RESUMEN
<p><b>OBJECTIVE</b>To explore the effects of long-term exposure to particulate matter 2.5 (PM2.5) from automobile exhaust on the reproductive function of Sprague Dawley (SD) rats.</p><p><b>METHODS</b>Forty-five male SD rats, weighing 80 - 94 g and aged 28 days, were randomly assigned to receive intra-tracheal administration of 0.9% normal saline (control group, n = 15), PM2. 5 at 2 μg per 100 g body weight per day (low-dose PM2.5 group, n = 15), and PM2.5 at 16 μg per 100 g body weight per day (high-dose PM2.5 group, n = 15), qd, for 60 successive days. After the last 24-hour exposure, 10 rats were taken from each group for copulation with normal female ones, while the others were sacrificed, their testes removed for sperm count and deformity, pathological examination, and determination of the Connexin43 expression.</p><p><b>RESULTS</b>The conception rate was significantly decreased in the low- and high-dose PM2.5 groups as compared with that of the control (70% and 50% vs 100%), and so were the sperm count and quality. The rats in the PM2.5-exposed groups showed significantly disordered histological structure of the seminiferous tubules, reduced sperm count in the testicular lumen, some exfoliated secondary spermatocytes, downregulated Connexin43 expression in the testis, and damaged blood-testis barrier.</p><p><b>CONCLUSION</b>Long-term exposure to PM2.5 from automobile exhaust damages the reproductive function of male SD rats.</p>