Assessment of Sexual Behavior of Male Mice

Summary

This article describes how to perform sexual behavior tests in male mice.

Abstract

Sexual behavior is highly species-specific. Although rodents have slightly different sexual behaviors, mice and rats have a similar sexual behavioral pattern. The purpose of this article is to describe the hormone-induced estrus ovariectomized female model and the experimental procedure for the assessment of sexual behavior of male mice. The most important sexual behavioral elements are demonstrated in the video and illustrations. The critical steps, advantages, and limitations of the sexual behavior test are explained as well. Finally, the behavior parameters are presented, and mounting, intromission, and ejaculation processes in mating are distinguished. Behavioral parameters are assessed in terms of the occurred duration and counts during the test period.

Introduction

Sexual behavior in mature male mice results from the interaction of a series of related and interdependent hormonal systems and neural systems in different brain circuits¹. It also requires developmental experiences, learning, context, and an appropriate partner. Behavioral analysis is an important reflection on neural or neurocrine function. Hence, sexual behavior study on animal models has been widely used in behavioral neuroscience and other related research². The ethogram of sexual behaviors in rodents has been explained in many articles and books^1,3,

Protocol

All experiments were performed in compliance with the guidelines of the Principles of Laboratory Animal Care (NIH Publication No. 80-23, revised 1996) and under the approval and supervision of the Academy of Experimental Animal Centre of the Institute of Medicinal Plant Development (China).

1. Animal husbandry

1. House female and male mice at 25 °C for 12 h light/12 h dark cycles.
2. Provide free access to water and a standard pelleted diet.
3. Allow mice to acclimate to their environment for 7 days prior to the operation if transported from a different facility.

2. Ovariectomy in....

Results

A comparison of sexual behavior between CD-1 mice reared in isolation and group-housed CD-1 mice is shown. Male CD-1 mice were randomly assigned into an isolation-reared group (IS, one mouse per cage, n = 30) and a group-housed group (GH, five mice per cage, n = 15). The mice underwent isolation rearing from postnatal day 23 to day 93. Then, both groups of mice were assessed for sexual behavior. Our study found that the success rate of copulation tended to be lower in the IS group than in the GH group (IS: 80.0%, GH: 86........

Discussion

There are a few critical steps in the presented protocol. Regarding the ovariectomy of females, the surgery incision opening from the back is less detrimental than that from the abdomen. Given that the position of the ovary is deep, pulling other organs when the incision is cut open from the abdomen often leads to bleeding and results in unclear surgical vision²⁰. We performed the incision on the back to reach the ovary easily and shorten the surgical time, as well as to ensure the safety of the s.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Choral hydrate	Sinopharm Chenmical Reagent Co., Ltd.	20160225
Coated VICRYL Plus Sutures	Ethicon, Inc.	missing
Estradiol benzoate	J&K Scientific, Ltd.	L930Q170
Ethanol absolute	Beijing Chemical Works Co., Ltd.	20160715
Ibuprofen (Children's Motrin)	Shanghai Johnson & Johnson Co., Ltd.	160629478
Isoflurane	RWD Life Science Co., Ltd.	217180501
Lidocaine	HebeI Tiancheng Pharmacreutical Co., Ltd.	1170506107
Male and female CD-1 mice	Vital River Beijing	SCXK()2013-0023
Olive oil
Penicillin sodium	North China Pharmaceutical Co., Ltd.	F5126420
Progesterone	J&K Scientific, Ltd.	LR50Q07
Sony digital camera	Sony Corporation	HDR-CX290E
Test box			DIY
ThinkStation Computer	Lenovo	S/N PCOGLQKG
Vaporizer for Isoflurane	RWD Life Science Co., Ltd.	E05904-009M