Suppressing SNAP-25 and reversing glial glutamate transporters relieves neuropathic pain in rats by ameliorating imbalanced neurotransmission / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Neuropathic pain results from a lesion or disease affecting the somatosensory system at either the peripheral or central level. The transmission of nociception within the central nervous system is subject to modulation by release and reuptake of neurotransmitters, which maintain a dynamic balance through the assembly and disassembly of the SNARE complex as well as a series of neurotransmitter transporters (inhibitory GABA transporters GAT and excitatory glutamate transporters GT). Neuronal hyper-excitability or defected inhibition involved in neuropathic pain is one of the outcomes caused by imbalanced neurotransmission. SNAP-25, which is one of the SNARE complexes, can modulate the release of neurotransmitters. Glia glutamate transporter (GLT) is one of the two glutamate transporters which account for most synaptic glutamate uptake in the CNS. The role of SNAP-25 and GLT as well as GAT is not clearly understood.</p><p><b>METHODS</b>We used the rat chronic constriction injury (CCI) model for research, and degraded SNAP-25 by a single intrathecal administration of BoNT/A. The mechanical (MWT) and thermal withdrawal latency (TWL) were tested. The level of SNAP-25, GLT, and GAT-1 were assayed using RT-PCR and Western blotting.</p><p><b>RESULTS</b>SNAP-25 was suppressed by a single intrathecal administration of 0.01U BoNT/A and the reduction of SNAP- 25 was correlated with the relief of nociceptive responses in CCI rats. MWT and TWL returned to normal from the 5th to 14th day (P < 0.05) after the administration. On the 14th day after surgery, compared to the sham group, the upregulation of SNAP-25 in CCI rats was reversed after BoNT/A treatment (P < 0.05). The decreased GLT was reversed after BoNT/A treatment but increased GAT-1 was not influenced by BoNT/A treatment.</p><p><b>CONCLUSIONS</b>SNAP-25 and GLT play important roles in the development of neuropathic pain, and the mechanism may involve the imbalance of neurotransmission after peripheral nerve injury. Intrathecal administration of BoNT/A reversed the upregulation of SNAP-25 and downregulation of GLT after CCI, but had no significant effect on the expression of GAT-1.</p>

GAT-1 and GAD65 mRNA expressions in different brain regions in dogs at brain propofol uptake equilibrium / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the expressions of gamma aminobutyric acid transporter 1 (GAT-1) and glutamate decarboxylase 65 (GAD65) mRNA in different brain regions at brain propofol uptake equilibrium in dogs.</p><p><b>METHODS</b>Eighteen 12- to 18-month-old healthy hybrid dogs were randomized equally into control group (group C), low dose group (group L), and high dose group (group H). In groups L and H, anesthesia was administered by intravenous injection of 5.5 and 7.0 mg/kg propofol followed by propofol infusion at a constant rate of 55 and 70 mg·kg(-1)·h(-1) for 50 min, respectively. Blood samples were taken from the internal carotid artery and jugular vein to measure plasma propofol concentrations, and the brain tissues of the hypothalamus, sub thalamus, dorsal thalamus, hippocampus, pons, parietal lobe and frontal lobe were examined for GAT-1 and GAD65 mRNA expressions using quantitative real-time PCR.</p><p><b>RESULTS</b>In groups L and H, propofol infusion at a constant rate for 50 min resulted in comparable plasma propofol concentrations between the internal carotid artery and jugular vein (P>0.05), but the concentrations differed significantly between the two groups (P<0.01). GAT-1 mRNA levels in the hypothalamus and hippocampus were significantly higher in groups L and H than in group C (P<0.05 and P<0.01), but comparable between the former two groups. The variations of GAT-1 mRNA levels between the hypothalamus and hippocampus were similar in both group L [(61.26∓7.17)% and (79.34∓39.95)%, P>0.05] and group H [(74.64∓19.63)% and (97.12∓32.31)%, P>0.05]. GAT-1 mRNA levels in other brain regions showed no significant difference among the 3 groups. GAD65 mRNA levels were similar between group L and group H, but both significantly higher than that in group C (P<0.01). GAD65 mRNA in other brain regions had no significant difference among the 3 groups.</p><p><b>CONCLUSION</b>GAT-1 mRNA in the hypothalamus and hippocampus and GAD65 mRNA in the dorsal thalamus are upregulated when propofol uptake reaches an equilibrium in the brain of dogs.</p>

Effect of down-regulation of GAT-1 on analgesic action of oxysophoridine / 中国中药杂志

<p><b>OBJECTIVE</b>To study the effect of GABA transporter (GAT-1) on the analgesic action of oxysophoridine (OSR) in the central nervous system of mice.</p><p><b>METHOD</b>Hot plate test was used to observe and analyze the effect of gamma aminobutyric acid and the inhibitor of GAT-1 (NO-711) on the analgesic action of oxysophoridine. Real time RT-PCR was used to investigate the influence of OSR on the expression of GAT-1 mRNA induced by formalin in spinal cord and brain of mice.</p><p><b>RESULT</b>Both GABA (2.0 mg x kg(-1), icv) and NO-711(0.125 mg x kg(-1), icv) enhanced the analgesic action of OSR (32.0 mg x kg(-1), iv) in the hot plate test, and the latencies was markedly increased (P < 0.05, P < 0.01). OSR (500.0 mg x kg(-1), iv) significantly inhibited the expression of GAT-1 mRNA induced by formalin (P < 0.05).</p><p><b>CONCLUSION</b>GAT-1 was involved in the analgesia effect of OSR and the down-regulation of GAT-1 mRNA enhanced the analgesic effect.</p>

Suppression of gamma-aminobutyric acid transporter current by activation of ionotropic glutamate receptors on retinal horizontal cells / 生理学报

In the present study, the modulatory effect of AMPA receptors on gamma-aminobutyric acid (GABA) transporter current was investigated on enzymatically isolated horizontal cells of carp retina. The GABA transporter current elicited by 1 mmol/L GABA was decreased immediately after pre-application of AMPA (30 mumol/L or 3 mmol/L) for 50 s. Application of 10 mmol/L BAPTA in intracellular solution inhibited the suppression effect of AMPA on GABA transporter current. The suppression effect induced by co-application of 3 mmol/L AMPA and 3 mmol/L NMDA was similar to that of 3 mmol/L AMPA or 3 mmol/L NMDA alone. These results suggest that the activation of AMPA receptors inhibits GABA transporter-mediated current by affecting intracellular Ca(2+) processes in the retinal horizontal cells, which is identical with the modulatory effect of NMDA receptors on GABA transporters.

New insight into pathogenesis of idiopathic myelofibrosis--review / 中国实验血液学杂志

Idiopathic myelofibrosis is a type of chronic myeloproliferative disorders characterized by splenomegaly, a leukoerythroblastic blood picture, teardrop poikilocytosis, in various degrees of bone marrow fibrosis and extramedullary hematopoiesis. In this paper, the biological characters and pathogenesis of idiopathic myelofibrosis such as mutation of tyrosine kinase receptor, mutation of GABA transporter 1, JAK2 mutation and c-MPl mutation, as well as other pathogenesis related with idiopathic myelofibrosis were reviewed.

Differential Expression of GABA Transporters in Developing Rat Retina / 대한해부학회지

To investigate the spatial and temporal distribution of g-aminobutyric acid (GABA) transporters in the developing rat retina, we localized two GABA transporter proteins, GAT-1 and GAT-3 by immunocytochemistry. GAT-1 immunoreactivity appeared from embryonic day 20 (E20) in the punctate-like structures in the inner plexiform layer. At postnatal day 3 (P3), immunolabeling of cell bodies in the inner nuclear and ganglion cell layers and processes in the inner plexiform layer became much stronger, reaching a maximum staining intensity during the second postnatal week, and the expression pattern and intensity became almost identical to those of the adult retina by P14. In addition, Miller cells also began to show weak immunlabeling for GAT-1 from P10 onward. In contrast, develop-mentally transient immunolabeling for GAT-1 was found in horizontal cells located at the scleral border of the inner nuclear layer during the second postnatal week. The initial immunolabeling for GAT-3 immunoreactivity was already noted in scattered cell bodies and processes of the neuroblastic layer at E18, the earliest time point. During the first week of the postnatal life, GAT-3 immunoreactivity increased in the cell bodies in the inner nuclear and ganglion cell layers, and processes in the inner plexiform layer. From P10 onward, this labeling began to decline, and remained faintly in the neuronal somata of the inner nuclear layer by P14. Instead, the labeling was predominantly localized in Mler cells. Astrocytes in the nerve fiber layer showed the transient labeling during the first postnatal week. Our results showed distinct temporal patterns of two GABA transporter proteins in the developing rat retina, and it suggests specialized roles for GABA transporters in the development of the rat retina.

Effects of kainic Acid-induced seizures on GABA and GABA transporter in the cerebellum of the rat / 대한해부학회지

The effects of kainic acid-induced seizures on GABA and GABA transporter in the rat cerebellum were examined by means of immunohistochemical and Western blot methods. Immunocytochemical analysis showed that kainic acid-induced seizures led to a decreased immunoreactivity for GABA to 3 weeks after seizures with an slight increase in the immunoreactivity of cerebellum 24 h after treatment. Immunoreactivities of GABA transporters, GAT-1 and GAT-3 which are localized neurons and astrocytes, were increased at 24 and 48h and after that weak immunoreactivites for GABA transporters were shown in the cerebellar tissues. Our results indicate that kainic acid-induced seizures exerts specific effects on GABA contents and the GABA transporters in the cerebellum and a decrease of GABA contents might not always associated with the decrease in the number of GABA transporters in the rat cerebellum.

Expression of GABA Transporters in the Rat's Olfactory Bulb during Development

Developmental changes in the expression of two GABA (gamma-aminobutyric acid) transporter proteins, GAT-1 and GAT-3, in the olfactory bulb of embryonic and postnatal rats were examined with immunocytochemistry using antisera against GAT-1 and GAT-3. The expression and localization of GAT-1 and GAT-3 showed distinct temporal patterns during olfactory bulb development. GAT-1 immunoreactivity appeared weakly in most likely growing axons of the presumptive glomerular layer from embryonic day 18 and increased during the first postnatal week. In contrast, GAT-3 immunoreactivity, first detected at E16, was found in radial glial cell fascicles and was replaced by what were likely astroglial cells postnatally. At P7, GAT-1 and GAT-3 immunoreactivities reached the adult pattern i.e., GAT-1 immunoreactivity was observed in the labeled punctate structures in all layers of the olfactory bulb except the nerve fiber layer, while GAT-3 immunoreactivity was observed in the astroglial processes of all layers of the olfactory bulb. Our results suggest that GABA transporters, especially GAT-3, play important roles in regulating the GABA levels of developing olfactory bulbs.