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Research Article |
Department of Anaesthesia,4 Royal Women's Hospital, Carlton, Victoria 3053, Australia
Department of Pharmaceutical Biology,5 Victorian College of Pharmacy, Monash University, Parkville, Victoria 3052, Australia
Instituto de Investigaciones Químicas,6 41092 Sevilla, Spain
School of Life Sciences,7 Kingston University London, Kingston-upon-Thames, Surrey KT1 1LQ, United Kingdom
Department of Pharmacology,8 Monash University, Clayton, Victoria 3800, Australia
Royal Children's Hospital and Mercy Hospital for Women,9 Parkville, Victoria 3052, Australia
University of Melbourne Department of Obstetrics and Gynaecology,10 Royal Women's Hospital, Carlton, Victoria 3053, Australia
ABSTRACT
Regulation of the contractile effects of tachykinins and histamine on the human uterus was investigated with biopsy sections of the outer myometrial layer. The effects of neurokinin A (NKA) and human hemokinin-1 (hHK-1) in tissues from pregnant but not from nonpregnant women were enhanced by the inhibition of neprilysin. The effects of NKA and eledoisin were blocked by the NK2 receptor antagonist SR 48968 but not by the NK1 receptor antagonist SR 140333 in tissues from both groups of women. Human HK-1 acted as a partial agonist blocked by SR 48968 and, to a lesser extent, by SR 140333; endokinin D was inactive. In tissues from pregnant women, responses to high potassium-containing Krebs solution were 23-fold higher than those from nonpregnant women. Mepyramine-sensitive maximal responses to histamine were similarly enhanced. The absolute maximum responses to NKA and its stable NK2 receptor-selective analogue, [Lys5MeLeu9Nle10]NKA(410), were increased in pregnancy, but their efficacies relative to potassium responses were decreased. Tachykinin potencies were lower in tissues from pregnant women than in those from nonpregnant women. These data 1) show for the first time that hHK-1 is a uterine stimulant in the human, 2) confirm that the NK2 receptor is predominant in mediating tachykinin actions on the human myometrium, and 3) indicate that mammalian tachykinin effects are tightly regulated during pregnancy in a manner that would negate an inappropriate uterotonic effect. The potencies of these peptides in tissues from nonpregnant women undergoing hysterectomy are consistent with their possible role in menstrual and menopausal disorders.
eledoisin, endokinin, female reproductive tract, hemokinin, histamine, human myometrium, [Lys5MeLeu9Nle10]NKA(410), neprilysin, neurokinin A, neuropeptides, NK1 and NK2 receptors, pregnancy, signal transduction, tachykinins, uterine contractions, uterus
1 Supported by grants from the National Health and Medical Research Council of Australia to J.N.P. and the Ministerio de Educación y Ciencia (BFU2005-04495-C02-01/BFI), Spain. J.N.P. and E.P. contributed equally to this work.
2 Correspondence. FAX: 61 39 833 3754; jocelyn.oneil{at}vcp.monash.edu.au
3 Correspondence: M. Luz Candenas, Centro de Investigaciones Científicas Isla de La Cartuja, Instituto de Investigacones Químicas, Avda. Americo Vespucio 49, 41092 Sevilla, Spain. FAX: 34 95 446 0565; e-mail: luzcandenas{at}iiq.csic.es
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