异丙酚对在体大鼠前额叶皮质细胞外液谷氨酸和 氨基丁酸含量的影响

1、异丙酚对在体大鼠前额叶皮质细胞外液谷氨酸和 氨基丁酸含量的影响Effects of propofol on extracellular glutamate and gamma aminobutyric acid in the prefrontal cortex of ratsThis article source: paper /Abstract Objective To observe the effects of local infusion of propofol on glutamate and gamma aminobutyric acid (GABA) in the extrace

2、llular fluid of prefrontal cortex in rats. Methods a total of 30 adult male rats were randomly divided into experimental group (n = 24) and control group (n = 6), and microdialysis probes were placed in prefrontal cortex. The experimental group was perfused with 2 l/min CSF containing different conc

3、entrations of propofol (1 n=6, 3, 10, 30 mol/l, 4 subgroups, each group) according to propofol concentration. The control group contained no propofol in the perfusate. The perfusate was collected at 10 min, and the concentrations of glutamate and GABA were determined by reversed-phase high-performan

4、ce liquid chromatography. Results after local infusion of propofol 1 mol/l 10 min, there was no significant difference between the glutamic acid content in the perfusate at different time points and the basic value (p 0.05). After local infusion of 3 mol/l of propofol, the glutamic acid content in t

5、he perfusate dropped to 60% of the basal value at tenth, twentieth min (p 0.05), then gradually recovered to the basal value level. After the local infusion of propofol 10 mol/l 10 min in the prefrontal cortex, the glutamate content in the perfusate was significantly lower than the basal value at te

6、nth min to 30 min (p 0.01 or 0.05). After local infusion of propofol 30 mol/l 10 min, the glutamate content in the perfusate decreased significantly from tenth min to 40 min (p 0.01 or 0.05). Conclusion propofol can decrease glutamate content in the extracellular fluid of prefrontal cortex in rats,

7、but has no effect on the content of gaba.keyword two propofol, anterior prefrontal cortex extracellular fluid, glutamate, GABA (GABA)Abstract:objective to investigate the effect of propofol locally perfused into the rat prefrontal cortex (PFC) on glutamate and GABA extracellular levels.methods Thirt

8、y male adult rats were randomly divided into 4 groups: test groups and 1 control group (n=6 each), with a microdialysis probe inserted into the PFC. in the test groups, artificial cerebrospinal fluid (ACSF) containing different concentrations of propofol (1, 3, 10 and 30 mol/l respectively was into

9、the PFC) perfused at 2 l/min; in the control group, only ACSF was infused. the perfusate was collected every throughout the experiment to 10 min measure the concentrations of glutamate and GABA in the perfusate by reversed-phase high performance liquid chromatography.结果灌流液中谷氨酸水平没有明显改变时，丙泊酚1mol/L（P&g

10、t；0.05），但显着下降为10和20 min时，丙泊酚3molL（P <；0.05）。随着丙泊酚浓度的增加（10和30mol/L），谷氨酸水平下降到40分钟（p0.01，0.05）。然而，在灌流液中GABA水平没有改变在不同浓度的异丙酚灌注（P>；0.05）。结论异丙酚可降低大鼠前额叶皮质细胞外谷氨酸水平，但对GABA水平没有影响关键词：异丙酚；前额叶皮层；细胞外液；谷氨酸；-氨基丁酸（-氨基丁酸异丙酚为目前临床最常用的全身麻醉药，其临床效应主要为意识及记忆消失。哺乳动物大脑联合皮质在意识、记忆等高级认知功能的调节中发挥着极其重要的作用，而前额叶皮质作为联合皮质的重要部分，与高级认知

11、功能有着更加密切的关系1-2。并且临床研究亦发现，异丙酚产生催眠效应的同时主要使前额叶皮质内血流量下降3。因此异丙酚引起的临床效应可能与作用于前额叶皮质有关。在哺乳动物前额叶皮质内，谷氨酸和-氨基丁酸（GABA）是最重要的兴奋性和抑制性神经递质4，其含量的95%以上存在于细胞内（突触前膜的囊泡和胞质中），而细胞外液所占比例很低，但前额叶皮质生理功能的发挥取决于细胞外液中的递质含量5。故研究异丙酚的临床效应与前额叶皮质细胞外液中谷氨酸和-氨基丁酸GABA含量的影响本实验应用在体微透析技术观察前额叶皮质内局部灌注异丙酚对前额叶皮质细胞外液中谷氨酸和含量的关系具有重要意义1材料和方法1.1实验动物与

12、仪器SD成年雄性大鼠，体重200250 g，由中国科学院上海生命科学研究院实验动物中心提供。实验前1周，将大鼠饲养于35厘米35厘米40厘米笼中，光照/黑暗交替（12 / 12小时，800am-800pm为光照时间），环境温度为（242），自由摄取水和食物。微透析探头（CMA / 12，同心圆型）、外套管（CMA / 12）、微灌注泵（CMA / 100）均为瑞典卡耐基医学公司产品。1.2人工脑脊液（ACSF）的制备6微透析灌流液应用学联，其成分为（mmol/L）：氯化钠126.5、碳酸氢钠27.5、氯化钾2.4、磷酸二氢钾0。5, CaCl2 1.1, MgCl2 0.83, Na2SO4

13、0.5, glucose 11.8. Applying 0.1 mol/l NaOH, the pH value was adjusted to 7.3, and the impurities were removed by 0.22 m microporous filter membrane, stored at 0 4 DEG C and filled with 95% o2/5% CO2 mixture to saturation state.In the 1.3 group, 30 rats were randomly divided into the experimental gro

14、up (n = 24) and the control group (n = 6), and microdialysis probes were placed in the prefrontal cortex. The experimental group was perfused with 2 l/min ACSF containing different concentrations of propofol (1 n=6, 3, 10, 30 mol/l, 4 subgroups) according to propofol concentration, while the control

15、 group was perfused with acsf.The microdialysis experiments of 1.4 prefrontal cortex rats were performed at 10 00am-3 00pm to exclude the effect of circadian rhythms on glutamate and GABA levels in the extracellular fluid of prefrontal cortex. Remove the rats from the cage and act as gently as possi

16、ble to minimize irritation. Application of 10% chloral hydrate intraperitoneal injection of 400 mg/kg, until after the onset of anesthesia rats were fixed on the stereotaxic instrument (Jiangwan type) in the prefrontal cortex, embedded microdialysis outer tube. Stereotaxic localization of prefrontal

17、 cortex according to rat brain atlas 7: a/p, 3.3, mm, l/m, 1.2, mm, v/d, 5, mm. The outer tubes were fixed with the denture powder, and the rats were kept in cages. After 48 h, the core of the outer tube was taken out, and a microdialysis probe was placed to connect the micro flow pump. The continuo

18、us infusion of ACSF 60 min at 2 l/min was used as the equilibrium phase, and the neurotransmitter content in the perfusate was stabilized. The perfusate was collected at a subsequent 30 min, 1 times per 10 min for 3 times, and the mean value of glutamic acid and GABA content in the perfusate 3 times

19、 was used as the basis value. Then, the experimental group was perfused with different concentrations of propofol (130 mol/l) with a microdialysis probe for 10 min (the control group was perfused with no propofol ACSF) and then changed to a normal ACSF perfusion of 70 min. Every 10 min, 1 perfusate

20、was collected and stored in -70 centigrade refrigerator. The content of glutamic acid and GABA in perfusate was determined by reversed phase high performance liquid chromatography (RP-HPLC).1.5 statistical processing data measured at + s indicated that the glutamic acid and GABA content in the extra

21、cellular fluid at different points were expressed as a percentage of the base value. Using SPSS 10 statistical software for statistical analysis, the group and the basic values were compared by using two factor analysis of variance and dunnett-t test. The basic values of each group were compared by

22、single factor analysis of variance. P 0.05). After the local perfusion of propofol 1 mol/l 10 min, the glutamic acid content in the perfusate at different time points was not significantly different from the baseline value (p 0.05).After 10 min local infusion of propofol 3 mol/l, the glutamic acid c

23、ontent in the perfusate dropped to 60% of the basal value at tenth, twentieth min (p 0.05), then gradually recovered to the basal value level. Propofol infusion of 10 mol/l after 10 min, the content of glutamic acid in liquid perfusion at tenth min to the basic value of 34% (p 0.01), at twentieth mi

24、n and 30 min were significantly lower than the baseline value (p 0.01 or 0.05); then gradually recovered to the baseline level. After 10 min local infusion of propofol 30 mol/l, the change trend of glutamate content in the perfusate was similar to that of local perfusion of propofol 10 mol/l 10 min.

25、 At tenth min, to the lowest point (p 0.01), then gradually picked up, but until fortieth min, glutamic acid content is still significantly lower than the basic value level (p 0.01 or 0.05), as shown in figure 2. 3 discussionIn the mammalian central nervous system within the prefrontal cortex is an

26、important component of the joint cortex, external information and various stimulus signals reach the central nervous system, are required to integrate processing 8 in the prefrontal cortex. In recent years, glutamate has been found to play an important role in regulating the formation of consciousne

27、ss and different levels of consciousness (8). Glutamate can activate NMDA receptor to induce ca2+ influx through a series of intracellular reactions, such as activation of ca2+/ calmodulin dependent protein kinase II, the final formation and the degree of awareness of consciousness of regulation 9.

28、Research shows that thiopental intraperitoneal injection or local perfusion of the prefrontal cortex can significantly reduce the content of extracellular glutamate 10. Therefore, propofol may reduce the glutamate content in the extracellular fluid of prefrontal cortex, which may be one of the cause

29、s of its clinical effects such as unconsciousness.Nerve transfer is largely determined by the concentration of neurotransmitters in the synaptic cleft, and the relationship between the concentration of neurotransmitters in the synaptic cleft and the extracellular fluid is not yet clear, but the chan

30、ge of cells in a certain extent extracellular neurotransmitter concentration can reflect the change of synaptic neurotransmitter concentration. This experiment found that propofol can decrease glutamate levels in the prefrontal cortex in the extracellular fluid, and the concentration of extracellula

31、r glutamate release by presynaptic reuptake and take decisions, including nerve endings and glial cells play an important role in reuptake in 11. Research shows that propofol can inhibit rat hippocampal synaptosomes or cortical glutamate dependent release of ca2+ 12, and on glutamate reuptake does n

32、ot affect, therefore propofol decreased glutamate in extracellular fluid may be due to inhibition of presynaptic glutamate release caused by.The prefrontal cortex, GABA and peripheral nerve fibers to glutamate nerve terminals formed axo somatic and axo axonal synapses, glutamate release activity and

33、 thus can inhibit the endings of pyramidal neurons of the prefrontal cortex excitatory output play an important regulatory role in 13-15. In this study, propofol had no significant effect on the GABA content in the extracellular fluid,Therefore, the extracellular fluid GABA in prefrontal cortex may

34、not be involved in the central action of propofol. But the previous research found that the application of GABAA receptor antagonist can decrease propofol on glutamate release in cerebral cortex slices inhibited 12, showed that the GABAA receptor can mediate the inhibitory effect of propofol on the

35、glutamate release, therefore propofol in this experiment to reduce extracellular glutamate content may also be directly related to GABAA receptor, but further studies.Conclusion: propofol can decrease glutamate content in the extracellular fluid of prefrontal cortex in rats, but has no effect on the

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