Steroid hormones regulate essential physiological processes, and inadequate levels are associated with various pathological conditions. In testosterone-producing Leydig cells, steroidogenesis is strongly stimulated by luteinizing hormone (LH) via its receptor leading to increased cyclic AMP (cAMP) production and expression of the steroidogenic acute regulatory (STAR) protein, which is essential...

Primary points of control in steroidogenesis are the transport of cholesterol from intracellular stores to the inner mitochondrial membrane, and the subsequent conversion of cholesterol to pregnenolone by the cholesterol side-chain cleavage enzyme (P450scc). Testosterone production has been shown to decline in Brown Norway rat Leydig cells as the rats age. To better understand the mechanism by ...

The LH signal transduction pathway features the activation of protein tyrosine phosphatases (PTPs) as one of the components of a cascade that includes other well characterized events such as cAMP-dependent protein kinase A (PKA) activation. Moreover, the action of PTPs is required to increase the rate-limiting step in steroid biosynthesis, namely the cAMP-regulated transfer of cholesterol to th...

Backgr ound and Objective: To examine the acute effects of propylthiouracil (PTU) on corticosterone release by rat adrenal Zona Fasciculata Reticularis (ZFR) cells. Materials and Methods: Male rats were infused with alkaline saline or PTU (10 mg kgG1) via right jugular catheter. The blood samples were collected at 0, 30, 60, 120, 180 and 240 min after infusion. Rat ZFR cells were treated with P...

Endometriosis is a common, chronic and estrogen-dependent gynaecological disorder associated with pelvic pain and infertility. In addition to, or perhaps as a consequence of, immune, environmental and genetic factors, endometriotic lesions show high estradiol (E(2)) biosynthesis and low E(2) inactivation compared with normal endometrium. Current medical therapies of pain, which aim to lower cir...

Intracellular cAMP and Ca(2+) are involved in the regulation of steroidogenic activity in Leydig cells, which coordinate responses to luteinizing hormone (LH) and human chorionic gonadotropin (hCG). However, the identification of Ca(2+) entry implicated in Leydig cell steroidogenesis is not well defined. The objective of this study was to identify the type of Ca(2+) channel that affects Leydig ...

The aim of the present study was to identify the sites of the inhibitory action of TNFalpha (tumor necrosis factor alpha) on LH/hCG-stimulated testosterone formation. By using cultured porcine Leydig cells as a model, TNFalpha was shown to inhibit testosterone secretion when testicular cells were stimulated with hCG but not when incubated with 22R-hydroxycholesterol (a cholesterol substrate der...