Para-chloroamphetamine-induced ejaculation in anaesthetised rat
Objective
To induce a complete ejaculatory response in anaesthetised rat. In this model, physiological markers of the emission and expulsion phases of ejaculation induced by the amphetamine derivative para-chloroamphetamine (PCA) can be measured. Contractions of the seminal vesicle and the bulbospongiosus muscle are regarded as physiological markers of, respectively, emission and expulsion phases of ejaculation (figure 1).
Summarized methodology
Under anaesthesia (isoflurane, urethane or pentobarbital), the carotid artery and the right seminal vesicle are catheterized to measure concomitantly arterial pressure (AP) and seminal vesicle pressure (SVP). Electrical activity of the bulbospongiosus muscle (BS EMG) is also recorded. Physiological markers are monitored before and over 30 min after PCA systemic injection (i.v. or i.p.). Computerized analysis of the recordings is then performed a posteriori using custom-written analysis programs (Sadoc, CNRS, Gif-sur-Yvette, France).
Endpoints
- Number and latency of ejaculations (corresponding to the expulsion of a seminal plug)
- Number, latency, amplitude, duration and area under the curve of SVP increases
- Number, latency, frequency and duration of BS contractions
- Time interval between SVP increase and BS contractions
Remarks
PCA triggers ejaculation by releasing serotonin and noradrenalin at the spinal level. Therefore, this model is suitable for studying peripheral and spinal modulations of the ejaculatory process and not recommended for investigating supra-spinal modulations.
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| Figure 1: Example of recording of seminal vesicle pressure (SV-P) and bulbospongious muscle electromyogram (BS-EMG) during ejaculation induced by i.p. p-chloroamphetamine (PCA). On the left panel are illustrated the successive SVP and BS-EMG peaks that occur over the 30 min-period following PCA injection (5 mg/kg). Right panel: a sample response from the left panel shows the time shift (T) between the beginning of the SVP rise and the first consistent BS contraction (Pelvipharm, internal data). |
J Androl (2006) : 27:381-389
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