Changes in nitric oxide synthase (NOS) positive neurons in limbic system induced by isoflurane or enflurane in rats / 中华麻醉学杂志

0.05) compared to control group. Conclusion Induction of anesthesia with isoflurane or enflurane decreases the number of NOS positive neurons in the 6 nuclei in limbic system. The changes in NOS positive neurons in limbic system may be involved in the mechanism of isoflurane and enflurane anesthesia.

The changes in nitric oxide synthase activity and nitric oxide content in rat brain during different stages of enflurane anesthesia / 中华麻醉学杂志

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.