Effect of the glucocorticoid receptor antagonist Org 34850 on fast and delayed feedback of corticosterone release.
We investigated the effect of the glucocorticoid receptor (GR) antagonist Org 34850 on fast and delayed inhibition of corticosterone secretion in response to the synthetic glucocorticoid methylprednisolone (MPL). Male rats were implanted with a catheter in the right jugular vein, for blood sampling and MPL administration, and with an s.c. cannula for Org 34850 administration. All experiments were conducted at the diurnal hormonal peak in the late afternoon. Rats were connected to an automated sampling system and blood samples were collected every 5 or 10 min. Org 34850 (10 mg/kg, s.c.) or vehicle (5% mulgofen in saline) was injected at 1630 h; 30 min later, rats received an injection of MPL (500 microg/rat, i.v.) or saline (0.1 ml/rat). We found that an acute administration of MPL rapidly decreased the basal corticosterone secretion and this effect was not prevented by acute pretreatment with Org 34850. However, blockade of GR with Org 34850 prevented delayed inhibition of MPL on corticosterone secretion measured between 4 and 12 h after MPL administration. Our data suggest an involvement of GR in modulating delayed, but not fast, inhibition induced by MPL on basal corticosterone secretion.
Spiga
Francesca
F
Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, University of Bristol, Whitson Street, Bristol BS1 3NY, UK. f.spiga@bristol.ac.uk
Harrison
Louise R
LR
Wood
Susan A
SA
MacSweeney
Cliona P
CP
Thomson
Fiona J
FJ
Craighead
Mark
M
Grassie
Morag
M
Lightman
Stafford L
SL
D000818:Animals; D002940:Circadian Rhythm; D003345:Corticosterone / Q000037:antagonists & inhibitors / Q000097:blood / Q000378:metabolism*; D025461:Feedback, Physiological / Q000187:drug effects*; D005938:Glucocorticoids / Q000494:pharmacology*; D006801:Humans; D008297:Male; D008775:Methylprednisolone / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011965:Receptors, Glucocorticoid / Q000037:antagonists & inhibitors* / Q000502:physiology; D013256:Steroids / Q000494:pharmacology*; D013450:Sulfones / Q000494:pharmacology*; D013997:Time Factors
D005938:Glucocorticoids; C526063:Org 34850; D011965:Receptors, Glucocorticoid; D013256:Steroids; D013450:Sulfones; D003345:Corticosterone; D008775:Methylprednisolone