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  • Author: S Rehfeld x
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J. F. Rehfeld, A. H. Johnsen, L. Ødum, L. Bardram, S. Schifter and L. Scopsi

ABSTRACT

The expression of gastrin/cholecystokinin (CCK) peptides and their precursors was examined in 16 medullary carcinomas of the human thyroid. Measurements with libraries of sequence-specific radioimmunoassays before and after enzymatic cleavage of extracts and chromatographic fractions showed that the carcinomas contained 1·7 pmol carboxyamidated CCK/g tissue (median; range 0·6–21·8 pmol/g), 0·9 pmol glycine-extended precursor/g (median; range < 0·2–2·3 pmol/g) and 2·3 pmol further COOH-terminal-extended proCCK/g (median; range 0·9–6·2 pmol/g). Neither carboxyamidated gastrins nor any progastrins could be measured. Gel and reverse-phase chromatography revealed only small molecular forms, i.e. > 90% of the amidated immunoreactivity eluted like non-sulphated CCK-8 or CCK-7. The results show that human medullary thyroid carcinomas synthesize CCK peptides. The predominance of non-sulphated CCK is unusual. Taken together with earlier observations from dogs and pigs, our results raise the possibility that small non-sulphated CCK peptides modulate thyroid C-cell secretion in an autocrine manner.

Journal of Endocrinology (1990) 124, 501–506

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S E Ulbrich, S Rehfeld, S Bauersachs, E Wolf, R Rottmayer, S Hiendleder, M Vermehren, F Sinowatz, H H D Meyer and R Einspanier

Nitric oxide synthases (NOS) account for the endogenous production of nitric oxide (NO), a small and permeable bioreactive molecule. NO is known to act as a paracrine mediator during various processes associated with female reproduction. In the present study, the mRNA expression of the endothelial (eNOS) and inducible (iNOS) NO synthases were examined in bovine oviduct epithelial cells (BOEC) during the oestrous cycle. In addition, eNOS and iNOS mRNA and protein were localised by in situ hybridisation and immunocytochemistry respectively. Furthermore, the effects of exogenously applied oestradiol-17β and progesterone on NOS mRNA regulation were studied in a suspension culture of BOEC. The eNOS mRNA abundance was low around ovulation (day 0) and increased significantly until pro-oestrus (day 18) in the ampulla. Immunoreactive protein of eNOS was detected predominantly in endothelial cells as well as in secretory oviduct epithelial cells at pro-oestrus. The iNOS mRNA concentration was significantly reduced in the isthmus at pro-oestrus (day 18) and oestrus (day 0) compared with persistently high levels in the ampulla. By in situ hybridisation, specific iNOS transcripts were additionally demonstrated in the oviduct epithelium. Immunoreactive iNOS protein was localised in secretory epithelial cells as well as in the lamina muscularis. The in vitro stimulation showed that both NOS were stimulated by progesterone, but not by oestradiol-17β. The region-specific modulated expression of eNOS and iNOS provides evidence for an involvement of endogenously produced NO in the regulation of oviductal functions.