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

Abstract

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 3 mu g/kg, and intra-seminal vesicle pressure (ISVP) was recorded in freely moving rats after an injection of apomorphine (80 mu g/kg). Same rats repeated experiment with tamsulosin 10 mu g/kg, silodosin 1 mg/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 30 minutes was 1.5 +/- 0.1. The maximal ISVP values in rats receiving 3 mu g/kg (30.0 +/- 5.2 mm Hg) and 10 mu g/kg tamsulosin (15.1 +/- 1.6 mm Hg) and 1 mg/kg silodosin (12.9 +/- 2.2 mm Hg) were significantly lower than that in control rats (61.4 +/- 13.4 mm Hg, P ˂ 0.05). The AUC values in rats receiving 3 mu g/kg (72.7 +/- 18.9 mm Hg x s) and 10 mu g/kg tamsulosin (23.5 +/- 6.1 mm Hg) and 1 mg/kg silodosin (23.9 +/- 8.0 mm Hg) were also lower than that of control rats (162.6 +/- 34.3 mm Hg, P ˂ 0.05). Conclusions. Telemetric ISVP assessment is reliable and feasible for investigating apomorphine-induced ejaculation in rats. Tamsulosin (3 mu g/kg and 10 mu g/kg) and silodosin 1 mg/kg decreased the ISVP during ejaculation.