Inducible Nitric Oxide Synthase Expression and Luteal Cell DNA Fragmentation of Porcine Cyclic Corpora Lutea

Yong Tao,Xiufen Chen,Lei Lei,Zhuo Fu,Jie Yang,Guoliang Xia

doi:10.5713/ajas.2005.626

Abstract

Nitric oxide (NO) derived from inducible nitric oxide synthase (iNOS) is involved in cell apoptosis, which contributes to luteal regression and luteolysis in some species. In large domestic animals, no direct evidence for the relationship between NO and cell apoptosis in the process of corpus luteum regression is reported. The present study was conducted to investigate the localization of iNOS on porcine corpora lutea (CL) during the oestrus cycle and its relation to cell DNA fragmentation and CL regression. According to morphology, four luteal phases throughout the estrous cycle were defined as CL1, CL2, CL3 and CL4. By isoform-specific antibody against iNOS, the immunochemial staining was determined. Luteal cell DNA fragmentation was determined by flow cytometry. The results showed that no positive staining for iNOS was in CL1 and that iNOS was produced but limited to the periphery of CL2, while in the CL3, the spreading immunochemical staining was found inside the CL. No iNOS positive staining was detected in CL4. Meanwhile, DNA fragmentation increased dramatically when CL developed from CL2 to CL3 (p<0.05). In CL4, higher proportion of luteal cells still had fragmented DNA than that of luteal cells from CL1 or CL2 (p<0.05). These results indicate that iNOS expression is closely related to luteal cell apoptosis and then to luteal regression. (Asian-Aust. J. Anim. Sci. 2005. Vol 18, No. 5 : 626-631)

Highlights

In the mammalian ovary, the corporus luteum (CL) is a showed evidence that nitric oxide (NO) was involved in mouse and transitory tissue formed from post-ovulatory follicles
The objective of this study is to test if inducible nitric oxide synthase (iNOS) expression in porcine CL is parallel with luteal cell apoptosis and CL regression
We find that luteal cell DNA fragmentation was closely related to iNOS secretion and that luteal development and regression is parallel with luteal cell DNA fragmentation, and iNOS expression is prior to luteal cell DNA fragmentation

Summary

Introduction

The corporus luteum (CL) is a showed evidence that NO was involved in mouse and transitory tissue formed from post-ovulatory follicles. Accumulating evidence has shown that apoptosis is the (bNOS), endothelial NOS (eNOS) and inducible NOS underlying mechanism of follicle atresia and the regression (iNOS). Among the 3 isoforms of NOS, iNOS hallmarks of apoptosis and can be used to evaluate produces the highest amount of NO, which is related to the the apoptotic cells (Matsuyama et al, 1996; Tao et al, apoptotic effect (Dixit and Parvizi, 2001). Localization of iNOS, the previous reports were not identical, It is well known that nitric oxide (NO) is an important even in the same animal, such as in rat (Jablonka-Shariff biological messenger which exhibits a wide range of effects and Olson, 1997; Matsumi et al, 1998)

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