中缝背核中5-羟色胺能和非5-羟色胺能细胞的鉴别特征：电生理学和免疫组织化学研究
Distinguishing characteristics of serotonin and non-serotonin-containing cells in the dorsal raphe nucleus: electrophysiological and immunohistochemical studies.
作者信息
Kirby L G, Pernar L, Valentino R J, Beck S G
机构信息
Department of Pediatrics, Joseph Stokes Jr. Research Institute, Abramson Research Center, 4th Floor North, Children's Hospital of Philadelphia, Philadelphia, PA 19104-4318, USA.
出版信息
Neuroscience. 2003;116(3):669-83. doi: 10.1016/s0306-4522(02)00584-5.
The membrane properties and receptor-mediated responses of rat dorsal raphe nucleus neurons were measured using intracellular recording techniques in a slice preparation. After each experiment, the recorded neuron was filled with neurobiotin and immunohistochemically identified as 5-hydroxytryptamine (5-HT)-immunopositive or 5-HT-immunonegative. The cellular characteristics of all recorded neurons conformed to previously determined classic properties of serotonergic dorsal raphe nucleus neurons: slow, rhythmic activity in spontaneously active cells, broad action potential and large afterhyperpolarization potential. Two electrophysiological characteristics were identified that distinguished 5-HT from non-5-HT-containing cells in this study. In 5-HT-immunopositive cells, the initial phase of the afterhyperpolarization potential was gradual (tau=7.3+/-1.9) and in 5-HT-immunonegative cells it was abrupt (tau=1.8+/-0.6). In addition, 5-HT-immunopositive cells had a shorter membrane time constant (tau=21.4+/-4.4) than 5-HT-immunonegative cells (tau=33.5+/-4.2). Interestingly, almost all recorded neurons were hyperpolarized in response to stimulation of the inhibitory 5-HT(1A) receptor. These results suggested that 5-HT(1A) receptors are present on non-5-HT as well as 5-HT neurons. This was confirmed by immunohistochemistry showing that although the majority of 5-HT-immunopositive cells in the dorsal raphe nucleus were double-labeled for 5-HT(1A) receptor-IR, a small but significant population of 5-HT-immunonegative cells expressed the 5-HT(1A) receptor. These results underscore the heterogeneous nature of the dorsal raphe nucleus and highlight two membrane properties that may better distinguish 5-HT from non-5-HT cells than those typically reported in the literature. In addition, these results present electrophysiological and anatomical evidence for the presence of 5-HT(1A) receptors on non-5-HT neurons in the dorsal raphe nucleus.
在脑片标本中，运用细胞内记录技术测定大鼠中缝背核神经元的膜特性和受体介导的反应。每次实验后，将记录的神经元用神经生物素填充，并通过免疫组织化学鉴定为5-羟色胺（5-HT）免疫阳性或5-HT免疫阴性。所有记录神经元的细胞特征均符合先前确定的中缝背核5-羟色胺能神经元的经典特性：自发活动细胞的缓慢、节律性活动，宽动作电位和大的超极化后电位。在本研究中，确定了两个区分5-HT和不含5-HT细胞的电生理特征。在5-HT免疫阳性细胞中，超极化后电位的初始阶段是逐渐的（时间常数τ=7.3±1.9），而在5-HT免疫阴性细胞中是突然的（时间常数τ=1.8±0.6）。此外，5-HT免疫阳性细胞的膜时间常数（时间常数τ=21.4±4.4）比5-HT免疫阴性细胞（时间常数τ=33.5±4.2）短。有趣的是，几乎所有记录的神经元在受到抑制性5-HT（1A）受体刺激时都会发生超极化。这些结果表明，5-HT（1A）受体存在于非5-HT以及5-HT神经元上。免疫组织化学证实了这一点，结果显示，尽管中缝背核中大多数5-HT免疫阳性细胞对5-HT（1A）受体免疫反应性呈双重标记，但一小部分但数量可观的5-HT免疫阴性细胞表达5-HT（1A）受体。这些结果强调了中缝背核的异质性，并突出了两个膜特性，与文献中通常报道的特性相比，这两个特性可能能更好地区分5-HT和非5-HT细胞。此外，这些结果为中缝背核非5-HT神经元上存在5-HT（1A）受体提供了电生理和解剖学证据。
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