The monoamine oxidase B (MAO-B) is an enzyme involved in the metabolism of dopamine, benzylamine, phenylethylamine, tyramine and tryptamine. MAO-B activity was associated many times with some psychiatric diseases including affective disorders. The A/G polymorphism in intron 13 of the MAO-B gene was previously associated with a variability of the MAO-B enzyme activity. The aim of the present association study was to examine the relationship between the A/G polymorphism in intron 13 and postoperative pain intensity. We examined 284 subjects (105 males and 179 females) that underwent planned tonsillectomy. PCR method with allele specific primers for the detection of A/G polymorphism was used. The intensity of pain was tested by visual analogue scale (VAS). We found a relationship between the A/G polymorphism in intron 13 of the MAO-B gene and average intensity of postoperative pain in male subjects. We found statistically significantly higher average intensity of postoperative pain in males with G allele in comparison with males with A allele. Results of our study indicate the relationship between the MAO-B polymorphism and postoperative pain intensity in Czech male population. The potential role of the MAO-B in feeling of pain intensity is discussed mainly in the context of the influence of MAO-B on the mood.

        Key words: gene, polymorphism, pain, MAO-B, association.