In recent years, disorders related to the development and function of the male reproductive tract has increased, thus generating a surprising decrease in semen volume and sperm count. We examined the effects of low protein and estrogen on sexual behavior and testicular maturation in male rats. We also examined FSH, LH and testosterone levels and histological damage of testis tissue. The male rats were subjected to standard long-term treatment with estradiol by oral and paranteral delivery. The number of mounts, copulatory efficiency and ejaculation latencies for the paranteral protein diet (PPD) group was significantly lower than those in a group nourished with a low protein diet (LPD) and oral protein diet (OPD) groups (P<0.05). Testes and epididymis sections were examined by four grades, according to the level of damage of epithelium in the testes and epididymis. Higher histological damage was also detected in the PPD group. In conclusion, the present study confirmed that unwanted estrogen effects were higher in the paranteral administered group on examination of sexual behavior and histological damage of epithelium in the testes and epididymis of male rats.

KEY WORDS: Estrogen; Low protein; Sexual behavior; Histological damage.