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(591) EXPRESSION OF THE INSL3 / LGR8 HORMONE-RECEPTOR SYSTEM IN THE TESTIS. Anand-Ivell, Ravinder1, 2, Balvers, Marga2, Telgmann, Ralph2, Ivell, Richard1, 2, 1 School of Molecular and Biomedical Sciences, Adelaide, SA, Australia2 Institute for Hormone and Fertility Research, Hamburg, Germany ABSTRACT- The peptide hormone Insl3 (insulin-like factor 3, alternatively known as relaxin-like factor, RLF) is a major secreted product of the Leydig cells in all species of mammals. In rodents it has been shown to be responsible for the transabdominal phase of testicular descent, its absence or down-regulation in the fetus leading to cryptorchidism. Recently, a novel G-protein coupled receptor, LGR8, was identified as the specific receptor for Insl3. In order to characterize possible testicular roles for the Insl3/LGR8 system, we have developed and validated novel antibodies against the LGR8 receptor, and used these in immunohistochemistry in both human and rodent tissues to identify cells potentially able to respond to the peptide hormone. Furthermore, we have applied RT-PCR analysis for the specific receptor transcripts to testicular cells, cell-lines and tissues, in order to corroborate these findings. Both immunohistochemistry and RT-PCR analysis confirmed the Leydig cells as a major site of LGR8 receptors in the adult testis, supporting an autocrine role for Insl3. In addition LGR8 receptors appear to be present in an intratubular location, most probably the germ cells, since Sertoli cell-lines and germ cell-depleted testes have no or reduced LGR8 mRNA, respectively. This research was funded in part by the Innovation Funds of the City of Hamburg and by the German Research Council (DFG Graduiertenkolleg 336). KEY WORDS: Leydig cells, LGR8, cryptorchidism, relaxin-like factor |
