[Expression of thyrotropin-releasing hormone receptor mRNA in the rat testis development]

In order to investigate the regulation of thyrotrophin-releasing hormone receptor (TRH-R) expression in rat testis, and to study their function in spermatogenesis, oligonucleotide primers were designed from the sequences of rat pituitary TRH-R cDNA for reverse transcription-polymerase chain reaction (RT-PCR). Specific fragments of TRH-R cDNA were cloned. DNA sequence analysis indicated that cDNA sequence of TRH-R from rat testis was consistent with those of pituitary TRH-R cDNA. The non-radioactive in situ hybridization (NR-ISH) technique was applied to localize cells encoding TRH-R mRNA in the rat testis. Hybridization signals were detected exclusively in the leydig cells, but not in the spermatogenetic cells of the rat testis. TRH-R mRNA in the testis was quantitated in RNA samples prepared from rats at different developmental stages by real time quantitative RT-PCR. The quantitative analyses demonstrated that no TRH mRNA could be detected at the earliest stage (day 8). TRH mRNA signals were detected on day 15 and increased progressively on day 20, 35, 60 and 90. These results suggested that rat testis could specifically express TRH-R, and the transcription of TRH-R gene in the rat testis was development-dependent.