Millesi Eva, Hoffmann Ilse E, Steurer Sabine, Metwaly Mohammed, Dittami John P
Institute of Zoology, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
Horm Behav. 2002 Feb;41(1):51-8. doi: 10.1006/hbeh.2001.1735.
This field study was aimed at examining hypothalamic involvement in the behavioral changes of male European ground squirrels (Spermophilus citellus) before, during, and after the mating season. The effects of exogenous gonadotropin-releasing hormone (GnRH) application on androgen secretion and behavioral patterns were investigated. Animals were captured, bled, and injected intramuscularly with 40 ng/100 g of GnRH. A second plasma sample was collected 40 min after the treatment to document changes in testosterone secretion. Behavioral parameters such as intra-sexual aggression, scent marking, and home range size were compared on the days before and after the stimulation. In the first two phases, before female emergence and during mating, GnRH-injection caused increases in plasma testosterone. In the post-mating phase, initial plasma testosterone levels had decreased and no elevation could be induced. Sham treatment of controls had no effect in any phase. Conditional parameters like emergence body mass and testicular size covaried with androgen increases only in the pre-mating period. Behavioral changes after GnRH administration occurred during the pre-mating period. Intra-sexual aggression, scent marking, and home range size increased significantly in experimental individuals. Later, during mating and post-mating, we found no behavioral changes associated with the GnRH treatment or the testosterone increase. The results demonstrate changes in the endocrine and behavioral sensitivity to GnRH application, according to the phases of the active season. An exogenous pulse of GnRH can apparently release behavior in male European ground squirrels, which is normally context dependent with the emergence of females.
这项实地研究旨在考察雄性欧洲地松鼠（Citellus citellus）在交配季节之前、期间和之后行为变化过程中下丘脑的参与情况。研究了外源性促性腺激素释放激素（GnRH）的应用对雄激素分泌和行为模式的影响。捕获动物、采集血液样本，并给动物肌肉注射40 ng/100 g的GnRH。在治疗后40分钟采集第二份血浆样本，以记录睾酮分泌的变化。在刺激前后的几天，比较诸如同性攻击、气味标记和活动范围大小等行为参数。在前两个阶段，即雌性出现之前和交配期间，GnRH注射导致血浆睾酮水平升高。在交配后阶段，初始血浆睾酮水平下降，且无法诱导其升高。对对照组进行假处理在任何阶段均无效果。诸如出蛰体重和睾丸大小等条件参数仅在交配前期与雄激素增加相关。GnRH给药后的行为变化发生在交配前期。实验个体的同性攻击、气味标记和活动范围大小显著增加。之后，在交配和交配后阶段，我们未发现与GnRH治疗或睾酮增加相关的行为变化。结果表明，根据活跃季节的不同阶段，内分泌和行为对GnRH应用的敏感性存在变化。外源性GnRH脉冲显然可以释放雄性欧洲地松鼠的行为，而这种行为通常与雌性的出现有关，依赖于具体情境。
