Fouriezos G, Francis S
School of Psychology, University of Ottawa, Ont., Canada.
Behav Brain Res. 1992 Nov 30;52(1):73-80. doi: 10.1016/s0166-4328(05)80326-2.
The participation of dopamine neurons in reward produced by electrical stimulation of the brain was examined by measuring self-stimulation thresholds after injections of apomorphine, a direct agonist of dopamine receptors. Rats were trained to press a lever to obtain 0.3-s trains of electrical stimulation applied to lateral hypothalamic electrodes in a paradigm where the pulse frequency was decreased every eight stimulations by approximately 20%. The pulse frequency interpolated at 50% of maximum rate was taken as threshold. In a completely within-subject design, five doses of apomorphine from 0.01 to 1.00 mg/kg and the ascorbic acid vehicle were injected in a random order and thresholds were tracked at intervals of 5 min for 2 h postinjection. Low doses from 0.01 to 0.10 mg/kg caused thresholds to increase while the two higher doses, 0.30 and 1.00 mg/kg, caused thresholds to drop; the switch in the direction of the behavioural effect is thought to parallel the shift in apomorphine's action from presynaptic to predominantly postsynaptic activation of dopamine receptors as the concentration of apomorphine increases.
通过测量注射阿扑吗啡（一种多巴胺受体直接激动剂）后的自我刺激阈值，研究了多巴胺神经元在脑电刺激产生的奖赏中的参与情况。在一种实验范式中，大鼠经过训练按压杠杆以获得施加于下丘脑外侧电极的0.3秒电刺激序列，在此范式中，每八次刺激后脉冲频率大约降低20%。将最大频率50%时的脉冲频率作为阈值。在完全的受试者内设计中，以随机顺序注射0.01至1.00mg/kg的五种剂量阿扑吗啡以及抗坏血酸载体，并在注射后2小时内每隔5分钟追踪阈值。0.01至0.10mg/kg的低剂量导致阈值升高，而0.30和1.00mg/kg这两种较高剂量导致阈值下降；行为效应方向的转变被认为与随着阿扑吗啡浓度增加，其作用从多巴胺受体的突触前激活转变为主要的突触后激活相平行。
