孕期酒精暴露抑制低氧环境下新生大鼠耗氧量和基本节律性呼吸放电

Prenatal alcohol exposure inhibits oxygen consumption and rhythmic respiratory discharge activity of neonatal rats under hypoxia condition

目的研究孕期酒精暴露对低氧环境下新生大鼠在体耗氧量和离体延髓脑片基本节律性呼吸放电（RRDA）有无抑制作用。方法成年大鼠分为酒精暴露组和对照组,酒精暴露组从合笼前3天开始以8%酒精水溶液为唯一饮用水源,对照组正常饮食,其余饲养条件相同,使用两组孕鼠产下的新生大鼠：1采用体积描记法测量2-10 d新生大鼠在空气、15%氧浓度、10%氧浓度、5%氧浓度下单位时间内耗氧量,比较两组新生大鼠在不同氧浓度下耗氧量有无差异;2使用2 d新生大鼠制作离体延髓脑片标本,记录RRDA,依次使用经95%氧O2＋5%二氧化碳CO2、80%O2＋4.2%CO2＋15.8%氮N2、65%O2＋3.4%CO2＋31.6%N2、50%O2＋2.6%CO2＋47.4%N2充分饱和的0℃改良kreb’s（MKS）从高氧到低氧灌流脑片,记录并分析各组脑片RRDA的改变。结果 1在体耗氧量实验显示在空气、15%氧浓度、10%氧浓度下两组新生大鼠单位时间内耗氧量差异无统计学意义,在5%氧浓度下,酒精暴露组耗氧量低于对照组。2酒精暴露组脑片放电弱于对照组,即RRDA的吸气时程（TI）、呼吸周期（RC）、放电积分幅度（IA）均弱于对照组。3随着灌流液氧浓度下降,两组脑片放电均逐渐减弱,TI缩短、RC延长、IA降低,酒精暴露组RRDA降低程度大于对照组。结论 1孕期酒精暴露抑制新生大鼠在低氧浓度下摄取氧的能力及离体延髓脑片RRDA。2两组新生大鼠整体耗氧量在5%氧浓度下差异有统计学意义,而离体脑片放电在80%氧浓度即下降的实验结果间接证实外周化学感受器对呼吸有着重要的调节作用。

[Objective] To investigate the effect of prenatal alcohol exposure on oxygen consumption in vivo and rhythmic respiratory discharge activity （RRDA） in medullary slices of neonatal rats in vitro under hypoxia condition. [Methods] Adult rats were divided into alcohol exposure group and control group, which were housed in identical breeding conditions with an additional exposure to 8% alcohol solution for 3 days before mating in the alcohol exposure group. Their neonatal rats were used in this experiment. （1）Plethysmog- raphy was used to measure oxygen consumed per unit time in 2~10 d neonatal rats of both groups in the air, 15% oxygen, 10% oxygen and 5% oxygen. The neonatal rat oxygen consumption under different oxygen concentrations was compared between the two groups. （2）Ex vivo medullary slices of 2 d neonatal rats were prepared and perfused with modified Kreb＇s solution （MKS） which was fully saturated with oxygen （95.0% O2 ＋5.0% CO2, 80.0% O2 ＋ 4.2% CO2 ＋ 15.8% N2, 65.0% O2 ＋ 3.4% CO2 ＋ 31.6 %N2, 50.0% 02 ＋ 2.6% CO2 ＋ 47.4% N2） from high to low oxygen concentrations in turn, then the changes of RRDA were recorded and analyzed. [Results] （1）The in vivo oxygen consumption experiments showed that there was no significant difference in oxygen consumption per unit time in the air, 15% oxygen or 10% oxygen between the neonatal rats of both groups, and oxygen consumption in 5% oxygen in the neonatal rats of the alcohol exposure group was lower than that of the control group. （2）In the alcohol exposure group discharges in medullary slices including the inspiratory time （TI）, respiratory cycle （RC） and integral amplitude （IA） were weaker than those in the control group. （3）With oxygen concentration decreasing, the brain slice discharges of both groups showed gradually shortened TI, extended RC and decreased IA, but the decreased extent of RRDA in the alcohol exposure group was larger than that in the control group. [Conclusion] （1）Prenatal alcohol exposure reduces the oxygen intake capacity and RRDA in medulla oblongata respiratory center of neonatal rats under low oxygen concentration. （2）A significant difference in the oxygen consumption of neonatal rats under the condition of 5% oxygen concentration and declined in vitro brain slice discharge at 80% oxygen concentration indicate that the peripheral chemoreceptor plays an important role in regulating breathing.