Carbofuran-induced endocrine disruption in adult male rats.

The objective of this investigation was to determine the acute toxic effects of the carbamate insecticide carbofuran on the levels of endocrine hormones in the serum of male Sprague-Dawley rats. Using chemiluminescent immunoassay, the hormones determined were progesterone, cortisol, estradiol, testosterone, triidothyronine (T3), total thyroxine (total T4), and non-protein-bound thyroxine (free T4). Rats exposed to an acute dose of carbofuran (1.5 mg/kg, s.c.) showed the onset of cholinergic signs (salivation, chewing, and fine tremors) within 5-7 min. With increasing intensity, toxic signs of maximal severity (severe convulsions and fasciculations) were observed within 30-60 min, and lasted for about 2 to 3 h. Time courses of hormones for 24 h revealed significant alterations in hormone levels during 0.5 to 3 h, with the exception of estradiol at 6 h. The levels of progesterone, cortisol, and estradiol were significantly increased (1279%, 202%, and 150%, respectively), while the levels of testosterone were decreased by 88%. No significant change occurred in thyroid hormones (T3, total T4, and free T4) at any time during the time course, despite the fact that body temperature was significantly low at 1 to 2 h after carbofuran injection. Carbofuran caused a >2-fold increase in glucose during early hours of toxicity. The results suggest that an acute exposure to carbofuran may cause transient endocrine disruption, which may consequently lead to serious reproductive problems following repeated exposure.