title: Effects of alpha- and beta-adrenergic agonists on Toxoplasma gondii infection in murine macrophages.
abstract: We investigated the effects of alpha- and beta-adrenergic receptor agonists on the ability of Toxoplasma gondii to infect and proliferate in cultured murine macrophages. Macrophages pretreated in vitro with varying concentrations of alpha- and beta-adrenergic agonists and incubated with the RH strain of T. gondii did not result in a significant increase in the percentage of infected macrophages compared with negative controls. When parasites were pretreated with L-phenylephrine, an alpha-agonist, and L-isoproterenol, a beta-agonist, before infection, there was no significant change in the percentage of infected macrophages. Clonidine, an alpha2-adrenergic agonist, led to a significant decrease in the number of infected macrophages at all concentrations tested. The effects of clonidine were blocked by yohimbine, a specific alpha2-adrenergic antagonist, but not by phentolamine, an alpha1-adrenergic antagonist. These results suggest that the antiparasitic effects exhibited by clonidine (alpha2-adrenergic agonist) are mediated through an alpha2-adrenoreceptor found on the surface of T. gondii.
authors.affiliation: Department of Biological Sciences, Northern Arizona University, PO Box 5640, Flagstaff, Arizona 86011, USA.
authors.forename: Julie
authors.initials: J
authors.lastname: Gets
authors.forename: Fernando P
authors.initials: FP
authors.lastname: Monroy
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D002478:Cells, Cultured; D003000:Clonidine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D006801:Humans; D007545:Isoproterenol / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects / Q000276:immunology / Q000469:parasitology*; D051379:Mice; D010646:Phentolamine / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D018341:Receptors, Adrenergic, alpha-2 / Q000378:metabolism; D014122:Toxoplasma / Q000187:drug effects* / Q000502:physiology; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D000318:Adrenergic beta-Agonists; D018341:Receptors, Adrenergic, alpha-2; D010656:Phenylephrine; D015016:Yohimbine; D007545:Isoproterenol; D003000:Clonidine; D010646:Phentolamine