Heterogeneity of ventral tegmental area neurons: Single-unit recording and iontophoresis in awake, unrestrained rats
Heterogeneity of ventral tegmental area neurons: Single-unit recording and iontophoresis in awake, unrestrained rats
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DOI：
10.1016/s0306-4522(98)00054-2
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发表时间：
1998-08-01
期刊：
影响因子：
3.3
通讯作者：
Rebec, GV
中科院分区：
文献类型：
--
作者：
Kiyatkin, EA;Rebec, GV
在清醒、不受约束的大鼠中使用单单位记录结合多巴胺、GABA 和谷氨酸的离子电渗疗法来表征自然发生的行为条件下腹侧被盖区神经元的电生理和受体特性。对所有分离的腹侧被盖区域单位（n = 90）进行了分析，并与从红前区域和红核的背侧邻近区域记录的细胞（n = 58）进行了比较。在腹侧被盖区识别出不同的神经元组：具有三相、长持续时间尖峰的单元（78/90）和具有双相、短持续时间尖峰的单元（12/90）。尽管所有长尖峰单元都以不规则的爆发模式放电，并且尖峰幅度有不同程度的爆发内衰减，但它们可以进一步细分为至少三个不同的子组。 I型长钉单位（36/78）以相对缓慢且稳定的速率放电（平均值：6.03 imp/s；范围：0.42-15.78），运动过程中没有明显的波动。这些细胞受到多巴胺和 GABA 的抑制，并以低强度的兴奋对谷氨酸做出反应，伴随着尖峰幅度的显着下降和强大的反弹抑制。 II 型长钉单位 (23/78) 具有相对较高且不稳定的放电速率（平均值：22.82 imp/s；范围：4.42-59.67），并且经常表现出与运动相关的阶段性激活，随后部分或完全停止发射。一些 II 型细胞 (4/9) 受到多巴胺的抑制，但所有细胞都在非常低的电流 (0-10 nA) 下被谷氨酸激发。随着电流的增加，谷氨酸引起的兴奋常常(18/22)进展为放电停止。所有这些细胞均被 GABA 抑制，随后出现强烈的反弹激发 (8/9)，这也经常 (6/8) 导致放电停止。 III 型长刺单元 (19/78) 具有与 I 型或 II 型细胞不同的特性，包括缺乏自发放电 (5/19)。短尖峰腹侧被盖区单位要么沉默（4/12），对多巴胺和 GABA 无反应，要么自发活跃（范围：0.89-34.13 imp/s）并被 GABA 抑制，在某些情况下（2/8）被多巴胺抑制；所有这些都在运动和谷氨酸离子电渗疗法期间被阶段性激活。 看来，腹侧被盖区神经元，包括那些具有长时间尖峰的神经元，在清醒、不受约束的大鼠中并不构成均匀的群体。 I 型长尖峰单元与组织化学鉴定的多巴胺神经元的特征相匹配，并且它们似乎表达多巴胺自身受体，这可以解释相对缓慢、稳定的活动速率以及对兴奋性输入的有限反应。尽管我们的样本中其他长刺单元的性质尚不清楚，但它们可能包括没有自身受体的多巴胺神经元以及非多巴胺细胞。腹侧被盖区神经元的异质性是进一步尝试评估中皮质边缘多巴胺系统在动机行为中的作用的重要考虑因素。 (C) 1998 国际广播组织。由爱思唯尔科学有限公司出版
Single-unit recording combined with iontophoresis of dopamine, GABA, and glutamate was used in awake, unrestrained rats to characterize the electrophysiological and receptor properties of neurons in the ventral tegmental area under naturally occurring behavioural conditions. All isolated ventral tegmental area units (n=90) were analysed and compared with cells (n=58) recorded from dorsally adjacent areas of the pre-rubral area and red nucleus. Tyro distinct neuronal groups were identified in the ventral tegmental area: units with triphasic, long-duration spikes (78/90) and units with biphasic, short-duration spikes (12/90). Although all long-spike units discharged in an irregular, bursting pattern with varying degrees of within-burst decrements in spike amplitude, they could be further subdivided into at least three distinct subgroups. Type I long-spike units (36/78) discharged at a relatively slow and stable rate (mean: 6.03 imp/s; range: 0.42-15.78) with no evident fluctuations during movement. These cells were inhibited by dopamine and GABA and responded to glutamate with a low-magnitude excitation accompanied by a pronounced decrement in spike amplitude and a powerful rebound inhibition. Type II long-spike units (23/78) had relatively high and unstable discharge rates (mean: 22.82 imp/s; range: 4.42-59.67) and showed movement-related phasic activations frequently followed by partial or complete cessation of firing. Some Type II cells (4/9) were inhibited by dopamine, but all were excited by glutamate at very low currents (0-10 nA). With an increase in current, the glutamate-induced excitation often(18/22) progressed into a cessation of firing. All these cells were inhibited by GABA followed by a strong rebound excitation (8/9), which also frequently (6/8) resulted in cessation of firing. Type III long-spike units (19/78) had properties that differed from either Type I or Type II cells, including a lack of spontaneous firing (5/19). Short-spike ventral tegmental area units were either silent (4/12) and unresponsive to dopamine and GABA or spontaneously active (range: 0.89-34.13 imp/s) and inhibited by GABA and, in some cases (2/8), by dopamine; all were phasically activated during movement and glutamate iontophoresis.It appears that ventral tegmental area neurons, including those with long-duration spikes, do not comprise a uniform population in awake, unrestrained rats. Type I, long-spike units match the characteristics of histochemically-identified dopamine neurons, and they appear to express dopamine autoreceptors, which may explain the relatively slow, stable rate of activity and the limited responsiveness to excitatory inputs. Although the nature of the other long-spike units in our sample is unclear, they may include dopamine neurons without autoreceptors as well as non-dopamine cells. The heterogeneity of ventral tegmental area neurons is an important consideration for further attempts to assess the role of the mesocorticolimbic dopamine system in motivated behaviour. (C) 1998 IBRO. Published by Elsevier Science Ltd.