A multiple timepoint study of N-terminal pro-opiomelanocortin in depression using a two-site recognition immunoradiometric assay.
N-pro-opiomelanocortin (N-POMC) is secreted from the same precursor as ACTH and beta-endorphin. Elevated plasma ACTH and beta-endorphin/beta-lipotrophin concentrations have been reported in depression, however there have been no previous studies of N-POMC. Twenty-five patients with major depression and 18 control subjects were studied at five timepoints to examine diurnal rhythm and the effect of a dexamethasone suppression test. N-POMC was measured using a newly developed two-site recognition immunoradiometric assay (IRMA). This demonstrated advantages of sensitivity, specificity and simplicity compared with existing radioimmunoassays. N-POMC exhibited a pattern of diurnal rhythm and suppression in response to dexamethasone as described for other POMC derived peptides. Depressed subjects had higher levels of N-POMC at 0900 h post-dexamethasone than did control subjects. In conclusion, the results of this study are consistent with a hypothesis of cosecretion of POMC-derived peptides. N-POMC has a similar pattern of abnormal concentrations to ACTH and beta-endorphin/beta-lipotrophin in depression. This constitutes probable evidence of POMC-derived peptide resistance to glucocorticoid feedback in this condition.
Charlton
B G
BG
MRC Neuroendocrinology Unit, Newcastle General Hospital, Newcastle upon Tyne, UK.
Ferrier
I N
IN
Leake
A
A
Edwardson
J A
JA
Eccleston
D
D
Crowcombe
K
K
McLean
J
J
Jackson
S
S
Lowry
P
P
D000328:Adult; D002940:Circadian Rhythm / Q000187:drug effects; D003863:Depression / Q000097:blood*; D003907:Dexamethasone; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000097:blood*; D011333:Pro-Opiomelanocortin / Q000097:blood*; D011863:Radioimmunoassay
D010446:Peptide Fragments; D011333:Pro-Opiomelanocortin; D003907:Dexamethasone