BACKGROUND/AIMS: Agmatine, the compound formed by decarboxylation of arginine, is believed to be an endogenous neurotransmitter through interaction with the imidazoline receptors. However, it also appears to regulate rat hepatocyte polyamines by modifying both their synthesis and their catabolism. As the decrease in polyamine content has been correlated with apoptosis, we examined the possibility that agmatine has an effect on this phenomenon. METHODS: Apoptotic cells were detected by visualizing nuclear shrinkage/fragmentation in hepatocytes cultured at 21 and 5% oxygen tension. Caspase-3 activity, cleavage of PARP, release of cytochrome c and mitochondrial swelling were therefore measured in the two conditions and in the presence or not of agmatine. RESULTS: In rat hepatocytes agmatine promoted apoptosis, procaspase 3 processing and increase of caspase-3 like activity. This occurred through mitochondria swelling and release of cytochrome c. Cyclosporin A and catalase blocked the swelling. CONCLUSIONS: Our experiments show that agmatine, besides all the known biological effects, has also part, at least in hepatocytes, in the modulation of programmed cell death.
Agmatine induces apoptosis in rat hepatocyte cultures
GARDINI, Giulia;SOLINAS, Sandro Paolo;GRILLO, Maria Angelica;COLOMBATTO, Sebastiano
2001-01-01
Abstract
BACKGROUND/AIMS: Agmatine, the compound formed by decarboxylation of arginine, is believed to be an endogenous neurotransmitter through interaction with the imidazoline receptors. However, it also appears to regulate rat hepatocyte polyamines by modifying both their synthesis and their catabolism. As the decrease in polyamine content has been correlated with apoptosis, we examined the possibility that agmatine has an effect on this phenomenon. METHODS: Apoptotic cells were detected by visualizing nuclear shrinkage/fragmentation in hepatocytes cultured at 21 and 5% oxygen tension. Caspase-3 activity, cleavage of PARP, release of cytochrome c and mitochondrial swelling were therefore measured in the two conditions and in the presence or not of agmatine. RESULTS: In rat hepatocytes agmatine promoted apoptosis, procaspase 3 processing and increase of caspase-3 like activity. This occurred through mitochondria swelling and release of cytochrome c. Cyclosporin A and catalase blocked the swelling. CONCLUSIONS: Our experiments show that agmatine, besides all the known biological effects, has also part, at least in hepatocytes, in the modulation of programmed cell death.
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