Adenosine a1 receptor agonist protects against hippocampal neuronal injury after lithium chloride-pilocarpine-induced epilepsy

Abstract Background Adenosine A1 receptor (AA1R) is widely present in the central nervous system, exerting brain protective antiepileptic effects, mainly by binding corresponding G proteins. We evaluated the neuroprotective effects of AA1R on hippocampal neuronal injury after lithium chloride-pilocarpine-induced epilepsy in rats. Materials and Methods A total of 60 male SD rats were randomly divided into four groups (n = 15/group): normal control, epilepsy, epilepsy + AA1R antagonist (DPCPX), and epilepsy + AA1R agonist (2-CAdo). An epilepsy model was established through kindling by lithium chloride-pilocarpine. The four groups were observed on days 1, 14, and 30. Pathological and morphological changes of hippocampal neurons were observed by HE staining; apoptosis was detected by TUNEL assay. Caspase-3 and GABA receptor expressions were detected by Western blot. Results In the hippocampal CA3 area of the epilepsy group, the cellular structure was not neatly arranged, and some neurons were swelling, thick, and incomplete. Compared with the epilepsy group at the same time point, cells in the epilepsy + DPCPX group had an increased distortion, disorganization, edema, cytoplasmic vacuoles, and degeneration. In the epilepsy + 2-CAdo group, cell arrangement was regular and orderly, and structural damages were lessened. Compared with the normal control group at the same time point, the epilepsy group underwent evident neuronal apoptosis, with a significantly higher apoptotic index (AI) (p < 0.05). Compared with the epilepsy group, the neuronal apoptosis of the epilepsy + DPCPX group was boosted, and the AI significantly increased (p < 0.05). The neuronal apoptosis of the epilepsy + 2-CAdo group was inhibited, and the AI significantly decreased (p < 0.05). Compared with the epilepsy group, the caspase-3 expression levels of the epilepsy + DPCPX group on days 14 and 30 were significantly upregulated (p < 0.05), but those of the epilepsy + 2-CAdo group were significantly downregulated (p < 0.05). Conclusions AA1R abated cell edema and reduced apoptosis, exerting neuroprotective effects on hippocampal neuronal injury after lithium chloride-pilocarpine-induced epilepsy.

Stimulation of adenosine A1 receptor attenuates angiotensin II induced myocardial hypertrophy in neonatal rats via the extracellular signal-regulated kinase signal pathways / 中华心血管病杂志

<p><b>OBJECTIVE</b>To observe the impact of adenosine A1 receptor stimulation on extracellular signal-regulated kinase 1/2 (ERK1/2) signal pathways on angiotensin II (AngII) stimulated cardiomyocytes of neonatal rats in vitro.</p><p><b>METHODS</b>Cardiomyocytes of neonatal rats were cultured in vitro. Cardiomyocytes hypertrophy was induced by AngII (0.1 µmol/L). The antihypertrophic effect of adenosine A1 receptor stimulation via adenosine A1 receptor agonist R-PIA (1 µmol/L) was observed in the presence or absence of ERK1/2 inhibitor 1, 4-Diamino-2, 3-dicyano-1, 4-bis(o-aminophenylmercapto) butadiene (U0126) 1 µmol/L, PKC inhibitor Ro-31-8220 (50 nmol/L), and pertussis toxin (PTX, 5 mg/L). The total protein content was assayed by the method of Lowry. The expression of mRNA of atrial natriuretic peptide (ANP) was determined by RT-PCR. [Ca(2+)]i was measured by confocal microscope using Fluo-3/AM as fluorescent indicator. The relative expression of ERK1/2 was determined by Western blot.</p><p><b>RESULTS</b>Compared with normal control group, AngII induced significant cardiomyocyte hypertrophy. Compared with AngII group, R-PIA significantly inhibited AngII-induced increase of the protein content, cardiomyocytes volume and expression of ERK1/2, calcium ion fluorescence intensity, similar as U0126 and Ro-31-8220. The inhibitory effects on AngII induced cardiomyocytes hypertrophy of R-PIA were lost when preincubated with PTX.</p><p><b>CONCLUSION</b>Adenosine A1 receptor can inhibit AngII induced cardiomyocyte hypertrophy through downregulating ERK signal pathways and reducing intracellular Ca(2+).</p>

Effects of injecting adenosine A1 receptor agonist into baihui (GV20) on the cerebral cortex in ischemia/reperfusion injury model rats / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To investigate the effects of injecting adenosine A1 receptor agonist (CCPA) into Baihui (GV20) on the cerebral cortex induced by the ischemia/reperfusion of middle cerebral artery occlusion (MCAO) in rats.</p><p><b>METHODS</b>Twenty-four SD rats were randomly divided into four groups, i. e., the sham-operation group, the model group, the DMSO group, and the CCPA group. The MCAO model was established by thread embolism method. At the moment of ischemia/reperfusion, the rats in DMSO group and the CCPA group were injected with DMSO (20 microL) and CCPA (0.1 mmol) 20 microL into Baihui respectively. The rats' behavior, the histomorphology of ischemic penumbra in the cerebral cortex, the expressions of Bcl-2 protein, and the apoptosis rate of neurocytes were assessed.</p><p><b>RESULTS</b>Compared with the model group and the DMSO group, the rats' behavior were markedly improved in the CCPA group (P<0.05). No obvious karyopyknosis and cytoplasm empty dye of neurons appeared. The Bcl-2 expressions in rats' cerebral cortex obviously increased (P<0.01). The apoptosis number of neurons obviously decreased (P<0.01).</p><p><b>CONCLUSIONS</b>Injecting CCPA into Bahui improved the rats' behavior and histomorphology in the ischemic penumbra, elevated the expressions of Bcl-2 protein, and reduced the neurons apoptosis rate in the ischemic penumbra. It alleviated the cerebral ischemia-reperfusion injury. Therefore, it could be taken as a new treatment method.</p>

Proteomics analysis of adenosine A1 receptor agonist-induced delayed myocardial protection in rabbits / 中南大学学报(医学版)

OBJECTIVE@#To investigate the changes of myocardial protein expression profiles in 2-chloro-N6-cyclopentyladenosine (CCPA), an adenosine A1 receptor agonist-induced delayed myocardial protection in New Zealand rabbits .@*METHODS@#A total of 8 rabbits were randomly divided into a CCPA group (CCPA group) and a normal saline group (NS group). CCPA and NS were infused into rabbits in the CCPA group and the NS group respectively. Twenty-four hours later, the rabbits were subjected to 30 min left anterior descending coronary artery occlusion and were reperfused for 2 hours, then the ischemic zone tissues of left ventricle were sampled for proteomic analysis.A total of 12 other New Zeland rabbits were divided into a sham group (Sham group), a normal saline group (NS group) and a CCPA group (CCPA group). The expression of αB-crystalline, one of the differential proteins, was confirmed by Western blot.@*RESULTS@#Analysis of two dimensional gel electrophoresis showed that the expression of 55 protein spots were different between the two groups, 17 protein spots were preliminarily identified with the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and Mascot and Expasy bioinformatics software. These proteins included stress proteins, metabolism-associated proteins, signal transduction pathway-related proteins, ionophorous proteins, immunity-associated proteins, and so on. Western blot showed that the expression of αB-crystalline was significantly up-regulated in the CCPA group.@*CONCLUSION@#The myocardial protein expression profiles are changed markedly in the preconditioning late phase of CCPA .The differential proteins might be involved in the delayed cardioprotection induced by CCPA.

The Effects of Intrathecal Adenosine A1 Receptor Agonists (R-PIA) on the Morphine Tolerance in a Rat Model of Postoperative Pain / 대한마취과학회지

BACKGROUND: Analgesic tolerance to opioids has been described in both experimental and clinical conditions, which may limit their clinical utility. This study investigated the effects of intrathecal adenosine A1 receptor agonist (R-PIA) on spinal morphine tolerance. METHODS: SD rats were given intrathecal injections of saline 10microliter, R-PIA 10microgram, morphine 10microgram, or R-PIA plus morphine combinations for 7 days (R-PIA given for days 1-7; days 1-3; or days 5-7). Antiallodynic testing using von Frey filaments was carried out before and 30 minutes after the drug injection. On day 8, an antiallodynic dose-response curve was constructed and the 50% effective dose (ED(50)) for morphine (given alone) was calculated for each study group. RESULTS: The coinjection group of R-PIA with morphine blocked the development of tolerance, as shown by the preservation of morphine antiallodynia over 7 days the concomitant decrease in the ED(50) values on day 8, compared with the morphine-alone group. Although additive analgesia over days 1-7 cannot be ruled out, the reductions of the ED(50) in the R-PIA and morphine combination group suggest some suppression of tolerance. CONCLUSIONS: These results suggest that intrathecal R-PIA prevents the development of spinal opioid tolerance. Future studies will be needed to examine the respective roles of supraspinal and peripheral sites of R-PIA and morphine interaction, and to investigate the mechanisms underlying the action of R-PIA on opioid tolerance.