Holmes L J, Wise R A
Brain Res. 1985 Feb 4;326(1):19-26. doi: 10.1016/0006-8993(85)91380-0.
Unilateral morphine application to sites in the ventral tegmentum caused contralateral circling. Positive sites were restricted to the region of the dopamine-containing cells in the ventral tegmental area and substantia nigra; rates were highest with ventral tegmental application. The opiate receptor antagonists naltrexone and naloxone blocked morphine-induced circling whether given before or during the sessions. Pimozide pretreatment also blocked morphine-induced circling at doses that spared muscimol-induced circling. Morphine induced little postural asymmetry and induced forward locomotion in all 4 limbs. The radius of morphine-induced circling was large or small depending on the size of the test environment; thus the behavior was controlled by environmental (sensory) and not central (motor) constraints. These studies suggest that morphine-induced circling results from activation of dopaminergic circuitry involved in sensory-motor integration, particularly that involved in forward locomotion.
向腹侧被盖区的位点单侧注射吗啡会导致对侧转圈。阳性位点局限于腹侧被盖区和黑质中含多巴胺细胞的区域；向腹侧被盖区注射时发生率最高。阿片受体拮抗剂纳曲酮和纳洛酮，无论在实验前还是实验期间给药，均可阻断吗啡诱导的转圈。匹莫齐特预处理也可在不影响蝇蕈醇诱导的转圈的剂量下阻断吗啡诱导的转圈。吗啡几乎不引起姿势不对称，且能诱导四肢向前运动。吗啡诱导的转圈半径大小取决于测试环境的大小；因此，该行为受环境（感觉）而非中枢（运动）限制的控制。这些研究表明，吗啡诱导的转圈是由参与感觉运动整合的多巴胺能神经回路激活所致，尤其是参与向前运动的神经回路。
