脑室内注射orexin-A和orexin-B对下丘脑组胺释放的影响

摘要

Objective To provide new evidences for understanding the mechanisms of promo-tive role of orexins in anesthetic emergence and the effect of microinjection of orexin-A/orexin-B into cerebral ventricle on the release of histamine.Methods Male SD rats were randomly divided into sa-line (control ), orexin-A and orexin-B groups. The microdialysis probe was inserted into hypothalamus under stereotaxic apparatus.The perfused fluid from the area of hypothalamic tube-romammillary nucleus was collected using in vivo microdialysis at 1 h,2 h and 3 h after 1 nmol or 5 nmol orexin-A or orexin-B microinjection into the cerebral ventricle (n =5 each).The concentrations of histamine at each time point in dialysates of perfused fluid were detected by high performance liquid chromatography (HPLC)to analyze its dynamic changes.After one week,each group was microin-jected with 10 nmol,15 nmol and 20 nmol orexin-A and orexin-B (n =5)into the cerebral ventricle respectively,dialysates was collect and histamine was detected at 1 h to analyze its dosage response. After one week,each group was microinjected 0.3 μl saline orexin-A and orexin-B (n =6)into the tu-beromammillary nucleus.Results Compared with the control group,microinjection of 1 nmol orexin-A significantly increased histamine release at 1 h,but the same dose of orexin-B had no such effect,5 nmol of orexin-A or orexin-B injections significantly facilitated histamine release at 2 h and 3 h (P <0.01).Microinjection of 10 nmol,15 nmol and 20 nmol orexin-A and orexin-B into ventricle caused an significant increase of histamine release at 1 h while the effect was the strongest in 20 nmol (P <0.05).Compared with the control group,microinjection of orexin-A significantly decreased time of the righting reflex (P <0.01),but the same dose of orexin-B had no such effect.Conclusion Micro-injection of both orexin-A or orexin-B into cerebral ventricle could promote the release of histamine, while the effect of orexin-A was stronger.Microinjection orexin-A into tuberomammillary nucleus sig-nificant facilitated recovery from isoflurane.%目的 观察脑室内微注射orexin-A和orexin-B对下丘脑组胺释放的影响,为orexins促麻醉觉醒的机制提供新的解释.方法 成年雄性SD大鼠随机分为三组:生理盐水组、orexin-A组和orexin-B组.在立体定位仪下将微透析管置入下丘脑结节乳头体核区.实验分为两部分:先收集脑室内分别注射orexin-A、orexin-B 1 nmol和5 nmol后1、2 h和3 h的微透析液(n=5),采用高效液相色谱法(HPLC)检测微透析液中组胺含量的时程变化.1周后,各组大鼠分别注入不同剂量的orexin-A和orexin-B(10、15 nmol和20 nmol,n=5),收集微注射后1 h的透析液,检测组胺释放的剂量效应.在立体定位仪下结节乳头体核置入微注射管,1周后给予1.4%异氟醚(1 MAC)麻醉30 min,各组大鼠分别微注射生理盐水、orexin-A和orexin-B 0.3μl(n=6),记录翻正反射恢复时间.结果 与生理盐水组比较,脑室内微注射orexin-A 1 nmol 2 h后下丘脑组胺含量明显增加,但同样剂量的orexin-B无明显作用,注射orexin-A和orexin-B 5 nmol后2、3 h组胺含量均明显增加(P<0.01).脑室内微注射10 nmol、15 nmol和20 nmol的orexin-A和orexin-B后1 h组胺含量明显高于生理盐水,且20 nmol含量最高(P<0.05).结节乳头体核微注射orexin-A后翻正反射恢复时间明显短于生理盐水(P<0.01),微注射orexin-B后无明显作用.结论脑室内微注射orexin-A和orexin-B均可促进下丘脑组胺递质的释放,但orexin-A的作用更强.结节乳头体核微注射orexin-A促进异氟醚麻醉的觉醒.