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. 1979 Sep;64(3):737–742. doi: 10.1172/JCI109517

Measurement, Characterization, and Source of Somatostatin-like Immunoreactivity in Human Amniotic Fluid

David Fitz-Patrick 1,2,3,4, Yogesh C Patel 1,2,3,4
PMCID: PMC372175  PMID: 468988

Abstract

Somatostatin-like immunoreactivity (SLI) is widely distributed in tissues and biological fluids. To determine whether SLI is also present in amniotic fluid, samples obtained by amniocentesis from 30 normal and 27 abnormal pregnancies were studied by radioimmunoassay. Direct incubation of [125I-Tyr1]tetradecapeptide somatostatin (SRIF) with amniotic fluid resulted in 89% tracer degradation. Damage was reduced to <5% when samples were acidified and boiled before the assay. With this technique, SLI was detectable in all normal amniotic fluid samples; the mean level at 15-20 wk of gestation (320±55 pg/ml, n = 15) being 4.5 times higher than the mean at 32-43 wk (70±12 pg/ml, n = 15) (P < 0.001). In cases of preeclampsia (n = 6), gestational diabetes (n = 5), anencephaly (n = 1), and meningomyelocele (n = 1), SLI values were in the normal range, but in one juvenile diabetic and one patient with chronic renal failure, SLI was undetectable (<10 pg/ml). In a pair of monochorionic diamniotic twins, SLI levels were very different (33 and 197 pg/ml), which suggests that fetal factors are more important than materno-placental ones in determining amniotic fluid SLI. Serial dilutions of amniotic fluid showed parallelism with standard SRIF. When concentrates of pooled amniotic fluid were chromatographed on Sephadex G-25 columns, all SLI eluted in the void volume ahead of SRIF even after treatment with 8 M urea and dithiothreitol. This “big” SLI incubated in amniotic fluid showed 100% stability over 24 h at 37°C, whereas SRIF was rapidly inactivated (t½ ≅ 7 min). Extracts of placenta and fetal membranes contained no SLI, but small amounts (6-20% of total amniotic fluid SLI) were found in cells from fresh fluid. Radioimmunoassay of SLI in extracts of seven paired cord arterial and venous plasma samples showed no arteriovenous gradient consistent with fetal origin of cord blood SLI. It is concluded that (a) amniotic fluid contains SLI which is of fetal origin and (b) normal levels vary with gestational age. The SLI has a higher molecular weight (≥5,000) and is more stable in amniotic fluid than SRIF.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Arimura A., Sato H., Dupont A., Nishi N., Schally A. V. Somatostatin: abundance of immunoreactive hormone in rat stomach and pancreas. Science. 1975 Sep 19;189(4207):1007–1009. doi: 10.1126/science.56779. [DOI] [PubMed] [Google Scholar]
  2. BERSON S. A., YALOW R. S., BAUMAN A., ROTHSCHILD M. A., NEWERLY K. Insulin-I131 metabolism in human subjects: demonstration of insulin binding globulin in the circulation of insulin treated subjects. J Clin Invest. 1956 Feb;35(2):170–190. doi: 10.1172/JCI103262. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Brazeau P., Epelbaum J., Tannenbaum G. S., Rorstad O., Martin J. B. Somatostatin: isolation, characterization, distribution, and blood determination. Metabolism. 1978 Sep;27(9 Suppl 1):1133–1137. doi: 10.1016/0026-0495(78)90031-8. [DOI] [PubMed] [Google Scholar]
  4. Brazeau P., Vale W., Burgus R., Ling N., Butcher M., Rivier J., Guillemin R. Hypothalamic polypeptide that inhibits the secretion of immunoreactive pituitary growth hormone. Science. 1973 Jan 5;179(4068):77–79. doi: 10.1126/science.179.4068.77. [DOI] [PubMed] [Google Scholar]
  5. Conlon J. M., Srikant C. B., Ipp E., Schusdziarra V., Vale W., Unger R. H. Properties of endogenous somatostatin-like immunoreactivity and synthetic somatostatin in dog plasma. J Clin Invest. 1978 Dec;62(6):1187–1193. doi: 10.1172/JCI109238. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Dupont A., Alvarado-Urbina G. Conversion of big pancreatic somatostatin without peptide bond cleavage into somatostatin tetradecapeptide. Life Sci. 1976 Nov 1;19(9):1431–1433. doi: 10.1016/0024-3205(76)90444-6. [DOI] [PubMed] [Google Scholar]
  7. Ensinck J. W., Laschansky E. C., Kanter R. A., Fujimoto W. Y., Koerker D. J., Goodner C. J. Somatostatin biosynthesis and release in the hypothalamus and pancreas of the rat. Metabolism. 1978 Sep;27(9 Suppl 1):1207–1210. doi: 10.1016/0026-0495(78)90043-4. [DOI] [PubMed] [Google Scholar]
  8. Harris V., Conlon J. M., Srikant C. B., McCorkle K., Schusdziarra V., Ipp E., Unger R. H. Measurements of somatostatin-like immunoreactivity in plasma. Clin Chim Acta. 1978 Jul 15;87(2):275–283. doi: 10.1016/0009-8981(78)90348-0. [DOI] [PubMed] [Google Scholar]
  9. Healy D. L., Muller H. K., Burger H. G. Immunofluorescence shows localisation of prolactin to human amnion. Nature. 1977 Feb 17;265(5595):642–643. doi: 10.1038/265642a0. [DOI] [PubMed] [Google Scholar]
  10. Hökfelt T., Efendić S., Hellerström C., Johansson O., Luft R., Arimura A. Cellular localization of somatostatin in endocrine-like cells and neurons of the rat with special references to the A1-cells of the pancreatic islets and to the hypothalamus. Acta Endocrinol Suppl (Copenh) 1975;200:5–41. [PubMed] [Google Scholar]
  11. Kronheim S., Berelowitz M., Pimstone B. L. The characterization of growth hormone release inhibiting hormone-like immunoreactivity in normal urine. Clin Endocrinol (Oxf) 1977 Oct;7(4):343–347. doi: 10.1111/j.1365-2265.1977.tb01332.x. [DOI] [PubMed] [Google Scholar]
  12. Kronheim S., Berelowitz M., Pimstone B. L. The characterization of somatostatin-like immunoreactivity in human serum. Diabetes. 1978 May;27(5):523–529. doi: 10.2337/diab.27.5.523. [DOI] [PubMed] [Google Scholar]
  13. Larsson L. I., Hirsch M. A., Holst J. J., Ingemansson S., Kühl C., Jensen S. L., Lundqvist G., Rehfeld J. F., Schwartz T. W. Pancreatic somatostatinoma. Clinical features and physiological implications. Lancet. 1977 Mar 26;1(8013):666–668. doi: 10.1016/s0140-6736(77)92113-4. [DOI] [PubMed] [Google Scholar]
  14. Lind T., Kendall A., Hytten F. E. The role of the fetus in the formation of amniotic fluid. J Obstet Gynaecol Br Commonw. 1972 Apr;79(4):289–298. doi: 10.1111/j.1471-0528.1972.tb15799.x. [DOI] [PubMed] [Google Scholar]
  15. Noe B. D., Fletcher D. J., Bauer G. E., Weir G. C., Patel Y. Somatostatin biosynthesis occurs in pancreatic islets. Endocrinology. 1978 Jun;102(6):1675–1685. doi: 10.1210/endo-102-6-1675. [DOI] [PubMed] [Google Scholar]
  16. Patel Y. C., Burger H. G. A simplified radioimmunoassay for triiodothyronine. J Clin Endocrinol Metab. 1973 Jan;36(1):187–190. doi: 10.1210/jcem-36-1-187. [DOI] [PubMed] [Google Scholar]
  17. Patel Y. C., Reichlin S. Somatostatin in hypothalamus, extrahypothalamic brain, and peripheral tissues of the rat. Endocrinology. 1978 Feb;102(2):523–530. doi: 10.1210/endo-102-2-523. [DOI] [PubMed] [Google Scholar]
  18. Patel Y., Rao K., Reichlin S. Somatostatin in human cerebrospinal fluid. N Engl J Med. 1977 Mar 10;296(10):529–533. doi: 10.1056/NEJM197703102961002. [DOI] [PubMed] [Google Scholar]
  19. Pearse A. G. The diffuse neuroendocrine system and the apud concept: related "endocrine" peptides in brain, intestine, pituitary, placenta, and anuran cutaneous glands. Med Biol. 1977 Jun;55(3):115–125. [PubMed] [Google Scholar]
  20. Rees L. H., Burke C. W., Chard T., Evans S. W., Letchworth A. T. Possible placental origin of ACTH in normal human pregnancy. Nature. 1975 Apr 17;254(5501):620–622. doi: 10.1038/254620b0. [DOI] [PubMed] [Google Scholar]
  21. Spiess J., Vale W. Investigation of larger forms of somatostatin in pigeon pancreas and rat brain. Metabolism. 1978 Sep;27(9 Suppl 1):1175–1178. doi: 10.1016/0026-0495(78)90038-0. [DOI] [PubMed] [Google Scholar]
  22. Wallenburg H. C. The amniotic fluid I. Water and electrolyte homeostasis. J Perinat Med. 1977;5(5):193–205. [PubMed] [Google Scholar]

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