Pfaus J G, Wilkins M F
Department of Psychology, Concordia University, Montréal, Québec, Canada.
Physiol Behav. 1995 Jun;57(6):1045-9. doi: 10.1016/0031-9384(94)00394-k.
Relative to sexually experienced male rats, sexually naive males typically display a pattern of copulatory behavior that is characterized by a larger proportion of rats that do not copulate: those that do copulate during their first exposure to a sexually receptive female have longer mount, intromission, and ejaculation latencies, and longer postejaculatory intervals. A male rat's first sexual experience often coincides with the first exposure to handling and to the novel testing apparatus. Because handling or exposure to novel environments is stressful and can induce the release of endogenous opioids, and because the opioid antagonist naloxone can facilitate the copulatory behavior of sexually naive male rats, we examined whether preexposure to handling alone, or to handling and a novel testing chamber, would diminish the magnitude of the relative disruption observed in sexually naive male rats. Handling alone did not increase the proportion of males that mounted or intromitted, whereas preexposure to the chamber increased these proportions significantly and decreased the mount and intromission latencies, and the number of mounts without intromission. Naloxone hydrochloride (10 mg/kg) facilitated the display of mounts and intromissions in rats that were preexposed to handling alone, but had no effect in rats that had been additionally preexposed to the testing chambers. In contrast, the copulatory behavior of rats with extensive sexual experience was not adversely affected in a novel testing chamber. Novelty disrupts the copulatory behavior of sexually naive males and may do so by increasing endogenous opioid activity. However, sexual experience appears to diminish or eliminate the disruptive effect of a novel environment.
与有性经验的雄性大鼠相比，性幼稚的雄性大鼠通常表现出一种交配行为模式，其特征是不交配的大鼠比例更高：那些在首次接触性接受雌鼠时进行交配的大鼠，其爬跨、插入和射精潜伏期更长，射精后间隔时间也更长。雄性大鼠的首次性经历往往与首次接触处理和新型测试装置同时发生。由于处理或接触新环境会产生压力并能诱导内源性阿片类物质的释放，且由于阿片类拮抗剂纳洛酮可促进性幼稚雄性大鼠的交配行为，我们研究了单独预先接触处理，或预先接触处理和新型测试室，是否会减少在性幼稚雄性大鼠中观察到的相对干扰程度。单独的处理并没有增加进行爬跨或插入的雄性大鼠比例，而预先接触测试室则显著增加了这些比例，并缩短了爬跨和插入潜伏期，以及无插入的爬跨次数。盐酸纳洛酮（10毫克/千克）促进了仅预先接触处理的大鼠的爬跨和插入行为表现，但对另外还预先接触测试室的大鼠没有影响。相比之下，有丰富性经验的大鼠在新型测试室中的交配行为并未受到不利影响。新奇性会干扰性幼稚雄性大鼠的交配行为，可能是通过增加内源性阿片类物质的活性来实现的。然而，性经验似乎会减少或消除新环境的干扰作用。
