吸入安氟醚大鼠不同麻醉阶段脑NOS活性和NO产量变化

The changes in nitric oxide synthase activity and nitric oxide content in rat brain during different stages of enflurane anesthesia

目的 观察安氟醚吸入麻醉大鼠不同时期各脑区一氧化氮合酶(NOS)活性和一氧化氮(NO)产量变化,结合行为学改变,探讨安氟醚的麻醉作用机制。方法 40只SD雌性大鼠随机等分为5组:对照组、诱导期组、麻醉期组、恢复期组和清醒期组。分光光度法测定不同麻醉时期大脑皮层、脑干、海马NOS活性和NO产量。结果 各脑区NOS活性和NO产量在诱导期即开始下降(P<0.05或P<0.01),大脑皮层、脑干、海马NOS活性分别降低40.5％、38.3％和37.7％,NO产量分别降低20.9％、20.1％和26.5％;麻醉期组降至最低水平(P<0.01),大脑皮层、脑干、海马NOS活性分别降低64.7％、63.8％和61.7％,NO产量分别降低45.6％、48.0％和46.3％;而恢复期组又开始上升,但仍明显低于对照组水平,大脑皮层、脑干、海马NOS活性分别降低25.7％、27.5％和38.9％(P<0.05),NO产量分别降低32.8％、28.3％和26.8％(P<0.01);清醒期组NOS活性和NO产量基本恢复至对照组水平(P>0.05)。且麻醉深度变化与NOS活性及NO产量变化相关。结论 安氟醚可明显抑制鼠脑NOS活性和NO产量,且与行为变化相平行,提示安氟醚可通过抑制NOS活性和NO产量而发挥麻醉效应,麻醉深浅与抑制程度有关。

Objective To determine the effect of enflurance on nitric oxide synthase (NOS) activity and nitric oxide (NO) content in different brain regions at different anesthesia stages.Methods Forty female SD rats weighing 250-350 g were randomly divided into five groups of 8 animals each, group 1: control; group 2: induction of anesthesia; group 3: maintenance of anesthesia; group 4: recovery from anesthesia and group 5: complete recovery. Animals were placed in a special glass anesthesia box. The concentration of enflurane in the box was measured by anesthesia gas monitor (Normac). The induction of anesthesia started from staggering of the animal to loss of righting reflex, maintenance of anesthesia from 1 min after loss of righting reflex, recovery of anesthesia from recovery of righting reflex to staggering after enflurance anesthesia was discontinued and glass box was opend and complete recovery from 1h after recovery of righting reflex. The animals were decapitated at different stages of anesthesia. Cerebral cortex, hippocampus and brain stem were immediately removed on ice and frozen in liquid nitrogen. Their NOS activity and NO content were measured by spectroscopic analysis. Results The average duration from the beginning of 2.2% enflurane inhalation to loss of righting reflex was (169±30) s. The average duration of anesthesia induction was (138±36)s. The maintenance of anesthesia lasted (229±30) s and the recovery period averaged (266±41) s. The NOS activity and NO content in different brain regions began to decrease during induction of anesthesia and reached their lowest level during maintenance of anesthesia, began to increase during recovery from anesthesia and returned to preanesthetic level during complete recovery. Conclusion Enflurane significantly inhibits the NOS activity and NO content in the brain. The inhibits is closely related to the depth of anesthesia. NO is a message transmitter in central nervous system and may be involved in the mechanism of enflurane anesthesia.