The Novel Role of Kisspeptin and GPR54 in Mice Reproduction
Date Issued
2011
Date
2011
Author(s)
Hsu, Meng-Chieh
Abstract
In recent studies, it has been reported that kisspeptin act as an upstream regulator of hypothalamus-pituitary-gonad axis (HPG axis), the main regulatory system of animal reproduction. Kisspeptin, a short peptide encoded from Kiss1 gene, is a ligand of G protein-coupled receptor 54 (GPR54) that is expressed in GnRH neurons. Kisspeptin is able to stimulate GnRH neurons through GPR54 and its downstream signals, and elicit the hormone transductions in HPG axis. Kiss1 and Gpr54 have been found expressed in various tissues including testis and ovary, but their functions are still not well understood. The purpose of this study is to investigate the expression profiles and functions of kisspeptin and GPR54 in mice testis and ovary.
Tissue samples were collected from adult ICR strain mice and extracted total RNA for semi-quantitative RT-PCR. The results showed that Gpr54 gene was highly expressed in testis and other tissues. Also, we used collagenase and filter for testis tissues dissociation and found that Gpr54 mRNA was mainly expressed in seminiferous tubule cells but not Leydig cell. For identifying the possible location of GPR54 in seminiferous tubules, the testis tissues were analyzed by immunohistochemistry staining method. On further examination, GPR54 was specifically expressed in spermatid, but not spermatogonia, spermatocyte, or sertoli cell. Because of GPR54 expressed pattern was closed to the site of acrosome, the testis sections were stained with GPR54, SP56 (an acrosome marker) antibodies and Hoechst 33342, as triple-label immunofluorescense staining. The results showed that GPR54 was located in acrosome area of both spermatids and mature sperms. Interestingly, we also observed that GPR54’s ligand kisspeptin was expressed in culumus-oocyte complex and oviduct’s epithelium on ovary and oviduct section. Based on above results, we hypothesized kisspeptin and GPR54 might be involved in fertilization controls when sperm reaches female reproductive ducts. Through in vitro fertilization (IVF) method, it was revealed that blocking kisspeptin signal by antagonist peptide-234 decreased the fertilization rate.
To summarize, the present studies indicated that kisspeptin and GPR54 were existed in both male and female gametes and other surrounding cells, suggested that they were related to the process of fertilization. Owing to fertilization includes multiple control mechanisms, the exact physiological role of the kisspeptin-GPR54 system in regulating sperm function remains to be elucidated.
Subjects
testis
sperm
fertilization
Type
thesis
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