溶酶体在垂体—肾上腺皮质激素分泌调节中的作用

LYSOSOMES IN THE REGULATION OF HORMONE SECRETION IN THE PITUITARY-ADRENAL GLAND AXIS

本实验用地塞米松造成大鼠垂体促皮质激素细胞及其靶腺肾上腺皮质束状带细胞分泌抑制,对这两种细胞中的溶酶体及分泌自噬和自体吞噬活动进行了超微结构观察、CMP 酶细胞化学定性和形态计量。实验结果显示,在分泌受抑制状态下,垂体促皮质激素细胞中分泌自噬和自体吞噬作用加强,与此同时,肾上腺皮质细胞中自体吞噬作用也业著加强。这些结果表明,在分泌类固醇激素的细胞中,溶酶体以自体吞噬的方式清除一部分生产激素的细胞器,可能是一种普遍存在的分泌调节机制,正如在分泌蛋白质和肽类激素的细胞中普遍存在着分泌自噬这一调节机制一样。

The morphology and morphometrics ofthe lysosomes and associated structureswere studied in hyposecreting corticotrophsand the cells of adrenal cortex zona fasci-adculata of the rats.Hyposecretion of thistwo types of the cells in the pituitary-adrenal gland axis was induced by dexame-thasone administration.The lysosomes andother hydrolydase-positive structures wereidentified with CMPase cytochemistry.Quantitative evaluation of the lysosomes,crinophagic and autophagic vacuoles wascarried out on the micrographs with MOP-Videoplan system.The results indicated that while inhi-bited secretion of ACTH accompanied bythe increase of the crinophagic and auto-phagic vacuoles in corticotrophs,inhibitedsecretion of corticosterone accompanied bythe increase of the autophagic vacuolescontaining the mitochondria,ER whichwere steroid-synthesizing apparatus inadrenal cortex cells.The findings in the present study sug-gested that lysosomal degradation mechani-sm play a significant role in the regula-tion of hormone secretion in pituitary-adrenal gland axis.In addition to affirm-ing earlier data that lysosomes took partin the regulation of protein secretion bycrinophagy,the main conclusion derivedfrom the present study was that lysosomesalso functioned in the regulation of ste-roid secretion.By the way of autophagyi.e.sequesting and degrading a part ofthe steroid-synthesizing apparatus,the ly-sosomes rendered a mechanism in steroid-secreting cells to involve to the regulationprocess of hormone secretion.This mightbe an important and general rule as thecrinophagy be to the protein-secretingcells.