Effects of propranolol and atenolol on immobilization stress-induced hypertension and down-regulation of central beta-adrenoceptors in rats.
Effects of chronic treatment with propranolol or atenolol on stress-induced changes in blood pressure, body weight, and cerebral beta-adrenoceptors in rats were examined and compared with the effects of chronic treatment with prazosin. Immobilization stress (2 h daily for 2 weeks) induced a moderate elevation of blood pressure, loss of body weight gain, and downregulation of cerebral beta-adrenoceptors, but produced no changes in the cerebral alpha 1-adrenoceptors. Chronic administration of propranolol (5 or 50 mg.kg-1), atenolol (5 or 50 mg.kg-1) or prazosin (2 or 20 mg.kg-1) inhibited stress-induced hypertension but did not affect loss of body weight gain. Propranolol increased the density of cerebral beta-adrenoceptors by 77% and reduced the downregulation induced by stress. Atenolol also increased the density of cerebral beta-adrenoceptors by 34% and abolished the stress-induced downregulation in cerebral beta-adrenoceptor density. In contrast, prazosin had no effect on the cerebral beta-adrenoceptors in nonstressed or stressed rats. These results suggest that the antihypertensive action of propranolol and atenolol may be partly associated with the inhibition of stress-activated central beta-adrenoceptor transmission.
Takita
M
M
Department of Pharmacology, Fukui Medical School, Japan.
Oda
Y
Y
Kigoshi
S
S
Muramatsu
I
I
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D001262:Atenolol / Q000097:blood / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism; D004082:Dihydroalprenolol; D015536:Down-Regulation / Q000187:drug effects*; D004326:Drinking / Q000187:drug effects; D006973:Hypertension / Q000209:etiology / Q000503:physiopathology*; D007103:Immobilization; D008297:Male; D011224:Prazosin / Q000494:pharmacology; D011433:Propranolol / Q000097:blood / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013315:Stress, Psychological / Q000150:complications*; D015430:Weight Gain / Q000187:drug effects
D000319:Adrenergic beta-Antagonists; D001262:Atenolol; D004082:Dihydroalprenolol; D011433:Propranolol; D011224:Prazosin