The effects of monensin on inhibition of steroidogenesis and disruption of the Golgi complex in adrenal cells are both reversible!

Following 15-30 min exposure to monensin, adrenocorticotropic hormone (ACTH)-stimulated steroidogenesis in cultured adrenal cells is inhibited by 37-48%. Electron microscopic studies reveal that, in monensin-treated cells, the Golgi complexes are disrupted into large vacuolar structures with loss of its organized structure indicating that the action of monensin on the organelles is comparably rapid. The inhibition is fully reversed after removal of the monensin-containing medium and exposure to fresh growth medium for a subsequent 4-24 h prior to stimulation. Concomitant with the restoration of full steroidogenic activity, the disrupted organelles are extensively reorganized in the cells after exposure to fresh growth medium for 4-24 h. These findings, which demonstrate, for the first time, a correlation between the morphology of the Golgi complex and steroidogenic activity, strengthen the possibility that the organelle may be involved in the regulation of steroidogenesis.