New Methodology for Investigating Ejaculation Dysfunction: Measuring Intraluminal Seminal Vesicle Pressure in Rats with a Telemetric Device

Introduction: Ejaculation dysfunction is one of the most common male sexual disorders. Despite its prevalence and adverse impact on patients, little attention has been given to investigating ejaculation dysfunction. Aim: We introduce a new method for evaluating ejaculation dysfunction in rats with a telemetric device. Methods: A pressure transducer was surgically implanted in the seminal vesicles of 7-week-old male Sprague-Dawley rats. One week later, the rats were subcutaneously administered tamsulosin 3μg/kg, and intra-seminal vesicle pressure (ISVP) was recorded in freely moving rats after an injection of apomorphine (80μg/kg). Same rats repeated experiment with tamsulosin 10μg/kg, silodosin 1mg/kg, and normal saline with 3-day intervals. Main Outcome Measure: Sexual events were visually identified and recorded. Ejaculation was confirmed by visualization of a copulatory plug in the tip of the penis. We compared the maximal ISVP and area under the curve (AUC) of the ISVP. Results: Adequate ISVP data were easily recorded and available in 66.6% rats (10/15) over a 6-week telemetric recording period (12 recordings). The mean number of ejaculations during an inspection time of 30minutes was 1.5±0.1. The maximal ISVP values in rats receiving 3μg/kg (30.0±5.2mmHg) and 10μg/kg tamsulosin (15.1±1.6mmHg) and 1mg/kg silodosin (12.9±2.2mmHg) were significantly lower than that in control rats (61.4±13.4mmHg, P<0.05). The AUC values in rats receiving 3μg/kg (72.7±18.9mmHg×s) and 10μg/kg tamsulosin (23.5±6.1mmHg) and 1mg/kg silodosin (23.9±8.0mmHg) were also lower than that of control rats (162.6±34.3mmHg, P<0.05). Conclusions: Telemetric ISVP assessment is reliable and feasible for investigating apomorphine-induced ejaculation in rats. Tamsulosin (3μg/kg and 10μg/kg) and silodosin 1mg/kg decreased the ISVP during ejaculation.