Effects of mineralocorticoids on α-Na+/K+ ATPase expression and parasite morphology in T. crassiceps WFU cysticerci.

Mineralocorticoids are corticosteroid hormones that, in vertebrates, regulate extracellular fluid volume and salt balance by modulating the expression and activity of Na+/K+ ATPase, the enzyme that generates and maintains Na+ and K+ gradients across plasma membranes. However, the function of mineralocorticoids in invertebrates has not been well studied. Cysticerci (larvae) of the parasite Taenia crassiceps WFU synthesize the corticosteroids 11-deoxycorticosterone (DOC) and corticosterone in vitro. Here, we searched the genome and transcriptome of T. crassiceps for the presence of α-Na+/K+ ATPase sequences. We also studied the effects of corticosteroids on α-Na+/K+ ATPase expression and on the morphology of T. crassiceps WFU cysticerci in vitro. Cysticerci were obtained from the peritoneal cavity of previously infected female mice and cultured in the presence of corticosterone, DOC, spironolactone (a mineralocorticoid receptor antagonist) or metyrapone (a corticosteroid synthesis inhibitor) at different concentrations and for different periods of time. ATPase expression was evaluated by Western blotting. Genome and transcriptome searches revealed two highly conserved α-Na+/K+ ATPase sequences in T. crassiceps WFU. DOC was found to increase α-Na+/K+ ATPase expression in a concentration-dependent manner. The incubation of parasites with spironolactone, but not with metyrapone, significantly decreased the expression of the enzyme. In addition, DOC increased parasite size, whereas spironolactone and metyrapone altered parasite shape and size, respectively. These results suggest a role for mineralocorticoids in salt-water regulation of T. crassiceps WFU. A deep understanding of these mechanisms could contribute to improving therapeutic strategies for cysticercosis.