OBJECTIVETo investigate the impact of in utero exposure to di-n-butyl phthalate (DBP) on the apoptosis of testicular cells in the pubertal male rat offspring.

METHODSTen pregnant SD rats were randomly divided into a control and an experimental group to be treated intragastrically with olive oil (1 ml per day) and DBP (500 mg per kg of body weight per day) respectively between gestation days 12 and 19. At the pubertal age (postnatal day 45, PND 45), the testes of the male rat offspring were removed for observation of the cell structure under the transmission electron microscope and the development of different spermatogenetic cells by HE staining. The apoptosis of testicular cells was detected by the TUNEL method, the expressions of the apoptosis-regulating proteins Bcl-2, Bcl-XL, Bax and p53 were determined by immunohistochemistry and Western blot, and the data obtained were compared between the two groups by t-test.

RESULTSTransmission electron microscopy revealed increased apoptosis and vacuolization of testicular cells in the PND-45 rat offspring, HE staining showed markedly decreased numbers of different spermatogenetic cells, TUNEL manifested significantly increased apoptosis of testicular cells in the experimental group as compared with the control (12.00 ± 5. 22 vs 3.17 ± 1.47, P < 0.01), and immunohistochemistry and Western blot exhibited remarkably higher expressions of Bax and p53 in the former than in the latter group (P < 0.05).

CONCLUSIONIn utero exposure to DBP can increase the apoptosis of germ cells and Sertoli cells, induce the vacuolization of testicular cells, and significantly elevate the expressions of the apoptosis-promoting proteins Bax and p53 in the pubertal male rat offspring.