Protective effect of epigallocatechin-3-gallate against neuroinflammation and anxiety-like behavior in a rat model of myocardial infarction.

Individuals who experience myocardial infarction (MI) often experience anxiety. Green tea has potent antioxidative properties and, epigallocatechin-3-gallate (EGCG), which is a primary component of tea polyphenols, has advantageous effects on anxiety and depression. However, its mechanism of action regarding the inhibition of anxiety-like symptoms after MI remains unclear. This study examined whether EGCG alleviated anxiety-like behavior in MI rats and its possible mechanism.Rats were administered a daily gavage of EGCG (50 mg/kg) 7 days before and 14 consecutive days after the MI procedure. The open-field test and light/dark shuttle box were performed to evaluate anxiety-like behavior. Serum and hippocampus interleukin (IL)-6 levels were tested using ELISA. Caspase 3, caspase 8, caspase 9 and bcl-2 messenger RNA levels in the hippocampus were determined using quantitative polymerase chain reaction, and STAT3 protein was detected by Western blot.Results of the open field test and light/dark shuttle box task demonstrated that the MI procedure induced anxiety-like behavior in the animals, and this impairment was improved by EGCG. Daily EGCG administration significantly decreased the level of IL-6 both in serum and hippocampus after MI. The administration of EGCG also significantly moderated the expression of caspases 3, 8, and 9 mRNA, which was related to apoptosis in the hippocampus. Furthermore, EGCG also downregulated the expression of STAT3, which was related to the activity of IL-6. These results suggest that EGCG alleviated anxiety-like behavior by inhibiting increases in neuroinflammation and apoptosis in the rat hippocampus. In addition, EGCG reversed alterations of IL-6 and STAT3 in the brain to alleviate apoptosis in the hippocampus.Thus, EGCG reversed anxiety-like behavior through an anti-inflammation effect to alleviate apoptosis in neurons and may be a useful therapeutic material for anxiety-like behavior after MI.