Effect of TCDD on corpus cavernosum histology and smooth muscle physiology

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Abstract
A polyhalogenated aromatic hydrocarbon, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), is one of the most potent toxic environmental pollutants. Decreases in spermatogenesis and the ability to conceive and carry a pregnancy to term are the most sensitive signs of reproductive toxicity by TCDD in the mammal, but no report of its effect on the erectile function exists. We performed this study to investigate the effect of TCDD on the erectile function. New Zealand white rabbits were treated intraperitoneally with 1 g/kg of TCDD. At 4 (Gr I) and 8 (Gr II) weeks after the administration of TCDD, cavernosal tissues were harvested for strip study in the organ bath and testes were prepared for histologic examination. Compared to the maximal amplitude of 17.14.12 mN in normal control (Gr III), the contractions to cumulative concentrations of NE (10-8–10-4 M) were significantly decreased to 6.571.34 and 5.451.01 mN in Groups I and II, respectively. Compared to 51.127.38% in Gr III, relaxation to cumulative concentration (10-8–10-4 M) of acetylcholine was significantly decreased to 17.252.17% (Gr I) and 9.732.17% (Gr II) at a concentration of 10-4 M, respectively. Compared to 75.1213.18% in Gr III, relaxation to cumulative concentration (10-8–10-4 M) of SNP was significantly decreased to 31.497.89% (Gr I) and 18.546.12% (Gr II) at a concentration of 10-4 M, respectively. Histologically, intracavernosal fibrosis, abnormal subtunical deposition of fat and decreased sinusoidal space with consequent increase of trabecular smooth muscle contents were identified in TCDD-treated groups. In TCDD-treated animals, seminiferous tubules showed a decrease of germ cells with vacuolar degeneration and apoptotic cells. Spermatids were hardly seen. These results suggest that TCDD inhibits spermatogenesis and has a potential harmful effect on erectile function via changes of corpus cavernosum histology and smooth muscle physiology.