ABSTRACT
<p><b>OBJECTIVE</b>To study the influence of electromagnetic irradiation on cytochrome P450 cholesterol side chain lyase (P450scc) in adult rat testis tissues and to assess the protective effect of the copper shield.</p><p><b>METHODS</b>Healthy male Wistar rats were randomized into a control group, an electromagnetic irradiation group and a wholly shielded group (with the copper shielding net). The electromagnetic irradiation group and the shielded group were set for 4 phases of 3, 6, 24 and 72 hours after irradiation, 15 rats for each phrase. The testosterone contents in the serum of the irradiated rats at 3, 6, 24 and 72 hours and in that of the controls were measured by radioimmunoassay(RIA), and so was the level of the P450scc mRNA in the testis tissues by semi-quantitative RT-PCR. And the effect of the copper shielding net on testosterone and P450scc mRNA was observed.</p><p><b>RESULTS</b>The contents of testosterone and the P450scc mRNA level in the irradiated group were significantly lower than in the control rats, decreased by 83.9% and 56.9% at 3 hours (P < 0.01), 54.8% and 27.3% at 6 hours (P < 0.01), restored to normal at 24 hours, but again reduced by 60.1% and 56.1% respectively (P < 0.01). While in the shielded group, no significant change was observed either in the testosterone of the serum or in the P450scc mRNA expression in the testis tissues.</p><p><b>CONCLUSION</b>Electromagnetic irradiation may affect the transcription of P450scc in adult rat Leydig cells and thereby decrease the testosterone synthesis. Whole-body shielding with the copper net may achieve satisfactory effect.</p>