热适应形成中的神经化学机制:热适应兔脑室灌流液降低肛温的效应

NEURO-CHEMICAL MECHANISM IMPLICATED IN THE FORMATION OF HEAT ACCLIMATION: THE LOWERING EFFECT OF CEREBRO- VENTRICULAR PERFUSATE FROM HEAT ACCLIMATED RABBITS ON RECTAL TEMPERATURE

侧脑室前角和导水管埋有导管的雄性灰兔39只,随机分为供液组和受液组。供液兔经热锻炼适应后在高温和常温下的脑室灌流液,给受液兔进行脑室灌流。结果发现:能使受液兔常温下灌流60min时的肛温降低,分别比灌流人工脑脊液对照低0.5℃和0.4℃;使高温下灌流60min时的肛温上升减慢,分别较对照低0.3℃和0.33℃,与供液兔自身热锻炼适应后所能提高的耐热能力相近。而未热锻炼和初次热应激供液兔的脑室灌流液,对受液兔的肛温无明显影响。这表明热适应后的脑室液中,出现了能诱发未热适应兔产生相似热适应效应的、降低肛温的神经活性物质——致热适应因子(heat acclimato-inducing factor)。从而揭示了在脑中枢的特定部位,存在促进热适应形成的神经化学机制;并讨论了该神经活性物质可能是一种多次。

39 male rabbits were divided into donor and recipient groups and catheters were inserted in the anterior horn of both lateral ventricles and aquaeductus cerebri. Perfusion of cerebral ventricle of recipient rabbits with the cerebro-ventricular perfusate from heat acclimated donor in hot or neutral environment, caused a fall of rectal temperature in neutral environment or reduction of the temperature rise in hot environment. The average temperature at 60th minutes of perfusion was 0.5-0.4℃ and 0.3-0.33℃ lower than that of control perfused with artificial CSF in neutral and hot environment respectively. The change of rectal temperature of recipients during heat exposure was quite similar to that of acclimated donor. However, perfusate from unacclimated donor or donor under 1st heat stress had no such effect. These results provided direct evidence of presence of a humoral transferable neu-roactive substance-heat acclimato-inducing factor in CSF of heat acclimated rabbits, andthus indicated that a neuro-chemical mechanism was implicated in heat acclimation. It was postulated that this substance may be a polypeptide.