黑质多巴胺触液神经元

将30％ HRP 8—10μl或3％碘化丙啶(PI)3μl分别注入两组动物单侧侧脑室内,48小时后将鼠处死,检查中脑切片。发现双侧黑质均司见HRP标记细胞群,但以同侧为主。标记范围以中脑中上部为多。标记细胞主要分布在黑质致密带内侧部,网状带中仅少数散在。注射PI例所见类同,但标记细胞远较HRP标记细胞为多。TH免疫组化法发现黑质DA神经元投射纤维分散布于尾壳核,并见TH阳性投射纤维在室管膜上皮细胞的深面形成密集的膨大,个别地区还见阳性终末突入侧脑室。另外,在接受胚中脑黑质移植存活良好的受体鼠纹状体中,发现少数移植存活的TH阳性黑质DA神经元胞体或其突起伸入侧脑室室管膜上皮细胞间甚或突入室腔。实验表明部分黑质多巴胺神经元系触液神经元,提示可能直接释放DA入脑脊液。当胚黑质细胞被移植入受体脑纹状体后,部分黑质DA神经元重演其发育的规律,将其突起或胞体伸入室管膜上皮细胞间或突入侧脑室,以代偿其原有的功能。

CEREBROSPINAL FLUID(CSF) CONTACTING DOPAMINERGIC NEURONS IN THE SUBSTANTIA NIGRA

Injecting HRP or propidium iodide (PI) into the unilateral lateral ventricle of the Sprague-Dawley rats, HRP labeled neurons were found bilaterally in the substantia nigra (SN) of the midbrain with intense labeled cells ipsilaterally. Labeled neurons were located mainly in the medial part of the pars compacta of the SN. A few la beled cells were found in the pars reticulata of the SN. Almost all of the dopaminergic neurons in the SN bilaterally exhibited PI fluoresence. With the immunocytochemistry ABC method, the distribution of tyrosine hydroxylase (TH) immunoreaction positive fibers of nigrostriatal projections were studied. The TH positive fibers were distri buted diffusely in the caudateputamen. Beneath the ependymal epithelium numerous immunostained varicosities were observed. In some regions TH positive terminals extended into the lateral ventricle. Dopaminergic neurons were studied in transplants of the embryonic SN survived for 1-16 months in the brain of host rats of which the motor imbalance was successfully restored. TH immunoreactive cells and their processes were found in the parenchyma of the caudate nucleus. Some of them were in contact with or entering into the ependyma or gave rise to dendrites to the ependyma. The results indicated that a part of SN dopaminergic neurons are cerebrospinal fluid contacting neurons which might secrete dopamine directly into CSF and during transplantation the survived dopaminergic neurons contacting with CSF might repeat their developmental process.