Background: Positive emotions influence endocrinological and immunological response. This study examined the effect of laughter,as an expression of positive emotion, in terms of gene expression changes.
Methods: Using a microarray technique, we analyzed the changes in expression of 18,716 genes from peripheral blood leukocytes in patients with type 2 diabetes, which were induced by laughter.
Results: Of the 18,716 genes, 23 genes showed significantly different expression changes after listening to the comic story compared to the lecture. Eight were relatively upregulated and 15 were downregulated 1.5 h after the laughing episode. However, these genes did not include genes that are directly involved in blood glucose metabolism. Among the 23 genes discriminated, all 4 genes encoding proteins involved in the immune response and all 4 signal transduction genes were downregulated. Moreover, it is noteworthy that 5 of the 8 relatively upregulated genes were related to the cell cycle, apoptosis, and cell adhesion.
Conclusions: We demonstrated that laughter, which is an expression of positive emotion, is linked to gene expression. However, the finding of this study does not allow reasonable interpretation for the regulation of gene expression by laughter. A more focused study is needed that may identify the candidate genes for the association between physical condition and positive emotion.
Copyright 2006 S. Karger AG, Basel.