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健康家兔24只,分成4组,每组6只。1组为热应激组;2～4组为热习服组,分别热习服6天、11天和16天。热习服各组每天热暴露至肛温(Tr)41.5℃。用放射免疫法测定了各组末次热暴露前和Tr 41.5℃、42.5℃时家兔血浆、脑脊液(CSF)和视前区——下丘脑前区(POAH)环腺苷酸(cAMP)含量。各组末次热暴露耐热时间较首次延长26%～45%。热前血浆cAMP含量较第1组分别增高23%、53%和76%;Tr 41.5℃时增幅由第1组的160%分别降为76%、39%和19%,Tr 42.5℃时则由254%分别降为180%、118%和88%,而其绝对含量较第1组降低不明显(p>0.05)。CSF中cAMP含量变化类似血浆,但含量值均较第1组明显升高,第3、4组Tr 42.5℃时较41.5℃时反有降低趋势(p>0.05),第4组Tr 42.5℃时较第1组仅增高10%(p>0.05)。POAH中cAMP含量变化与CSF中相反,负相关非常显著(p<0.01),第4组Tr 42.5℃时,与第1组几无差别。以上表明,第3、4组热习服后耐热时间显著延长,血浆、CSF和POAH中cAMP含量的变化反映了热应激植物性反应的减弱,以16天组(第4组)最好;CSF中cAMP与POAH中cAMP的代谢有密切关系。
24 healthy rabbits were divided into 4 groups with 6 in each group. 1 group was heat stress group; 2 ~ 4 group was heat treatment group, respectively, heat served 6 days, 11 days and 16 days. Each group was exposed to heat by daily heat exposure to rectal temperature (Tr) 41.5 ℃. The levels of cAMP in plasma, cerebrospinal fluid (CSF) and preoptic area - hypothalamic precordial area (POAH) were measured by radioimmunoassay before final heat exposure and at Tr 41.5 ℃ and 42.5 ℃. The heat-exposure time of last heat exposure of each group was 26% ~ 45% longer than the first time. Pre-heat plasma cAMP levels increased by 23%, 53% and 76%, respectively, compared to group 1; the increase in Tr at 41.5 ° C was reduced from 160% in group 1 to 76%, 39% and 19%, respectively; 254% were reduced to 180%, 118% and 88%, respectively, while the absolute content was lower than the first group was not significant (p> 0.05). CSF content of cAMP changes similar to the plasma, but the content values were significantly higher than the first group, 3,4 group Tr 42.5 ℃ anti-41.5 ℃ anti-anti-trend (p> 0.05), the fourth group Tr 42.5 ℃ Only 10% higher than Group 1 (p> 0.05). The change of cAMP content in POAH was opposite to that in CSF, and the negative correlation was significant (p <0.01). There was no difference between group 4 and group 1 when the temperature was 42.5 ℃. The above showed that the heat-tolerance time of Group 3 and 4 was significantly prolonged after heat-acclimation, and the change of cAMP content in plasma, CSF and POAH reflected the decrease of plant-induced heat stress, which was best in 16-day group (Group 4) ; CAMP in CSF is closely related to cAMP metabolism in POAH.