Hypoxia-induced hypothermia mediated by GABA in the rostral parapyramidal area of the medulla oblongata.
Hypoxia-induced hypothermia mediated by GABA in the rostral parapyramidal area of the medulla oblongata.
复制标题
延髓头端锥体旁区 GABA 介导缺氧引起的体温过低。
DOI：
10.1016/j.neuroscience.2014.02.035
复制
发表时间：
2014
期刊：
影响因子：
3.3
通讯作者：
Osaka T.
中科院分区：
文献类型：
--
作者：
Kubota T;Furuta M;Fukushima A;Kakehashi C;Funabashi T. Akema T.;高瀬堅吉・柳井修一・山口哲生監訳;Osaka T;Osaka T.;Osaka T.
缺氧会引起多种动物的体核温度（Tc）有规律地降低。这种反应的神经元机制包括，至少部分地，下丘脑的外侧视前区（LPO）中的多巴胺能激活。由于延髓的交感运动前神经元在下丘脑下行的体温调节神经元通路中起着重要的中继作用，因此，对它们的抑制也可能与缺氧引起的体温降低的机制密切相关。在这里，我研究了这一假设，即缺氧诱导的体温过低是由谷氨酸反应神经元介导的LPO激活GABA能传递的头中缝苍白（rRPa）和相邻的旁锥体区（PPy）的延髓在氯醛糖麻醉，神经肌肉阻断，人工通气大鼠。将GABA（15 nmol）注入大鼠rRPa和PPy区，可引起尾部皮肤温度（Ts）迅速升高，Tc、耗氧率（VO 2）和心率下降。然后，将GABA A受体阻断剂甲碘荷包牡丹碱（bicuculline methiodide，BMI，10 pmol）单独微量注射到rRPa中，引起了意想不到的矛盾反应：Ts，VO 2和心率同时增加，Tc下降。然后，将BMI双侧微量注射到PPy中，没有观察到对Ts的直接影响;产热和心动过速反应轻微。然而，用BMI预处理PPy，而不是溶剂盐水，大大减弱了低氧（10%O2-90%N2，5分钟）通气或双侧LPO中微量注射谷氨酸（5 nmol，每侧）引起的低温反应。结果表明，缺氧诱导的低温介导的，至少部分，在PPy的GABA A受体的激活。
Hypoxia evokes a regulated decrease in the body core temperature (Tc) in a variety of animals. The neuronal mechanisms of this response include, at least in part, glutamatergic activation in the lateral preoptic area (LPO) of the hypothalamus. As the sympathetic premotor neurons in the medulla oblongata constitute a cardinal relay station in the descending neuronal pathway from the hypothalamus for thermoregulation, their inhibition can also be critically involved in the mechanisms of the hypoxia-induced hypothermia. Here, I examined the hypothesis that hypoxia-induced hypothermia is mediated by glutamate-responsive neurons in the LPO that activate GABAergic transmission in the rostral raphe pallidus (rRPa) and neighboring parapyramidal region (PPy) of the medulla oblongata in urethane–chloralose-anesthetized, neuromuscularly blocked, artificially ventilated rats. Unilateral microinjection of GABA (15 nmol) into the rRPa and PPy regions elicited a prompt increase in tail skin temperature (Ts) and decreases inTc, oxygen consumption rate (VO2), and heart rate. Next, when the GABAAreceptor blocker bicuculline methiodide (bicuculline methiodide (BMI), 10 pmol) alone was microinjected into the rRPa, it elicited unexpected contradictory responses: simultaneous increases inTs, VO2and heart rate and a decrease inTc. Then, when BMI was microinjected bilaterally into the PPy, no direct effect onTswas seen; and thermogenic and tachycardic responses were slight. However, pretreatment of the PPy with BMI, but not vehicle saline, greatly attenuated the hypothermic responses evoked by hypoxic (10%O2–90%N2, 5 min) ventilation or bilateral microinjections of glutamate (5 nmol, each side) into the LPO. The results suggest that hypoxia-induced hypothermia was mediated, at least in part, by the activation of GABAAreceptors in the PPy.