γ-羟基丁酸受体在羟丁酸钠保护大鼠海马缺氧复氧损伤中的作用

目的探讨γ-氨基丁酸(GABA)受体与γ-羟基丁酸(GHB)受体在羟丁酸钠(SO)对脑缺血的保护中何者更重要,为临床治疗脑缺血再灌注损伤寻找新的药物靶标。方法采用大鼠海马脑片缺氧复氧(H-R)损伤模型。设正常对照组、H-R模型组、SO1,10和100μmol·L-1组;NCS-382(GHB受体拮抗剂)100μmol·L-1组、荷包牡丹碱(Bic,GABAA受体拮抗剂)100μmol·L-1+saclofen(Sac,GABAB受体拮抗剂)100μmol·L-1(Bic+Sac)组、SO100μmol·L-1+NCS-382100μmol·L-1(SO+NCS-382)组、SO100μmol·L-1+Bic100μmol·L-1+Sac100μmo·lL-1(SO+Bic+Sac)组和SO100μmol·L-1+NCS-382100μmo·lL-1+Bic100μmol·L-1+Sac100μmol·L-1(SO+NCS-382+Bic+Sac)组。用比色法测定乳酸脱氢酶(LDH)释放率及TTC染色法检测脑组织损伤。结果模型组LDH释放率为(41.5±8.1)%,明显高于对照组(n=6,P<0.01);TTC染色的A490nm值为0.030±0.008,显著低于对照组(n=6,P<0.01)。SO1,10和100μmo·lL-1组的LDH释放率较模型组显著降低(n=6,P<0.05,P<0.01,P<0.01);TTC染色的A490nm值则明显升高(n=6,P<0.05,P<0.01,P<0.01)。单用GHB受体阻断剂NCS-382,或联合使用GABAA与GABAB受体阻断剂Bic+Sac,LDH释放率和TTC染色的A490nm值均接近模型组(n=6,P>0.05)。SO+NCS-382组LDH释放率较SO100μmol·L-1组明显升高(n=6,P<0.01);SO+NCS-382组和SO+Bic+Sac组TTC染色的A490nm值较SO100μmol·L-1组显著降低(n=6,P<0.01,P<0.05);而SO+NCS-382+Bic+Sac组LDH释放率和TTC染色的A490nm值都与SO100μmol·L-1组有明显差异(n=6,P<0.01),且较SO+Bic+Sac组更明显(n=6,P<0.01),但与SO+NCS-382比较没有明显差异。结论阻断GHB受体比阻断GABA受体对SO对大鼠海马脑片H-R损伤的保护作用影响更大。

Effect of gamma-hydroxybutyric acid receptor on protection of hypoxia-reoxygenation injured hippocampus in rats by sodium oxybate

AIM To exploreγ-aminobutyric acid(GABA) receptor or γ-hydroxybutyric acid(GHB) receptor, is more important in protection against ischemic injury of brian by sodium oxybate(SO). It may provide new ways for the clinical remedy of cerebral ischemic reperfusion injury. METHODS Experimental model of hypoxia-reoxygenation(H-R) injury of rat hippocampal slices was adopted. Slices were equally divided into eight groups: control group; H-R(model) group; SO 1, 10 and 100 μmol·L^-1 group; NCS-82 (GHB receptor antagonist)100 μmol·L^-1 group; bicuculline(Bic)(GABA_A receptor antagonist) 100 μmol·L^-1+saclofen(Sac)(GABA_B receptor antagonist) 100 μmol·L^-1 group; SO 100 μmol·L^-1+NCS-382 100 μmol·L^-1（SO+NCS 382）group; SO100 μmol·L^-1+Bic 100 μmol·L^-1+Sac 100 μmol·L^-1（SO+Bic+Sac）group; SO 100 μmol·L^-1+NCS-382 100 μmol·L^-1+ Bic 100 μmol·L^-1+Sac 100 μmol·L^-1 (SO+NCS-382+Bic+Sac) group. Lactate dehydrogenase(LDH) release rate was detected with colorimetry and brain injury with TTC staining. RESULTS LDH release rate in model group was (42±8)%, significantly higher that in control group; in SO 1, 10 and 100 μmol·L^-1 group was (32±5)%, (26±4)% and (17±4)%, respectively, lower than that in model group. The value of A_{490 nm}in TTC staining in model group was 0.030±0.008, obviously less than that in control group; in SO 1, 10 and 100 μmol·L^-1 group was (0.044±0.012), (0.053±0.012) and (0.067±0.010), higher than that in model group. GHB receptors antagonist NCS-382 100 μmol·L^-1 or GABAA receptors antagonist Bic 100 μmol·L^-1 and GABA_B receptors antagonist Sac 100 μmol·L^-1 alone did not influence LDH release rate and A_{490 nm} value. In SO+NCS-382 group, LDH release rate (32±6)% was higher than SO 100 μmol·L^-1 group. In SO+NCS-382 and SO+Bic+Sac group A_{490 nm} value was (0.039±0.008) and (0.051±0.009) respectively, smaller than that in SO 100 μmol·L^-1 group. In SO+NCS-382+Bic+Sac group, LDH release rate and A_{490 nm} value were significantly different from that of SO 100 μmol·L^-1 group（n=6, P<0.01），and more significant than SO+Bic+Sac group（n=6, P<0.01）, but no difference with SO+NCS-382 group. CONCLUSION The block of GHB receptors in the protection effect of SO on H-R injury is more important than that of GABA receptors.