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This Article Full Text Full Text (PDF) All Versions of this Article: JOE-08-0267v1 199/3/481    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Prickett, T. C R Articles by Espiner, E. A Search for Related Content PubMed PubMed Citation Articles by Prickett, T. C R Articles by Espiner, E. A

Department of Medicine, University of Otago, PO Box 4345, Christchurch 8140, New Zealand¹ Agriculture & Life Sciences Division, Lincoln University, Canterbury, 7647, New Zealand

(Correspondence should be addressed to T C R Prickett; Email: tim.prickett{at}otago.ac.nz)

Although C-type natriuretic peptide (CNP) is crucial to post-natal endochondral growth, roles for the hormone in pubertal bone growth and the physiological effects of sex steroid substitution on CNP synthesis are not known. Using a plasma marker of CNP tissue synthesis (amino-terminal proCNP, NTproCNP), we have studied the effect of exogenous oestrogen (E₂) or testosterone (T) on plasma CNP forms and bone alkaline phosphatase (bALP) in pre-pubertal lambs. Responses to E₂ in non-cycling adult ewes were also studied. In 15-week-old intact ewe lambs, E₂ promptly increased plasma NTproCNP and CNP (P<0.001) to peak on day 2, and bALP (P<0.001 peaking on day 7), whereas no significant stimulation in response to T was observed in male lambs. Linear bone growth and live weight were unaffected. In adult anoestrous ewes, basal concentrations of CNP forms and bALP were lower than in ewe lambs, in keeping with skeletal maturity, but adults responded similarly to E₂. Prompt and sustained increases in NTproCNP and CNP, and a later threefold rise in bALP (all P<0.001), were induced by E₂. Possible contributions to these increases in plasma CNP forms by reproductive tissues (a known site of E₂-induced CNP expression) were excluded by showing similar E₂-induced CNP responses in adult ewes after surgical removal of reproductive tissues. These results are the first to show that E₂ stimulates plasma CNP forms and bALP in lambs and adult sheep and raise the possibility that CNP also participates in bone formation in the mature skeleton.