Insulin receptor substrates (IRS) mediate the biological actions of insulin, growth factors and cytokines. This action is via receptor-mediated tyrosine phosphorylation of IRS proteins. The aim of present study was to demonstrate the distribution of IRS-1-3, the glucose transporter class I subfamily (GLUT-1-4), signal regulatory protein 1alpha (SIRP1alpha), protein kinase B (PKB) and phosphatidylinositol kinase (PI3-K) in the human testis to determine whether signal transduction mediated by these proteins is active in testicular cells. In the present study, the expression of IRS-1-3, GLUT-1-4, SIRP1alpha, P13-K and PKB was studied in the human testis at the protein level using immunohistochemistry and western blotting. A positive immunoreaction for IRS-1 was found in the human testis in peritubular myoid cells and macrophage-like interstitial cells. A positive immunoreaction for GLUT-3 was found in the human testis in Sertoli cells, peritubular myoid cells, early spermatocytes, macrophage-like interstitial cells and cells in the small vessels walls. Western blotting demonstrated IRS-1, IRS-2 and GLUT-3 proteins in the human testis. Expression of IRS-3, GLUT-1, GLUT-2, GLUT-4, SIRP1alpha, P13-K and PKB was not detected in the human testis. The results of the present study suggest that proteins like insulin and certain cytokines using IRS-1, IRS-2 and GLUT-3 in their signal transduction pathways can have effects on different cell types of the testis in humans.

Insulin receptor substrate (IRS) proteins are key mediators in insulin signaling from the insulin receptor. It takes place through receptor-mediated tyrosine phosphorylation of IRS proteins. The aim of the present article is to demonstrate the distribution of IRS 1-3, glucose transporters 1-4 (GLUT 1-4), signal regulatory protein 1alpha (SIRP1alpha), PKB, and PI 3-kinase in the rat testis to see if signal transduction mediated by these proteins is active in testicular cells. Wistar rats were used as donors of testis tissue. Expression of these genes was studied at the protein level by using immunohistochemistry and Western blotting. IRS-1, IRS-2, GLUT 1, GLUT 2, GLUT 3, and SIRP1alpha were strongly expressed in the Sertoli cells (except GLUT 1), early spermatocytes, peritubular myoid cells, macrophage-like interstitial cells, and testicular endothelial cells in all the testes investigated by immunohistochemistry. IRS-2 was also expressed in the Leydig cells. Immunoblotting experiments demonstrated the presence of about 26-67 kDa reactive with anti- IRS-1, IRS-2, GLUT 1, GLUT 2, GLUT 3, PKB, and SIRP1alpha. The present results suggest that proteins like insulin and certain cytokines using IRS-1, IRS-2, GLUT 1, GLUT 2, GLUT 3, PKB, and SIRP1alpha in their signal transduction can have effects on the different types of testicular cells in the rat.

The role of luteinizing hormone (LH) in the regulation of normal reproductive functions in males and females is quite well established. Besides the expression of LH receptors in the target cells in gonads, it has been found in several extragonadal organs. There is no information about the expression of LH receptors in the penis up to now. The aim of the present study is to investigate the expression of the LH receptor in the mouse penis to see if LH effects are possible in the penis. BALB/c mice were used as donors of normal penis and testis tissue. Immunocytochemistry, Western blotting, and quantitative reverse transcriptase polymerase chain reactions (RT-PCRs) were used for the detection of the LH receptor.Positive immunoreaction for LH receptors was present in the nuclei of urethral epithelium and endothelial cells of cavernous spaces in the corpus cavernosum and corpus spongiosum penis. Western blotting experiments demonstrated the presence of LH antigen at M r 5 97.4 and 78 kd. Quantitative RT-PCRs confirmed the expression of LH receptor in the penis. Our results show that LH receptor is expressed in the body of the mouse penis; thus, it may directly regulate functions of penile tissue.