ABSTRACT
The porcine corpus luteum (CL) is NOT sensitive to the luteolytic effects of PGF-2α until days 12-13 of cycle. The control of "luteolytic sensitivity" (LS) of the pig CL to PGF-2α is unknown, but it is temporally associated with macrophage infiltration into the CL. Since macrophages are the predominant source of TNF-α in the porcine CL, in other studies we examined the effects of TNF-α on porcine luteal cells in culture and showed that TNF-α induces LS in vitro. In Experiment 1 of this study possible mechanisms involved in the control of LS were examined, and involved measurement of the protein levels of PTGER2/EP-2, and PTGER3/EP-3 in porcine CL collected before (days 7-10), versus after (day 13), the onset of the LS. In Experiment 2, an examination of potential mechanisms involved in the control of LS by TNF-α, was carried out in which the effects of TNF-α on mRNA and protein expression of EP-2, EP-3 and FP in cultured luteal cells, were examined. The results of Experiment 1 showed that PTGER-3/EP-3 (but not PTGER-2/EP-2) levels decreased in porcine CLs after (day 13) compared to before (day 7-10) LS. In Experiment 2, the data obtained showed that TNF-α decreased PTGER-3/EP-3 and increased PTGFR/FP protein (in EARLY stage CL). In conclusion, these studies suggest a role for PTGER-3/EP-3 in the acquisition of LS, and support the hypothesis that TNF-α from CL macrophages plays a critical role in the control of LS in the porcine CL, by increasing PTGFR/FP, and decreasing PTGER-3/EP-3 protein.
Subject(s)
Corpus Luteum/drug effects , Prostaglandins E/pharmacology , Prostaglandins F/pharmacology , Tumor Necrosis Factor-alpha/pharmacology , Animals , Estrous Cycle , Female , Gene Expression Regulation/drug effects , Luteal Cells , Prostaglandins E/administration & dosage , Prostaglandins F/administration & dosage , Receptors, Prostaglandin/genetics , Receptors, Prostaglandin/metabolism , Receptors, Prostaglandin E, EP2 Subtype/metabolism , Receptors, Prostaglandin E, EP3 Subtype/metabolism , Swine , Tumor Necrosis Factor-alpha/administration & dosageABSTRACT
Improving our understanding of the mechanisms controlling the corpus luteum (CL) and its role in regulating the reproductive cycle should lead to improvements in the sustainability of today's global animal industry. The corpus luteum (CL) is a transient endocrine organ composed of a heterogeneous mixture steroidogenic, endothelial and immune cells, and it is becoming clear that immune mechanisms play a key role in CL regulation especially in luteolysis. Toll-like receptors (TLR) mediate innate immune mechanisms via the production of pro-inflammatory cytokines, especially within various tissues, although the role of TLR within CL remains unknown. Thus, the objectives of this study were to characterize TLR mRNA expression in the CL during the oestrous cycle and in pregnancy (day 30-50), and to examine the role of TLR signalling in luteal cells. Corpora lutea were collected at various stages of the cycle and pregnancy and analysed for TLR and cytokine mRNA expression. In addition, luteal cells were cultured with the TLR4 ligand (lipopolysaccharide, LPS) for 24 h to evaluate the role of TLR4 in regulating luteal function. Toll-like receptors 1, 2, 4, 6, tumour necrosis factor alpha (TNF), interferon gamma (IFN-G), and interleukin (IL)-12, mRNA expressions were greatest in regressing CL compared with earlier stages (p < .05), whereas no change was observed for IL-6 mRNA expression. Cytokine mRNA expression in cultured luteal cells was not altered by LPS. Based on these data, one or more of the TLRs found within the CL may play a role in luteolysis, perhaps via pro-inflammatory cytokine mRNA expression.
Subject(s)
Corpus Luteum/metabolism , Cytokines/genetics , Estrous Cycle/genetics , Pregnancy, Animal/genetics , RNA, Messenger/genetics , Toll-Like Receptors/genetics , Animals , Cattle , Corpus Luteum/drug effects , Estrous Cycle/metabolism , Female , Gene Expression Regulation , Lipopolysaccharides/pharmacology , Luteolysis/genetics , Pregnancy , Pregnancy, Animal/metabolism , RNA, Messenger/metabolism , Toll-Like Receptors/metabolismABSTRACT
STUDY QUESTION: Are daily cycles in urinary melatonin and oxidative stress marker levels (8-hydroxydeoxyguanosine) altered in PCOS, and is this associated with changes in sleep quality? SUMMARY ANSWER: There is an association between elevated nighttime melatonin and 8-hydroxy-2-deoxyguanosine (8-OHdG) levels, and poor sleep quality in our PCOS study group. WHAT IS KNOWN ALREADY: Women with PCOS are known to have poorer sleep. However, there have been few studies examining the possible association between melatonin levels and sleep quality in women with polycystic ovarian syndrome (PCOS). STUDY DESIGN, SIZE, DURATION: This is a case-control study of PCOS (n = 26) and non-PCOS control (n = 26) subjects recruited from a tertiary gynaecological centre. PARTICIPANTS/MATERIALS, SETTING, METHODS: The participants were requested to complete sleep questionnaires for a month. In a subgroup from these cohorts (PCOS, n = 15; controls, n = 18), urine samples were also collected at various time points over a 24-h period. In addition, their sleep patterns and lighting environment were monitored for 3 consecutive days and nights using a wrist-mounted Actiwatch device. MAIN RESULTS AND THE ROLE OF CHANCE: PCOS women had significantly elevated night-time urinary levels of the melatonin metabolite 6-sulfatoxymelatonin (aMT6s) and of 8-OHdG (both at P < 0.05), as well as significantly reduced sleep quality (P < 0.05), compared with the controls. LIMITATIONS, REASONS FOR CAUTION: Due to the small sample size of the study, further studies will be required to confirm our findings. WIDER IMPLICATIONS OF THE FINDINGS: Our preliminary work provides a possible new insight into the interactions between melatonin, increased oxidative stress and sleep in women with PCOS. STUDY FUNDING/COMPETING INTEREST(S): The study was funded by the Faculty of Medicine, University of Southampton.
