Olds M E
Division of Biology, California Institute of Technology, Pasadena 91125.
Physiol Behav. 1992 Jan;51(1):39-50. doi: 10.1016/0031-9384(92)90201-c.
We previously have reported that nondopamine (non-DA) neurons in substantia nigra (SN) and ventral tegmental area (VTA) of the rat show increased discharge rates during amphetamine (AMPH) and apomorphine (APO)-induced motor activity. The present study represents an attempt to determine the contribution of nucleus accumbens (ACC) dopaminergic activity to these effects, and to ascertain whether the effects in VTA differ from those seen in SN when dopaminergic activity is enhanced locally in ACC. The experiments were carried out in male albino rats (300-400 g) chronically implanted with multiple fine wire electrodes (62 microns) aimed at the pars reticulata of SN (SNR) and VTA. Unit activity was recorded extracellularly in the behaving rat, from neurons identified on the basis of the properties of their action potentials as representing the output of the non-DA neurons in these two structures. In each drug session, unit activity was recorded in parallel from several probes, while motor activity was measured with the open-ended wire technique. But with the recording technique used, a unit represented in most instances the output of a small family of neurons (3-10). Each animal underwent a series of tests given on consecutive days. During these tests, motor and unit activity were measured for 90 min before the drug was administered, and for 135 min after. The first test was of the effects of AMPH, 5 mg/kg, given by the systemic route. The second was of the effects of saline containing 0.1% ascorbic acid (the vehicle) injected bilaterally in ACC, in a volume of 2 microliters per side. The third and all subsequent tests were of the effects of a mixture containing 40 micrograms AMPH, 20 micrograms DA, and 20 micrograms pargyline (P) dissolved in 2 microliters of the vehicle, injected bilaterally in ACC. The results showed that systemic AMPH made the animal hyperactive and at the same time, increased the discharge rate of the non-DA neurons. The bilateral injections of the vehicle in ACC, increased motor activity for about 7 min, an effect interpreted as a rebound from the restraint of the animal during the intracerebral injections, and then depressed motor throughout the 135 min of the postinjection recording period. The effect of the vehicle was to depress unit activity. The effects of injecting the mixture in ACC was to increase motor activity, but with the magnitude and duration of the increase depending on the number of treatments received.(ABSTRACT TRUNCATED AT 400 WORDS)
我们之前报道过，大鼠黑质（SN）和腹侧被盖区（VTA）中的非多巴胺（non-DA）神经元在苯丙胺（AMPH）和阿扑吗啡（APO）诱导的运动活动期间放电率增加。本研究旨在确定伏隔核（ACC）多巴胺能活动对这些效应的作用，并确定当ACC局部多巴胺能活动增强时，VTA中的效应是否与SN中的不同。实验在慢性植入多根细线电极（62微米）的雄性白化大鼠（300 - 400克）身上进行，电极指向SN的网状部（SNR）和VTA。在行为学大鼠中通过细胞外记录单位活动，这些神经元根据其动作电位特性被鉴定为代表这两个结构中非DA神经元的输出。在每次给药实验中，从多个探针并行记录单位活动，同时用开放式电线技术测量运动活动。但就所使用的记录技术而言，一个单位在大多数情况下代表一小群神经元（3 - 10个）的输出。每只动物连续几天接受一系列测试。在这些测试中，在给药前90分钟和给药后135分钟测量运动和单位活动。第一次测试是关于全身给予5毫克/千克AMPH的效果。第二次测试是关于双侧在ACC注射含0.1%抗坏血酸的生理盐水（溶剂）的效果，每侧注射体积为2微升。第三次及所有后续测试是关于将含40微克AMPH、20微克多巴胺和20微克帕吉林（P）溶解在2微升溶剂中的混合物双侧注射到ACC的效果。结果表明，全身给予AMPH使动物活动亢进，同时增加了非DA神经元的放电率。双侧在ACC注射溶剂使运动活动增加约7分钟，这一效应被解释为脑内注射期间动物受到约束后的反弹，然后在注射后记录期的135分钟内运动活动受到抑制。溶剂的作用是抑制单位活动。在ACC注射混合物的作用是增加运动活动，但增加的幅度和持续时间取决于接受治疗的次数。（摘要截短至400字）
