Nogueira G P, Barnabe R C
Departamento de Reprodução Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, Brasil.
Braz J Med Biol Res. 1997 Oct;30(10):1237-9. doi: 10.1590/s0100-879x1997001000016.
Thoroughbred fillies were divided into three groups according to age: group 1, 7 fillies aged 1 to 2 years (G1) starting the training program; group 2, 9 fillies aged 2 to 3 years (G2) in a full training program; group 3, 8 older fillies 3 to 4 years of age (G3) training and racing. Blood samples were collected weekly from July to December. Cortisol was quantified using a solid phase DPC kit. The intra- and interassay coefficients of variation were 12.5% and 15.65% and sensitivity was 1.9 +/- 0.2 nmol/l. The semester average of cortisol levels varied between groups: G1 = 148.8 +/- 6.7, G2 = 125.7 +/- 5.8, G3 = 101.1 +/- 5.4 nmol/l, with G3 differing statistically from the other groups. The lower cortisol levels observed in the older fillies leads us to propose that the stress stimulus, when maintained over a long period of time, may become chronic and result in a reduction of hypophyseal corticotropin-releasing hormone receptors. The secretion of endogenous opioids may also lead to low serum cortisol levels.
第一组，7匹1至2岁的雌马（G1）开始训练计划；第二组，9匹2至3岁的雌马（G2）进行全面训练计划；第三组，8匹3至4岁的大龄雌马（G3）进行训练和比赛。从7月至12月每周采集血样。使用固相DPC试剂盒对皮质醇进行定量。批内和批间变异系数分别为12.5%和15.65%，灵敏度为1.9±0.2nmol/l。皮质醇水平的学期平均值在各组之间有所不同：G1 = 148.8±6.7，G2 = 125.7±5.8，G3 = 101.1±5.4nmol/l，G3与其他组在统计学上存在差异。在大龄雌马中观察到的较低皮质醇水平使我们提出，当应激刺激长期持续时，可能会变为慢性，并导致垂体促肾上腺皮质激素释放激素受体减少。内源性阿片类物质的分泌也可能导致血清皮质醇水平降低。
