Russo Scott J, Jenab Shirzad, Fabian Sosimo J, Festa Eugene D, Kemen Lynne M, Quinones-Jenab Vanya
Department of Psychology, Hunter College of the City University of New York, New York 10021, USA.
Brain Res. 2003 Apr 25;970(1-2):214-20. doi: 10.1016/s0006-8993(03)02346-1.
Several recent reports have demonstrated sex differences in the behavioral and neurochemical response to cocaine. However, it is not clear whether differences exist in cocaine reward or the extent to which adrenal hormones regulate cocaine-induced conditioned place preference (CPP) in either sex. To address these questions, side-by-side comparisons were conducted to determine the effects of conditioning length, cocaine dose and adrenalectomy on cocaine CPP in male and female rats. Female rats demonstrated cocaine CPP after four pairing sessions, while male rats required eight pairing sessions to develop CPP for cocaine. Also, female rats developed CPP at cocaine doses of 5 and 10 mg/kg while male rats required higher cocaine doses (20 mg/kg). Overall, females had higher blood serum levels of corticosterone. Furthermore, a dose-dependent effect on serum levels of corticosterone was observed only in female rats, where rats conditioned with 20 mg/kg cocaine had significantly higher serum levels of corticosterone than rats conditioned with 5 mg/kg cocaine. However, adrenalectomy did not affect CPP for cocaine in either sex. These results suggest that a female's higher sensitivity to cocaine's rewarding effects is not completely mediated by the hypothalamic-pituitary-adrenal axis. Therefore, sex differences in the acquisition and/or expression of cocaine CPP may be regulated by other mechanisms, such as the hypothalamic-pituitary-gonadal axis.
最近的几份报告显示，在对可卡因的行为和神经化学反应方面存在性别差异。然而，目前尚不清楚在可卡因奖赏方面是否存在差异，或者肾上腺激素在何种程度上调节两性中可卡因诱导的条件性位置偏爱（CPP）。为了解决这些问题，我们进行了并行比较，以确定条件化时长、可卡因剂量和肾上腺切除术对雄性和雌性大鼠可卡因CPP的影响。雌性大鼠在四次配对实验后表现出可卡因CPP，而雄性大鼠则需要八次配对实验才能形成对可卡因的CPP。此外，雌性大鼠在5和10mg/kg的可卡因剂量下形成了CPP，而雄性大鼠则需要更高的可卡因剂量（20mg/kg）。总体而言，雌性大鼠的血清皮质酮水平更高。此外，仅在雌性大鼠中观察到对血清皮质酮水平的剂量依赖性效应，用20mg/kg可卡因进行条件化的大鼠血清皮质酮水平显著高于用5mg/kg可卡因进行条件化的大鼠。然而，肾上腺切除术对两性的可卡因CPP均无影响。这些结果表明，雌性对可卡因奖赏效应的更高敏感性并非完全由下丘脑-垂体-肾上腺轴介导。因此，可卡因CPP获得和/或表达中的性别差异可能受其他机制调节,如下丘脑-垂体-性腺轴。
