Aloisi A M, Ceccarelli I, Lupo C
Institute of Human Physiology, University of Siena, Italy.
Brain Res Bull. 1998 Sep 1;47(1):57-62. doi: 10.1016/s0361-9230(98)00063-x.
The formalin test was used to measure the analgesia induced by restraint in male and female rats. Animals were restrained for 30 min or left undisturbed in their cage and then (1) killed immediately to collect blood for hormonal determinations; or (2) subcutaneously injected with formalin in the hind paw (or sham-injected), introduced to an open field for recording of behaviour, and killed at the end of this procedure. In both experiments, corticosterone was found to be higher in females. In Experiment 1, the ability of restraint to be stressful was confirmed by the increase in corticosterone in both sexes and by the decrease of testosterone in males. In Experiment 2, restraint-treatment induced a reduction in licking and flexing that was limited to the second phase. The reduction occurred in different periods and to a different degree in the two sexes; it was greater in females. Spontaneous behaviours showed sex differences in restraint-treated but not in formalin-treated animals. The results show that the hormonal effects observed after restraint are not present after the formalin test and that the marked analgesia observed with phasic painful stimuli does not occur with a longer-lasting one such as that induced by formalin, after which only partial and short-lasting effects were observed.
采用福尔马林试验来测定雄性和雌性大鼠因束缚引起的镇痛作用。将动物束缚30分钟或使其在笼中不受干扰，然后：(1) 立即处死以采集血液用于激素测定；或 (2) 在后爪皮下注射福尔马林（或假注射），放入旷场以记录行为，并在该程序结束时处死。在这两个实验中，均发现雌性大鼠的皮质酮水平较高。在实验1中，两性皮质酮水平的升高以及雄性大鼠睾酮水平的降低证实了束缚具有应激性。在实验2中，束缚处理导致舔舐和屈曲行为减少，且仅限于第二阶段。这种减少在两性中发生的时期不同且程度不同；在雌性中更明显。自发行为在接受束缚处理的动物中表现出性别差异，但在接受福尔马林处理的动物中未表现出性别差异。结果表明，束缚后观察到的激素效应在福尔马林试验后不存在，并且与阶段性疼痛刺激所观察到的明显镇痛作用不同，福尔马林诱导的持续性疼痛刺激仅观察到部分和短暂的效应。
