Lacaille J C, Schwartzkroin P A
Department of Neurological Surgery, University of Washington, Seattle 98195.
J Neurosci. 1988 Apr;8(4):1400-10. doi: 10.1523/JNEUROSCI.08-04-01400.1988.
Stable intracellular recordings were obtained from nonpyramidal cells (interneurons) in stratum lacunosum-moleculare (L-M) of the CA1 region of guinea pig hippocampal slices. The intracellular response characteristics of these interneurons were distinctly different from responses of pyramidal cells and of other interneurons (basket cells and oriens-alveus interneurons). L-M interneurons had a high resting membrane potential (-58 mV), a high input resistance (64 M omega), and a large amplitude (60 mV), relatively long duration (2 msec) action potential. A large afterhyperpolarization (11 mV, 34 msec) followed a single action potential. Most L-M interneurons did not display any spontaneous firing. Lucifer yellow (LY)-filled L-M interneurons showed nonpyramidal morphology. Cells were generally fusiform or multipolar, with aspinous, beaded dendritic processes ramifying in stratum lacunosum-moleculare, radiatum, and (sometimes) oriens. The varicose axon originated from a primary dendrite, projected along stratum lacunosum-moleculare, branched profusely in stratum radiatum, and coursed toward and into stratum pyramidale and occasionally into oriens. Processes of cells with somata in the L-M region of CA1 were not restricted to the CA1 region. The dendritic and axonal processes of some L-M interneurons were seen ascending in stratum lacunosum-moleculare, crossing the hippocampal fissure, and coursing in stratum moleculare of the dentate gyrus. Excitatory and inhibitory postsynaptic potentials (EPSPs and IPSPs) were evoked in L-M interneurons from stimulation of major hippocampal afferents. EPSPs were most effectively elicited by stimulation of fiber pathways in transverse slices, whereas IPSPs were predominantly evoked when major pathways were stimulated in longitudinal slices. We have identified a population of interneurons with intracellular response characteristics and morphology distinctly different from previously described pyramidal and nonpyramidal neurons of CA1 region. The possible role of these interneurons in hippocampal circuitry is discussed.
从豚鼠海马切片CA1区的腔隙-分子层（L-M）中的非锥体细胞（中间神经元）获得了稳定的细胞内记录。这些中间神经元的细胞内反应特性与锥体细胞以及其他中间神经元（篮状细胞和海马槽-海马伞中间神经元）的反应明显不同。L-M中间神经元具有较高的静息膜电位（-58 mV）、较高的输入电阻（64 MΩ）以及幅度较大（60 mV）、持续时间相对较长（2毫秒）的动作电位。单个动作电位之后会出现较大的超极化后电位（11 mV，34毫秒）。大多数L-M中间神经元不表现出任何自发放电。用荧光黄（LY）标记的L-M中间神经元呈现出非锥体形态。细胞通常呈梭形或多极形，无棘、串珠状的树突分支在腔隙-分子层、辐射层以及（有时）海马槽层中延伸。曲张的轴突起源于一条初级树突，沿腔隙-分子层投射，在辐射层大量分支，并朝向并进入锥体层，偶尔进入海马槽层。胞体位于CA1区L-M区域的细胞的突起并不局限于CA1区。一些L-M中间神经元的树突和轴突突起可见于在腔隙-分子层中上升，穿过海马裂，并在齿状回的分子层中延伸。通过刺激主要的海马传入纤维在L-M中间神经元中诱发了兴奋性和抑制性突触后电位（EPSP和IPSP）。横向切片中纤维通路的刺激最有效地诱发了EPSP，而纵向切片中主要通路受到刺激时则主要诱发IPSP。我们已经鉴定出了一群中间神经元，其细胞内反应特性和形态与先前描述的CA1区锥体神经元和非锥体神经元明显不同。讨论了这些中间神经元在海马回路中的可能作用。
