Aika Y, Ren J Q, Kosaka K, Kosaka T
Department of Anatomy and Neurobiology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Exp Brain Res. 1994;99(2):267-76. doi: 10.1007/BF00239593.
The numerical density of neurons in the CA1 region of the rat dorsal hippocampus has been estimated by a stereological method, the disector, using pairs of video images of toluidine blue-stained, plastic-embedded, 0.5-microns-thick sections, 3 microns distant from each other. The chemical properties of those disector-counted cells were further analyzed by postembedding immunocytochemical methods on adjacent, semithin sections using antibodies against gamma-aminobutyric acid (GABA) and a specific calcium-binding protein, parvalbumin (PV). The density of neurons in the CA1 region was 35.2 x 10(3)/mm3; numerical densities in the stratum oriens (SO), stratum pyramidale (SP), and strata radiatum-lacunosum-moleculare (SRLM) were 11.3 x 10(3)/mm3, 272.4 x 10(3)/mm3, and 1.9 x 10(3)/mm3, respectively. The numerical densities of GABA-like immunoreactive (GABA-LIR) and PV-immunoreactive (PV-IR) neurons were 2.1 x 10(3)/mm3 and 1.1 x 10(3)/mm3, respectively, which were 5.8% and 3.2% of all neurons, respectively. In the CA1 region only about 60% of PV-positive neurons were GABA-LIR. However, taking the previous observation into consideration that almost all hippocampal PV-positive neurons were immunoreactive for the GABA-synthesizing enzyme glutamic acid decarboxylase (GAD), neurons that were immunoreactive to either GABA or PV or both (GABA+ and/or PV+ neurons) were regarded as a better representative of GABAergic neurons in this region; thus, the numerical density of these GABA+ and/or PV+ neurons was 2.5 x 10(3)/mm3 and they were 7.0% of all neurons in the CA1 region. Lamellar analysis showed that the numerical densities of GABA+ and/or PV+, GABA-LIR, and PV-IR neurons were highest in the SP, where they were 8.2 x 10(3)/mm3, 6.2 x 10(3)/mm3, and 5.4 x 10(3)/mm3, respectively. The results of the present study indicate that the proportions of GABAergic neurons and a subpopulation of them, PV-containing GABAergic neurons, to other presumable non-GABAergic neurons are far smaller in the CA1 region of the hippocampus than in several neocortical regions previously reported.
采用体视学方法——分割法，通过成对的视频图像，对大鼠背侧海马CA1区的神经元数量密度进行了估计。这些视频图像来自甲苯胺蓝染色、塑料包埋、厚度为0.5微米、间距为3微米的切片。使用抗γ-氨基丁酸（GABA）抗体和一种特异性钙结合蛋白——小白蛋白（PV），通过对相邻半薄切片进行包埋后免疫细胞化学方法，进一步分析了这些通过分割法计数的细胞的化学性质。CA1区神经元的密度为35.2×10³/mm³；海马下托（SO）、锥体层（SP）和辐射层-腔隙层-分子层（SRLM）的神经元数量密度分别为11.3×10³/mm³、272.4×10³/mm³和1.9×10³/mm³。GABA样免疫反应性（GABA-LIR）神经元和PV免疫反应性（PV-IR）神经元的数量密度分别为2.1×10³/mm³和1.1×10³/mm³，分别占所有神经元的5.8%和3.2%。在CA1区，仅约60%的PV阳性神经元为GABA-LIR。然而，考虑到之前的观察结果，即几乎所有海马PV阳性神经元对GABA合成酶谷氨酸脱羧酶（GAD）均有免疫反应，对GABA或PV或两者均有免疫反应的神经元（GABA+和/或PV+神经元）被视为该区域GABA能神经元的更好代表；因此，这些GABA+和/或PV+神经元的数量密度为2.5×10³/mm³，占CA1区所有神经元的7.0%。分层分析表明，GABA+和/或PV+、GABA-LIR和PV-IR神经元的数量密度在SP中最高，分别为8.2×10³/mm³、6.2×10³/mm³和5.4×10³/mm³。本研究结果表明，海马CA1区GABA能神经元及其一个亚群——含PV的GABA能神经元，在所有可能的非GABA能神经元中所占比例，远小于先前报道的几个新皮质区域。
