Expression of CaSR in neurons and cardiomyocytes incubated with magnesium-free extracellular fluid and its relationship with the MAPK pathway / 医学研究生学报

ABSTRACT

Objective At present, studies on the calcium sensing receptor (CaSR) in the pathogenesis of epilepsy are carried out in animal models in vivo and in single cells cultured in vitro. This study was to investigate the expression of CaSR and its relationship with the MAPK pathway in the rat model of epilepsy.Methods The neurons and cardiomyocytes of 3-day-old Wistar rats were cultured for 10 days and randomly divided into groups A (control), B (magnesium-free), C (magnesium free+spermine), D (magnesium free+calhex231), and E (magnesium free+spermine+calhex231). The model of epilepsy was made by abnormal discharge of the neurons induced by coculturing magnesium-free extracellular fluid with cardiomyocytes. The morphological changes of the cells were observed by HE staining and transmission electron microscopy, their survival rate detected by MTT, and the expressions of the CaSR, Bcl-2, P-ERK, P-JNK and P-P38 proteins in the cocultured cells determined by Western blot.Results Compared with the cells in group B, those in group C were swollen and broken with nuclear fragmentation, those in group D showed a relative integrity, and those in group E were also swollen and broken but improved in comparison with those in group C. The survival rates of the cells were (61.08±15.44)%, (82.80±14.37)% and (82.04±17.37)% in groups C, D and E, respectively, all significantly lower than in A (\[100.00±0.00\]%, P<0.01) and B (\[88.88±9.85\]%, P<0.01). The expression of CaSR was markedly higher in group B than in A (\[0.73±0.19\] vs \[0.45±0.12\], P<0.01) but lower than in C (1.32±0.15) and E (1.19±0.12) (P<0.01). The expression levels of Bcl-2 and P-ERK were remarkably lower in group B than in A but higher than in C (P<0.01), and those of P-JNK and P-P38 significantly higher in group B than in A and lower than in C and E (P<0.05).Conclusion Magnesium-free extracellular fluid can damage neurons and cardiomyocytes, increase the expression of CaSR, participate in the MAPK signaling pathway, and mediate the apoptosis of neurons and cardiomyocytes, while CaSR inhibitors can relieve the CaSR agonist-induced damage to the cells.