Pregnancy-induced changes in substance P and neurokinin 1 receptor (NK1-R) expression in the rat uterus.
Adrenergic nerve fibres of the mammalian uterus degenerate during pregnancy. The behaviour of peptidergic fibres, such as substance P-positive fibres and of its preferred neurokinin 1 receptor (NK1-R), is poorly studied in the pregnant rat uterus. The present study analysed the changes in substance P immunoreactivity and in the expression of NK1-R protein in the uterus of non-pregnant, pregnant (days 7, 14 and 21) and postpartum rats (days 1, 8 and 22) by immunohistology, dot blot analysis and western blot analysis. In non-pregnant rats, substance P-positive fibres were localized to the myometrium; these fibres progressively disappeared during gestation and were almost absent at term (day 21). At day 22 post partum, substance P-positive fibres had recovered to numbers comparable with those in the non-pregnant uterus. Dot blot analysis revealed a significant decrease in the immunoreactivity of substance P in the uterus at mid-pregnancy (day 14) and especially at term. Expression of the NK1-R protein showed a progressive increase throughout pregnancy reaching a peak on day 1 post partum; downregulation of NK1-R protein occurred on day 8 post partum. The low and high expressions of NK1-R protein were coincident with a large number of eosinophils and almost no eosinophils in the uterus at oestrus and at term, respectively. It was concluded that substance P immunoreactivity is inversely correlated with NK1-R protein expression in the pregnant and postpartum uterus. The marked upregulation of NK1-R protein at term and after birth indicates that the NK1-R may be involved in the complex regulation of labour and postpartum physiology. However, it is likely that the NK1-protein is not involved in the recruitment of eosinophils into the uterus at oestrus.
Schmidt
C
C
Institute of Anatomy, University of Leipzig, Liebigstrasse 13, Leipzig D-04103, Germany.
Lobos
E
E
Spanel-Borowski
K
K
D000818:Animals; D005260:Female; D015151:Immunoblotting / Q000379:methods; D007150:Immunohistochemistry / Q000379:methods; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000378:metabolism*; D051381:Rats; D011920:Rats, Inbred WF; D018040:Receptors, Neurokinin-1 / Q000032:analysis / Q000378:metabolism*; D013373:Substance P / Q000032:analysis / Q000378:metabolism*; D014599:Uterus / Q000737:chemistry / Q000378:metabolism*
D018040:Receptors, Neurokinin-1; D013373:Substance P