THE EFFECT OF 6-AMINONICOTINAMIDE ON TESTICULAR DEVELOPMENT IN THE RAT

6-Aminonicotinamide (6-AN), a niacin antagonist, was administered sc t o pregnant female (1.0, 3.0, or 6.0 mg 6-AN/kg body weight) and neonat al male (1.5, 3.0, 6.0 or 12.0 mg 6-AN/kg body weight) Sprague-Dawley rats on the 15th, 17th and 19th days of gestation or the 5th, 7th and 9th days of life respectively, to determine the effects of the antimet abolite on testicular morphology and development. In prenatal males, m icroscopic alterations were present in testes of fetuses from females treated with 6.0 mg 6-AN/kg and consisted of necrosis and loss of gono cytes, and vacuolation of interstitial cells. Histologic changes in te stes of neonatal rats treated with 3.0, 6.0 or 12.0 mg 6-AN/kg were qu alitatively similar with necrosis and loss of spermatogonia and suppor ting cells, and increased cross-sectional areas of affected tubules. Q uantitation of the number of nuclei/cm(2) of seminiferous tubule indic ated 6-AN caused a significant reduction in the numbers of supporting cells and spermatogonia/tubular cross-section.