Background: The rat is one of the most important experimental animals, which plays an indispensable role in biomedical research, particularly in reproduction. However, according to our best knowledge, there is no easy and efficient method available for semen collection from rats.
Results: In this study, we successfully collected semen through penile vibratory stimulation ejaculation (PVSE) from laboratory rats. This is an easier and more efficient method compared with rectal probe electro-ejaculation (RPE).
We found that the ejaculation rate, volume, concentration and motility of semen collected with PVSE were substantially better than those of RPE. Although PVSE was time-consuming compared to RPE, the quality of semen was better; additionally, sperm concentration and motility of semen were statistically-significantly higher with a two-day interval between collections compared to a 5-day interval. Moreover, we found that electrical stimulation, use of anesthesia and increased age of rats have a negative effect on sperm quality.
In the last experiment, 4 fertile female rats were artificially inseminated with PVSE-collected semen, and healthy offspring were born.
Conclusion: Here, for the first time, we established the repeated collection of semen using the PVSE method in rats.
[Keywords: rat, sperm, penile vibratory stimulation ejaculation, fertilization]
…5. Penile vibratory stimulation ejaculation: Penile vibratory stimulation ejaculation was performed using a battery-operated FertiCareR personal vibrator (Multicept, Rungsted, Denmark). The basic modifications were similar to those described by et al 2000. Additionally, the plastic collecting 1.5 mL-EP-tube attached to the silicon rubber holder was 20 mm long with 5 mm internal diameter. This provided a better contact with the target and was more effective in achieving the required level of stimulation. Animals were placed in a homemade holder, as shown in Figure 1a & Figure 1b. Before we carried out sperm collection, the penis was gently washed with warmed saline by using sterile cotton. To arouse erection, external genitals were mildly rubbed for 1 min with wetted cotton ball. Then, the vibrating tube was placed on the genitals. Vibration parameters were set as follows: from an initial stimulation at 80 Hz and two mm amplitude, intensity was increased in 1 min. This stimulation protocol was repeated once (following a 2–3 min rest period) until ejaculation was completed. As an indicator of adequate stimulation, a rhythmic contraction and expansion of the penis occurred prior to ejaculation. The ejaculate could be seen as a clear droplet on the urogenital orifice, as show in Figure 1c && Figure 1d.
