Persson S A
Eur J Pharmacol. 1979 Apr 15;55(2):121-8. doi: 10.1016/0014-2999(79)90383-2.
Acute systemic administration of morphine (10 mg/kg s.c.) to rats increased in vivo tyrosine hydroxylation in the striatum measured as the accumulation of DOPA after decarboxylase inhibition. DOPA accumulation reached a maximum 30-60 min after morphine. The morphine antagonist naloxone (1, 10 or 100 mg/kg s.c.) did not significantly after DOPA accumulation. However, naloxone completely antagonized the effect of morphine. The DA agonist apomorphine decreased and the DA antagonist haloperidol increased DOPA accumulation. The effect of apomorphine (0.05 mg/kg) was counteracted by morphine. Naloxone did not significantly change the accumulation of DOPA after apomorphine or after haloperidol. In rats treated with gamma-butyrolactone (GBL) or with reserpine DOPA accumulation was not altered by treatment with morphine or naloxone. However, the inhibiting effect of apomorphine (0.5 mg/kg) on the accumulation of DOPA in rats treated with reserpine was weakly counteracted by morphine (0.5 mg/kg) on the accumulation of DOPA in rats treated with reserpine was weakly counteracted by morphine (10 mg/kg s.c.). Since the effects of morphine on the apomorphine-induced inhibition of DOPA accumulation were antagonized by naloxone, we suggest that the effects on striatal DOPA accumulation produced by morphine were mediated via opioid receptors and not directly via DA receptors.
对大鼠进行吗啡（10毫克/千克，皮下注射）急性全身给药后，纹状体内的体内酪氨酸羟化作用增强，通过抑制脱羧酶后多巴（DOPA）的积累来衡量。吗啡给药后30 - 60分钟，DOPA积累达到最大值。吗啡拮抗剂纳洛酮（1、10或100毫克/千克，皮下注射）对DOPA积累没有显著影响。然而，纳洛酮完全拮抗了吗啡的作用。多巴胺（DA）激动剂阿扑吗啡降低了DOPA积累，而DA拮抗剂氟哌啶醇则增加了DOPA积累。阿扑吗啡（0.05毫克/千克）的作用被吗啡抵消。纳洛酮对阿扑吗啡或氟哌啶醇给药后的DOPA积累没有显著影响。在用γ-丁内酯（GBL）或利血平处理的大鼠中，吗啡或纳洛酮处理不会改变DOPA积累。然而，吗啡（10毫克/千克，皮下注射）对利血平处理的大鼠中阿扑吗啡（0.5毫克/千克）抑制DOPA积累的作用有微弱的抵消作用。由于纳洛酮拮抗了吗啡对阿扑吗啡诱导的DOPA积累抑制的作用，我们认为吗啡对纹状体DOPA积累的作用是通过阿片受体介导的，而不是直接通过DA受体。
