Magnesium yields opposite effects on the nuclear and cytosolic cascades of apoptosis in different rat brain regions

OBJECTIVE: Magnesium is considered as potential neuroprotective and therapeutic agent, but certain studies have provided evidence of its apoptotic effectiveness in neurons. We aimed to evaluate the possible apoptotic effects of long-term magnesium use in healthy adult rat brains. MATERIALS AND METHODS: Magnesium citrate and magnesium glycinate compounds were administered orally to rats for 8 weeks (36 mg/kg). Expression levels of Bcl-2, Bax and Cyt-C genes were analyzed by real-time polymerase chain reactions (RT-PCR) in the prefrontal cortex, hippocampus and striatum regions. Bcl-2, Bax and CytC protein levels were measured using ELISA kits. Tissue sections were evaluated histopathologically with hematoxylin-eosin staining. RESULTS: Compared to the control group, the magnesium-administered groups indicated gene expression reductions in almost all brain regions; pro-apoptotic Bax, anti-apoptotic Bcl-2 and Cyt-C gene expression levels were reduced. With magnesium, the Bcl-2 and Bax protein levels were increased. Bax/Bcl-2 gene and protein ratio were also increased in the striatum and hippocampus, whereas Cyt-C protein levels were decreased or did not change in the magnesium treated groups. There was no pathological finding in histological evaluation. CONCLUSIONS: Long-term magnesium usage can promote apoptotic cascade in brain tissue by increasing Bax/Bcl-2 ratio. Cyt-C, a prominent factor processing caspase pathway, was decreased or unchanged. In addition, taking into account the histological evaluation, we supposed that the absence of Cyt-C in the cytosol can prevent the subsequent apoptotic pathway. Consequently, we obtained the findings of apoptotic initiation with magnesium in brain, but this cascade seems to be arrested at later stages