ntial mechanism we investigated fenvalerate's effect on T-type Ca2+ channels in mouse pachytene spermatocytes using a whole-cell patch clamp technique. Fenvalerate significantly inhibited T-type Ca2+ currents in a concentration-dependent manner. The maximal inhibitory concentration was 1μM. The inhibitory effect of fenvalerate was slow and irreversible after washout of the drug. The curves of activation and inactivation simultaneously shifted to hyperpolarization, about 14mV, suggesting the open time of Ca2+ channel was unchanged. Voltage-dependent gating of Ca2+ channel indicated a change in permeability to ions that contributed to fenvalerate's inhibition on Ca2+ current. Taken together with our previous findings, these data suggest that the changes of T-type Ca2+ currents contribute to the suppression of acrosome reaction and fertilizing ability caused by fenvalerate.

In this study, primary serum-free cultured rat granulosa cells(rGCs)were used as a cellular model to investigate the effects of fenvalerate on progesterone production. Various concentrations(0, 1, 5, 25, 125 and 625μM)of fenvalerate were added to the cell cultures for 24 h. rGCs were stimulated by compounds such as follicle-stimulating hormone(FSH), 8-bromo-cAMP or 22(R)-hydroxycholesterol(22R-HC). Progesterone production and intracellular cAMP content were measured in control and treated groups. Expression of P450 side chain cleavage enzyme(P450scc)and steroidogenic acute regulatory protein(StAR)were monitored by real-time PCR and Western blotting. Results showed that fenvalerate inhibited basal progesterone production in rGCs in the absence of stimulators. This inhibition was stronger in the presence of FSH and was not fully reversed by 8-bromo-cAMP or 22R-HC. The increase of cAMP content, stimulated by FSH, was inhibited by fenvalerate implicating that the intracellular cAMP-dependent signal pathway was involved. Fenvalerate reduced mRNA and protein expression of P450scc. These results suggested that multi-site inhibition of progesterone production by fenvalerate including a cAMP-dependent protein kinase pathway and reduction on P450scc gene expression and/or its enzymatic activity in rGCs.

To investigate the toxic effect of terephthalic acid(TPA)on testicular functions of rats, male Sprague-Dawley rats were orally administered TPA in diet at the levels 0(control), 0.2, 1 and 5% for 90 days. Testicular functions were assessed by histopathology, testicular sperm head counts, daily sperm production, sperm motility(measured by computer-assisted sperm analysis, CASA), biochemical indices(marker testicular enzymes), and serum testosterone. Oral feeding with terephthalic acid did not cause body and testes weight loss in TPA-treated groups. Histopathologically, damages of spermatogenic cells and Sertoli cells were observed by electron microscope, testicular sperm head counts, daily sperm production, and activities of sorbitol dehydrogenase(SDH)were decreased significantly in the 5% TPA group. The motility of spermatozoa was reduced significantly in all treated groups, which was correlated with administration doses. Serum testosterone concentrations were not declined in treated groups. In conclusion, TPA can cause impairment of testicular functions. The primary sites of action may be spermatogenic cells and Sertoli cells. The results of the present study provide first information of TPA on testicular functions in male rats.

目的 为了建立一个合理、客观评价药物或毒物对生殖系统影响的细胞模型，研究了机械分离、未经酶消化的小鼠精母细胞Ca2+通道特性及硝苯地平对其的作用。方法 采用全细胞膜片钳技术。结果 阻断K+电流后，当钳制电位-90 mV、指令电压-80～+10 mV、步阶电压10mV时，记录到Ca2+电流，二价无机阳离子对Ca2+电流的抑制作用Ni2+>Cd2+，而L型Ca2+通道激动剂BayK8644对电流无任何影响。分析小鼠精母细胞上记录的Ca2+电流为T型Ca2+通道开放产生。L型Ca2+通道阻断剂硝苯地平对精母细胞Ca2+电流有明显的抑制作用，半数最大抑制浓度为0.39μmolL-1，而且细胞外液冲洗恢复缓慢，这支持了二氢吡啶类药物可用于男性避孕。结论 机械分离、未经酶消化的小鼠精母细胞模型适合进行药理学和毒理学研究。

获能是哺乳动物精子受精前必须经历的一个生理过程。获能涉及精子膜性质的改变、Ca2+通道活化、胞内cAMP增加，以及蛋白酪氨酸磷酸化（PTP）等。实验证明，HCO3-在该过程中起重要作用。本文旨在介绍HCO3-介导的cAMP信号转导途径。