The effects of intracerebroventricular administration of adrenergic agonists and antagonists on adrenaline secretion from the adrenal medulla in stressed conscious rats.
The effects of intracerebroventricular (i.c.v.) administration of adrenergic agonists and antagonists on the increase in serum adrenaline (Ad) induced by immobilization stress were examined in unanesthetized, unrestrained rats. The serum Ad of rats showed a significant linear increase as time elapsed after the induction of immobilization stress. This immobilization stress-induced increase was inhibited by the i.c.v. administration of a small amount of noradrenaline (NA) and phenylephrine. Isoproterenol and clonidine failed to inhibit the immobilization stress-induced increase. The inhibition of the immobilization stress-induced increase by i.c.v. administration of NA was antagonized by pretreatment with phentolamine and prazosin, but not by pretreatment with yohimbine and propranolol. These results suggested that NA administered via an i.c.v. route may inhibit the stress-induced increase in adrenomedullary Ad secretion by an action on the central alpha 1-adrenoceptor.
Nakamura
M
M
Department of Pharmacology, Kyorin University School of Medicine, Tokyo, Japan.
Kamata
K
K
Inoue
H
H
Matsuyama
K
K
Inaba
M
M
D000313:Adrenal Medulla / Q000187:drug effects / Q000378:metabolism*; D000322:Adrenergic Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D003000:Clonidine / Q000494:pharmacology; D004837:Epinephrine / Q000378:metabolism*; D007103:Immobilization; D007276:Injections, Intraventricular; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013312:Stress, Physiological / Q000378:metabolism; D013565:Sympatholytics / Q000008:administration & dosage / Q000494:pharmacology*
D000322:Adrenergic Agonists; D013565:Sympatholytics; D010656:Phenylephrine; D007545:Isoproterenol; D003000:Clonidine; D009638:Norepinephrine; D004837:Epinephrine