The aims of this study were to assess the effects of the dopamine agonist apomorphine on experimental pain models in healthy subjects and to explore the possible association between these effects and a common polymorphism within the dopamine transporter gene.

Healthy volunteers (n=105) participated in this randomized double-blind, placebo-controlled, cross-over trial. Heat pain threshold and intensity, cold pain threshold, and the response to tonic cold pain (latency, intensity, and tolerance) were evaluated before and for up to 120 min after the administration of 1.5 mg apomorphine/placebo. A polymorphism (DAT-1) within the dopamine transporter gene (SLC6A3) was investigated.

Inclusion Criteria:

- healthy and free from chronic pain of any type did not use any medications other than oral contraceptives were able to understand the purpose and instructions of the study.

Exclusion Criteria:

- any type of medical or painful condition use of medications or recreational drugs pregnancy.