醋酸可的松对神经分泌影响的超微结构研究

ULTRASTRUCTURAL OBSERVATION OF THE EFFECT OF CORTISONE ON THE NEUROSECRETION OF NEUROHYPOPHYSIS

本研究将大剂量醋酸可的松(25mg/d)注射于大白鼠肌内,并于不同用药次数后,分别取垂体神经部以戊二醛固定,常规包埋,超薄切片和染色,在电镜下观察垂体神经部的超微结构变化。发现用药后垂体神经部神经分泌纤维及其末梢呈现膨胀;分泌颗粒滞留;透明小泡增多。随着剂量加大,神经分泌颗粒外溢、神经纤维变性、质膜溶解。垂体细胞出现活跃的吞噬现象。退变的神经分泌纤维被垂体细胞包卷,分泌颗粒被吞噬。我们认为大剂量可的松对视上核和室旁核神经分泌细胞有明显的抑制作用。本文还就可的松抑制神经分泌的机理、垂体细胞与各种细胞器之间的关系作了讨论。

Twelve adult male rats were used for this study.They were divided into five groups.Experiments were undertaken by intramuscular injection of large dosage of cortisone acetate at different intervals.The neurohypophysis were taken and fixed in 4%glutaraldehyde in buffered phosphate,postfixed in OsO,dehydrated,embedded,ultrathin sectioned,stained with uranium acetate and lead citrate and observed under electronmicroscope.After the injection of 25 mg of cortisone,the neurosecretory endings and the Herring’s bodies were swollen,and the number of neurosecretory granules(NSG)and lucent vesicles were increased.A part of the NSG entered the pericapillary space.After consecutive 3-dose injections the electronic density of the NSG were descreased and vacuoles appeared inside the nerve fibers and endings.The lucent vesicles were incresed in number.Some of the non myelinated nerve fibers showed signs of degeneration and were wrapped up in the cytoplasm of pituicytes,in which the number of lysosomes were markly increased.After 6 dose of cortisone injections,the plasmalemma at the end of swollen nerve fibers in neurohypophysis showed signs of dissolution,In the cytoplasm of pituicytes,numerous NSG and sccondary lysosomes were found.This study indicated that a large dosage of cortisone administration has an obvious inhibitary Effect on the releasing of neurohormone from the supraoptic and paraventricular nucleis.The inhibitory influence of cortisone on the release of hormone from neurohypophysis and functional relationship between organelles of neurosecretory cell and pituicytes were also discussed.