Age and Dose-Specific Testicular Histomorphometry and Hormonal Profile in Lead-Intoxicated Rats

In the present study, we report the relationship between doses of oral lead exposure, duration of exposure, and the hormonal and testicular histomorphometric changes in male Wistar rats at specific stages of postnatal development. Male juvenile Wistar rats (average weight of 34 g) were administered lead acetate at concentrations of 0.5% (5000 ppm), 1.0% (10,000), and 1.5% (15,000 ppm) via drinking water. Rats were killed at 3 weeks, 6 weeks, 9 weeks, and 12 weeks of postnatal development, representing the early juvenile, late juvenile, peripubescent and early postpubescent stages of life. Sera were analyzed for gonadotropins (Gn) and testosterone (T). Testicular histomorphometry was studied by the H&E and toluidine blue techniques; while caudal epididymal sperm cells were analyzed for density and motility. Serum T and Gn levels were significantly reduced (P<0.05) in the leadexposed rats at the peripubescent and early post-pubescent periods. Sperm density showed significant decreases in the lead-treated rats only at the early post-pubescent age; while sperm motility was adversely impacted not only at postnatal week 12, but also at week 9 and week 6. In addition, testicular histology showed marked loss of germ and interstitial cells that was most severe at postnatal week 12, while germinal epithelium height and seminiferous tubule diameter were significantly attenuated in the lead groups at each of the age categories studied. These findings indicate that the adverse effects of juvenile oral lead on male reproductive profile are most pronounced in the peripubescent and early post-pubescent postnatal periods.

Key Words: Lead, testicular, histomorphometry, sex hormones, Age