抄録
Although it has been reported that the ovarian expression of metastin (also called kisspeptin) mRNA is increased on proestrus, the physiological role of this increase is still unknown. In the present study, we further examined the metastin mRNA expression in the ovary during estrous cycle and clarified an ovarian component in which metastin is synthesized. Changes in GnRH mRNA expression in the ovary were also evaluated. Real-time PCR analysis showed a single peak of metastin mRNA expression at 20:00 h on proestrus. Metastin mRNA expression was stimulated by hCG. Follicles, corpus luteum and the interstitial tissues were cut from frozen ovary sections of proestrous 20:00 h by Laser Microdisection (LMD) and RNA was extracted. Metastin mRNA was shown to be included solely in follicles. When metastin antagonist, p234, was given into the hemi-lateral ovarian bursa for three days from proestrous morning with an osmotic minipump, the weight of the ovary became significantly smaller than that of the contra-lateral ovary given saline. There were two peaks in the variation of GnRH mRNA expression in the ovary, the first peak was at 20:00 h of diestrous 2 and the second peak was at 17:00 h of proestrus. Ten amino acid sequence of N terminus (Metastin45-54, kiss-10) given into ovarian bursa stimulated GnRH mRNA expression a little but significantly. Although metastin is thought at least partially to stimulate GnRH mRNA expression, there was no direct relationship between metastin and GnRH. Present data suggest that preovulatory LH surge facilitates follicular expression of metastin mRNA and metastin is involved in tissue reconstruction accompanying with the ovulation.
