[PPARs, metabolic syndrome and cardiac diseases]

The nuclear receptor PPARs (peroxisomal proliferators-activated receptors) are transcription factors activated by natural and synthetic ligands. Three different isoforms of PPARs have been described, PPARalpha, PPARbeta/ delta, and PPARgamma. PPARs isoforms are tissue-dependent expressed and they regulate the gene expression of proteins involved in glucose and lipid metabolism. Selective pharmacological activation of these isoforms has revealed their role in cellular physiology. Nowadays, two kinds of PPARs agonists are currently used in the clinical practice, the fibrate hypolipidemic drugs, used in the treatment of dyslipidemia, are synthetic ligands for PPARalpha, whereas thiazolidinediones or glitazones have PPARgamma selectivity and are used as hypoglycemic agents. The main cellular effect of PPAR activation lies on fatty acid oxidation and mobilization (PPARalpha) as well as they act as insulin sensitizers on peripheral tissues (PPARgamma). In addition to these beneficial effects of PPARs, it has also been demonstrated that PPARs activation can prevent cardiac dysfunction in diabetic patients as well as the anti-inflammatory processes developed in many diseases. Recent development of PPARbeta/delta and hybrid PPARs alpha and gamma agonists, and their clinical trials are giving promising outcomes in the therapeutics of metabolic syndrome, diabetes and cardiac diseases.