Postnatal exposure of 2,2',3,3',4,6'-hexachlorobiphenyl and 2,2',3,4',5',6-hexachlorobiphenyl on sperm function and hormone levels in adult rats.

Polychlorinated biphenyls (PCBs) are known to affect reproductive system in animals and in accidentally or occupationally exposed humans. Information is lacking on effects of non-dioxin like chlorinated biphenyls (CB) congeners on male reproduction. The aim of this study is to determine whether treatment of postnatal non-dioxin like CB congeners affects sperm function and hormone levels in rats. Male Sprague-Dawley rats received either 2,2',3,3',4,6'-hexachlorobiphenyls (CB 132) or 2,2',3,4',5',6-hexachlorobiphenyls (CB 149) by ip injection of 9.6 or 96 mg/kg at day 21. At 16 weeks, the animals were sacrificed; sperm quality and hormone levels were measured. Body weight, testis and cauda epididymis weights, sperm counts, ROS generation, acrosome reaction rate, serum thyroxine (T(4)), free T(4) and testosterone (TT) concentrations were unaffected. However, treatment of CB 132 and CB 149 caused decreases in sperm motility, curvilinear velocity (VCL), average path velocity (VAP), straight-line velocity (VSL), amplitude of lateral head displacement (ALH) and beat cross frequency (BCF). Serum triiodothyronine (T(3)) level was significantly decreased in CB 132 9.6 mg/kg dose group compared with the controls. On the other hand, a significant decrease was found in free T(3) concentration both in 96 mg/kg of CB 132 and CB 149 groups. In summary, this study showed that CB 132 and CB 149 affects serum levels of triiodothyronine as well as sperm motility, velocity and capability of penetrating oocytes. The mechanism of action and potential effects on human warrant further investigation.