Elsevier

Theriogenology

Volume 106, 15 January 2018, Pages 192-197
Theriogenology

High efficient and non-invasive collection of ejaculates from rats using penile vibratory stimulation

https://doi.org/10.1016/j.theriogenology.2017.10.024Get rights and content

Highlights

  • Here for the first time we successfully collected semen through penile vibratory stimulation ejaculation (PVSE) from laboratory rat.

  • Ejaculation rate, volume, concentration and motility of semen collected with PVSE were substantially better than that of RPE.

  • Sperm concentration and motility of semen was significantly higher in two-day interval than that of five-day interval.

Abstract

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 significantly higher with a two-day interval between collections compared to a five-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, four 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.

Introduction

Rats have many valuable features that highlight their potential as experimental animals in biomedical research, including their genetic, anatomical, and biomechanical similarities with humans [1]. Historically, the first attempt to investigate the reproductive biology of rats was described by Hewer in 1914 [2]. Recently, sperm collection, in vitro fertilization, embryo transplantation and gene knock-out in rats have been successfully reported [3], [4], [5]. The demand for a genetically modified rat model for biomedical and genetic research has been increasing exponentially [6], [7]; however, the purchasing and transportation of genetically modified rats are very expensive.

It is well established that much time and energy has been spent on exploring female reproductive issues whereas male issues have not received much attention [8].Sperm plays an irreplaceable role in assisted reproductive techniques [9].Sperm collection via an artificial vagina, squeezing or slicing of the epididymis, and electro-ejaculation are the most commonly used methods in small animals [10], [11].However, the application of these methods in rats is limited. The vaginal washing method is time consuming and tedious [12]. The epididymal sperm collection method is costly, and the same animal cannot be used for the next sperm collection [13]. Rectal probe electro-ejaculation (RPE) is a potential sperm collection method, but the quality of sperm significantly decreases due to use of electro-stimulation and anesthesia, which limits its application [14].Therefore, an efficient and repeatable sperm collection method from rats is still needed.

Recently, pharmacologically induced ejaculation has been successfully reported in different species, such as stallions [15]. However, this technique is not successful in rats yet. Therefore, it is very important to introduce some new valuable and possible sperm collection methods for rats. Currently, penile vibratory stimulation ejaculation (PVSE) method has been reported as a repeatable noninvasive sperm collection method in marmoset monkeys [16]. It has been reported that the PVSE method is superior compared to other methods because it produced significantly higher semen samples with high sperm motility [17]. Additionally, successful application of PVSE has been reported in patients with spinal cord injuries [18]. However, the application of PVSE in rats has not yet been reported. Therefore, the current study was designed to explore the application of the PVSE method in rats and its effect on sperm quantity, quality and motility.

Section snippets

Animals

A total of 50 fertile adult male rats (age 18 or 60 weeks) and four adult females (Rattus norvegicus) were obtained from a breeding colony at Southern Medical University Center. All animals were kept in individual cages (320 mm × 180 mm × 160 mm) with controlled temperature (20–25 °C) and humidity (40–60%), a cycle of 12 h light and 12 h darkness, and free access to water and food. Before the start of the experiment, sperm quality of all animals was measured, and then the animals were randomly

Experiment 1: Comparison of ejaculation characteristics between the PVSE and RPE methods in mature rats

The ejaculation rate, time taken, seminal volume, concentration, motility and malformation of sperm from PVSE and RPE are shown in Table 1. All the animals underwent penile vibratory stimulation ejaculation or rectal probe electro-ejaculation once. The successful ejaculation rate was slightly high with PVSE compared with that of the RPE method, although the difference was not significant (P > 0.05). Ejaculation time with PVSE was significantly higher (P < 0.01) compared with RPE. The total

Discussion

Siosteen was the first person to report penile vibratory stimulation ejaculation method to collect semen from spinal-cord injury patients [21].PVSE has also been successfully reported in common marmosets [16]. However, this technique had not yet been reported in rats. Here, for the first time, we report PVSE in rats as an alternative to RPE. Our results show that PVSE is a highly efficient, non-invasive and simple method for collecting semen in rats, as shown in the recorded video. Moreover, it

Authors' contributions

Xiaoxing Liu, Zulqarain baloch, Senren Xue, Ge Wang, and Sien Qiu had done the experiments. Zulqurain Baloch, Xiaoxing Liu, took part in the data collection and analyzed the data and wrote the paper. Prof. Shihua Yang and Qunshan Huang designed and supervised the study. All of the authors read and approved the final manuscript.

Competing interests

All authors declare that they have no actual or potential competing interests.

Acknowledgements

This work was financially supported by funding from Science and Technology Major Project of Guangdong Province (2014B020225007). The funders played no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. We especially thank the two anonymous reviewers for constructive and useful comments.

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  • Cited by (0)

    1

    The authors contribute equally to this work as the first author.

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