Trulson M E, Trulson T J
Exp Neurol. 1987 Apr;96(1):68-81. doi: 10.1016/0014-4886(87)90169-5.
We examined the electrophysiologic and pharmacologic properties of dopamine-containing ventral tegmental area neurons in the mouse using extracellular single-unit recording techniques in both chloral hydrate-anesthetized mice and in vitro mouse midbrain slices. In vivo the ventral tegmental area neurons had long-duration action potentials (2 to 5 ms) and discharged at 1 to 9 spikes/s with either a decremental burst pattern or a regular pattern. Systemic administration of the dopamine agonist, apomorphine, decreased their firing rate, and the dopamine receptor blocker, haloperidol, reversed this effect. Similarly, systemic administration of the dopamine-releasing agent, d-amphetamine, suppressed their discharge rate, an effect blocked by pretreatment of the animals with alpha-methyl-p-tyrosine. When recorded in vitro from midbrain slices, ventral tegmental area neurons showed electrophysiologic properties similar to those found in vivo; however, the neurons recorded in vitro fired at a significantly faster rate and their firing pattern tended to be more pacemaker-like, especially when recordings were made in an incubation medium that blocked synaptic transmission (i.e., low calcium/high magnesium). The activity of most of these neurons was suppressed by addition of apomorphine to the incubation medium, an effect reversed by haloperidol. Pretreatment with alpha-methyl-p-tyrosine produced no significant change in the discharge pattern or rate for cells recorded in vitro. These data indicate that mouse ventral tegmental area dopamine neurons in vivo exhibit the same electrophysiologic and pharmacologic properties as do rat and cat dopamine-containing neurons and that in vitro they fire with pacemaker regularity in a low-calcium/high-magnesium medium. The in vitro preparation offers an approach to examining the fundamental properties of ventral tegmental area dopamine-containing neurons in the absence of afferent inputs.
我们运用细胞外单单位记录技术，在水合氯醛麻醉的小鼠以及体外小鼠中脑切片上，研究了小鼠中含多巴胺的腹侧被盖区神经元的电生理和药理特性。在体内，腹侧被盖区神经元具有长时间的动作电位（2至5毫秒），以递减爆发模式或规则模式，每秒发放1至9个峰电位。全身给予多巴胺激动剂阿扑吗啡会降低其放电频率，而多巴胺受体阻滞剂氟哌啶醇可逆转此效应。同样，全身给予多巴胺释放剂d-苯丙胺会抑制其放电频率，用α-甲基-p-酪氨酸预处理动物可阻断此效应。从中脑切片进行体外记录时，腹侧被盖区神经元显示出与体内发现的类似的电生理特性；然而，体外记录的神经元放电速度明显更快，其放电模式更倾向于起搏器样，尤其是在阻断突触传递的孵育介质（即低钙/高镁）中进行记录时。向孵育介质中添加阿扑吗啡可抑制这些神经元中的大多数的活性，氟哌啶醇可逆转此效应。用α-甲基-p-酪氨酸预处理对体外记录的细胞的放电模式或频率没有显著影响。这些数据表明，体内的小鼠腹侧被盖区多巴胺神经元表现出与大鼠和猫含多巴胺神经元相同的电生理和药理特性，并且在体外，它们在低钙/高镁介质中以起搏器规律性放电。体外制备方法为在无传入输入的情况下研究腹侧被盖区含多巴胺神经元的基本特性提供了一种途径。
