Hollingsworth E B, McNeal E T, Burton J L, Williams R J, Daly J W, Creveling C R
J Neurosci. 1985 Aug;5(8):2240-53. doi: 10.1523/JNEUROSCI.05-08-02240.1985.
A particulate preparation was obtained by low speed centrifugation of guinea pig cerebral cortical homogenates prepared with a Krebs-Henseleit buffer. Light microscopic examination, using a reflected light differential interference contrast system, reveals the presence of intact neurons, axonal fragments, glial cells, and erythrocytes along with an abundance of small spherical entities (diameter about 1.1 micron) and snowman-shaped entities (diameter of larger sphere about 1.1 micron, diameter of attached smaller sphere about 0.6 micron). Many unattached smaller spherical entities are also present (diameter about 0.6 micron). Pressure filtration through 5- or 10-micron Millipore filters, followed by low speed centrifugation and resuspension, removes most of the larger entities to afford a suspension composed mainly of the small spherical and snowman-shaped entities. Electron microscopic examination reveals the presence of many synaptosomes with attached resealed postsynaptic entities. It is proposed that these correspond to the snowman-shaped entities to be termed synaptoneurosomes. Accumulations of cyclic AMP elicited by 2-chloroadenosine and histamine, and by combinations of 2-chloroadenosine, histamine, norepinephrine, and forskolin, are lower in filtered than in unfiltered preparations, whereas accumulations elicited by forskolin are unchanged. Levels of adenylate cyclase are reduced by filtration, whereas levels of phosphodiesterase are unchanged. Filtration reduces levels of markers for whole cells and endothelial cells, whereas neuronal markers such as acetylcholinesterase activity and norepinephrine uptake are increased. Levels of S-100 protein, a marker for glial cells, are not significantly decreased. There is no apparent change in the density of many receptors or ion channels. Levels of A1-adenosine and H1-histamine receptors are increased, whereas levels of so-called peripheral benzodiazepine-binding sites are decreased.
用Krebs-Henseleit缓冲液制备豚鼠大脑皮质匀浆，通过低速离心获得颗粒制剂。使用反射光微分干涉对比系统进行光学显微镜检查，发现存在完整的神经元、轴突片段、神经胶质细胞和红细胞，以及大量小的球形实体（直径约1.1微米）和雪人状实体（较大球体直径约1.1微米，附着的较小球体直径约0.6微米）。也存在许多未附着的较小球形实体（直径约0.6微米）。通过5或10微米的微孔滤膜进行压力过滤，然后低速离心并重新悬浮，去除了大部分较大的实体，得到主要由小的球形和雪人状实体组成的悬浮液。电子显微镜检查发现存在许多带有附着的重新封闭的突触后实体的突触体。有人提出，这些对应于将被称为突触神经小体的雪人状实体。2-氯腺苷和组胺以及2-氯腺苷、组胺、去甲肾上腺素和福斯可林组合引起的环磷酸腺苷积累，过滤后的制剂比未过滤的制剂低，而福斯可林引起的积累没有变化。腺苷酸环化酶水平通过过滤降低，而磷酸二酯酶水平没有变化。过滤降低了全细胞和内皮细胞标志物的水平，而神经元标志物如乙酰胆碱酯酶活性和去甲肾上腺素摄取增加。神经胶质细胞标志物S-100蛋白的水平没有显著降低。许多受体或离子通道的密度没有明显变化。A1-腺苷和H1-组胺受体水平增加，而所谓的外周苯二氮䓬结合位点水平降低。
