Temporary increase of plasma epinephrine affects stress responses 24 h later.
The impact of temporary (24 h) implantation of epinephrine tables on catecholamine responses to handling and immobilization 24 h later was investigated in rats. Free plasma epinephrine responded with an increase to both types of stress (77% and 326%, respectively) while controls showed a weaker response to immobilization. The basal level of free plasma norepinephrine was reduced (46% vs. controls) after epinephrine pretreatment, but neither handling nor immobilization had a specific effect on this parameter. In contrast, the basal level of free plasma dopamine was increased after epinephrine pretreatment (183%); however, as with free norepinephrine, there was no specific effect of handling or immobilization. Conjugated plasma epinephrine was significantly lowered after epinephrine pretreatment (44% vs. controls). It did not respond specifically to handling or immobilization except for a stronger response after 20 min of immobilization. Conjugated norepinephrine showed no specific response, but increased nonspecifically after extended immobilization. Conjugated dopamine was lowered (30%-48%) in the E-treated group and did not respond to stress at any time. Thus, a temporary elevation of free plasma epinephrine affected, differentially, basal levels and stress responses of free and conjugated catecholamines 24 h later.
Porta
S
S
Institute of General and Experimental Pathology, Endocrinological Research Unit, University of Graz, Austria.
Epple
A
A
Kvetnansky
R
R
Leitner
G
G
Emsenhuber
W
W
Radkohl
W
W
D000322:Adrenergic Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D004298:Dopamine / Q000097:blood; D004343:Drug Implants; D004837:Epinephrine / Q000008:administration & dosage / Q000097:blood* / Q000494:pharmacology*; D006234:Handling, Psychological; D007103:Immobilization; D008297:Male; D009638:Norepinephrine / Q000097:blood; D051381:Rats; D017207:Rats, Sprague-Dawley; D013315:Stress, Psychological / Q000097:blood*
D000322:Adrenergic Agonists; D004343:Drug Implants; D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine