Gomez Alexa, Petrucci Alexandra N, Dance Lauren, Morales-Valenzuela Jessica, Gibbs Nicole, Dahlhausen Cara C, Villatoro Jessica R, Frohardt Russell F, Guarraci Fay A
Department of Psychology, Southwestern University, Georgetown, TX 78626, USA.
Department of Psychology, Francis Marion University, Florence, SC 29506, USA.
Pharmacol Biochem Behav. 2016 Nov-Dec;150-151:100-107. doi: 10.1016/j.pbb.2016.09.005. Epub 2016 Sep 28.
The present study was designed to test the effects of an acute, high dose of methylphenidate (MPH; trademarked as Ritalin) on sexual behavior in female Long-Evans rats. In Experiment 1, naturally cycling subjects in estrus were tested for partner preference 20min after receiving an i.p. injection of MPH 10mg/kg (n=8) or saline (n=7). During the partner-preference test, female subjects were given the choice to interact with a sexually active male stimulus or a sexually receptive female stimulus. Physical contact was limited by placing the stimulus animals behind a wire mesh during the no-contact phase of the test, whereas physical contact was not limited during the contact phase. Female subjects that received MPH spent significantly less time with the male stimulus than the saline-treated subjects during both phases (no-contact and contact) of the partner-preference test. This acute dose of MPH did not affect visits to the female stimulus; however, MPH-treated subjects made fewer visits to the male stimulus than the saline-treated subjects during the contact phase of the partner-preference test. Consistent with previous findings, MPH increased line crossings when subjects were tested in an open field immediately after the partner-preference test. In Experiment 2, female subjects were ovariectomized (OVX), primed with estradiol benzoate and progesterone, and tested for partner preference 20min after receiving an injection of MPH 10mg/kg (n=8) or saline (n=8). Similar to the results of Experiment 1, OVX hormone-primed subjects that received MPH spent significantly less time with the male stimulus than the saline-treated subjects during both phases of the partner-preference test. Although MPH-treated subjects were sexually receptive, they displayed fewer proceptive behaviors (i.e., hops and darts) than saline-treated subjects. Two-weeks later, the subjects from Experiment 2 were tested in an open field 20min after receiving an injection of MPH 10mg/kg or saline (counterbalancing previous MPH exposure). Once again MPH increased locomotor activity. In conclusion, the effects of MPH were equally as robust in naturally cycling subjects as in the more commonly used OVX-hormone primed subjects. The results of the present study suggest that an acute, non-therapeutic dose of MPH disrupts approach and interest in a male stimulus during a test of partner preference. This avoidance of the male stimulus may be the result of a decrease in the incentive value of a sexual partner.
本研究旨在测试急性高剂量哌甲酯（MPH；商品名为利他林）对雌性Long-Evans大鼠性行为的影响。在实验1中，对处于发情期的自然发情雌性大鼠，腹腔注射10mg/kg的MPH（n = 8）或生理盐水（n = 7）20分钟后，测试其对配偶的偏好。在配偶偏好测试中，雌性受试动物可选择与性活跃的雄性刺激动物或性接受的雌性刺激动物互动。在测试的无接触阶段，通过将刺激动物放置在金属丝网后面来限制身体接触，而在接触阶段则不限制身体接触。在配偶偏好测试的两个阶段（无接触和接触）中，接受MPH的雌性受试动物与雄性刺激动物相处的时间均显著少于接受生理盐水处理的受试动物。这种急性剂量的MPH不影响对雌性刺激动物的访问；然而，在配偶偏好测试的接触阶段，接受MPH处理的受试动物对雄性刺激动物的访问次数少于接受生理盐水处理的受试动物。与先前的研究结果一致，在配偶偏好测试后立即在旷场中测试时，MPH增加了受试动物的穿格次数。在实验2中，对雌性受试动物进行卵巢切除（OVX），用苯甲酸雌二醇和孕酮进行预处理，并在注射10mg/kg的MPH（n = 8）或生理盐水（n = 8）20分钟后测试其对配偶的偏好。与实验1的结果相似，在配偶偏好测试的两个阶段中接受MPH的OVX激素预处理受试动物与雄性刺激动物相处的时间均显著少于接受生理盐水处理的受试动物。尽管接受MPH处理的受试动物具有性接受能力，但它们表现出的求偶行为（即跳跃和飞奔）比接受生理盐水处理的受试动物少。两周后，对实验2中的受试动物在注射10mg/kg的MPH或生理盐水（平衡先前的MPH暴露）20分钟后在旷场中进行测试。MPH再次增加了运动活性。总之，MPH对自然发情受试动物的影响与对更常用的OVX激素预处理受试动物的影响同样显著。本研究结果表明，急性非治疗剂量的MPH在配偶偏好测试中会破坏对雄性刺激动物的接近和兴趣。对雄性刺激动物的这种回避可能是性伴侣激励价值降低的结果。
