Carelli R M, Deadwyler S A
Center for The Neurobiological Investigation of Drug Abuse, Department of Physiology and Pharmacology, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, North Carolina, USA.
J Pharmacol Exp Ther. 1996 Apr;277(1):385-93.
At the initiation of cocaine self-administration sessions, neurons in the rat nucleus accumbens (NA) exhibit a spontaneous transition in firing rate from activity unrelated to the reinforced response to one of four types of patterned discharges. This transition in NA activity is accompanied by a shift from high response rates at the start of the session ("Load-Up" behavior) to a lower rate for the remainder of the session. In this study, the relationship between transitions in behavioral responding and NA activity was examined further by changing the dose of cocaine per session (0.66, 0.50, 0.33, 0.16 or 0.08 mg/inf). Results show that the number of Load-Up responses significantly increased at lower cocaine doses [0.16, 0.08 mg/infusion (inf)] and decreased at higher doses (0.33, 0.50, 0.66 mg/inf). Thereafter, animals responded either with regularly spaced interinfusion intervals (INTs) at high doses (0.33, 0.50 and 0.66 mg/inf), or frequent bursts and pauses in responding at low doses (0.16 and 0.08 mg/inf. NA neurons exhibited a spontaneous transition in firing rate that was significantly correlated with this shift in behavioral responding across different doses of cocaine. Pretreatment with the dopamine D1 receptor antagonist SCH23390 (5 or 10 microgram/kg) prolonged the onset of NA patterned discharges, similar to responding for low doses of cocaine (0.08 and 0.16 mg/inf. These findings are discussed in terms of a functional role of the NA in mediating the reinforcing properties of cocaine.
在可卡因自我给药实验开始时，大鼠伏隔核（NA）中的神经元放电率会自发地从与强化反应无关的活动转变为四种模式放电之一。NA活动的这种转变伴随着实验开始时高反应率（“加载”行为）到实验剩余时间较低反应率的转变。在本研究中，通过改变每次实验的可卡因剂量（0.66、0.50、0.33、0.16或0.08mg/次注射），进一步研究了行为反应转变与NA活动之间的关系。结果表明，在较低可卡因剂量[0.16、0.08mg/次注射（次注）]时，“加载”反应的数量显著增加，而在较高剂量（0.33、0.50、0.66mg/次注）时减少。此后，高剂量（0.33、0.50和0.66mg/次注）时动物以规则间隔的注射间期（INTs）做出反应，低剂量（0.16和0.08mg/次注）时则频繁出现反应爆发和停顿。NA神经元的放电率发生了自发转变，这与不同剂量可卡因行为反应的这种转变显著相关。用多巴胺D1受体拮抗剂SCH23390（5或10μg/kg）预处理可延长NA模式放电的起始时间，类似于低剂量可卡因（0.由这些发现讨论了NA在介导可卡因强化特性中的功能作用。
原文最后一句“0.08 and 0.16 mg/inf.”后面似乎内容不完整，但按照要求完整翻译了给定文本。
