Pyridoxamine reverts methylglyoxal-induced impairment of survival pathways during heart ischemia

Abstract

Background and aims: Increased levels of advanced glycation end-products (AGE) and their precursors, such as methylglyoxal (MG), in patients with diabetes may account for impaired response to heart ischemia. Pyridoxamine is a derivate of vitamin B6, which has been shown to reduce AGE formation. Our goal was to assess the role of pyridoxamine in protecting from MG-induced impaired heart response to ischemia.

Methods: Wistar rats were subjected to MG administration (WM), MG plus pyridoxamine (WMPyr), or no treatment (W). Half of the hearts from each group were submitted to ischemia and the other half were perfused as control. The levels of CEL, Bcl-2, Bax, and total and phosphorylated forms of JNK and Akt were determined.

Results: Methylglyoxal led to higher levels of AGE and AGE receptor (RAGE) than in the W group. During ischemia, MG caused an impairment of survival pathways and Bcl-2/Bax ratio, a marker of apoptosis. Pyridoxamine treatment decreased glycation and restored the activation of JNK and Akt during ischemia. These events were followed by levels of Bcl-2/Bax ratio similar to W group.

Conclusion: Methylglyoxal-induced AGE accumulation impairs the activation of cell survival pathways during ischemia. Pyridoxamine-induced decrease of glycation inhibited the effects of MG accumulation in the heart, suggesting that it can be of added value to usual diabetic therapy.

Keywords: AGE; Diabetes; Heart ischemia; Methylglyoxal; Pyridoxamine.