016

Objectives: Quercetin is a flavonoid and an important dietary constituent of fruits and vegetables. In recent years, several pharmacological activities of quercetin, such as its neuroprotective activity and, more specifically, its anti-convulsant effects in animal models of epilepsy, have been reported. This study evaluated the role of quercetin pretreatment on gene expression of ${\gamma}$-amino butyric acid type A ($GABA_A$) receptor beta subunits in kainic acid (KA)-induced seizures in mice. Methods: The animals were divided into four groups: one saline group, one group in which seizures were induced by using KA (10 mg/kg) without quercetin pretreatment and two groups pretreated with quercetin (50 and 100 mg/kg) prior to seizures being induced by using KA. Next, the messenger ribonucleic acid (mRNA) levels of the $GABA_A$ receptor ${\beta}$ subunits in the hippocampus of each animal were assessed at 2 hours and 7 days after KA administration. Quantitative real-time polymerase chain reaction (RT-PCR) assay was used to detect mRNA content in hippocampal tissues. Results: Pretreatments with quercetin at doses of 50 and 100 mg/kg prevented significant increases in the mRNA levels of the ${\beta}_1$ and the ${\beta}_3$ subunits of the $GABA_A$ receptor at 2 hours after KA injection. Pretreatment with quercetin (100 mg/kg) significantly inhibited ${\beta}_1$ and ${\beta}_3$ gene expression in the hippocampus at 7 days after KA injection. But, this inhibitory effect of quercetin at 50 mg/kg on the mRNA levels of the ${\beta}_3$ subunit of the $GABA_A$ receptor was not observed at 7 days after KA administration. Conclusion: These results suggest that quercetin (100 mg/kg) modulates the expression of the $GABA_A$ receptor ${\beta}_1$ and ${\beta}_3$ subunits in the KA model of epilepsy, most likely to prevent compensatory responses. This may be related to the narrow therapeutic dose range for the anticonvulsant activities of quercetin.

• Archives of Pharmacal Research
• /
• v.28 no.2
• /
• pp.238-242
• /
• 2005

Many reports demonstrate that extremely low frequency magnetic fields (ELF MFs, 60 Hz) may be involved in hyperalgesia. In a previous investigation, we suggested that MFs may produce hyperalgesia and such a response may be regulated by the benzodiazepine system. In order to further confirm this effect of MFs, we used diazepam and/or flumazenil with MFs exposure. When testing the pain threshold of rats using hot plate tests, MFs or diazepam ($0.5\;{\mu}g$, i.c.v.; a benzodiazepine receptor agonist) induced hyperalgesic effects with the reduction of latency. These effects were blocked by a pretreatment of flumazenil (1.5 mg/kg, i.p.; a benzodiazepine receptor antagonist). When the rats were exposed simultaneously to MFs and diazepam, the latency tended to decrease without statistical significance. The induction of hyperalgesia by co-exposure to MFs and diazepam was also blocked by flumazenil. However, the pretreatment of GABA receptor antagonists such as bicuculline ($0.1\;{\mu}g$, i.c.v.; a $GABA_A$ antagonist) or phaclofen ($10\;{\mu}g$, i.c.v.; a $GABA_B$ antagonist) did not antagonize the hyperalgesic effect of MFs. These results suggest that the benzodiazepine system may be involved in MFs-induced hyperalgesia.

• The Korean Journal of Physiology and Pharmacology
• /
• v.25 no.1
• /
• pp.27-38
• /
• 2021

Excessive salt intake induces hypertension, but several gamma-aminobutyric acid (GABA) supplements have been shown to reduce blood pressure. GABA-salt, a fermented salt by L. brevis BJ20 containing GABA was prepared through the post-fermentation with refined salt and the fermented GABA extract. We evaluated the effect of GABA-salt on hypertension in a high salt, high cholesterol diet induced mouse model. We analyzed type 1 macrophage (M1) polarization, the expression of M1 related cytokines, GABA receptor expression, endothelial cell (EC) dysfunction, vascular smooth muscle cell (VSMC) proliferation, and medial thicknesses in mice model. GABA-salt attenuated diet-induced blood pressure increases, M1 polarization, and TNF-α and inducible nitric oxide synthase (NOS) levels in mouse aortas, and in salt treated macrophages in vitro. Furthermore, GABA-salt induced higher GABAB receptor and endothelial NOS (eNOS) and eNOS phosphorylation levels than those observed in salt treated ECs. In addition, GABA-salt attenuated EC dysfunction by decreasing the levels of adhesion molecules (E-selectin, Intercellular Adhesion Molecule-1 [ICAM-1], vascular cell adhesion molecule-1 [VCAM-1]) and of von Willebrand Factor and reduced EC death. GABA-salt also reduced diet-induced reductions in the levels of eNOS, phosphorylated eNOS, VSMC proliferation and medial thickening in mouse aortic tissues, and attenuated Endothelin-1 levels in salt treated VSMCs. In summary, GABA-salt reduced high salt, high cholesterol diet induced hypertension in our mouse model by reducing M1 polarization, EC dysfunction, and VSMC proliferation.

• The Korean Journal of Physiology and Pharmacology
• /
• v.24 no.5
• /
• pp.433-440
• /
• 2020

The substantia gelatinosa (SG) of the trigeminal subnucleus caudalis (Vc) is the first relay site for the orofacial nociceptive inputs via the thin myelinated Aδ and unmyelinated C primary afferent fibers. Borneol, one of the valuable time-honored herbal ingredients in traditional Chinese medicine, is a popular treatment for anxiety, anesthesia, and antinociception. However, to date, little is known as to how borneol acts on the SG neurons of the Vc. To close this gap, the whole-cell patch-clamp technique was applied to elucidate the antinociceptive mechanism responding for the actions of borneol on the SG neurons of the Vc in mice. In the voltage-clamp mode, holding at -60 mV, the borneol-induced non-desensitizing inward currents were not affected by tetrodotoxin, a voltage-gated Na⁺ channel blocker, 6-cyano-7-nitro-quinoxaline-2,3-dione, a non-N-methyl-ᴅ-aspartate (NMDA) glutamate receptor antagonist and DL-2-amino-5-phosphonopentanoic acid, an NMDA receptor antagonist. However, borneol-induced inward currents were partially decreased in the presence of picrotoxin, a γ-aminobutyric acid (GABA)_A receptor antagonist, or strychnine, a glycine receptor antagonist, and was almost suppressed in the presence of picrotoxin and strychnine. Though borneol did not show any effect on the glycine-induced inward currents, borneol enhanced GABA-mediated responses. Beside, borneol enhanced the GABA-induced hyperpolarization under the current-clamp mode. Altogether, we suggest that borneol contributes in part toward mediating the inhibitory GABA and glycine transmission on the SG neurons of the Vc and may serve as an herbal therapeutic for orofacial pain ailments.

• The Korean Journal of Physiology and Pharmacology
• /
• v.21 no.1
• /
• pp.65-74
• /
• 2017

Here we investigated the central processing mechanisms of mechanical allodynia and found a direct excitatory link with low-threshold input to nociceptive neurons. Experiments were performed on male Sprague-Dawley rats weighing 230-280 g. Subcutaneous injection of interleukin 1 beta ($IL-1{\beta}$) ($1ng/10{\mu}L$) was used to produce mechanical allodynia and thermal hyperalgesia. Intracisternal administration of bicuculline, a gamma aminobutyric acid A ($GABA_A$) receptor antagonist, produced mechanical allodynia in the orofacial area under normal conditions. However, intracisternal administration of bicuculline (50 ng) produced a paradoxical anti-allodynic effect under inflammatory pain conditions. Pretreatment with resiniferatoxin (RTX), which depletes capsaicin receptor protein in primary afferent fibers, did not alter the paradoxical anti-allodynic effects produced by the intracisternal injection of bicuculline. Intracisternal injection of bumetanide, an Na-K-Cl cotransporter (NKCC 1) inhibitor, reversed the $IL-1{\beta}$-induced mechanical allodynia. In the control group, application of GABA ($100{\mu}M$) or muscimol ($3{\mu}M$) led to membrane hyperpolarization in gramicidin perforated current clamp mode. However, in some neurons, application of GABA or muscimol led to membrane depolarization in the $IL-1{\beta}$-treated rats. These results suggest that some large myelinated $A{\beta}$ fibers gain access to the nociceptive system and elicit pain sensation via $GABA_A$ receptors under inflammatory pain conditions.

• Journal of Dental Anesthesia and Pain Medicine
• /
• v.23 no.3
• /
• pp.153-162
• /
• 2023

Background: Recent animal studies have suggested the role of GABA type A (GABA-_A) receptors in salivation, showing that GABA-_A receptor agonists inhibit salivary secretion. This study aimed to evaluate the effects of propofol (a GABA-_A agonist) on salivary secretions from the submandibular, sublingual, and labial glands during intravenous sedation in healthy volunteers. Methods: Twenty healthy male volunteers participated in the study. They received a loading dose of propofol 6 mg/kg/h for 10 min, followed by 3 mg/kg/h for 15 min. Salivary flow rates in the submandibular, sublingual, and labial glands were measured before, during, and after propofol infusion, and amylase activity was measured in the saliva from the submandibular and sublingual glands. Results: We found that the salivary flow rates in the submandibular, sublingual, and labial glands significantly decreased during intravenous sedation with propofol (P < 0.01). Similarly, amylase activity in the saliva from the submandibular and sublingual glands was significantly decreased (P < 0.01). Conclusion: It can be concluded that intravenous sedation with propofol decreases salivary secretion in the submandibular, sublingual, and labial glands via the GABA-_A receptor. These results may be useful for dental treatment when desalivation is necessary.

• Korean Journal of Pharmacognosy
• /
• v.30 no.2
• /
• pp.211-215
• /
• 1999

This study was aimed to evaluate an agonistic activity to benzodiazepine receptor of several medicinal plants, which have been used as sedatives in oriental medicine. Methanol extracts of medicinal plants which were used in this study inhibited the binding of $[^3H]Ro15-1788$, a selective benzodiazepine receptor antagonist to benzodiazepine receptor of rat cortices. Inhibitory activity of Cyperus rotundus was observed to be the highest among the tested medicinal plants. Methanol extracts of Cyperus rotundus and Zizypus jujuba inhibited a $[^3H]flunitrazepam$, a selective benzodiazepine receptor agonist, binding to benzodiazepine receptor. GABA significantly enhanced the inhibition of $[3H]flunitrazepam$ binding by Cyperus rotundus and Zizypus jujuba, and these positive GABA shifts supported the strong possibility of agonistic activity to benzodiazepine receptor. From these results, it may be concluded that the substance or substances with neurochemical properties characteristic of a benzodiazepine receptor agonist may be important components and contribute to the sedative property of these medicinal plants.

• Molecules and Cells
• /
• v.20 no.3
• /
• pp.305-314
• /
• 2005

Investigation of chemically synthesized inositol 1,4,5-trisphosphate [$Ins(1,4,5)P_3$] analogs has led to the isolation of a novel binding protein with a molecular size of 130 kDa, characterized as a molecule with similar domain organization to phospholipase C-${\delta}1$ (PLC-${\delta}1$) but lacking the enzymatic activity. An isoform of the molecule was subsequently identified, and these molecules have been named PRIP (PLC-related, but catalytically inactive protein), with the two isoforms named PRIP-1 and -2. Regarding its ability to bind $Ins(1,4,5)P_3$ via the pleckstrin homology domain, the involvement of PRIP-1 in $Ins(1,4,5)P_3$-mediated $Ca^{2+}$ signaling was examined using COS-1 cells overexpressing PRIP-1 and cultured neurons prepared from PRIP-1 knock-out mice. Yeast two hybrid screening of a brain cDNA library using a unique N-terminus as bait identified GABARAP ($GABA_A$ receptor associated protein) and PP1 (protein phosphatase 1), which led us to examine the possible involvement of PRIP in $GABA_A$ receptor signaling. For this purpose PRIP knock-out mice were analyzed for $GABA_A$ receptor function in relation to the action of benzodiazepines from the electrophysiological and behavioral aspects. During the course of these experiments we found that PRIP also binds to the b-subunit of $GABA_A$ receptors and PP2A (protein phosphtase 2A). Here, we summarize how PRIP is involved in $Ins(1,4,5)P_3$-mediated $Ca^{2+}$ signaling and $GABA_A$ receptor signaling based on the characteristics of binding molecules.

• Journal of Oriental Neuropsychiatry
• /
• v.19 no.1
• /
• pp.43-54
• /
• 2008

Objective: The aim of this study is to evaluate the anticonvulsive effects of Gamiheichumhwan extract and to explain its action in GABAergic neuromodulation of the rat brain. Method: The extracts of Gamiheichumhwan were investigated for their inhibitory effect on GABA transaminase activity, their influence on brain GABA and glutamate levels, their agonistic activity on GABA/benzodiazepine receptor and anticonvulsive action using in vitro and in vivo assays. Results: 1. The extract inhibited dose-dependently GABA transaminase (GABA-T) activity by 4.6% and 18.9%, respectively at dosages of 250 mg/kg and 500mg/kg mouse (p.o.). 2. Brian GABA level was increased to 72.0% and brain glutamate level was decreased to 9.6% at a dosage of 500 mg/kg mouse (p.o.). 3. The extract suppressed [3H]Ro15-1788 binding to rat cerebral cortical membrane by $81.4{\pm}0.8%$ at a dosage of 3.2 mg, suggesting its agonistic activity on GABA/benzodiazepin receptor. 4. The extract showed anticonvulsive effect by lengthening the onset time of convulsion, shortening the convulsion duration and diminishing the lethality. Conclusion : It is suggested that Gamiheichumhwan can be used to somnipathy and adapted to treatment and prevention of epilepsy or convulsion.