Nitric oxide synthases (NOS) account for the endogenous production of nitric oxide (NO), a small and permeable bioreactive molecule. NO is known to act as a paracrine mediator during various processes associated with female reproduction. In the present study, the mRNA expression of the endothelial (eNOS) and inducible (iNOS) NO synthases were examined in bovine oviduct epithelial cells (BOEC) during the oestrous cycle. In addition, eNOS and iNOS mRNA and protein were localised by in situ hybridisation and immunocytochemistry respectively. Furthermore, the effects of exogenously applied oestradiol-17β and progesterone on NOS mRNA regulation were studied in a suspension culture of BOEC. The eNOS mRNA abundance was low around ovulation (day 0) and increased significantly until pro-oestrus (day 18) in the ampulla. Immunoreactive protein of eNOS was detected predominantly in endothelial cells as well as in secretory oviduct epithelial cells at pro-oestrus. The iNOS mRNA concentration was significantly reduced in the isthmus at pro-oestrus (day 18) and oestrus (day 0) compared with persistently high levels in the ampulla. By in situ hybridisation, specific iNOS transcripts were additionally demonstrated in the oviduct epithelium. Immunoreactive iNOS protein was localised in secretory epithelial cells as well as in the lamina muscularis. The in vitro stimulation showed that both NOS were stimulated by progesterone, but not by oestradiol-17β. The region-specific modulated expression of eNOS and iNOS provides evidence for an involvement of endogenously produced NO in the regulation of oviductal functions.
S E Ulbrich, S Rehfeld, S Bauersachs, E Wolf, R Rottmayer, S Hiendleder, M Vermehren, F Sinowatz, H H D Meyer and R Einspanier
Julie A Meyers, Amy Y Liu, Anne McTiernan, Mark H Wener, Brent Wood, David S Weigle, Bess Sorensen, Zehava Chen-Levy, Yutaka Yasui, Alanna Boynton, John D Potter and Cornelia M Ulrich
Experimental studies and case reports suggest a multifunctional role of leptin in immune function. However, clinical studies of leptin in healthy individuals with a comprehensive assessment of immunity are lacking. This study investigated associations between serum leptin concentrations and multiple biomarkers of cellular immunity and inflammation among 114 healthy postmenopausal, overweight, or obese women. Leptin was measured by RIA. C-reactive protein (CRP) and serum amyloid A (SAA) were measured by nephelometry. Flow cytometry was used to measure natural killer (NK) cell cytotoxicity and to enumerate and phenotype lymphocyte subsets. T-lymphocyte proliferation was assessed in response to phytohemagluttinin, as well as to anti-CD3 antibodies by the flow cytometric cell division tracking method. Multiple linear regression analysis with adjustment for confounding factors and log transformation, where appropriate, was used. Serum leptin concentrations were positively associated with serum CRP, SAA, and interleukin 6 (IL6) (P<0.0001, P=0.01, and P=0.04 respectively), more strongly among women with a body mass index (BMI) <30 kg/m2. The associations were attenuated after adjustment for measured body composition, yet remained significant for CRP and SAA. No statistically significant associations were observed between leptin and NK cytotoxicity, lymphocyte subpopulations, or T-lymphocyte proliferation. This study fills an important gap in knowledge about the relationship between leptin concentrations and immune function in healthy individuals. Findings support an association between serum leptin and the inflammatory proteins CRP and SAA, which appears to be mediated only partly by adipose tissue. Our study does not support a link between leptin and other immune parameters among overweight or obese, but otherwise healthy postmenopausal women, perhaps because such effects are only present at low or deficient leptin concentrations.