Mechanism of γ-bungarotoxin induced respiratory disorder in mice
10.3867/j.issn.1000-3002.2025.02.005
- VernacularTitle:γ-银环蛇毒素致小鼠呼吸障碍机制
- Author:
Mingyang HUO
1
;
Wei CHEN
;
Na ZHAO
;
Chengbiao SUN
;
Mingxin DONG
;
Yan WANG
;
Na XU
;
Wensen LIU
Author Information
1. 延边大学医学院生理学与病理生理学教研室,吉林 延吉 133002
- Publication Type:Journal Article
- Keywords:
γ-bungarotoxin;
medulla oblongata;
glutamate;
γ-aminobutyric acid;
respiratory distur-bance
- From:
Chinese Journal of Pharmacology and Toxicology
2025;39(2):118-128
- CountryChina
- Language:Chinese
-
Abstract:
OBJECTIVE To investigate the roles and mechanisms of γ-bungarotoxin(γ-BGT)in inducing respiratory distress in mice.METHODS Six male Kunming mice were selected and anesthe-tized before tracheal intubation and respiratory recording.After stabilizing respiration,the mice were intraperitoneally injected with γ-BGT at a dose of 6 mg·kg-1.Once a decrease in respiratory frequency was observed,the mice were intravenously injected with nikethamide at a dose of 12.5 mg·kg-1.Respi-ratory frequency was monitored using the BL420 signal acquisition and processing system.Male Kunming mice were randomly divided into the normal control group(saline,ip),γ-BGT group(6 mg·kg-1,ip),and γ-BGT+nikethamide group(γ-BGT 6 mg·kg-1,ip,followed by nikethamide 12.5 mg·kg-1,ip,when shal-low breathing and enhanced abdominal respiration were observed).The levels of Glu and GABA in the medulla oblongata were measured using ELISA.The protein expression levels of GAD65 and GAD67 in the medulla oblongata were determined by Western blotting.Primary mouse medullary neurons were cultured in vitro and divided into the following groups:cell control group,γ-BGT group,carbachol group,gallamine group,γ-BGT+H-89 group,and γ-BGT+Y-27632 group.The γ-BGT group,carbachol group,and gallamine group were incubated with γ-BGT(40 mg·L-1),carbachol(100 mmol·L-1),and gallamine(100 mmol·L-1),respectively,for 4 h.The γ-BGT+H-89 and γ-BGT+Y-27632 groups were pretreated with γ-BGT(40 mg·L-1)for 4 h,followed by incubation with the protein kinase A(PKA)inhibitor H-89(50 mmol·L-1)and the Ca2+channel inhibitor Y-27632(50 mmol·L-1)for another 2 h,respectively.ELISA was used to measure the levels of Glu,GABA,cAMP,and calpain in the primary mouse medul-lary neurons.Western blotting was employed to assess the protein expression levels of GAD65 and GAD67,and PKA phosphorylation levels.Fluo-4 fluorescent probe was used to detect the intracellular Ca2+level.RESULTS The respiratory rate of mice significantly decreased after iv administration of γ-BGT(γ-BGT group)(P<0.05).After treatment with nikethamide(nikethamide group),the respiratory rate significantly recovered(P<0.05).Compared with the normal control group,the γ-BGT group exhib-ited a significant decrease in Glu content(P<0.05),a significant increase in GABA content(P<0.05),and a significant decrease in the Glu/GABA ratio.Additionally,the protein expression levels of GAD65 and GAD67 were significantly elevated(P<0.05).Compared with the γ-BGT group,the γ-BGT+niketh-amide group showed a significant increase in Glu content(P<0.05),a significant decrease in GABA content(P<0.05),a significant increase in the Glu/GABA ratio,and a significant reduction in GAD65 and GAD67 protein expression levels(P<0.05).Compared to the cell control group,the γ-BGT group demonstrated a significant decrease in Glu content(P<0.05),a significant increase in GABA content(P<0.05),and a significant reduction in the Glu/GABA ratio.Furthermore,the protein expression levels of GAD65 and GAD67 were significantly elevated(P<0.05).Additionally,cAMP content,PKA phosphor-ylation levels,Ca2+levels,and calpain activity were all significantly increased(all P<0.05).Glu,GABA,Glu/GABA ratio,and GAD expression levels in the γ-BGT group changed in the same way as in the gallamine group;In the γ-BGT+Y-27632 group,calpain activity and expression levels of GAD65 and GAD67 were all significantly decreased(all P<0.05).In the γ-BGT+H-89 group,Ca2+levels and calpain activity were significantly reduced(all P<0.05).CONCLUSION γ-BGT-induced poisoning can lead to respiratory distress in mice,possibly through the antagonism of M2 muscarinic acetylcholine receptors in medullary neurons,activation of the cAMP/PKA signaling pathway,elevation of intracellular Ca2+levels,and increased expression and activity of GAD,resulting in an imbalance of Glu and GABA in the medulla.
