TESTICULAR EXPRESSION OF HUMAN PROTEIN HO RMONES

The human (h) protein hormones, growth hormone (hGH-N) and prolactin ( hPRL), are mainly produced in the pituitary, whereas the human placent a expresses the other four members of the protein hormone gene family, designated placental lactogens (PL-A, PL-B, PL-L) and growth hormone variant (GH-V). GH-N stimulates somatic growth, supports nitrogen-, ph osphate- and potassium retention and promotes lipolytic and anabolic m etabolism, whereas PRL acts on the mammary gland and induces mammogene sis, lactogenesis and galactopoesis. Both hyperprolactinemia and growt h hormone deficiency affect the onset of puberty and reproduction in m an and mice. In addition to the glycoprotein hormones, these hormones play a role in the maintenance of testicular function. Our group previ ously demonstrated eutopic production of glycoprotein hormones hLH (hu man luteinizing hormone) and hCG (human chorionic gonadotropin) in the testis. We have now extended our investigations to the local testicul ar expression of protein hormones.By means of the molecular biology te chniques of the reverse transcription-polymerase chain reaction (RT-PC R), Southern blot: and by restriction endonuclease analyses of the gen erated PCR products we demonstrated the eutopic expression of genes co ding for the protein hormones. GH-N gene transcripts were detected onl y in the pituitary and abundant PL-A/B and a few GH-V gene transcripts were demonstrable in the placenta. In contrast, in the testis GH/PL a nd PRL genes are transcribed. Since testicular protein hormone gene ex pression is rather low, these hormones may act locally and not as syst emic factors; they presumably modulate the LH/CG-mediated testosterone biosynthesis and/or may act on the spermatogenesis.