Sato S M, Mains R E
Department of Neuroscience, Johns Hopkins University, Baltimore, Maryland 21205.
Endocrinology. 1988 Jan;122(1):68-77. doi: 10.1210/endo-122-1-68.
Intermediate pituitary lobe cells from newborn rats were maintained in culture to determine the extent to which they continue to exhibit the tissue-specific properties of the newborn and adult intermediate pituitary lobes. At all times examined these cultures contained mostly alpha MSH-sized and corticotropin-like intermediate lobe peptide-sized peptides; the alpha MSH-sized peptides were predominantly diacetyl-ACTH-(1-13)NH2. After 6 days in culture, the intermediate pituitary lobe cells retained the ability to synthesize diacetyl-ACTH-(1-13)NH2. Compared to that of the adult, the newborn anterior pituitary lobe is enriched in high mol wt forms of ACTH-related molecules. Therefore, the ability of newborn anterior pituitary lobe cell cultures to develop the adult processing pattern in culture was investigated. After 6 days in culture, peptides the size of alpha MSH predominated rather than ACTH-(1-39), which is the major form found in the adult. Immunocytochemical studies showed that all cultured newborn corticotropes strongly stained for alpha MSH-related material. The alpha MSH-sized molecules were identified as ACTH-(1-13)NH2 by reverse phase HPLC. In 6-day-old cultures of neonatal anterior pituitary lobes grown in the presence of a synthetic glucocorticoid, dexamethasone, the amount of alpha MSH-sized material was diminished, and instead, precursor forms of the ACTH-related peptides were detected. In biosynthetic labeling experiments, the ratio of newly synthesized ACTH-(1-13)NH2 to ACTH-(1-39) was greatly reduced by treatment of the cells with dexamethasone. The extensive cleavage of ACTH-(1-39) and its regulation by dexamethasone are unique to newborn anterior pituitary lobe corticotropes; such plasticity is not observed in cultures of adult tissue.
对新生大鼠的垂体中间叶细胞进行培养，以确定它们在多大程度上继续表现出新生和成年垂体中间叶的组织特异性特性。在所有检测时间点，这些培养物中大多含有α-MSH大小和促肾上腺皮质激素样中间叶肽大小的肽；α-MSH大小的肽主要是二乙酰化促肾上腺皮质激素-(1-13)NH2。培养6天后，垂体中间叶细胞仍保留合成二乙酰化促肾上腺皮质激素-(1-13)NH2的能力。与成年大鼠相比，新生大鼠的垂体前叶富含高分子量形式的促肾上腺皮质激素相关分子。因此，研究了新生垂体前叶细胞培养物在培养中形成成年加工模式的能力。培养6天后，占主导地位的是α-MSH大小的肽，而不是成年大鼠中主要形式的促肾上腺皮质激素-(1-39)。免疫细胞化学研究表明，所有培养的新生促肾上腺皮质激素细胞均强烈染色显示与α-MSH相关的物质。通过反相高效液相色谱法将α-MSH大小的分子鉴定为促肾上腺皮质激素-(1-13)NH2。在添加合成糖皮质激素地塞米松的条件下培养6天的新生垂体前叶培养物中，α-MSH大小物质的量减少，取而代之的是检测到促肾上腺皮质激素相关肽的前体形式。在生物合成标记实验中，用地塞米松处理细胞后，新合成的促肾上腺皮质激素-(1-13)NH2与促肾上腺皮质激素-(1-39)的比例大大降低。促肾上腺皮质激素-(1-39)的广泛裂解及其受地塞米松的调节是新生垂体前叶促肾上腺皮质激素细胞所特有的；在成年组织培养物中未观察到这种可塑性。
