ABSTRACT
ABSTRACT Neuropathic pain is a chronic pain condition caused by damage or dysfunction of the central or peripheral nervous system. Electroacupuncture (EA) has an antinociceptive effect on neuropathic pain, which is partially due to inhibiting astrocyte activation in the spinal cord. We found that an intrathecal injection of 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), a selective adenosine A1 receptor antagonist, reversed the antinociceptive effects of EA in a chronic constriction injury-induced neuropathic pain model. The expression of GFAP in L4-L6 spinal cord was significantly upgraded, while DPCPX suppressed the effect of the EA-mediating inhibition of astrocyte activation, as well as wiping out the EA-induced suppression of cytokine content (TNF-α). These results indicated that the adenosine A1 receptor is involved in EA actions during neuropathic pain through suppressing astrocyte activation as well as TNF-α upregulation of EA, giving enlightenment to the mechanisms of acupuncture analgesia and development of therapeutic targets for neuropathic pain.
RESUMO A dor neuropática é uma condição de dor crônica causada por dano ou disfunção do sistema nervoso central ou periférico. A eletroacupuntura (EA) tem um efeito antinociceptivo durante a dor neuropática, que é parcialmente devido à inibição da ativação de astrócitos na medula espinhal. Descobrimos que a injeção intratecal de 8-ciclopentil-1,3-dipropilxantina (DPCPX), um antagonista seletivo do receptor de adenosina A1, reverteu os efeitos antinociceptivos da EA no modelo de dor neuropática induzida por lesão por constrição crônica (CCI). A expressão da GFAP na medula espinal L4-L6 foi significativamente melhorada, enquanto a DPCPX suprimiu o efeito da inibição mediadora da EA na ativação de astrócitos, bem como eliminou a supressão induzida pela EA do conteúdo de citocina (TNF-α). Esses resultados indicam que o receptor de adenosina A1 está envolvido nas ações da EA durante a dor neuropática, suprimindo a ativação astrocitária, bem como o aumento da TNF-α na EA, fornecendo esclarecimentos sobre os mecanismos de analgesia da acupuntura e o desenvolvimento de alvos terapêuticos para dor neuropática.
Subject(s)
Animals , Male , Rats , Spinal Cord/drug effects , Xanthines/pharmacology , Electroacupuncture/methods , Astrocytes/metabolism , Receptor, Adenosine A1/metabolism , Neuralgia/therapy , Sciatic Nerve/injuries , Spinal Cord/metabolism , Xanthines/administration & dosage , Injections, Spinal , Astrocytes/drug effects , Rats, Sprague-Dawley , Receptor, Adenosine A1/administration & dosage , Disease Models, AnimalABSTRACT
Objective To observe the effect of adenosine A1 receptor (A1AR) on the megalin defect in type 1 diabetic mice with early kidney disease.Methods 7-8 week-old,baseline body weight and fasting blood glucose matched wild type (WT) C57BL/6J mice were selected,and randomly divided into two groups:control group (n=6) and WT DM group (n=6).In the same way,male A1AR knock-out C57BL/6J mice were selected as A1AR-/-DM group (n=6).DM model was established by intraperitoneal injection of streptozocin.The blood glucose (BG),body weight (BW),kidney weight (KW),24 h proteinuria (24hUP) and albumin creatine ratio (ACR) were measured at 4 weeks.The renal pathological lesion was observed and the expression of megalin in proximal tubules was examined by immunohistochemistry.The expression of caspase-1,IL-18 and A1AR were detected by Western blotting.Results At 4th week,compared with WT control mice,the BG,BW,KW and 24hUP of WT DM mice were increased significantly (n=6,P ＜ 0.01),with the pathological glomerular enlargement,mesangial cell proliferation,extracellular matrix accumulation and renal tubule hypertrophy being observed.Immunohistochemistry revealed decreased expression of megalin,an important multiligand protein receptor on the brush border of proximal tubular epithelial cells in WT DM mice,which was correlated with 24hUP (r=-0.645,P ＜ 0.01).Compared with the control mice,the expressions of caspase-1,IL-18 and A1AR were significantly increased in WT DM mice (P ＜ 0.05).For A1AR-/-DM mice,more serious pathological lesion and megalin defect,together with increasing of casapase-1 and heavier proteinuria were observed than those in WT DM mice.Conclusion A1AR may play a protective role in megalin expression of diabetic mice with early kidney disease,in which the mechanism may be associated with caspase-1 related pyroptosis pathway.The details need further exploration.
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Objective To evaluate the role of adenosine A1 receptors in hippocampal neurons in the cognitive dysfunction caused by isoflurane anesthesia in aged mice.Methods Sixteen male adenosine A1 receptor gene knockout homozygote mice (gene knockout mice) and 16 male wild-type mice,aged 18-22 months,weighing 27-32 g,were studied.Each type of mice was randomly divided into 2 groups (n=8 each) using a random number table:control group (group C) and isoflurane anesthesia group (group Ⅰ).Mice inhaled 1.4％ isoflurane in 100％ O2 for 2 h in group Ⅰ,and 100％ O2 for 2 h in group C.All the mice underwent Morris water maze test at 24 h after isoflurane or O2 inhalation.After the test,the mice were sacrificed and the hippocampal tissues were harvested to determine the number of β-amyloid1-42 (Aβ1-42) plaques (using immunohistochemistry) and expression of phosphorylated tau (p-tau) protein,and 2B subunit-containing N-methyl-D-aspartate receptors (NR2B) (by Western blot analysis).Results Compared with group C of wild type mice,the escape latency was significantly prolonged,the number of Aβ1-42 plaques was enlarged,the expression of p-tau protein was up-regulated,and the expression of N R2B was down-regulated in group Ⅰ of wild type mice.Compared with group Ⅰ of wild type mice,the escape latency was significantly shortened,the number of Aβ1-42 plaques was decreased,the expression of p-tau protein was down-regulated,and the expression of NR2B was up-regulated in group Ⅰ of gene knockout mice.There was no significant difference in the parameters mentioned above between group Ⅰ and group C of gene knockout mice.Conclusion Adenosine A1 receptors in hippocampal neurons mediate isoflurane anesthesia-induced cognitive dysfunction in aged mice,and the mechanism may be related to promotion of deposition of Aβ,phosphorylation of tau protein and inhibition of activities of NR2B.
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Objective To observe the effects of adenosine and adenosine receptor agonist on the expression of inter?leukin-18 (IL-18) in patients with unstable angina (UAP), and the mechanism of adenosine receptor agonists thereof. Meth?ods Fifteen UAP and 15 healthy volunteers were included in this study. The effects of adenosine and the selective adenos?ine receptor agonists on the expression of IL-18 were measured by enzyme-linked immunosorbent assay (ELISA). Results The lower concentration of adenosine (1-100μmol/L) increased the expression of IL-18 in UAP group;whereas the higher concentration of adenosine (1 mmol/L) inhibited the expression of IL-18. The adenosine A1 receptor agonist and A3 receptor agonist increased the expression of IL-18, while the adenosine A2a receptor agonist inhibited the expression of IL-18. There was no significant effect for A2b receptor agonist on the expression of IL-18. Conclusion The lower concentrations of ade?nosine can enhance the expression of IL-18 through adenosine A1 and A3 receptors in UAP. The higher concentrations of ade?nosine can inhibit the expression of IL-18 through adenosine A2a receptors. Adenosine can promote IL-18 expression in lower concentrations.
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A large number of animal experiments have confirmed that ischemic preconditioning can produce a powerful organ protective effect,but the progress and results of the conversion of animal experiments to clinical trials are unsatisfactory.It has great significance for studying of molecular mechanisms of ischemic preconditioning mediated neuroprotection,searching for safe and effective preconditioning induced ways which can be converted to clinical practice,improving the tolerance of nerve tissue ischemia and hypoxia in stroke and surgical patients and achieving a safe and effective neuroprotection.This article reviews the molecular mechanisms of ischemic preconditioning mediated neuroprotection from the aspects of pretreatment of activated receptor,mitochondria,transcription factor,and protein kinase.
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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 observe the effects of 1,3-dipropyl-8-cyclopentylxanthine(DPCPX),an adenosine A1 receptor antagonist,on brain neurons damage induced by hypoxia and reoxygenation(H/R),and to elucidate the relevant mechanisms.Methods An in vitro cultured rat cerebral cortical neuronal H/R damage model was established;the effects of DPCPX were detected at final concentrations of 0(control),25,50,100nmol/L on the lactate dehydrogenase(LDH) release from normoxic neurons and H/R neurons which were treated with hypoxia for 8,12,24 hours followed by reoxygenation for 24 hours;the changes of malondialdehyde(MDA) content,activities of xanthine oxidase(XO) and Ca2+-ATPase in H/R neurons which were treated with hypoxia for 12 hours and reoxygenation for 24 hours brought by administration of DPCPX at the concentration of 100nmol/L were also determined by use of specific reagents.Results With addition of 100nmol/L DPCPX,the LDH release from H/R neurons which were treated with hypoxia for 12 hours and reoxygenation for 24 hours was significantly increased compared with that in control group(P