Radiation Exposure Impairs Luteinizing Hormone Signal Transduction and Steroidogenesis in Cultured Human Leydig Cells

Abstract

Therapeutic, accidental, and experimental radiation exposures decreased serum testosterone in males, leading to various sexual problems. Since testicular Leydig cells are the predominant source of circulating testosterone, findings on the direct effects of radiation on Leydig cell steroidogenesis and the mechanism behind such effects would be of greater importance to the use of safer radiation doses in cancer therapy and to adopt preventive or therapeutic measures to alleviate postirradiation lesions, respectively. Therefore, this study was undertaken to explore the same using cultured human Leydig cells. Testicles removed from advanced prostatic carcinoma patients were used for isolation and purification of Leydig cells. Purified Leydig cells were cultured and then exposed to different doses (2, 4, 6, 8, and 10 Gy) of fractioned gamma radiation. Normal and irradiated cells were used for luteinizing hormone (LH) receptor quantification or total RNA isolation to study LH receptor mRNA expression or LH/cyclic AMP (cAMP) stimulation test. While LH-stimulated cells were used for cAMP assay, LH- and cAMP-stimulated cells were used for the estimation of steroidogenic enzymes, testosterone and estradiol production. Radiation exposure caused adverse effects on Leydig cell steroidogenesis in a dose-dependent manner. While lower doses (2 and 4 Gy) were ineffective, higher doses (6 Gy and above) drastically decreased LH receptor, basal and LH-stimulated cAMP generation, and basal, LH-, and cAMP-stimulated steroidogenesis. While 2 Gy of radiation exposure increased the LH receptor mRNA level, other doses did not induce any significant change. Therefore, it is concluded that higher doses of radiation impair Leydig cell steroidogenesis by affecting LH signal transduction at the level of both pre- and post-cAMP generation. Decreased level of LH receptors following higher doses of radiation exposure is not coupled with impaired expression of its mRNA.

Morphology and function of human Leydig cells in vitro. Immunocytochemical and radioimmunological analyses

“…Human Leydig cells arise from mesenchymal cells or fibroblast-like precursor cells through a hormonally regulated differentiation process (Chemes, 1996). Production of testosterone in human and mammalian Leydig cells is dependent on LH stimulation in vivo and on LH/hCG stimulation in in vitro conditions; to respond to hormonal regulation the cells are equipped with functional receptors for LH (Amador and Bartke, 1987; Simpson et al , 1987; Mendis-Handagama et al ,1990; Cooke, 1996; Ramadoss et al , 2006). In man, the Δ 5 -metabolic pathway is the major pathway for the metabolism of pregnenolone to testosterone (Rommerts, 1990).…”

Ameliorative Effect of Sugarcane (Blackstrap) Molasses against Gamma Radiation or Manganese- Induced Testicular Toxicity in Male Albino Rats

“…The decrease of LH level post-radiation or Mn-toxicity might be caused by the damage in Leydig cells, where luteinizing hormone releasing hormone (LHRH) receptors are located (Sivakumar et al, 2006).…”

Hypoxia reduces testosterone synthesis in mouse Leydig cells by inhibiting NRF1-activated StAR expression

“…The method used for the isolation and purification of Leydig cells was modified from one previously described for testis Leydig cells extraction [33]. Briefly, decapsulated Balb-c mice testes were immersed in 0.1% collagenase-PBS and were shaken for 30 min at 200 rpm, 37°C.…”