Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, Olsztyn, Poland.
Ecotoxicol Environ Saf. 2012 Apr;78:336-43. doi: 10.1016/j.ecoenv.2011.11.042. Epub 2011 Dec 23.
The effects of photoperiod on the cerebrospinal fluid (CSF) concentration of six ortho-substituted polychlorinated biphenyls (PCBs: PCB28, PCB52, PCB101, PCB138, PCB153, and PCB180), the effects of an orally administered low dose of PCB153 (0.3mg/kg, three times a week for three weeks) on PCBs and thyroid hormones (THs) concentrations in the CSF and plasma, and the release of luteinizing hormone (LH) were determined in ovariectomized, estradiol-implanted ewes (2.5 years old) maintained indoors under artificial long day (LD, 16L: 8D) and short day (SD, 8L: 16D) conditions. Concentrations of two PCBs (PCB28 and PCB153) in the plasma and four PCBs in the CSF (PCB101, PCB138, PCB153, and PCB180) were significantly higher during LD than SD. Following PCB153 treatment, its concentration in the plasma was higher in SD (1.2 ± 0.3 ng/ml) than LD (0.2 ± 0.05 ng/ml), but similar in the CSF (10.2 ± 3.7 pg/ml vs. 13 ± 0.7 pg/ml) under both photoperiods. During SD, the concentration of PCB153 in the CSF was higher in treated animals than controls, while no differences were noted under LD. These findings indicate that in ewes, exposure of the brain to more highly chlorinated, ortho-substituted PCBs may be modulated by photoperiod. PCB153 treatment had no effect on plasma THs, but reduced total triiodothyronine concentration during LD and free thyroxine during SD in the CSF. Under both photoperiods, PCB153 reduced basal plasma LH and reinforced the inhibition of pulsatile LH release during LD. As PCB153 reduced LH and THs (which are involved in the seasonal control of reproduction in ewes), it may have a braking effect on seasonal transitions between active and inactive phases of reproduction.
光周期对脑脊液（CSF）中六种邻位取代多氯联苯（PCBs：PCB28、PCB52、PCB101、PCB138、PCB153 和 PCB180）浓度的影响，口服低剂量 PCB153（0.3mg/kg，每周三次，共三周）对 CSF 和血浆中 PCBs 和甲状腺激素（THs）浓度的影响，以及促黄体激素（LH）的释放，在室内人工长日（LD，16L:8D）和短日（SD，8L:16D）条件下维持的去卵巢、雌二醇植入的母羊（2.5 岁）中进行了测定。两种 PCB（PCB28 和 PCB153）在血浆中的浓度和四种 PCB 在 CSF 中的浓度（PCB101、PCB138、PCB153 和 PCB180）在 LD 时明显高于 SD。在接受 PCB153 治疗后，SD 时其在血浆中的浓度（1.2±0.3ng/ml）高于 LD（0.2±0.05ng/ml），但在两种光周期下 CSF 中的浓度相似（10.2±3.7pg/ml 与 13±0.7pg/ml）。在 SD 期间，与对照组相比，处理动物 CSF 中 PCB153 的浓度较高，而在 LD 时则没有差异。这些发现表明，在母羊中，大脑接触高氯化、邻位取代的 PCBs 的情况可能会受到光周期的调节。PCB153 治疗对血浆 THs 没有影响，但在 LD 期间降低了 CSF 中的总三碘甲状腺原氨酸浓度，在 SD 期间降低了游离甲状腺素浓度。在两种光周期下，PCB153 降低了基础血浆 LH，并在 LD 期间增强了脉冲式 LH 释放的抑制作用。由于 PCB153 降低了 LH 和 THs（这两者都参与了母羊繁殖的季节性控制），它可能对繁殖活跃期和不活跃期之间的季节性转变产生制动作用。
