Martínez-Gómez M, Cruz Y, Salas M, Hudson R, Pacheco P
Centro de Investigaciones Fisiológicas-CIRA, Universidad, Autónoma de Tlaxcala, México.
Physiol Behav. 1994 Apr;55(4):651-7. doi: 10.1016/0031-9384(94)90040-x.
Pain threshold was determined in female rats using the tail flick test. Latency to respond depended on the locus of the tail heated, with the most distal sites resulting in the shortest response times (Experiment 1). Tail flick latency also varied according to the time of day, with shorter response times recorded around the middle of the dark phase than near its beginning or after its end. This was the case for intact, for ovariectomized, and for ovariectomized, estradiol-treated rats (Experiment 2). However, response times also varied across the estrous cycle, with significantly shorter latencies recorded during estrus and metestrus. Ovariectomy abolished these fluctuations, and whereas administration of estradiol increased response times, progesterone had little effect (Experiment 3). These results suggest that site of tail heating, time of day, and presence of ovarian hormones can influence tail flick latency independently, thus demonstrating the complexity of the mechanisms that may contribute to pain threshold even within the same paradigm.
采用甩尾试验测定雌性大鼠的痛阈。反应潜伏期取决于尾巴受热的部位，尾巴最远端受热时反应时间最短（实验1）。甩尾潜伏期也随一天中的时间而变化，在黑暗期的中间时段记录到的反应时间比黑暗期开始时或结束后更短。完整大鼠、去卵巢大鼠以及去卵巢并用雌二醇处理的大鼠均是如此（实验2）。然而，反应时间在发情周期中也有所不同，发情期和动情后期的潜伏期明显更短。去卵巢消除了这些波动，虽然给予雌二醇会增加反应时间，但孕酮几乎没有影响（实验3）。这些结果表明，尾巴受热部位、一天中的时间以及卵巢激素的存在均可独立影响甩尾潜伏期，从而证明即使在同一实验范式下，可能影响痛阈的机制也很复杂。
