Abstract: 【Objective】 This paper is to clone luteinizing hormone receptor (LHR) fragment from uterine tissue of guinea pig and to analyze evolutionary relationships and the expression characteristics of LHR mRNA during estrous cycle. 【Method】Total RNA extracted from the uterus of guinea pig and primers designed according to the conservative sequence of pig, rat and mice was used for RT-PCR to amplify LHR fragment. Positive clones were identified and sequenced. The DNAMAN software was applied to analyze the homology. ?-actin was used as an inner control and an optimal semi-quantitative RT-PCR method was established to analyze LHR mRNA expression levels in the uterus during 4 estrous cycle phases. 【Result】 Sequencing analysis indicated that there were two kinds of spliced variants: One was the 686 bp fragment and another was 611 bp with a deletion of 75 bp in exon 4. The 686 bp fragment was 83.8% identical to the reported human LHR mRNA, 84.6% to the cattle, 84.2% to the pig, 83.6% to the sheep, 93.7% to the rat, and 99.4% to the mice of LHR mRNA. The uterine LHR mRNA expression was different during 4 phases of the estrous cycle. The levels on day 0(0.635 ± 0.019) and day 4(0.617 ± 0.099) were both significantly lower than that on day 8(P＜0.05), then it rose to the highest on day 12(1.218 ± 0.049) of the cycle. 【Conclusion】 The fragment cloned was a partial sequence of LHR, and the mRNA alternatively spliced variant often existed. The expression level of LHR mRNA in the uterine decreased on days 0 and 4, and increased on day 12. The results have provided a theoretical basis for exploring the functions of LHR in non-gonad tissues of mammals, and meanwhile provided molecular data for further researches in regulation of reproductive endocrinology in other mammals.

Key words: guinea pig, estrous cycle, uterus, LHR mRNA, semi-quantitative RT-PCR, spliced variants