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Oxytocinase is a type of enzyme that metabolizes the endogenous neuropeptide, oxytocin.[1] The most well-characterized oxytocinase is leucyl/cystinyl aminopeptidase,[1][2] which is also an enkephalinase. Other oxytocinases are also known.[1][3] During pregnancy, oxytocinase plays a role in balancing concentration of oxytocin by degrading the oxytocin produced by the fetus, as production of oxytocin increases with growth of fetus.[2] One study found that concentration level of oxytocinase increased progressively with gestational age until labor, which indicates that pregnancy development can be statistically evaluated by comparing oxytocinase levels.[4]


Amastatin, bestatin (ubenimex), and puromycin have been found to inhibit the enzymatic degradation of oxytocin, though they also inhibit the degradation of various other peptides, such as vasopressin, met-enkephalin, and dynorphin A.[5][3][6] EDTA, L-methionine, o-phenanthroline, and phosphoramidon have also been found to inhibit the enzymatic degradation of oxytocin.[7]

See also[edit]


  1. ^ a b c Tsujimoto M, Hattori A (2005). "The oxytocinase subfamily of M1 aminopeptidases". Biochim. Biophys. Acta. 1751 (1): 9–18. doi:10.1016/j.bbapap.2004.09.011. PMID 16054015.
  2. ^ a b Nomura S, Ito T, Yamamoto E, Sumigama S, Iwase A, Okada M, Shibata K, Ando H, Ino K, Kikkawa F, Mizutani S (2005). "Gene regulation and physiological function of placental leucine aminopeptidase/oxytocinase during pregnancy". Biochim. Biophys. Acta. 1751 (1): 19–25. doi:10.1016/j.bbapap.2005.04.006. PMID 15894523.
  3. ^ a b Mizutani S, Yokosawa H, Tomoda Y (1992). "Degradation of oxytocin by the human placenta: effect of selective inhibitors". Acta Endocrinol. 127 (1): 76–80. doi:10.1530/acta.0.1270076. PMID 1355623.
  4. ^ Klimek, Marek (August 2005). "Comparative analysis of ACTH and oxytocinase plasma concentration during pregnancy". Neuro Endocrinology Letters. 26 (4): 337–341. ISSN 0172-780X. PMID 16136013.
  5. ^ Meisenberg G, Simmons WH (1984). "Amastatin potentiates the behavioral effects of vasopressin and oxytocin in mice". Peptides. 5 (3): 535–9. doi:10.1016/0196-9781(84)90083-4. PMID 6540873.
  6. ^ Stancampiano R, Melis MR, Argiolas A (1991). "Proteolytic conversion of oxytocin by brain synaptic membranes: role of aminopeptidases and endopeptidases". Peptides. 12 (5): 1119–25. doi:10.1016/0196-9781(91)90068-z. PMID 1800950.
  7. ^ Itoh C, Watanabe M, Nagamatsu A, Soeda S, Kawarabayashi T, Shimeno H (1997). "Two molecular species of oxytocinase (L-cystine aminopeptidase) in human placenta: purification and characterization". Biol. Pharm. Bull. 20 (1): 20–4. doi:10.1248/bpb.20.20. PMID 9013800.