Effect of 17β-Estradiol and Progesterone on Astrocytes Infected with Toxoplasma

Toxoplasma gondii is an opportunistic parasite that invade microglia, astrocytes, and neurons.In guinea pigs infected with Toxoplasma, brain cysts increased significantly in males subjected to gonadectomy and treated with hexoestrol, compared with control.The effect of 17β-estradiol and progesterone on astrocytes infected with Toxoplasma is unknown.The objective of the study was to evaluate the effect of 17β-estradiol and progesterone on Toxoplasma infection in astrocytes in vitro.Astrocytes were pre-treated with 17β-estradiol or progesterone at concentrations of 10, 20, 40, 80, or 160 nM for 48 hours and infected with Toxoplasma tachyzoites.The percentage of infected astrocytes was evaluated by immunocytochemistry and parasite replication by MTT.ANOVA and a Dunnett's T3 post-hoc test were used.Pretreatment with 17β-estradiol and 17β-estradiol + tamoxifen (1µM) resulted in a significant reduction in parasite replication at 48 hours post-infection.Infected astrocytes were gradually reduced whit 17β-estradiol plus tamoxifen.Progesterone reduced the parasite replication at 48 hours, and this effect was reversed by mifepristone.The percentage of infected astrocytes at 24 hours was reduced with progesterone at all doses.17β-estradiol plus progesterone had a synergistic effect, increasing Toxoplasma infection in astrocytes at 24 hours however, at 48 hours the infection was reduced.The 17β-estradiol + progesterone at 160 nM, as well as PPT and DPN, reduced Toxoplasma replication and percentage of infected astrocytes.Toxoplasma infection in astrocytes was reduced by the effect of 17β-estradiol and its agonist PPT as well as progesterone.These results suggest that ERα and PRs activation diminishes Toxoplasma-infection in astrocytes.