Considerable evidence supports a role for vasopressin (VP) as a local regulator of steroidogenesis in rat testes. I show that rat testes contain three distinct VP gene-related transcripts differing in size from the hypothalamic VP mRNA. Two of these transcripts contain exons B and C, but not the exon that encodes the nonapeptide VP. Hence, these transcripts are incapable of generating testicular irVP. The third transcript possesses exon A-like sequences, probably originating from expression of a VP-related gene. This transcript may encode the VP-like peptide that has been detected in testicular extracts. / The major biological effects of oxytocin (OT) are related to reproduction. I show that the tissues comprising the maternal-placental-fetal unit of the rat, i.e. the fetal membranes (placenta and amnion/chorion) and the uterus, possess a single species of OT gene transcript differing in size from the hypothalamic OT transcript as a result of differences in poly(A) tail lengths. The uterus of a term pregnant rat contains about 70 times more OT mRNA than the hypothalamus, identifying the uterus as the major site of OT gene expression at term pregnancy. All three peripheral tissues possess authentic OT and a noncovalent complex between OT and another molecule, probably Neurophysin I (NpI). OT mRNA and OT immunoreactivity are localizcd to several cell types in the placenta and to the endometrial epithelial cells of the pregnant uterus. OT binding studies reveal high numbers of OT receptors in rat uterine tissues (myometrium and endometrium), but no OT binding, sites were found in the fetal membranes. These findings suggest that OT may act in a paracrine fashion in the fetal membranes while uterine OT may act both as an autocrine and paracrine mediator of uterine functions during pregnancy. / Northern blot analysis shows that the OT gene is expressed in the nonpregnant rat uterus and that expression is regulated in a cycle stage-dependent manner. Also, ovarian steroids are involved in regulating the expression of the OT gene in the uterus. Interestingly, prostaglandins may also be involved in the mechanisms whereby the uterine OT gene responds to steroidal stimulation. (Abstract shortened by UMI.)
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.41031 |
| Date | January 1992 |
| Creators | Lefebvre, Diana Lynn |
| Contributors | Zingg, Hans H. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Division of Experimental Medicine.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001320063, proquestno: NN87895, Theses scanned by UMI/ProQuest. |
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