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Objective:To investigate the relationship between the mechanism of mental dependence of propofol and adenosine A2A receptor-neurotransmitter-extracellular signal-regulated kinase (ERK) pathway in rats.Methods:Forty-eight healthy male Sprague-Dawley rats, aged about 7 weeks, weighing 200-300 g, were used in this study.The model of propofol dependence was established by intraperitoneal injection of propofol 40 mg/kg for 14 consecutive days.The rats were divided into 6 groups ( n=8 each) using a random number table method: central control group (group c-C), central agonist group (group c-CGS), central antagonist group (group c-DMPX), peripheral control group (group p-C), peripheral agonist group (group p-CGS) and peripheral antagonist group (group p-DMPX). Adenosine A2A agonist CGS-21680 2.5 ng/0.5 μl was intracranially injected immediately after establishing the model in group c-CGS, while the equal volume of normal saline was given instead in c-C group.CGS-21680 0.1 mg/kg was intraperitoneally injected in group p-CGS, while the equal volume of normal saline was given instead in group p-C.Adenosine A2A receptor antagonist DMPX 50 ng/0.5 μl was intracranially injected at 20 min before each propofol injection in group c-DMPX, and DMPX 0.25 mg/kg was intraperitoneally injected in group p-DMPX.The position preference value (CPP value) was determined before establishing the model, immediately after establishing the model, and after administration of agonist or normal saline (after intervention). The animals were sacrificed at 1 day after establishing the model, and blood samples and brain tissues were obtained for determination of the levels of dopamine (DA) and glutamate (Glu) in plasma and hippocampus and content of serotonin (5-HT) in cerebral cortex (by enzyme-linked immunosorbent assay) and expression of phosphorylated ERK1/2 (p-ERK1/2) in cerebral cortex (by Western blot). Results:Compared with the baseline before establishing the model, CPP value was increased immediately after establishing the model in c-C, c-CGS, p-C and p-CGS groups ( P<0.05), and no significant change was found in CPP value immediately after establishing the model in c-DMPX and p-DMPX groups ( P>0.05). Compared with the value immediately after establishing the model, no significant change was found in CPP value after intervention in c-C and p-C groups ( P>0.05), and CPP value was increased after intervention in c-CGS and p-CGS groups ( P<0.05). Compared with group c-C, the contents of hippocampal DA and Glu were significantly increased in group c-CGS, and the contents of hippocampal Glu were decreased, the content of 5-HT in cerebral cortex was increased, and the expression of p-ERK1/2 was down-regulated in group c-DMPX ( P<0.05). Compared with group p-C, no significant change was found in levels of DA and glutamate (Glu) in plasma and hippocampus and 5-HT and p-ERK1/2 in cerebral cortex in group p-CGS ( P>0.05), and the contents of hippocampal DA and Glu were significantly decreased, the content of 5-HT in cerebral cortex was increased, and the expression of p-ERK1/2 was down-regulated in group p-DMPX ( P<0.05). Conclusion:The mechanism underlying the development of propofol mental dependence may be related to activating adenosine A2A receptors, increasing excitatory neurotransmitters in brain, and thus up-regulating ERK activity in rats.
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PURPOSE: To investigate the role of adenosine A2A receptors on 6-OHDA-induced motor disorder in rat. METHODS: In order to induce experimental model of Parkinson's disease, 6-hydoxydopamine (8 μg/rat) was injected unilaterally into the SNc. After three weeks as a recovery period, 6-OHDA-induced bradykinesia and balance disturbances were assessed by using beam traversal test 10, 30 and 60 minutes after intraperitoneal injections of the drugs (caffeine, SCH58261). RESULTS: The results showed that 6-OHDA (8 μg/rat, Intra-SNc) induced motor disorders of Parkinson's disease and increased elapsed time in the beam test (p<0.001). Injection of caffeine (30 mg/kg, i.p.) and SCH58261 (2 mg/kg, i.p.) attenuated elapsed time on beam (p<0.01 and p<0.001). We showed that acute administration of caffeine and SCH 58261 can improve the 6-OHDA-induced bradykinesia and motor disturbance. CONCLUSION: Adenosine A2AR antagonists improve 6-OHDA-motor deficit and this effect seems to be mediated by the inhibition of A2A presynaptic receptors in substantia nigra pars compacta.
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Animals , Male , Parkinson Disease, Secondary/chemically induced , Caffeine/pharmacology , Oxidopamine/adverse effects , Purinergic P1 Receptor Antagonists/pharmacology , Adenosine A2 Receptor Antagonists/pharmacology , Time and Motion Studies , Rats, Wistar , Hypokinesia/chemically induced , Disease Models, Animal , Motor Disorders/chemically induced , Motor Activity/drug effectsABSTRACT
Adenosine, which arises from the breakdown of adenosine triphosphate, is extensively distributed in mammalian tis-sues and cells. Adenosine exerts its regulating effects on cell function via binding to the specific membrane receptors. Adenosine receptors are belong to G-protein-coupled receptors and can be subdivided into A1, A2A, A2B and A3 receptors in mammals. Among these receptors, A2A has been demonstrated to be related to pathogenesis of many diseases. In the present review, we focus on the recent progress made in investigating the relationship between A2A and nervous system disorders, which may provide new strategies for treatment of these diseases.
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Adenosine, which arises from the breakdown of adenosine triphosphate, is extensively distributed in mammalian tissues and cells. Adenosine exerts its regulating effects on cell function via binding to the specific membrane receptors. Adenosine receptors are belong to G-protein-coupled receptors and can be subdivided into Ai, A2A, A2B and A3 receptors in mammals. Among these receptors, A2A has been demonstrated to be related to pathogenesis of many diseases. In the present review, we focus on the recent progress made in investigating the relationship between A2A and nervous system disorders, which may provide new strategies for treatment of these diseases.
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Objective To investigate the effect of adenosine A2A receptor on pituitary-adrenal axis response in acute phase of moderate craniocerebral trauma.Methods Eighteen adenosine A2A receptor knock-out mice in a C57BL/6 background and another eighteen their wild-type littermates were divided into normal control group and craniocerebral trauma for 4 hours group,and craniocerebral trauma for 24 hours group according to random number table,with siμ mice per group.Plasma levels of adrenocorticotropic-hormone (ACTH) and corticosterone at hours 4 and 24 postinjury were determined using ELISA method.Results At 4 and 24 hours,brain water content in wild-type mice [(80.950 ± 0.184) ％,(82.178 ± 0.255)％ respectively] was higher than that in gene knock-out mice [(80.006 ± 0.199)％,(81.091 ± 0.295)％ respectively,P ＜ 0.01].Besides,brain water content in both wild-type and gene knock-out mice increased after injury (P ＜ 0.01).Plasma levels of ACTH and corticosterone were higher in geneknock-out sham mice than in wild-type sham mice [(120.214 ± 2.472) ng/L vs (91.767 ±7.395) ng/L,(27.814 ±0.888) μg/L vs (11.430 ±0.644) μg/L respectively,P ＜0.0l].At 4 and 24 hours,plasma levels of ACTH [(174.776-± 5.040) ng/L,(189.613 ± 4.802) ng/L respectively] in geneknock-out mice showed a higher increase than those in wild-type mice [(119.594 ± 6.945) ng/L,(124.93-± 11.001 7) ng/L respectively,P ＜ 0.05].Moreover,plasma levels of corticosterone [(40.138 ±-0.805) μg/L] at 4 hours and [(37.440-0.485)μg/L] at 24 hours in gene knock-out mice showed a same result as compared with that in wild-type mice [(19.702 ± 0.804) μg/L,(17.602 ± 0.743) μg/L respectively,P ＜ 0.05].Conclusions Knock-out of adenosine A2A receptor increases the release of ACTH and corticosterone in acute stage of moderate craniocerebral trauma and promotes pituitary-adrenal stress response.This may provide a novel explanation for the neuroprotective effect of A2A receptor deficiency.
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Objective To study the behavioural changes and biological effects of selective adenosine A2A receptor antagonist (CSC) in a rat model of levodopa(L-DOPA) -induced dyskinesia (LID).Methods The hemi-parkinsonian rat model was produced by stereotaxically injecting 6-OHDA to the right medial forebrain bundle. Rats were randomly divided into 4 treatment groups with a random number generating program to receive intraperitoneal injections twice daily for 21 days (n = 10): saline, L-DOPA at 25 mg/kg with benserazide at 6. 25 mg/kg, CSC at 2. 5 mg/kg alone and CSC at 2.5 mg/kg with L-DOPA at 25 mg/kg plus benserazide at 6. 25 mg/kg. Forepaw adjusting steps, abnormal involuntary movements (AIM) and rotational response duration were observed on 2, 9, 11,18 and 21 d. After sacrifice, the expression of adenosine A2A R and mGluR5 was observed by Western blot. Results Co-administration of LDOPA with CSC significantly increased the forelimb adjusting steps of parkinsonian rats during 21 days of treatment when compared to L-DOPA alone. CSC treatment alone increased the forelimb adjusting steps significantly. Co-administration of L-DOPA with CSC ( ( 11 ± 5 ) score) significantly decreased the AIM scores of limb and orolingual muscles when compared to L-DOPA alone (( 17 ± 4) score; t = 2. 44, P ＜0. 05). The subchronic L-DOPA treatment upregulated the striatal expression of adenosine A2A R and mGluR5. However, co-administration of L-DOPA with CSC reversed the shortening of the rotational motor response duration induced by L-DOPA administration during the period of the treatment and attenuated the LDOPA-induced upregulation of adenosine A2A R and mGluR5 expressions. Conclusions CSC improves motor function in a hemi-parkinson rat model, potentiates the antiparkinsonian effects with L-DOPA and partly attenuates LID. Co-administration of L-DOPA with CSC reverses the L-DOPA-induced upregulated expression of A2A R and mGluR5, indicating the involvement of both A2A R and mGluR5 in the onset and progression of LID. Adenosine A2AR antagonists may be promising drugs for treatment of LID.
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Objective To investigate the dynamic changes of adenosine receptors, A1 (A1R) and A2a (A2aR) in the brain from the acute to chronic phase after kindling and to explore the correlation between seizure and expression level of A1R and A2aR. MethodsRats were randomly selected into the testing model, reference and normal control groups.Testing rats were kindled by lithium choride-pilocarpine, reference rats were treated with saline, and no treatment was given in normal control group. The dynamic expression of A1R and A2aR were detected by RT-PCR, immunofluorescence staining and Western blot at time-points of 24 hours, 1 month and 6 months post-kindling. Results In the acute phase of 24 hours after kindling, the A1R expression level (mRNA level was (1. 1483 ±0. 1182); Western blot result was ( 0. 7872± 0. 0621 ) ; immunofluorescence staining count was ( 76. 17 ± 4. 62 )/HP) was increased and A2aR (mRNA level was (0. 8338±0. 0572) ; Western blot result was (0. 2098 ±0. 0257) ; immunofluorescence staining count was (43. 83 ± 5. 12 )/HP) was decreased.The results showed statistically difference compared with the reference and normal groups (P< 0. 05 ). In the later chronic phase of 1 month and 6 months after kindling, the expression level of A1R was decreased and A2aR was increased. These data revealed statistically significant difference (P <0. 01 ). Furthermore, the comparison of the results in 1 month and 6 months after kindling found that the expression of AIR was lower in 6 months (mRNA level was (0. 5682 ±0. 0443) ; Western blot result was (0. 7749 ±0. 0262) ; immunofluorescence staining count was (38. 50 ±4. 81 )/HP) than in 1 month and that of A2aR was higher in 6 months (mRNA level was (1. 2169±0. 0332) ; Western blot result was (0. 7080 ±0. 0371 ); immunofluorescence staining count was (114. 50 ± 4. 04)/HP). The differences were statistical significant (t = - 19. 02--13.28, P < 0. 05). ConclusionsThe expressions of A1R and A2AR during and after kindling presents a bidirectional change. In the acute phas the expression of AR is regulated to suppress seizures. While in the chronic phase, the repeated seizures result in the change of A1R and A2aR expression in the opposite direction. This mechanism plays an important role in refractory seizures.
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Objective To investigate cellular and behavioral effects of adenosine A2A receptor antagonist in a rat model of levodopa-induced motor complications.Methods The hemi-parkinsonian rat model was produced by stereotaxically injecting 6-OHDA to right medial forebmin bundle(MFB).Animals were intraperitoneally treated with levodopa 50 mg/kg plus benserazide 12.5 mg/kg twice a day for 22 days levodopa + vehicle.Rotational duration was estimated.After they were sacrificed,the expression of adenosine A2A receptor was observed by immunohistochemistry and Western blot.Results CSC,reversing the shortened rotational duration induced by levodopa,prolonged the rotational duration.This effect was maintained fil the end of the treatment.The chronic levedopa treatment induced an upregulation of adenosine A2A receptor expression in the lesioned striatum (IOD,(11.55±2.75)×104).The subsequent CSC treatment decreased the adenosine A2A receptor expression to the level of control (IOD,(6.02±1.29)× 104) and PD group (IOD,(5.60±1.83)×104>,F=33.31,P<0.05).Conclusion These results suggest that adenosine A2A receptor is probably involved in the development of levodopa induced motor complications and adenosine A2A receptor antagonist could be useful in the treatment of motor comphcations in parkinsonian patients.
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Objective To investigate the effects of adenosine receptor A2a on the expression of epithelial sodium channel ?-subunit (?-ENaC) in alveolar epithelium A549 cells and the effects of adenosine receptor A2a in acute lung injury/aute respiratory distress syndrome. Methods After alveolar epithelium A549 Cells were incubated with 0,0.1,1,10 and 100 ?mol/L adenosine receptor A2a agonist CGS-21680 for 8 h or with 100 ?mol/L CGS-21680 for 0,1,4,8,24 and 48 h respectively,the mRNA and protein levels of ?-ENaC were determined by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis respectively. Results After A549 cells were incubated with CGS-21680 at different doses for 8 h,the mRNA and protein levels of ?-ENaC were elevated significantly at 0.1 ?mol/L CGS-21680 treatment compared with the control group (P
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Objective To investigate the effects of deletion of adenosine A2A receptors on peripheral leukocytes on cerebral white matter lesions induced by chronic cerebral hypoperfusion.Methods Twenty-four wild type(WT) male mice were given a ? irradiation of 12.5Gy,followed by receiving bone marrow cells tail vein from female A2A receptor knocked out(KO) mice via tail vein,were assigned as KO→WT group,while those received bone marrow cells from WT female mice were assigned as WT→WT group(n=20).The efficiency of reconstitution of bone marrow cells in recipient mice was assessed 7 weeks after transplantation by PCR and immunofluorescent technique.Then,the recipient mice were subjected to bilateral common carotid artery stenosis with internal diameter of 0.18mm by external banding using microcoils at 8 weeks after transplantation.On 7d,14d and 30d after the surgery,corpus callosum,fiber bundles of Caudoputamen and optic tract were harvested from the cerebral white matter,and stained with Kluver-Barrera staining for observing the changes in nerve fibers,and with GFAP and CD11b immunohistochemistry staining for observing the proliferation of microglia and astrocytes.Results At 7 weeks after successful transplantation,the genotype of sex chromosome in peripheral leukocytes of the male recipient mice was changed into female pattern.The expression rate of A2A receptor was 9.73%?2.05% in KO→WT group and 93.82%?11.24% in WT→WT group,with significant difference between the two groups(P