Urinary adrenalin and cortisol secretion patterns of social voles in response to adrenergic blockade under basal conditions.
The effect of alpha(1)- and beta-adrenergic blockade on daily rhythms of urinary adrenalin (ADR) and cortisol (CORT) under basal conditions were evaluated. Voles acclimated to a 12:12 h light/dark cycle at 26+/-2 degrees C received a single dose of either propranolol (PROP; 4.5 mg/kg) or prazosin (PRAZ; 1 mg/kg) 1 h before lights off. Urine samples were collected for 24 h at 4 h intervals. PROP evokes a significant increase in mean urinary ADR; although CORT was unaffected by PROP, PRAZ administration significantly decreased both urinary ADR and CORT during the scotophase as compared with control voles. Cosinor analysis indicated a significant 24 h rhythm in urinary ADR, but not in CORT secretion. ADR mesor and amplitude were increased and acrophase was significantly delayed by 5 h in PROP-treated voles; PRAZ elicited opposite effects. Unexpectedly, these changes in the 24 h ADR rhythm persisted 4-weeks after PROP-treatment. The 24 h rhythm components of urinary CORT were marginally altered 4-weeks post-PROP, but only the acrophase showed a significant change. Collectively, the results indicate that sympathetic activity has a redundant compensatory mechanism defending against physiological changes induced by beta-blockade. The simultaneous decrease in adrenal hormones induced by PRAZ suggests that alpha(1)-adrenoceptors may contribute to the mechanism of integrated stress responses.
Zubidat
Abed Elsalam
AE
Department of Evolution and Environmental Biology, University of Haifa, Haifa 31905, Israel. zubidat3@013.net.il
Nelson
Randy J
RJ
Haim
Abraham
A
D000222:Adaptation, Physiological; D000311:Adrenal Glands / Q000187:drug effects / Q000378:metabolism; D018674:Adrenergic Antagonists / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D003411:Arvicolinae / Q000652:urine*; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology*; D004837:Epinephrine / Q000652:urine*; D006854:Hydrocortisone / Q000652:urine*; D008297:Male; D017440:Photoperiod; D011224:Prazosin / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D018709:Statistics, Nonparametric
D018674:Adrenergic Antagonists; D011433:Propranolol; D006854:Hydrocortisone; D011224:Prazosin; D004837:Epinephrine