Adrenergic suppression of peripheral blood T cell reactivity in the rat is due to activation of peripheral alpha 2-receptors.
A 20-h treatment of rats with catecholamines using s.c.implantable retard tablets markedly suppresses the in vitro reactivity of peripheral blood (PBL) T lymphocytes, provided that beta-receptors are blocked with propranolol (Felsner et al., 1992). The results can be summarized as follows: (i) the suppressive effect of noradrenaline+propranolol to the concanavalin A (ConA) response of PBL was abolished by the simultaneous application of the alpha-blocker phentolamine. Using selective agonists, the relevant receptor was identified to belong to the alpha 2-subtype. (ii) The alpha-adrenergic suppression of the PBL T cell response was likewise observed in adrenalectomized animals, which rules out the participation of secondarily induced glucocorticoids. Furthermore, the combination of noradrenaline with the watersoluble beta-blocker nadolol was equally effective to suppress the ConA response of PBL. (iii) An analogous alpha-mediated suppression of T cell function of PBL, but not spleen cells, was observed 1 h after i.p. treatment with tyramine, which leads to the release of endogenous noradrenaline. From these results it is concluded that the adrenergic suppression of PBL T cell functions is primarily due to the activation of peripheral alpha 2-receptors and that it is likewise observed under acute indirect sympathomimetic treatment.
Felsner
P
P
Department of General and Experimental Pathology, School of Medicine, University of Graz, Austria.
Hofer
D
D
Rinner
I
I
Porta
S
S
Korsatko
W
W
Schauenstein
K
K
D000818:Animals; D003208:Concanavalin A / Q000494:pharmacology; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D008297:Male; D009638:Norepinephrine / Q000378:metabolism / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018341:Receptors, Adrenergic, alpha-2 / Q000502:physiology*; D013566:Sympathomimetics / Q000494:pharmacology*; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology; D014439:Tyramine / Q000494:pharmacology
D007166:Immunosuppressive Agents; D018341:Receptors, Adrenergic, alpha-2; D013566:Sympathomimetics; D003208:Concanavalin A; D009638:Norepinephrine; D014439:Tyramine