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Prepubertal overexposure to manganese induce precocious puberty through GABAA receptor/nitric oxide pathway in immature female rats.
Ecotoxicology and Environmental Safety ( IF 6.2 ) Pub Date : 2019-11-08 , DOI: 10.1016/j.ecoenv.2019.109898
Xinxin Yang 1 , Jichun Tan 2 , Xiaoyan Xu 2 , Haibo Yang 3 , Fengdi Wu 1 , Bin Xu 1 , Wei Liu 1 , Pengcheng Shi 4 , Zhaofa Xu 1 , Yu Deng 1
Affiliation  

Gamma-aminobutyric acid (GABA) plays a critical role in regulation of gonadotropin-releasing hormone (GnRH) through GABAA receptor (GABAAR). Nitric oxide (NO) production has correlation with GABA and regulates GnRH secretion. This study was performed to examine the mechanisms by which manganese (Mn) accelerate puberty onset involves GABAAR/NO pathway in the preoptic area-anterior hypothalamus (POA-AH) in immature female rats. First, female rats received daily dose of MnCl2 0 (saline), 2.5, 5 and 10 mg/kg b.w by oral gavage during postnatal day (PND) 21-32. Animals administered with 10 mg/kg MnCl2 exhibited earlier puberty onset age and advanced ovary and uterus development than these in saline-treatment group. Furthermore, we found that decrease of GABAAR result in elevated production of nitric oxide synthase1 (NOS1), NO and GnRH in the POA-AH. Second, we recorded the neuronal spikes alternation after perfusion with GABAAR inhibitor bicuculline (BIC), GABAAR agonist isoguvacine (isog), and MnCl2 from the POA-AH in acute brain slices of PND21 rats. Spontaneous firing revealed a powerful GABAAR-mediated action on immature POA-AH and confirm that MnCl2 has a significant effect on GABAAR. Third, we revealed that decrease in NOS1 and NO production by treatment with isog-alone or isog+MnCl2 contribute to the decrease of GnRH in the POA-AH and a delayed puberty onset age compared to treatment with MnCl2-alone. Together, these results suggested that excessive exposure to MnCl2 stimulates NO production through decreased GABAAR in the POA-AH to advance puberty onset in immature female rats.

中文翻译:

青春期前锰暴露通过GABAA受体/一氧化氮途径在未成熟雌性大鼠中诱发性早熟。

γ-氨基丁酸(GABA)在通过GABAA受体(GABAAR)调节促性腺激素释放激素(GnRH)中起着关键作用。一氧化氮(NO)的产生与GABA相关,并调节GnRH分泌。进行这项研究以检查未成熟雌性大鼠中锰(Mn)促进青春期发作的机制涉及GABAAR / NO途径在视前区-下丘脑前部(POA-AH)中的发生。首先,雌鼠在产后一天(PND)21-32期间通过管饲法每天接受MnCl2 0(盐),2.5、5和10 mg / kg bw的日剂量。与生理盐水治疗组相比,给予10 mg / kg MnCl2的动物具有更早的青春期发病年龄和更高的卵巢及子宫发育能力。此外,我们发现降低GABAAR会导致POA-AH中一氧化氮合酶1(NOS1),NO和GnRH的产生升高。其次,我们在PND21大鼠的急性脑切片中记录了用GABAAR抑制剂双小分子(BIC),GABAAR激动剂异古瓦汀(isog)和MnCl2从POA-AH灌注后的神经元突增交替。自发发射显示了强大的GABAAR介导的对未成熟POA-AH的作用,并证实MnCl2对GABAAR具有重要作用。第三,我们发现与单独使用MnCl2相比,通过单独使用isog或isog + MnCl2进行治疗可降低NOS1和NO的产生,从而降低POA-AH中GnRH的水平,并延缓青春期的发病年龄。总之,这些结果表明,过度暴露于MnCl2可以通过降低POA-AH中GABAAR的含量来刺激NO的产生,从而促进未成熟雌性大鼠的青春期发作。在PND21大鼠的急性脑切片中,GABAAR激动剂异guvacine(isog)和来自POA-AH的MnCl2。自发发射显示了强大的GABAAR介导的对未成熟POA-AH的作用,并证实MnCl2对GABAAR具有重要作用。第三,我们发现与单独使用MnCl2相比,通过单独使用isog或isog + MnCl2进行治疗可降低NOS1和NO的产生,从而降低POA-AH中GnRH的水平,并延缓青春期的发病年龄。总之,这些结果表明,过度暴露于MnCl2中会通过降低POA-AH中GABAAR的含量来刺激NO的产生,从而促进未成熟雌性大鼠的青春期发作。在PND21大鼠的急性脑切片中,GABAAR激动剂异guvacine(isog)和来自POA-AH的MnCl2。自发发射显示了强大的GABAAR介导的对未成熟POA-AH的作用,并证实MnCl2对GABAAR具有重要作用。第三,我们发现与单独使用MnCl2相比,通过单独使用isog或isog + MnCl2进行治疗可降低NOS1和NO的产生,从而降低POA-AH中GnRH的水平,并延缓青春期的发病年龄。总之,这些结果表明,过度暴露于MnCl2中会通过降低POA-AH中GABAAR的含量来刺激NO的产生,从而促进未成熟雌性大鼠的青春期发作。自发发射显示了强大的GABAAR介导的对未成熟POA-AH的作用,并证实MnCl2对GABAAR具有显著作用。第三,我们发现与单独使用MnCl2相比,通过单独使用isog或isog + MnCl2进行治疗可降低NOS1和NO的产生,从而降低POA-AH中GnRH的水平,并延缓青春期的发病年龄。总之,这些结果表明,过度暴露于MnCl2中会通过降低POA-AH中GABAAR的含量来刺激NO的产生,从而促进未成熟雌性大鼠的青春期发作。自发发射显示了强大的GABAAR介导的对未成熟POA-AH的作用,并证实MnCl2对GABAAR具有重要作用。第三,我们发现与单独使用MnCl2相比,通过单独使用isog或isog + MnCl2进行治疗可降低NOS1和NO的产生,从而降低POA-AH中GnRH的水平,并延缓青春期的发病年龄。总之,这些结果表明,过度暴露于MnCl2中会通过降低POA-AH中GABAAR的含量来刺激NO的产生,从而促进未成熟雌性大鼠的青春期发作。
更新日期:2019-11-08
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