Time Will Tell: Genetic Influences on Ejaculation Time

Abstract

Lifelong premature ejaculation (PE) is a male sexual disorder characterized by persistent short ejaculation times of less than about 1 minute, in more than 90% of intercourses, with nearly every female partner, since the first sexual activities of a man in puberty or adolescence (Waldinger 2007). In about 30% of these men, ejaculation becomes even more faster at the age of 30-35 years (Waldinger 2007). In the 1990s, it has been hypothesised that the short ejaculation time, e.g., the intravaginal ejaculation latency time (IELT) which is the time between intravaginal penetration and the moment of intravaginal ejaculation, is associated with a diminished central serotonin (5-hydroxytryptamine; 5-HT) neurotransmission, a hyperfunction of 5-HT1A receptors, a hypofunction of 5-HT2C receptors and genetic influences (Waldinger et al, 1998) The aim of the thesis was to study the role of serotonergic gene polymorphisms in men with lifelong premature ejaculation (PE) with regard to the duration of their IELT. The duration of the IELT was investigated with a stopwatch that had to be handled by the female partner of the male. After instruction on how to use the stopwatch during intercourse, the IELT was measured at home in a one month baseline period and during a period of daily paroxetine treatment, which is known for its ejaculation delaying effects. In addition, we investigated whether the duration of daily paroxetine treatment-induced ejaculation delay was associated with polymorphism of the 5-HT transporter gene, polymorphisms of the 5-HT1A receptor gene, and the 5-HT2C receptor gene. In addition, it was investigated whether paroxetine-induced ejaculation delay is associated with polymorphism of the 5-HT transporter gene. Another point of investigation was whether in men with lifelong PE response and non-response to paroxetine treatment was associated with paroxetine serum concentration, CYP2D6 genotype, and a number of other factors, such as an intact hypothalamic-pituitary gonadal axis, thyroid function and serum leptin levels. Finally, we analyzed the methodology and design of six studies that were published in recent years on 5-HTTLPR polymorphism and premature ejaculation.