Impairment of natural resistance to Toxoplasma gondii infection in rats treated with beta adrenergics, beta blockers, corticosteroids or total body irradiation.

The data shows that Fisher rats treated with propranolol, betamethasone or exposed to cobalt60-treatment before challenge with T. gondii exhibit an impaired resistance to this opportunistic parasite infection. In fact, in rats propranolol-treatment induces an increase mortality rate up to 66.6% (P < 0.01, with respect to controls). Whereas betamethasone or cobalt60-treatment induces an increased of mortality rate about 33.3% (P < 0.05 respectively, with respect to unirradiated rats). In contrast to beta blocker, corticosteroid-treated or irradiated rats, beta adrenergic-treated rats do not significantly differ from untreated rats in their time of survival. These data lead the authors to hypothesise that in rats the natural resistance to T. gondii can be modulate beta adrenergics or corticosteroids.