VISCOSITY OF RAT ADRENOCORTICAL LIPIDS IN DIFFERENT FUNCTIONAL-STATES- MORPHOLOGICAL-CHARACTERISTICS

Impaired adrenocortical steroidogenic activity is often concomitant wi th morphologically and physiologically altered lipids in the cells of the adrenal cortex. The physical state of these lipid droplets and the morphological characteristics of crystal-shaped bodies were studied i n different functional states of adrenocortical cells. In the perinata l period when steroidogenesis is suppressed by a negative feedback mec hanism, crystal-shaped bodies (i.e. rectangular, electron-lucent forma tions, either alone or in clusters, surrounded by lysosomal matrix or in close proximity of lysosomes) were frequently observed in the inner zona fasciculata and zona reticularis. In experimentally suppressed a drenocortical activity, following the administration of dexamethasone, aminoglutethimide or cycloheximide, almost identical crystal-shaped b odies were frequently observed in adrenocortical cells. These crystal- shaped bodies appear to be cholesterol, as revealed by the digitonin r eaction at the electron microscopic level. Following stimulation of th e zona fasciculata by ACTH treatment for 14 days, a marked increase in the fluidity of the lipid droplets was observed in the thermotropic p hase transitions with the polarizing microscope. In contrast, followin g aminoglutethimide treatment, the fluidity of the lipid droplets decr eased. The thermotropic phase transitions of normal and neoplastic hum an adrenal cells, namely adrenocortical tumours causing Conn's or Gush ing's syndrome, were also investigated. When hormone biosynthesis was enhanced, the appearance of birefringence and multiple phase transitio ns of lipid droplets was demonstrable in the low-temperature range. Co pyright (C) 1996 Elsevier Science Ltd.