The present study characterized the effects of weekly ketamine injections on sexual behavior and anxiety in female and male rats, using a dosing protocol that mimics human therapeutic treatment for depression. In Experiment 1A, ketamine (10 mg/kg, i.p.) or saline was injected once per week for four consecutive weeks. The partner preference paradigm was used to measure sexual motivation 30 min after each weekly injection. Briefly, subjects were first given a 10-min test during which they could choose to spend time in the vicinity of a sexually receptive female stimulus or a sexually experienced male stimulus, however physical contact was restricted (no-contact). Immediately after, subjects were given unrestricted access to the stimulus animals (contact). After a washout period, subjects received four additional weekly injections of ketamine or saline, and then were tested for anxiety-like behavior on the elevated plus maze (EPM) after the last injection (Experiment 1B). For Experiment 2, similar procedures were used to test the effects of weekly ketamine injections on sexual motivation (Experiment 2A) and anxiety (Experiment 2B) in male subjects. In female subjects, ketamine increased sexual motivation as measured by greater time spent with the male stimulus, decreased likelihood of leaving after receiving mounts, and shorter return latencies after receiving intromissions, when compared to saline controls. In male subjects, ketamine shortened latency to first mount and first intromission, as well as increased time spent with the female stimulus. Very little anxiety was observed in either group (ketamine or saline) of female or male subjects when tested on the EPM. In conclusion, even after four weeks of ketamine exposure, sexual dysfunction did not emerge in either females or males. In contrast, ketamine increased sexual motivation in both females and males, with an initial robust response. However, as both groups gained sexual experience, the impact of ketamine diminished.

本研究使用模拟人类抑郁症的给药方案，确定了每周注射氯胺酮对雌性和雄性大鼠性行为和焦虑的影响。在实验1A中，连续四周每周注射一次氯胺酮（10 mg / kg，ip）或生理盐水。每周注射30分钟后，使用伴侣偏好范例测量性动机。简短地说，首先对受试者进行10分钟的测试，在此期间，他们可以选择将时间花在接受性爱的女性刺激物或有性经历的男性刺激物附近，但是身体接触受到限制（无接触）。之后，立即让受试者不受限制地接触刺激动物（接触）。经过冲洗期后，受试者每周再接受四次氯胺酮或生理盐水注射，然后在最后一次注射后在高架迷宫（EPM）上进行焦虑样行为的测试（实验1B）。对于实验2，使用类似的程序测试每周氯胺酮注射对男性受试者性动机（实验2A）和焦虑（实验2B）的影响。与生理盐水对照组相比，在女性受试者中，氯胺酮增加了性动机，具体表现为男性刺激花费的时间更长，坐骑后离开的可能性降低，以及接受内服后返回的潜伏期较短。在男性受试者中，氯胺酮缩短了首次坐骑和首次引入的潜伏期，并增加了女性刺激所花费的时间。在EPM上进行测试时，无论是女性还是男性受试者（氯胺酮或生理盐水）中的任何一组，其焦虑都很少。总之，即使在氯胺酮暴露四个星期之后，无论男女，都不会出现性功能障碍。相比之下，氯胺酮在男性和女性中都增加了性动机，并产生了最初的强烈反应。但是，随着这两个群体都获得性经验，氯胺酮的影响减弱了。