[The role of adenosine in the early stage of anoxia of hippocampal slices and its mechanisms]

The role of adenosine in reversible inhibition of synaptic function during the early stage of anoxia and its mechanisms were investigated with extracellular recording technique in rat hippocampal slices. The results showed that acute anoxia led to the reversible inhibition of synaptic function, which is similar to the response to addition of high concentration of exogenous adenosine. The reversible inhibition could be suppressed by adenosine A1 receptor antagonist CPT and potassium channel blocker 4-AP, whereas TEA and ATP-sensitive potassium channel blocker glipzide had no effect. These results suggest that during the early stage of anoxia, the enhanced release of endogenous adenosine can inhibit the synaptic transmission by activating 4-AP-sensitive potassium channels via A1 receptors and thus play a role in protenction against anoxic injury. ATP-sensitive potassium channels may not be involved in the mechanisms of adenosine action.

ET-1 gene expression of rat brain during ischemia and reperfusion and the protective effect of radix Salviae miltiorrhizae

Endothelin-1 (ET-1) gene expression of rat brain during ischemia and reperfusion as well as the effect of Radix Salviae Miltiorrhizae (RSM) were studied with in situ hybridization. It was found that ET-1 gene expression of cerebral cortex and caudate-putamen was markedly increased both in 24 hours of ischemia and 24 hours of reperfusion groups (P < 0.01, P < 0.05). In RSM-treated rats, although the ET-1 gene expressions of ischemia and reperfusion sides were also increased as compared with contralateral cortex and caudate-putamen, they were significantly lower in RSM-treated rats than those of controls (P < 0.05, P < 0.01 respectively). The present study indicated that RSM can partly inhibit ET-1 gene expression of cerebral cortex and caudate-putamen during ischemia and reperfusion. This may be one of the protective mechanisms of RSM on cerebral ischemia and reperfusion.

Inhibitory effect of 764-3 on Ca2+ uptake in rat brain synaptosomes

In an attempt to examine the effect of 764-3, a purified component extracted from Radix Salviae Miltiorrhizae (RSM), on calcium channel, Ca2+ uptake in rat brain synaptosome stimulated by high-K+ and Glutamate (Glu) was investigated by using radioisotope labeled 45CaCl2. It was found that 764-3 could decrease the uptake of Ca2+ induced by high-K+ (60 mM) and 0.1 mM glutamate in a concentration-dependent manner. The maximum inhibiting rates were 45.22 +/- 4.88% and 37.58 +/- 4.52%, respectively. The results indicated that neuroprotective effect of RSM on cerebral ischemic injury may be related to its blocking effects on calcium channel.

Changes of endothelin-1 gene expression in rat brains during ischemia and ischemic reperfusion

OBJECTIVE

The experiment was designed to study the association of cerebral ischemia and reperfusion with endothelin-1 (ET-1) gene expression of rat brains and time-dependent changes of ET-1 gene expression during cerebral ischemia.

MATERIALS AND METHODS

Thirty-three male SD rats were divided into dot blot hybridization (n = 27) and in situ hybridization groups (n = 6). The focal cerebral ischemia and reperfusion models were made with suture embolism of middle cerebral artery. Dot blot hybridization groups were redivided into control and ischemic subgroups (ischemia for 0.5, 1, 1.5, 3, 6, 12, 24, 48 and 72 h respectively). In situ hybridization groups were redivided into ischemia and reperfusion groups. After 24 h ischemia and 24 h reperfusion, ET-1 gene expressions were investigated with in situ hybridization and the results were analyzed with IBAS 2000 Image Analysis System.

RESULTS

Dot blot hybridization showed that ET-1 mRNA of cerebral cortex and caudate-putamen was increased at 6 h of ischemia and reached peak at 24 h (3.9 and 3.7 fold respectively), and at 72 h of ischemia it remained at high levels (3.5 and 2.1 fold respectively). In situ hybridization showed that the levels of ET-1 mRNA of cerebral cortex and caudate-putamen were also markedly increased both in 24 h ischemia and 24 h reperfusion groups (P < 0.01, P < 0.05 respectively).

CONCLUSIONS

ET-1 gene expression in focal ischemic brain tissue were markedly and progressively increased during cerebral ischemia and reperfusion and down-regulation of ET-1 gene expression may be a new approach to the treatment of ischemic cerebrovascular diseases.

Effect of radix Salviae miltiorrhizae on nitric oxide in cerebral ischemic-reperfusion injury

It has been postulated that nitric oxide (NO) is produced in significant amount on reperfusion of ischemic brain and could cause brain edema and cell death. This study was undertaken in an attempt to determine whether Radix Salviae Miltiorrhizae (RSM) could reduce cerebral NO contents in 4-vessel occlusion rat model after 30 min of global ischemia and 15 min of reperfusion. There was a significant increase in cerebral NO level in untreated animals as compared with sham-operated ones. By pretreatment with RSM the cerebral NO concentration was reduced to normal level. The possibilities of neuroprotective role of RSM in cerebral ischemic-reperfusion injury were discussed.

Radix Salviae miltiorrhizae treatment results in decreased lipid peroxidation in reperfusion injury

In our pervious investigations we have found that Radix Salviae Miltiorrhizae (RSM) can reduce neurological deficits and ameliorate cellular damages, and its protective actions are associated with its effects on cerebral edema, monoamines, neuropeptides, neurotransmitter aminoacids, thromboxane A2, peroxidation and down-regulation of c-fos gene expression in ischemic animals. The purpose of present study was to investigate the protective effect of RSM against lipid peroxidation in 4-vessel occlusion and reperfusion rat model. We found that in RSM-treated rats the cerebral SOD activity is significantly increased, while the cerebral MDA level is significantly decreased when compared with untreated animals. The results suggested that RSM can reduce the lipid peroxidation and afford cerebroprotection against reperfusion injury.

Studies of Qingyangshen (II): modulatory effect of co-treatment with qingyangshen and diphenylhydantoin sodium on rat hippocampal c-fos expression during seizures

We have reported that, after KA treatment in rats, there was first a significant increase in hippocampal c-fos expression during acute seizures and then a long-term inhibition in hippocampal c-fos expression during chronic seizures. In this experiment, we examined the modulatory effect of Qingyangshen (QYS), a traditional Chinese medicine with antiepileptic property, and diphenylhydantoin sodium (DPH) on hippocampal c-fos expression during seizures. We found that after intraperitoneal injection of QYS + DPH (15 mg/kg and 50 mg/kg respectively, q.o.d. x 6), the peak level of hippocampal c-fos mRNA induction during KA-induced acute seizures was reduced by 56.27%; while the inhibition of hippocampal c-fos expression during KA-induced chronic seizures was disinhibited to control level. It is suggested that the inhibitory effect of QYS + DPH on KA-induced seizures, chronic seizures in particular, may have much to do with its modulatory effect on hippocampal c-fos expression.

Batroxobin accelerates lipid accumulation of peroxidized low density lipoprotein in mouse peritoneal macrophages

Mouse peritoneal macrophages were incubated in DMEM medium with batroxobin (DF-521) to determine the effect of batroxobin on the internalization of peroxidized low-density lipoprotein (pox-LDL) by transmission electron microscopy. Although the morphology of the mouse peritoneal macrophages after incubation with DMEM, normal LDL (n-LDL) and n-LDL plus batroxobin was similar to that of the cells before incubation, they exhibited numerous cytoplasmic lipid droplets after incubation with pox-LDL for 4 h. After addition of batroxobin to the medium containing pox-LDL, the production of lipid droplets in the mouse peritoneal macrophages was tremendously accelerated. Batroxobin accelerates the phagocytosis and degradation of pox-LDL by macrophages.

Studies of qingyangshen (I): Differential expression of hippocampal c-fos proto-oncogene during kainic acid induced acute and chronic seizures

We previously reported that Qingyangshen (QYS), a traditional Chinese medicine with antiepileptic property, had therapeutic effect on kainic acid (KA) induced experimental seizures (see JTCM 13 (4): 281-286, 1993 for reference). To investigate the mechanisms underlying the anticonvulsant action of QYS, we analyzed the modulatory effect of QYS on rat hippocampal c-fos proto-oncogene expression during KA-induced epileptogenesis in this and the following paper. The expression of hippocampal c-fos gene during KA-induced seizures were examined first. Rats were intraperitoneally injected with kainic acid (KA, 12 mg/kg) and hippocampal c-fos mRNA level was determined by Northern blot analysis during both acute (within one day after KA injection) and chronic (15 days after KA treatment) seizures. A mild increase in hippocampal c-fos mRNA level was observed 30 min after KA injection (being 1.98 +/- 0.70 times of control level), which corresponded temporally to the occurrence of the first limbic seizures. There was an 11.02 +/- 3.33 fold maximal induction of c-fos mRNA at 2 h after KA administration, which remained relatively stable even when behavioral seizures continued to aggravate 4 h after KA treatment. Twelve hours after KA administration, c-fos mRNA in the hippocampus returned to control level when acute seizures began to gradually disappear. In contrast, the induction of hippocampal c-fos mRNA during chronic seizures was inhibited significantly, being reduced by 55.40% compared to control. This suggested that c-fos is in different functional states at acute and chronic stages of epileptogenesis induced by KA.

Anti-inflammatory effects of tianrong acupoint on blood vessels of dura mater

Although Tianrong acupoint (SI 17) is used for migraine headache, its mechanism of action remains obscure. The effects of Tianrong acupoint therapy on neurogenically-mediated plasma protein extravasation (125I-BSA) in rat dura mater induced by electrical stimulation of the right trigeminal ganglion was studied. When the unilateral trigeminal ganglion was stimulated (5 Hz, 1.2 mA, 5 msec for 5 min), the ratio of stimulated side/unstimulated side (cpm/mg) was 1.6663 +/- 0.0217. The plasma extravasation was blocked by different kinds of treatment in different degrees. The order of the ratio was as follow: Tianrong acupoint therapy (1.0917 +/- 0.0266) and Tianrong electrical needle therapy (1.1281 +/- 0.0227) < Tianrong acupoint injection with normal saline (1.325 +/- 0.0444) < Quchi acupoint (LI 11) injection with prednisolonum (1.5284 +/- 1.1624). The results indicated that Tianrong acupoint therapy could inhibit the neurongenic inflammation on the affected side.

Protective effect of radix Salviae Miltiorrhizae Composita on cerebral ischemia

The protective effects of Radix Salviae Miltiorrhizae Composita (RSMC) on cerebral ischemia in gerbils produced by unilateral ligation of left common carotid artery and on the development of ischemic cerebral edema were studied. It was found that the administration of RSMC resulted in a very significant decrease in neurological deficits and the time for exhibiting first signs of neurological deficit delayed compared with untreated animals. Although the values of specific gravity of fresh cerebral tissue on the ligated side of common carotid artery in untreated animals (1.0406 +/- 0.0039 SD) and in RSMC-treated animals (1.0453 +/- 0.0009) were decreased significantly compared to that (1.0468 +/- 0.0003) of sham-operated animals, the specific gravity of cerebral tissue in RSMC-treated animals was significantly heavier than that in untreated animals (t = 5.5022, P < 0.001), i.e. the administration of RSMC decreased the severity of cerebral edema. A significant negative correlation was found between stroke index and specific gravity, and it suggests that one of the protective mechanisms of RSMC might be related to its ameliorating cerebral edema.

The effect of radix salviae miltiorrhizae composita and ligustrazine on lipid peroxidation in low density lipoprotein due to copper dichloride

It is well known that lipid peroxide in low density lipoprotein (LDL) plays an important role in atherosclerosis and atherosclerotic diseases. We used oxidized LDL generated by incubating LDL from healthy persons with copper dichloride as a model to investigate the anti-lipid-peroxide property of Radix Salviae Miltiorrhizae Composita (RSMC) and ligustrazine. The changes in concentrations of lipid peroxide and lipids in LDL due to Cu++ were studied, and the effects of RSMC and ligustrazine on the changes were studied. The results in our study indicate that RSMC has a potential role on anti-lipid-peroxidation, but it was not found that ligustrazine has similar anti-peroxidation action.

The effect of radix Salviae Miltiorrhizae Composita on peroxidation of low density lipoprotein due to copper dichloride

It is well known that plasma lipoprotein, particularly oxidized LDL, plays an important role in the pathogenesis of atherosclerosis and atherosclerotic diseases. We used oxidized LDL generated by incubating LDL from healthy persons with copper dichloride as a model to investigate the antioxidate property of Radix Salviae Miltiorrhizae Composita (RSMC). On photos, the spot X1 and the spot X2 were clearly found in the control group after the dialysis into copper dichloride for 24 and 48 hours, but they could not found in the RSMC group. The analysis of the constituents of lipids in LDL (by charring method) showed that after dialysis the percentages of the spot X1 and the spot X2 in the RSMC group were significantly lower than those in the control group (P < 0.01). The results suggest that RSMC plays a potential role in antioxidation of lipids or LDL.

Effect of radix salviae miltiorrhizae on EAA and IAA during cerebral ischemia in gerbils: a microdialysis study

The concentrations of amino acids (AA), stroke index and infarct area were determined in 26 gerbils which were divided into 3 groups: RSM-treated (n = 8), Saline-treated (n = 10) and sham-operated (n = 8). The levels of AA were measured with microdialysis technique in cerebral cortex. The concentrations of neurotransmitter AA, as Glu and GABA and Asp, were significantly increased during the first 60 min after CCA ligation, while the concentrations of non-neurotransmitter AA, as Thr and Ser, had no significant changes. In RSM-treated gerbils, the level of Glu was significantly lower than that of the saline-treated, but the GABA in RSM-treated was significantly higher than that of the saline-treated. The ratio of Glu/GABA was significantly decreased after ischemia. The RSM could improve the reduction of ratio of Glu/GABA during 0-30 min and 91-120 min after cerebral ischemia. There were statistically significant decrease in terms of stroke index in RSM-treated group when compared with saline-treated group at 24 h and 16 h after CCA ligation respectively. The RSM has a tendency to decrease the size of infarct area, but no statistical difference. The results suggest that the neurotransmitter AA involve in the pathophysiological procedures of cerebral ischemia and the RSM can attenuate dysfunctions of EAA and IAA. Furthermore, the results also imply that there may be an alternate way to treat cerebral ischemia by inhibiting the presynaptic releasing of Glu and stimulating the releasing of GABA.

Effect of qingyangshen on hippocampal alpha- and beta-tubulin gene expression during kainic acid induced epileptogenesis

Using alpha- and beta- tubulin cDNA Probes and Northern blot hybridization technique, we analyzed the effect of intraperitoneally injected Qingyangshen (QYS), a traditional Chinese medicine with antiepileptic property, and diphenylhydrantoin sodium (DPH) on hippocampal alpha- and beta-tubulin gene expression during kainic acid (KA) induced chronic seizures. It was found that: 1) thirty days after intraperitoneal injection of KA, alpha- and beta-tubulin mRNAs in animals showing chronic seizures increased 3.02 +/- 1.05 and 4.07 +/- 1.32 times respectively compared with control; 2) neither QYS (15 mg/kg, q.o.d. x 6) nor DPH (50 mg/kg, q.o.d. x 6), when used separately, could inhibit the above mentioned effect of KA; 3) when QYS (15 mg/kg, q.o.d. x 6) and DPH (50 mg/kg, q.o.d. x 6) were given in combination, the long-term increase in tubulin gene expression induced by KA was significantly reduced, with alpha- and beta-tubulin mRNAs being decreased to 0.44 +/- 0.08 and 0.50 x 0.10 times of corresponding values in animals treated with KA alone. The results indicate that the mechanism of antiepileptic effect of QYS is at least partially related to the inhibition of tubulin synthesis and subsequent reduction in mossy fiber sprouting and neosynaptogenesis.

Evidence for amelioration of cellular damage in ischemic rat brain by radix salviae miltiorrhizae treatment--immunocytochemistry and histopathology studies

The changes of somatostatin (SS)--like immunoreactive cells and morphology were observed in the models of ligation of right MCA and bilateral ligation of CCA respectively. The results showed: (1) a decline of SS immunoreactive nerve cell profiles in right cerebral cortex after 3h ligation of MCA as compared with left cerebral cortex and sham-operated group, while no significant difference was found between RSM-treated and saline-treated groups; (2) selective ischemic cell changes in cerebral cortex, hippocampus and caudate nucleus after 3h ligation of CCA. The changes included shrinkage and condensation of perikaryon, nuclear pyknosis, cytoplasmic eosinophilia in some neurons. The ischemic changes were more severe in saline-treated group than RSM-treated group. The experiments indicated that the selective ischemic cell changes could be improved by RSM, suggesting that treatment to modulate SS metabolism may be indicated after ischemic insults.

The effect of radix Salviae miltiorrhizae on the changes of ultrastructure in rat brain after cerebral ischemia

The effect of RSM on ultrastructural alterations of the cortical, hippocampal and caudate neucleus areas brought about by forebrain ischemia in rats were studied. In both RSM-treated and saline-treated groups the ischemic damage was detected in nearly all animals three hours after bilateral common carotid artery ligation, while it was much more mild in RSM-treated animals. The ultrastructural changes consisted of swollen mitochondria, partial loss of cristae, dilatation of rough endoplasmic reticulum and Golgi's complex. In addition, some dark neurons were present, capillary endothelial cells and processes of astrocytes were swollen and active pinocytosis appeared in the endothelial cells. Their presence was most severe in the hippocampus region and the least in the caudate nuclear area. No ultrastructural changes exhibited in the sham-operated animals. The findings of the present experiment demonstrate that RSM can reduce ultrastructural abnormalities of cerebral ischemia and are also direct evidence of the protective effect of RSM on cerebral ischemia.

The effect of radix Salviae Miltiorrhizae (RSM) on substance P in cerebral ischemia--animal experiment

The levels of substance P (SP) in rat brains were assayed in 64 rats. Bilateral common carotid artery ligation was done in 49 rats. Half an hour before ligation, 25 rats were given 10 g/kg of RSM; 24 rats were given the same volume of normal saline as controls. Sham operation was done in 15 rats. Half an hour and 3 hours after cerebral ischemia, the rats were quickly decapitated. SP concentration was assayed in the cerebral cortex, caudate nucleus and brain stem. In saline-treated animals, the SP level of caudate nucleus at 3-hour group was significantly decreased as compared with the 0.5-hour group and sham-operated group respectively. No significances were found among RSM-treated groups and sham-operated groups. The SP levels were shown: brain stem greater than caudate nucleus greater than cerebral cortex. The preliminary results suggest that SP may be involved in the pathophysiologic procedures of cerebral ischemia and RSM may attenuate the dysfunction of SP during cerebral ischemia.

The investigation of antiepileptic action of qingyangshen (QYS)--effect of QYS on the concentrations of neuropeptides in rat brain

The concentrations of central neuropeptides, somatostatin (SS) and substance-P (SP), were determined in the different brain regions of young-aged male rats after a long-term administration of anticonvulsants Qingyangshen (QYS), Diphenylhydantoin (DPH), and Carbamazepine (CBZ). The results were compared with Pentylenetetrazol (PTZ)-induced seizure model and normal saline-treated controls. No effects of QYS on the concentrations of SS and SP were found in the rats of four-week or eight-week group. Both of DPH and PTZ increased the SS levels in the midbrain of rats in four-week group. DPH, CBZ, and PTZ also increased the SP levels in the cerebral cortex, striatum, and brain stem of rats in eight-week group. Our present data indicated that the central neuropeptides SS and SP were involved in the processes of epilepsy and antiepilepsy. Since QYS did not influence the contents of SS and SP after a long-term administration, it suggested that the anticonvulsant mechanism of QYS may be different from those of DPH and CBZ, i.e. it may be not due to its effect on the central neuropeptide pathway.

The investigation of antiepileptic action of qingyangshen (QYS)--influences of QYS on the development of rat brain and memory behavior

As an anticonvulsant, the influences of Qingyangshen (QYS) on the development of brain and memory behavior were observed in four-week-old male rats. The dosage of QYS was 100 mg/kg/QOD and the period of administration was one month. The results showed that QYS had less influence on the development of body weight and brain wet weight in young-aged rats than diphenylhydantoin (DPH). However, QYS inhibited the establishment of passive avoidance conditional reflex and had influence on memory behavior in young-aged rats.