Liebman J, Segal D S
Brain Res. 1977 Nov 4;136(1):103-17. doi: 10.1016/0006-8993(77)90135-4.
The effects of morphine were investigated on self-stimulation from numerous electrode placements in the area of the substantia nigra or in the ventral half of mesencephalic central gray matter. Before pharmacological testing, current intensity was reduced to yield stable, submaximal rates of self-stimulation. Rats were then injected daily with morphine for 10 days, and were tested three hours after injection. Between days 5 and 10 of treatment, many rats self-stimulated at more than 150% of baseline, but some others reduced self-stimulation to as little as 3% of baseline. Histological evaluation revealed that morphine facilitated self-stimulation when the electrode tip was located more than 0.3 mm from substantia nigra or more than 0.2 mm from the midline of central gray. In rats with electrode tips closer to substantia nigra or to the midline of central gray, morphine often reduced or failed to alter self-stimulation rates. The effects of a low dose of D-amphetamine (0.1 mg/kg) were investigated on electrode placements in the substantia nigra area. Placements close to the dorsal border of substantia nigra yielded less facilitation of self-stimulation by D-amphetamine than did placements located more dorsally or medially. Possible catecholaminergic substrates of these differential effects are discussed.
研究了吗啡对从黑质区域或中脑中央灰质腹侧半区多个电极位置进行自我刺激的影响。在进行药理学测试之前，降低电流强度以产生稳定的、低于最大刺激率的自我刺激。然后，大鼠每天注射吗啡，持续10天，并在注射后3小时进行测试。在治疗的第5天至第10天期间，许多大鼠的自我刺激率超过基线的150%，但也有一些大鼠将自我刺激率降低至基线的3%。组织学评估显示，当电极尖端距离黑质超过0.3毫米或距离中央灰质中线超过0.2毫米时，吗啡会促进自我刺激。在电极尖端更靠近黑质或中央灰质中线的大鼠中，吗啡通常会降低或未能改变自我刺激率。研究了低剂量D-苯丙胺（0.1毫克/千克）对黑质区域电极位置的影响。靠近黑质背侧边界的电极位置比位于更靠背侧或内侧的电极位置，D-苯丙胺对自我刺激的促进作用更小。讨论了这些差异效应可能的儿茶酚胺能底物。
