Expression and regulation of functional oxytocin receptors in bovine T lymphocytes.
The corpus luteum (CL) produces oxytocin (OXT), which has been proposed to regulate the pulsatile release of prostaglandin F2alpha during luteolysis in ruminants. This action of OXT is mediated via oxytocin receptors (OXTRs) present on uterine epithelial cells. It is hypothesized that luteal OXT acts as a paracrine regulator of resident immune cells. In the present study, OXTR mRNA expression in bovine lymphocytes was analyzed, as well as its regulation during the estrous cycle. OXTR transcripts were observed in freshly purified bovine peripheral blood mononuclear cells and T lymphocytes. OXTR mRNA in bovine lymphocytes on Day 3 was numerically greater than but not significantly different from that of Day 19 of the estrous cycle (P=0.091). In cultured T cells, estradiol (E2) treatment significantly increased the steady-state concentrations of OXTR mRNA, but the stimulatory effect of E2 was inhibited by the addition of progesterone (P4). Each of the major T cell subsets (CD4+, CD8+, and gamma delta+) expressed OXTR mRNA, with no significant difference in expression among them. Western blot analyses demonstrated the presence of the bovine OXTR protein at about 45 kDa in lymphocytes, as well as expression of the 14-kDa precursor of OXT. When lymphocytes were treated with OXT, intracellular concentrations of calcium ([Ca2+]i) were rapidly and dramatically increased. This study demonstrated that bovine lymphocytes express OXTRs and that this expression can be regulated in a steroid-dependent manner. Furthermore, OXT elicited a functional [Ca2+]i response in T lymphocytes, supporting the possibility that OXT within the CL could act as a paracrine or autocrine regulator of resident T lymphocytes.
Ndiaye
Kalidou
K
Department of Animal Sciences, The Ohio State University/Ohio Agricultural Research and Development Center, Wooster, Ohio 44691, USA.
Poole
Daniel H
DH
Pate
Joy L
JL
D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000097:blood; D002417:Cattle / Q000097:blood*; D002478:Cells, Cultured; D018920:Coculture Techniques; D004958:Estradiol / Q000494:pharmacology; D030762:Estrous Cycle / Q000502:physiology; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D010121:Oxytocin / Q000494:pharmacology; D011374:Progesterone / Q000494:pharmacology; D012333:RNA, Messenger / Q000097:blood; D018045:Receptors, Oxytocin / Q000097:blood / Q000235:genetics*; D016176:T-Lymphocyte Subsets / Q000737:chemistry / Q000187:drug effects; D013601:T-Lymphocytes / Q000737:chemistry* / Q000187:drug effects
D012333:RNA, Messenger; D018045:Receptors, Oxytocin; D011374:Progesterone; D004958:Estradiol; D010121:Oxytocin; D002118:Calcium