ABSTRACT
<b>Objective::To investigate the mechanism of Buyang Huanwu Tang (BYHWT) in improving synaptic structural plasticity after cerebral ischemia-reperfusion in rats. <b>Method::Middle cerebral artery occlusion and reperfusion model was established. SD rats were randomly divided into sham-operated group, model group, BYHWT group, BYHWT+ Gap26(connexin43 inhibitor)groups. BYHWT was given twice a day(16 g·kg<sup>-1</sup>), Gap26 was intraperitoneally injected once a day since the third day after surgery (25 g·kg<sup>-1</sup>). Brain was taken out at the 7<sup>th</sup> day. The changes of neuronal synaptic and gap junction ultrastructure were observed by transmission electron microscopy. Synaptophysin (SYN) and growth-associated protein-43 (GAP-43) protein expression were detected by Western blot and immunofluorescence. <b>Result::The structure of synapses was integrated, and the gap junctions were clear in sham-operated group. In the hippocampus of model group, the structure was destroyed, and the gap junctions disappeared. Compared with the sham-operated group, model group up-regulated the expressions of SYN and GAP-43 (<italic>P</italic><0.05, <italic>P</italic><0.01). In the hippocampus of BYHWT group, the structure was close to the normal. Furthermore, BYHWT up-regulated the expressions of SYN and GAP-43 (<italic>P</italic><0.05, <italic>P</italic><0.01). However, after the combined administration with Cx43 inhibitor (Gap26), the damage of synaptic structural decreased, only a small number of gap junctions with the structural integrity can be seen, and the effect of BYHWT on SYN and GAP-43 was inhibited (<italic>P</italic><0.05, <italic>P</italic><0.01). <b>Conclusion::BYHWT could improve the hippocampal synaptic structural plasticity obviously after the CIRI. The mechanism may be related to the increase of the expression of Cx43 and the promotion of the intervention of SYN and GAP-43.
ABSTRACT
Recent studies have shown that astrocytes play important roles in ATP degradation and adenosine (a well known analgesic molecule) generation, which are closely related to pain signaling pathway. The aim of this study was to investigate whether morphine, a well known analgesic drug, could affect the speeds of ATP enzymolysis and adenosine generation in rat astrocytes. Intracellular calcium concentration ([Ca(2+)](i)) of astrocyte was measured by flow cytometry, and the time points that morphine exerted notable effects were determined for subsequent experiments. Cultured astrocytes were pre-incubated with morphine (1 μmol/L) and then were incubated with substrates, ATP and AMP, for 30 min. The speeds of ATP enzymolysis and adenosine generation were measured by high performance liquid chromatography (HPLC). The results showed that both 1.5 and 48 h of morphine pre-incubation induced maximal ATP enzymolysis speed in astrocytes among all the time points, and there was no statistical difference of ATP enzymolysis speed between morphine treatments for 1.5 and 48 h. As to adenosine, morphine pre-incubation for 1.5 h statistically increased adenosine generation, which was degraded from AMP, in cultured astrocytes compared with control group. However, no difference of adenosine generation was observed after 48 h of morphine pre-incubation. These results indicate that treatment of morphine in vitro dynamically changes the concentrations of ATP and adenosine in extracellular milieu of astrocytic cells. In addition, astrocyte can be regarded as at least one of the target cells of morphine to induce changes of ATP and adenosine levels in central nervous system.