Serotonin (5-HT) _1A and _1B receptors have been implicated in behavioral sensitization, but adult rats appear to develop tolerance to RU 24969 (a 5-HT_1A/1B receptor agonist) rather than a sensitized response. The purpose of the present study was to determine whether a one- or four-day pretreatment regimen of RU 24969 would cause sensitization or tolerance in male and female preweanling rats. Depending on experiment, rats were pretreated with RU 24969 (0, 2.5, or 5 mg/kg) for 1 or 4 days (PD 17–20), while testing with lower or higher doses of RU 24969 occurred on PD 22. Locomotor activity, motoric capacity, and axillary temperatures were recorded. The role of Pavlovian contextual conditioning was assessed by administering RU 24969 to rats in either the home cage or a novel environment. On the first pretreatment day, RU 24969 caused both an increase in forward locomotion and motoric impairment, along with a substantial decrease in axillary temperatures. Repeated treatment with the same dose of RU 24969 caused all three dependent measures to show a tolerance response. When given a higher dose of RU 24969 on the test day, the responses lost due to repeated drug treatment were fully (locomotor activity) or partially (motoric capacity and axillary temperatures) reinstated. There was no evidence of behavioral tolerance. Results are consistent with the hypothesis that a subsensitivity of 5-HT_1A/1B receptors is at least partially responsible for the tolerance caused by RU 24969, but dispositional tolerance cannot be excluded as a contributing factor.

血清素 (5-HT) _1A和_1B受体与行为致敏有关，但成年大鼠似乎对 RU 24969（5-HT _1A/1B受体激动剂）而不是致敏反应。本研究的目的是确定 RU 24969 的 1 天或 4 天预处理方案是否会导致雄性和雌性断奶前大鼠的致敏或耐受。根据实验，大鼠用 RU 24969（0、2.5 或 5 mg/kg）预处理 1 或 4 天（PD 17-20），同时在 PD 22 时用较低或较高剂量的 RU 24969 进行测试。记录运动能力和腋窝温度。巴甫洛夫语境条件反射的作用是通过在家庭笼子或新环境中对大鼠施用 RU 24969 来评估的。在预处理的第一天，RU 24969 导致向前运动和运动障碍的增加，以及腋窝温度的显着降低。用相同剂量的 RU 24969 重复治疗导致所有三个相关测量都显示出耐受反应。当在测试日给予更高剂量的 RU 24969 时，由于重复药物治疗而失去的反应完全（运动活动）或部分（运动能力和腋窝温度）恢复。没有行为容忍的证据。结果与 5-HT 不敏感的假设一致_1A/1B受体至少是 RU 24969 引起的耐受性的部分原因，但不能排除性格耐受性作为一个促成因素。