Instituto de Neurobiología, Universidad Nacional Autónoma de México, Boulevard Juriquilla 3001, Juriquilla-Querétaro, C.P. 76230, Mexico.
Behav Brain Res. 2010 Dec 25;214(2):225-30. doi: 10.1016/j.bbr.2010.05.028. Epub 2010 May 25.
An important number of Sprague-Dawley males selected by strict inbreeding process for their high spontaneous yawing frequency (HY) fail to copulate after repeated exposure to receptive females. These HY males that fail to mate are called non-copulators (HYNC). The causes of this behavioral deficit are still unknown. The aim of the present study was to make a detailed behavioral characterization of these animals by evaluating: their partner preference between a sexually receptive female as opposed to a sexually active male; their ability to detect food related odors and their preference for sexually relevant chemosensory cues between bedding from estrous females, bedding from sexually active males and clean bedding. We also evaluated whether these males had alterations in motor function using a rotarod or in their general reward system mediated by opioids by injecting them with 1mg/kg of morphine to evaluate if they develop conditioned place preference (CPP). At the end of these behavioral tests, we measured their plasmatic levels of testosterone (T). Together, these results will contribute to elucidate the causes of their deficient copulatory performance. Both HYNC and HY copulators (HYC) males showed a clear preference for receptive females as opposed to sexually active males. As well, both groups of animals had a similar ability to detect food related odors. HYC males had a clear preference for estrous female odors as opposed to male or clean bedding, but HYNC males spend the same amount of time sniffing estrous, anestrous, male and clean bedding. In both, HYC and HYNC, morphine induced CPP suggesting that in these males the reward system is functional. No differences were found in motor coordination or in T levels between HY and HYNC males. The behavioral deficit in HYNC male rats cannot be explained by an alteration in: partner preference, food related odor recognition, motor coordination, general reward system, or differences in plasmatic levels of T. However, HYNC males present clear deficits in recognizing sexually relevant odors. These results could, at least in part, explain the deficient execution of copulatory pattern in HYNC males.
许多通过严格近亲繁殖过程选择的 Sprague-Dawley 雄性大鼠由于自发的偏头运动频率较高（HY），在反复接触发情雌性后无法交配。这些无法交配的 HY 雄性大鼠被称为非交配者（HYNC）。这种行为缺陷的原因尚不清楚。本研究的目的是通过评估以下方面对这些动物进行详细的行为特征描述：它们对性接受的雌性与性活跃的雄性之间的伴侣偏好；它们检测食物相关气味的能力以及它们对发情雌性、性活跃雄性和清洁垫料的床上用品之间的性相关化学感觉线索的偏好。我们还通过给它们注射 1mg/kg 的吗啡来评估这些雄性的运动功能是否发生变化，或者评估它们是否通过阿片类药物介导的一般奖励系统产生条件位置偏好（CPP）。在这些行为测试结束时，我们测量了它们的血浆睾酮（T）水平。综上所述，这些结果将有助于阐明它们交配表现不佳的原因。HYNC 和 HY 交配者（HYC）雄性都明显偏爱发情雌性而不是性活跃的雄性。此外，两组动物都有类似的检测食物相关气味的能力。HYC 雄性对发情雌性的气味有明显偏好，而对雄性或清洁垫料则没有，而 HYNC 雄性对发情、非发情、雄性和清洁垫料的嗅探时间相同。在 HYC 和 HYNC 中，吗啡诱导 CPP 表明这些雄性的奖励系统是功能性的。HY 和 HYNC 雄性之间在运动协调或 T 水平上没有差异。HYNC 雄性大鼠的 HYNC 行为缺陷不能用以下因素来解释：伴侣偏好、食物相关气味识别、运动协调、一般奖励系统或血浆 T 水平的差异。然而，HYNC 雄性在识别性相关气味方面存在明显缺陷。这些结果至少可以部分解释 HYNC 雄性在执行交配模式方面的缺陷。
