Cycle dependent LH/hCG receptor gene expression in porcine nongonadal reproductive tissues

Uterine and other nongonadal reproductive tissues are a new target for LH and CG action in pig and many other mammalian species, including humans. Since rat and pig LH/CG receptor cDNAs have been cloned we have been prompted to look for the expression of this gene in porcine uteri and oviducts. Reverse transcription-polymerase chain reaction (RT-PCR) was carried out on total RNA isolated from endometrium, myometrium and oviduct. Ovarian and testicular RNA served as positive and skeletal muscle RNA as negative control. RT-PCR was designed to amplify part of the extracellular domain (exons II-IX) of the LH/CG receptor. Southern blot with cDNA probe was used to verify the authenticity of the cDNA species generated. A PCR product of an expected size of 619 bp corresponding to exons II-IX was detected in, besides gonads, both the endometrial and myometrial uterine layers as well as in oviducts. Southern blot revealed presence of additional, shorter fragment (about 400 bp) in corpus luteum, myometrium and oviduct. This additional fragment was found in myometrium during the follicular and late luteal phases as well in oviducts during early luteal, early and late follicular phases. Also, testes showed two RT-PCR products. There was no DNA amplification after reverse transcription in the reaction mixture containing skeletal muscle total RNA. The results of our paper have demonstrated that the LH/CG receptor gene is expressed in the porcine nongonadal reproductive tissues and the expression is dependent on the estrous cycle phase and probably is also tissue specific.