Ono H, Fukuda H
Neuropharmacology. 1984 Jun;23(6):637-42. doi: 10.1016/0028-3908(84)90144-8.
The experiments were performed on spinal rats transected at Cl. Intravenous administration of methamphetamine-HCl (MA-HCl, 2 mg/kg) and apomorphine-HCl (5 mg/kg) reduced the amplitude of the monosynaptic reflex (MSR), while the polysynaptic reflex was increased by methamphetamine. Depression of the monosynaptic reflex by both drugs was antagonized by haloperidol, but not by phentolamine. Depression of the monosynaptic reflex by methamphetamine was not antagonized by pretreatment with reserpine; however, the result was explained by the assumption that methamphetamine releases newly-synthesized dopamine or that methamphetamine may act directly on dopamine receptors. Depression of the monosynaptic reflex induced by methamphetamine was independent of peripheral changes in blood pressure. Oxygen tension in the spinal cord was slightly reduced by methamphetamine in rats treated with phentolamine and a change of pO2 in the spinal cord was ruled out as a possible mechanism of action. These results suggest that dopaminergic neurons in the spinal cord of the rat depress the transmission of monosynaptic spinal reflexes.
实验在脊髓于颈1水平横断的大鼠身上进行。静脉注射盐酸甲基苯丙胺（MA - HCl，2毫克/千克）和盐酸阿扑吗啡（5毫克/千克）可降低单突触反射（MSR）的幅度，而甲基苯丙胺可增加多突触反射。两种药物对单突触反射的抑制作用可被氟哌啶醇拮抗，但不能被酚妥拉明拮抗。甲基苯丙胺对单突触反射的抑制作用不能被利血平预处理所拮抗；然而，这一结果可通过以下假设来解释：甲基苯丙胺释放新合成的多巴胺，或者甲基苯丙胺可能直接作用于多巴胺受体。甲基苯丙胺诱导的单突触反射抑制与外周血压变化无关。在酚妥拉明处理的大鼠中，甲基苯丙胺可使脊髓中的氧分压略有降低，并且脊髓中pO2的变化被排除为一种可能的作用机制。这些结果表明，大鼠脊髓中的多巴胺能神经元抑制单突触脊髓反射的传递。
