Abstract

Previously, stress responses in gray Norway rats (Rattus norvegicus) selected for the absence or enhancement of aggressive and defensive behaviors toward humans (tame and aggressive behaviors, respectively) were studied mainly to nonsocial factors, whereas data on the consequences of social stress induced, specifically, by interactions with conspecifics are scarce. As has already been shown, the above selection of Norway rats causes attenuation or enhancement of intraspecific intermale aggression. To find out whether the differences in aggressiveness are accompanied by hormonal alterations, we addressed the dynamics of corticosterone and testosterone blood levels after intermale aggression testing in tame and aggressive rats, and unselected rats bred in a vivarium for 7–8 generations as a reference. The goal of this work was to investigate the effect of selection toward humans on agonistic interactions under conditions of an unfamiliar cage or neutral territory and on the subsequent dynamics of blood corticosterone and testosterone levels in tame, aggressive, and unselected rats. In our experiments, tame males, as compared to their aggressive or unselected conspecifics, demonstrated a longer attack latency, as well as a shorter duration and smaller number of patterns of aggressive behavior, approximating zero values. When tested on neutral territory, aggressive male rats were inferior to their unselected conspecifics in the total time of confrontations. More pronounced manifestations of aggression in unselected males compared to aggressive or tame animals arose against the background of elevated basal corticosterone levels and enhanced stress responsiveness to interacting with an unfamiliar male. At the same time, reduced aggressiveness of tame rats in the neutral territory test, as compared to unselected or aggressive animals, correlated with the lower testosterone level.

中文翻译：

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男性间相互作用对中性领土和随后动力学的驯服和侵略性挪威大鼠（大鼠褐皮鼠）皮质酮和睾丸激素水平的动态

摘要

以前，灰色挪威大鼠（Rattus norvegicus主要针对非社会因素研究了针对人类的攻击行为或防御行为（分别为驯服和攻击行为）的缺乏或增强（主要针对非社会因素），而关于社会压力后果的数据（特别是与特定物种的相互作用引起的数据）却很少。如已经显示的，挪威鼠的上述选择导致种内雄性间侵略的减弱或增强。为了弄清攻击性的差异是否伴随着激素的变化，我们研究了在驯服和攻击性大鼠中进行雄性间侵测后皮质酮和睾丸激素水平的动态变化，以及未选择的大鼠在饲养箱中饲养了7-8代作为参考。这项工作的目的是调查选择人类对陌生笼子或中性区域条件下的激动性相互作用的影响，以及对驯服，侵略性和未选择大鼠的血皮质激素和睾丸激素水平随后动态的影响。在我们的实验中，驯服的雄性与其攻击性或未选择的同种菌相比，表现出更长的攻击潜伏期，更短的持续时间和更少的攻击行为模式，接近零值。在中立地区进行测试时，雄性雄性大鼠的总对抗时间次于其未选定的物种。与激进或驯服的动物相比，未选择的雄性动物的侵略性表现出更高的背景，其中基础皮质酮水平升高，并且对与陌生的雄性动物互动的应激反应增强。同时，与未选择或具有攻击性的动物相比，在中性区域测试中驯服的大鼠的降低的攻击性与较低的睾丸激素水平相关。