Leydig cell tumors represent approximately one to three percent of all testicular tumors. Whereas in experimental animals predisposing conditions include administration of chemical carcinogens, hormones and heavy metals, environmental or endogenous factors in man are presently unrecognized. Leydig cell tumors do not show preferential lateralization or tendency for bilaterality. The symptoms are...

In addition to their role in steroidogenesis in the male, testicular Leydig cells constitutively express large amounts of the peptide relaxin-like factor (RLF), also known as Ley-IL. The Leydig cell-derived RLF belongs to the insulin-like superfamily, which also includes relaxin, insulin and the insulin-like growth factors, and within the testis is a specific marker of Leydig cells. Little info...

The neurotransmitter gamma-aminobutyric acid (GABA) and subtypes of GABA receptors were recently identified in adult testes. Since adult Leydig cells possess both the GABA biosynthetic enzyme glutamate decarboxylase (GAD), as well as GABA(A) and GABA(B) receptors, it is possible that GABA may act as auto-/paracrine molecule to regulate Leydig cell function. The present study was aimed to examin...

Progenitor Leydig cells are derived from stem cells. The proliferation and differentiation of progenitor Leydig cells significantly contributes to Leydig cell number during puberty. However, the regulation of these processes remains unclear. The objective of the present study was to determine whether luteinizing hormone (LH) or androgen contributes to the proliferation and differentiation of pr...

Development of the testis begins with the expression of the SRY gene in pre-Sertoli cells. Soon after, testis cords containing Sertoli and germ cells are formed and fetal Leydig cells subsequently develop in the interstitial space. Studies using knockout mice have indicated that multiple genes encoding growth factors and transcription factors are implicated in fetal Leydig cell differentiation....

By means of immunocytochemical methods, immunoreactivity for the brain isoform of nitric oxide synthase (NOS-I) was recognized in numerous Leydig cells of the human testis as well as in MA-10 tumor and TM3 non-tumor mouse Leydig cell lines. Within the Leydig cell cytoplasm, immunocytochemical results suggested the occurrence of factors known to activate NOS-I such as glutamate and aspartate, as...

The hypothalamic-pituitary-gonadal (HPG) axis comprises pulsatile GnRH from the hypothalamus impacting on the anterior pituitary to induce expression and release of both LH and FSH into the circulation. These in turn stimulate receptors on testicular Leydig and Sertoli cells, respectively, to promote steroidogenesis and spermatogenesis. Both Leydig and Sertoli cells exhibit negative feedback to...

Leydig cells undergo apoptosis in response to the cytotoxin ethane dimethanesulfonate (EDS), with numbers declining at 12-18 h and maximal apoptosis at 24 h postinjection. The Bcl-2 family members, Bcl-2, Bcl-xl, and Bax, appear not to be involved in this process. To further investigate this phenomena, a single dose of EDS was administered to adult rats to induce the killing of Leydig cells. Th...

The immunohistochemical reaction to oncostatin M (OSM) was studied in normal human testes at different ages (fetuses, newborns, children, pubertal boys, adults, and elderly men), as well as in several testicular disorders including carcinoma-in-situ cells (CIS), germ cell tumors, benign functioning Leydig cell tumor, androgen insensitivity syndrome, Klinefelter's syndrome, and cryptorchidism. P...