High efficient and non-invasive collection of ejaculates from rats using penile vibratory stimulation
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.
References (27)
Effects of sodium fluoride on reproductive function in female rats
Food Chem Toxicol
(2013)- et al.
Collection and evaluation of semen from captive howler monkeys (Alouatta caraya)
Theriogenology
(2004 Jul) Full-term development of rats from oocytes fertilized in vitro using cryopreserved ejaculated sperm
Cryobiology
(2011)Freezability of rat epididymal sperm induced by raffinose in modified Krebs–Ringer bicarbonate (mKRB) based extender solution
Cryobiology
(2007)- et al.
Cryopreservation of non-human primate sperm: priorities for future research
Anim Reprod Sci
(1998) Oral imipramine and intravenous xylazine for pharmacologically-induced ex copula ejaculation in stallions
Anim Reprod Sci
(2001)Electroejaculation versus vibratory stimulation in spinal cord injured men: sperm quality and patient preference
J Urol
(1997)The effects of different sugars on motility, morphology and DNA damage during the liquid storage of rat epididymal sperm at 4°C
Cryobiology
(2012)- et al.
Intrabursal transfer of spermatozoa (ITS): a new route for artificial insemination of mice
Theriogenology
(2001) Successful nonsurgical deep uterine embryo transfer in pigs
Theriogenology
(2004)
Rat genetics: attaching physiology and pharmacology to the genome
Nat Rev Genet
The effect of thymus feeding on the activity of the reproductive organs in the rat
J Physiol
Full-term development of rat after transfer of nuclei from two-cell stage embryos
Biol Reprod
Cited by (0)
- 1
The authors contribute equally to this work as the first author.