This study was designed to investigate the effect of diazepam on the spontaneous contraction and oxytocin induced contraction of the isolated rat uterus. Female rat (Sprague-Dawley) pretreated with oophorectomy and 4 days administration of estrogen. Weighing about 200 g, was sacrificed by cervical dislocation, and the uteruses were isolated. A longitudinal muscle strip was placed in temperature controlled (37℃) muscle chamber containing Locke's solution and myographied isometrically. Diazepam inhibited the spontaneous contraction and oxytocin induced contraction of the isolated rat uterus in a concentration-dependent manner. GABA, muscimol, a GABA A receptor agonist, bicuculline, a competitive GABA A receptor antagonist, picrotoxin, a non competitive GABA A receptor antagonist, baclofen, a GABA B receptor agonist, and delta-aminovaleric acid, a GABA B receptor antagonist, did not affect on the spontaneous and oxytocin induced contraction of the isolated rat uterus. The inhibitory actions of diazepam on the spontaneous and oxytocin induced contraction were not affected by all the GABA receptor agonists and antagonists, but exceptionally potentiated by bicuculline. This potentiation-effect by bicuculline was not antagonized by muscumol. In normal calcium PSS, addition of calcium restored the spontaneous contraction preinhibited by diazepam and recovered the contractile of oxtrocin preinhibited by diazepam. A23187, a calcium inophore, enhanced the restoration of both the spontaneous and oxytocin induced contraction by addition of calcium. In calcium-free PSS, diazepam suppressed the restoration of spontaneous motility by addition of calcium but allowed the recovery of spontaneous motility to a considerable extent. Diazepam could not inhibit some development of contractility by oxytocin in calcium-free PSS, but inhibited the increase in contractility by subsequent addition of calcium. These results suggest that the inhibitory action of diazepam on the rat uterine motility does not depend on or related to GABA receptors and that diazepam inhibits the extracellular calcium influx to suppress the spontaneous and oxytocin induced contractilities.
Animals ; Baclofen ; Bicuculline ; Calcimycin ; Calcium ; Diazepam* ; Dislocations ; Estrogens ; Female ; GABA Agonists ; GABA-A Receptor Agonists ; GABA-A Receptor Antagonists ; GABA-B Receptor Agonists ; GABA-B Receptor Antagonists ; gamma-Aminobutyric Acid ; Humans ; Muscimol ; Ovariectomy ; Oxytocin* ; Picrotoxin ; Rats* ; Receptors, GABA ; Uterus*

OBJECTIVE: The genes encoding for gamma-aminobutyric acid (GABA) A and B receptors may be considered as candidates for alcoholism; genetic alterations at this level may produce structural and functional diversity and thus play a role in the response to alcohol addiction treatment. To investigate these aspects further, we conducted a preliminary genetic association study on a population of Italian male alcohol addicts, focusing on GABA A and B receptors. METHODS: A total of 186 alcohol-dependent subjects (in the first phase 139, then 47 more samples) and 182 controls were genotyped for 25 single nucleotide polymorphisms (SNPs) of genes encoding the alpha-1 subunit of GABA A receptor (GABRA1) and subunits 1 and 2 of GABA B receptor (GABBR1 and GABBR2). The chi-squared test for allele and genotype distributions and Hardy-Weinberg equilibrium analysis of both subjects and controls were performed. Bonferroni's correction for multiple comparisons was applied. RESULTS: Preliminary results comparing 139 alcohol-dependent subjects and 182 controls showed differences in genotype distribution in the former for SNP rs29253, located in the intron region of the GABBR1 gene. In order to clarify the meaning of this association, 47 more samples from alcohol-dependent subjects were tested for this SNP only: the previously found association was not confirmed. CONCLUSION: The lack of significant differences between the two groups does not provide evidence that GABRA 1 and GABBR1 and 2 genes are candidates for alcoholism in this population. Further studies with larger samples are needed, together with investigation of other components of the GABA pathway.
Alcoholism* ; Alleles ; gamma-Aminobutyric Acid ; Genetic Association Studies ; Genotype ; Humans ; Introns ; Male ; Polymorphism, Single Nucleotide ; Receptors, GABA* ; Receptors, GABA-A ; Receptors, GABA-B

<b>OBJECTIVEb>To investigate whether or not the gamma-aminobutyric acid (GABA) receptor subtype A genes GABRA5 and GABRB3 are associated with childhood absence epilepsy (CAE).

<b>METHODSb>Two microsatellite DNA, GABRA5 and GABRB3, adjoining to chromosome 15q11.2-q12 were used as genetic markers. Both case-control study and transmission/disequilibrium test (TDT) as well as fluorescence-based semi-automated genotyping technique were used in 90 trios with CAE and 100 controls to conduct association analysis.

<b>RESULTSb>The allele frequencies of the 2 microsatellite DNA in Chinese normal population are in good agreement with Hardy-Weinberg equilibrium. The polymorphism information content of microsatellite DNA GABRA5 and GABRB3, are 0.80 and 0.66 respectively. The allele 2 frequency of microsatellite DNA GABRA5 and the allele 5 frequency of microsatellite DNA GABRB3 are significantly higher in CAE patients than those in normal controls(P<0.001).

<b>CONCLUSIONb>Both microsatellite DNA GABRA5 and GABRB3 are good genetic markers. The gamma-aminobutyric acid receptor subtype A genes GABRA5 and GABRB3 may be directly involved either in the etiology of CAE or in linkage disequilibrium with disease-predisposing sites.

Adolescent ; Alleles ; Case-Control Studies ; Child ; DNA ; genetics ; Epilepsy, Absence ; genetics ; Female ; Gene Frequency ; Humans ; Linkage Disequilibrium ; Male ; Microsatellite Repeats ; Receptors, GABA-A ; genetics ; Receptors, GABA-B ; genetics

The globus pallidus occupies a critical position in the 'indirect' pathway of the basal ganglia and, as such, plays an important role in the modulation of movement. In recent years, the importance of the globus pallidus in the normal and malfunctioned basal ganglia is emerging. However, the function and operation of various transmitter systems in this nucleus are largely unknown. GABA is the major neurotransmitter involved in the globus pallidus. By means of electrophysiological recording, immunohistochemistry and behavioral studies, new information on the distribution and functions of the GABAergic neurotransmission in the rat globus pallidus has been generated. Morphological studies revealed the existence of GABA(A) receptor, including its benzodiazepine binding site, and GABA(B) receptor in globus pallidus. At subcellular level, GABA(A) receptors are located at the postsynaptic sites of symmetric synapses (putative GABAergic synapses). However, GABA(B) receptors are located at both pre- and postsynaptic sites of symmetric, as well as asymmetric synapses (putative excitatory synapses). Consistent with the morphological results, functional studies showed that activation of GABA(B) receptors in globus pallidus reduces the release of GABA and glutamate by activating presynaptic auto- and heteroreceptors, and hyperpolarizes pallidal neurons by activating postsynaptic receptors. In addition to GABA(B) receptor, activation of GABA(A) receptor benzodiazepine binding site and blockade of GABA uptake change the activity of globus pallidus by prolonging the duration of GABA current. In agreement with the in vitro effect, activation of GABA(B) receptor, GABA(A) receptor benzodiazepine binding site and blockade of GABA uptake cause rotation in behaving animal. Furthermore, the GABA system in the globus pallidus is involved in the etiology of Parkinson's disease and regulation of seizures threshold. It has been demonstrated that the abnormal hypoactivity and synchronized rhythmic discharge of globus pallidus neurons associate with akinesia and resting tremor in parkinsonism. Recent electrophysiological and behavioral studies indicated that the new anti-epileptic drug, tiagabine, is functional in globus pallidus, which may present more information to understand the involvement of globus pallidus in epilepsy.
Animals ; Basal Ganglia ; metabolism ; physiology ; Epilepsy ; metabolism ; Globus Pallidus ; metabolism ; physiology ; Humans ; Parkinson Disease ; metabolism ; Presynaptic Terminals ; metabolism ; physiology ; Receptors, GABA ; physiology ; Receptors, GABA-A ; metabolism ; physiology ; Receptors, GABA-B ; metabolism ; physiology ; Synapses ; metabolism ; physiology ; gamma-Aminobutyric Acid ; metabolism

BACKGROUND: This study was conducted to investigate the roles of the spinal and peripheral gamma-aminobutyric acid (GABA)-ergic systems for the mechanical hypersensitivity produced by chronic compression of the dorsal root ganglion (CCD). METHODS: CCD was performed at the left 5th lumbar dorsal root ganglion. The paw withdrawal threshold (PWT) to von Frey stimuli was measured. The mechanical responsiveness of the lumbar dorsal horn neurons was examined. GABAergic drugs were delivered with intrathecal (i.t.) or intraplantar (i.pl.) injection or by topical application onto the spinal cord. RESULTS: CCD produced mechanical hypersensitivity, which was evidenced by the decrease of the PWT, and it lasting for 10 weeks. For the rats showing mechanical hypersensitivity, the mechanical responsiveness of the lumbar dorsal horn neurons was enhanced. A similar increase was observed with the normal lumbar dorsal horn neurons when the GABA-A receptor antagonist bicuculline was topically applied. An i.t. injection of GABA-A or GABA-B receptor agonist, muscimol or baclofen, alleviated the CCD-induced hypersensitivity. Topical application of same drugs attenuated the CCD-induced enhanced mechanical responsiveness of the lumbar dorsal horn neurons. CCD-induced hypersensitivity was also improved by low-dose muscimol applied (i.pl.) into the affected hind paw, whereas no effects could be observed with high-dose muscimol or baclofen. CONCLUSIONS: The results suggest that the neuropathic pain associated with compression of the dorsal root ganglion is caused by hyperexcitability of the dorsal horn neurons due to a loss of spinal GABAergic inhibition. Peripheral application of low-dose GABA-A receptor agonist can be useful to treat this pain.
Animals ; Back Pain ; Baclofen ; Bicuculline ; GABA-A Receptor Agonists ; GABA-A Receptor Antagonists ; GABA-B Receptor Agonists ; gamma-Aminobutyric Acid ; Ganglia, Spinal ; Hyperalgesia ; Hypersensitivity* ; Muscimol ; Neuralgia ; Posterior Horn Cells ; Rats* ; Receptors, GABA ; Spinal Cord

OBJECTIVE: To observe the expression of GABA(A) receptor alpha1 (GABA(A)alpha1) and GABA(B) receptor 1 (GABA(B)1) in human medulla oblongata solitary nucleus and ambiguous nucleus due to tramadol-induced death. METHODS: GABA(A)alpha1 and GABA(B)1 were detected by immunohistochemical SP method in tramadol-induced death group and control group. All results were evaluated by images analysis system. RESULTS: Low expression of GABA(A)alpha1 and GABA(B)1 were detected in solitary nucleus and ambiguous nucleus in the control brain tissue. In cases of tramadol-induced death, the expression of GABA(A)alpha1 and GABA(B)1 significantly increased. CONCLUSION The mechanism of tramadol intoxication death could be caused by respiratory depression induced by over-expression of GABA(A)alpha1 and GABA(B)1 in medulla oblongata solitary nucleus and ambiguous nucleus.
Adult ; Analgesics, Opioid/poisoning* ; Autopsy ; Case-Control Studies ; Cause of Death ; Female ; Forensic Toxicology ; Humans ; Immunohistochemistry ; Male ; Medulla Oblongata/metabolism* ; Receptors, GABA-A/metabolism* ; Receptors, GABA-B/metabolism* ; Respiration Disorders/etiology* ; Solitary Nucleus/metabolism* ; Staining and Labeling ; Tramadol/poisoning*

The mechanisms of general anesthesia, which was introduced about 170 years ago, remain poorly under- stood. Even less well understood are the effects of general anesthesia on the human body. Recently we identified 18 G-protein coupled receptor (GPCR) genes of Daphnia pulex, an invertebrate model organism. Phylogenetic analysis identified these genes to be the homologs of the human γ-aminobutyric acid, type B (GABAB) receptor, metabotropic glutamate receptors (mGluR), adrenergic receptor, serotonin (5-HT) receptor, dopamine receptor and muscarinic acetylcholine receptor (mAChR). Using reverse transcription and quantitative PCR techniques, we systematically measured the effects of propofol, etomidate and ethanol on these 18 GPCR mRNA expressions in Daphnia pulex.
Animals ; Daphnia ; drug effects ; metabolism ; Ethanol ; pharmacology ; Etomidate ; pharmacology ; Phylogeny ; Propofol ; pharmacology ; RNA, Messenger ; genetics ; metabolism ; Receptors, GABA-B ; genetics ; metabolism

<b>OBJECTIVEb>Febrile seizure (FS) is one of the most common seizure types in children. Our previous studies have demonstrated that both gamma-aminobutyric acid B receptor (GABABR) and hydrogen sulfide (H2S) are involved in the pathogenesis of FS. This study was designed to explore the effect of GABABR on H2S/cystathionine-beta-synthase (CBS) system in recurrent FS.

<b>METHODSb>Sixty-four Sprague-Dawley rats aged 21 days were randomly assigned into four groups: Control (37 degrees C water bath exposure), FS, FS+baclofen (GABABR excitomotor), and FS+phaclofen (GABABR inhibitor) groups (n=16 each). FS was induced by warm water bath exposure (45.2 degrees C, once every 2 days, 10 times in total. The plasma level of H2S was detected by the spectrophotometer. The expression of CBS mRNA was examined by in situ hybridization. The expressions of CBS protein was observed by immunohistochemistry.

<b>RESULTSb>The plasma level of H2S increased in the FS+baclofen group (427.45 +/- 15.91 micromol/L) but decreased in the FS+phaclofen group (189.72 +/- 21.53 micromol/L) compared with that in the FS group (362.14 +/- 19.71 micromol/L). The expressions of CBS mRNA and protein were up-regulated in the FS+baclofen group but were down-regulated in the FS+phaclofen group compared with those in the FS group.

<b>CONCLUSIONSb>GABABR modulated the expression of H2S/CBS system in recurrent FS.

Animals ; Baclofen ; pharmacology ; Cystathionine beta-Synthase ; genetics ; physiology ; Hydrogen Sulfide ; blood ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptors, GABA-B ; physiology ; Recurrence ; Seizures, Febrile ; metabolism

PURPOSE: The inhibition of phosphodiesterase 5 produces an antinociception through the increase of cyclic guanosine monophosphate (cGMP), and increasing cGMP levels enhance the release of gamma-aminobutyric acid (GABA). Furthermore, this phosphodiesterase 5 plays a pivotal role in the regulation of the vasodilatation associated to cGMP. In this work, we examined the contribution of GABA receptors to the effect of sildenafil, a phosphodiesterase 5 inhibitor, in a neuropathic pain rat, and assessed the hemodynamic effect of sildenafil in normal rats. MATERIALS AND METHODS: Neuropathic pain was induced by ligation of L5/6 spinal nerves in Sprague-Dawley male rats. After observing the effect of intravenous sildenafil on neuropathic pain, GABAA receptor antagonist (bicuculline) and GABAB receptor antagonist (saclofen) were administered prior to delivery of sildenafil to determine the role of GABA receptors in the activity of sildenafil. For hemodynamic measurements, catheters were inserted into the tail artery. Mean arterial pressure (MAP) and heart rate (HR) were measured over 60 min following administration of sildenafil. RESULTS: Intravenous sildenafil dose-dependently increased the withdrawal threshold to the von Frey filament application in the ligated paw. Intravenous bicuculline and saclofen reversed the antinociception of sildenafil. Intravenous sildenafil increased the magnitude of MAP reduction at the maximal dosage, but it did not affect HR response. CONCLUSION: These results suggest that sildenafil is active in causing neuropathic pain. Both GABAA and GABAB receptors are involved in the antinociceptive effect of sildenafil. Additionally, intravenous sildenafil reduces MAP without affecting HR.
Animals ; Baclofen/analogs & derivatives/pharmacology ; Bicuculline/pharmacology ; Blood Pressure/drug effects ; Dose-Response Relationship, Drug ; Heart Rate/drug effects ; Hemodynamics/drug effects ; Male ; Neuralgia/*drug therapy ; Pain Threshold/drug effects ; Phosphodiesterase Inhibitors/*therapeutic use ; Piperazines/*therapeutic use ; Purines/therapeutic use ; Rats ; Rats, Sprague-Dawley ; Receptors, GABA-A/antagonists & inhibitors/physiology ; Receptors, GABA-B/antagonists & inhibitors/physiology ; Sulfones/*therapeutic use

<b>OBJECTIVEb>This study investigated the effects of flurothyl-induced neonatal recurrent seizures on gamma-aminobutyric acid B1 receptor (GABAB1R) expression in neonatal and adult rat brain, and explored the possible relationship between the alterations of GABAB1R in mature brain and the changes of spatial memory and seizure susceptibility in adult rats.

<b>METHODSb>Forty-eight postnatal day (P) 7 Sprague-Dawley rats were randomly assigned into two groups: Control and Seizure group (n=24 each). Seizures were induced by inhalant flurothyl daily for six consecutive days in rat pups from the Seizure group. Twelve rats selected randomly in each group were sacrificed on the 7th day after the last seizure for detecting the expressions of GABAB1R mRNA and protein in cerebral cortex and hippocampus by reverse transcription-polymerase chain reaction (RT-PCR) and immuno-histochemistry method. The spatial memory was tested by using the Morris water maze task during P61 to P64 and the seizure threshold was measured at P75 following intraperitoneal injection of pentylenetetrazol ( PTZ ) in the remaining rats. The rats were then sacrificed for detecting the expressions of GABAB1R mRNA and protein in cerebral cortex and hippocampus.

<b>RESULTSb>The expressions of GABAB1R mRNA and protein in the cerebral cortex on the 7th day after the last seizure and at P75 decreased significantly in the Seizure group when compared with the Control group (P < 0.05). The GABAB1R protein expression in the dentate gyrus on the 7th day after the last seizure in the Seizure group was significantly lower than that in the Control group (P < 0.05), but the GABAB1R mRNA expression in the hippocampus was not different from that in the Control group. There were no significant differences in the expressions of GABAB1R mRNA and protein in the hippocampus between the two groups at P75. The escape latencies in water maze of the rats in the Seizure group at P64 were significantly longer than those in the Control group (98,533.8 +/- 27,205.4 ms vs 46,723.3 +/- 40,666.5 ms; P <0.05). There were no differences in the seizure threshold between the two groups.

<b>CONCLUSIONSb>The expressions of GABAB1R mRNA and protein in the cerebral cortex and hippocampus of neonatal rats with recurrent seizures decreased significantly, suggesting the changes of GABAB1R may be related to acute brain injury following neonatal recurrent seizures and the memory deficit in adult rats caused by neonatal recurrent seizures.

Animals ; Animals, Newborn ; Brain ; metabolism ; Cerebral Cortex ; metabolism ; Female ; Hippocampus ; metabolism ; Male ; Maze Learning ; RNA, Messenger ; analysis ; Rats ; Rats, Sprague-Dawley ; Receptors, GABA-B ; analysis ; genetics ; Recurrence ; Seizures ; metabolism