ONTOGENY OF DIAZEPAM-BINDING INHIBITOR-RELATED PEPTIDES (ENDOZEPINES) IN THE RAT-BRAIN
ONTOGENY OF DIAZEPAM-BINDING INHIBITOR-RELATED PEPTIDES (ENDOZEPINES) IN THE RAT-BRAIN
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DOI：
10.1016/0306-4522(93)90023-9
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发表时间：
1993-12-01
期刊：
影响因子：
3.3
通讯作者：
TONON, MC
中科院分区：
文献类型：
--
作者：
MALAGON, M;VAUDRY, H;TONON, MC
苯二氮卓类受体在胚胎期的大脑中表达非常早，这表明这些受体的内源性配体可能在中枢神经系统的个体发育过程中发挥重要作用。在本研究中，使用针对前体分子生物活性区域的抗体，研究了在胚胎和出生后发育过程中大鼠大脑中的地西泮结合的神经递质相关肽（endozepines）的分布和特征。免疫组织化学标记显示，在新生大鼠，endozepine样免疫反应存在于室管膜细胞的下丘脑。虽然阳性细胞的数量增加了第5天，在每个细胞的免疫反应的强度减弱。在15日龄大鼠，室管膜层的endozepine阳性细胞的数量和免疫反应的强度增加。在第40天，在正中隆起和弓状核中观察到免疫反应性伸长细胞和胶质细胞的密集积聚。早在胚胎第18天，通过放射免疫测定法就在大脑的所有区域检测到内皮素。在妊娠晚期，下丘脑和嗅球中内分泌相关肽的浓度增加。从出生到出生后第5天，在所有研究的大脑区域内，内分泌水平下降了2 - 4倍。此后，endozepine浓度逐渐增加，直至第25天。组织提取物的反相高效液相色谱分析显示，嗅球、垂体、下丘脑和小脑仅含有一个在39分钟洗脱的免疫反应峰（峰C）。在端脑中观察到两个峰：峰C和在34 min洗脱的第二个峰（峰B）。峰B早在胚胎第20天就存在，峰B/峰C的比率逐渐增加，直到第25天。在第25天，在海马、延髓、皮质和纹状体提取物中也检测到B峰。在任何脑区中，均未观察到与十八碳神经肽共洗脱的免疫反应性。Sephadex G-50凝胶过滤25日龄动物的下丘脑提取物，证实仅存在一种表观分子量为10，000的免疫反应性化合物。在端脑中，两个主要的物种被解析，具有10，000和8800的表观分子量，以及6500 mol.总之，本研究表明，endozepines早在胚胎第18天就在大鼠脑中表达，并且在出生前两天内，endozepine样物质的量迅速增加。结果还表明，地西泮结合抑制剂被加工成不同的分子形式，这取决于大脑区域。综合这些数据，支持内分泌素可能在大脑发育过程中发挥重要作用的概念。
Benzodiazepine receptors are expressed very early in the brain during embryonic life, suggesting that endogenous ligands for these receptors may play an important role during ontogenesis in the central nervous system. In the present study, the distribution and characterization of diazepam-binding inhibitor-related peptides (endozepines) in the rat brain was investigated during embryonic and postnatal development using an antibody raised against the biologically active region of the precursor molecule. Immunohistochemical labelling showed that, in newborn rats, endozepine-like immunoreactivity was present in ependymal cells of the hypothalamus. Although the number of positive cells increased by day 5, the intensity of the immunoreaction in each cell diminished. In 15-day-old rats, both the number of endozepine positive cells and the intensity of the immunoreaction increased in the ependymal layer. At day 40, a dense accumulation of immunoreactive tanycytes and glial cells was observed in the median eminence and the arcuate nucleus. Endozepines were detected by radioimmunoassay in all regions of the brain as early as embryonic day 18. The concentration of endozepine-related peptides increased in the hypothalamus and olfactory bulb during late gestation. Between birth and postnatal day 5, the levels of endozepines decreased two- to four-fold in all brain regions studied. Thereafter, endozepine concentration increased gradually until day 25. Reversed-phase high-performance liquid chromatography analysis of tissue extracts revealed that the olfactory bulb, pituitary, hypothalamus and cerebellum contained only one immunoreactive peak eluting at 39 min (peak C). In the telencephalon two peaks were observed: peak C and a second one eluting at 34 min (peak B). Peak B was present as early as embryonic day 20 and the ratio peak B/peak C gradually increased until day 25. At day 25 peak B was also detected in hippocampus, medulla oblongata, cortex and striatum extracts. In any brain region, no immunoreactivity co-eluting with the octadecaneuropeptide was observed. Sephadex G-50 gel filtration of hypothalamus extracts of 25-day-old animals, confirmed the existence of only one immunoreactive compound with an apparent molecular weight of 10,000. In the telencephalon two major species were resolved, with apparent molecular weights of 10,000 and 8800, and a minor one of 6500 mol. wt.In conclusion, the present study shows that endozepines are expressed in the rat brain as early as embryonic day 18 and the amount of endozepine-like material increases rapidly during the two days preceding birth. The results also indicate that diazepam-binding inhibitor is processed to different molecular forms depending on the brain region. Taken together these data support the concept that endozepines may play important functions during brain development.