Mondal Mukti, Sarkar Kaushik, Nath Partha Pratim, Khatun Ashma, Pal Sanghamitra, Paul Goutam
Molecular Neurotoxicology Laboratory, Department of Physiology, University of Kalyani, Kalyani, West Bengal 741235, India.
Molecular Neurotoxicology Laboratory, Department of Physiology, University of Kalyani, Kalyani, West Bengal 741235, India.
Reprod Biol. 2018 Mar;18(1):83-93. doi: 10.1016/j.repbio.2018.01.006. Epub 2018 Feb 3.
The aim of the study was to examine the toxic effects of Monosodium glutamate (MSG), an extensively used food additive, on the contraction of uterine visceral smooth muscle (UVSM) in rat and to elucidate the probable neurocrine mechanism involved in it. MSG produced significant potentiation of the force and inhibition of frequency of uterus recorded ex vivo in chronic MSG exposure and in single dose acute experiments. MSG also produced significant potentiation of force of acetylcholine induced contraction and no alterations in atropine induced contraction of uterus. Further, MSG produced significant increase in force and frequency of contraction of neostigmine incubated uterus. We have found significant potentiation of the post pause force of contraction of uterus when MSG was applied in adrenaline incubated uterus. MSG also produced significant decrease in frequency of contraction of sodium nitroprusside incubated uterus; increase in frequency of N-ω-Nitro-l-Arginine Methyl Ester incubated uterus and no significant changes in frequency of contraction of methylene blue incubated uterus. These results indicate that MSG potentiates the force of contraction of UVSM predominantly by augmenting the activity of cholinergic intrinsic efferents and inhibits the frequency of contraction probably by augmenting the activity of nitrergic efferents. In conclusion, MSG potentiates the force and inhibits the frequency of contraction of UVSM, and the MSG induced effect is probably mediated through the augmentation of acetylcholine and nitric oxide signaling pathways.
本研究的目的是检测广泛使用的食品添加剂谷氨酸钠（MSG）对大鼠子宫内脏平滑肌（UVSM）收缩的毒性作用，并阐明其中可能涉及的神经分泌机制。在慢性MSG暴露和单剂量急性实验中，MSG对离体记录的子宫收缩力有显著增强作用，并抑制其收缩频率。MSG还显著增强了乙酰胆碱诱导的子宫收缩力，而对阿托品诱导的子宫收缩无影响。此外，MSG使新斯的明孵育的子宫收缩力和频率显著增加。我们发现，当在肾上腺素孵育的子宫中应用MSG时，子宫收缩的后暂停力有显著增强。MSG还使硝普钠孵育的子宫收缩频率显著降低；使N-ω-硝基-L-精氨酸甲酯孵育的子宫收缩频率增加，而对亚甲蓝孵育的子宫收缩频率无显著影响。这些结果表明，MSG主要通过增强胆碱能内在传出神经的活性来增强UVSM的收缩力，并可能通过增强一氧化氮能传出神经的活性来抑制收缩频率。总之，MSG增强了UVSM的收缩力并抑制其收缩频率，且MSG诱导的效应可能是通过增强乙酰胆碱和一氧化氮信号通路介导的。
