The influence of psychological stress in early life on sexual maturation and sexual behavior in male and female rats

Kiyohito Yano; Toshiya Matsuzaki; Takeshi Iwasa; Yiliyasi Mayila; Rie Yanagihara; Altankhuu Tungalagsuvd; Munkhsaihan Munkhzaya; Takako Tokui; Shuhei Kamada; Aki Hayashi; Rie Masaki; Hidenori Aoki; Kou Tamura; Minoru Irahara

doi:10.1002/rmb2.12313

The influence of psychological stress in early life on sexual maturation and sexual behavior in male and female rats

Reprod Med Biol. 2019 Dec 26;19(2):135-141. doi: 10.1002/rmb2.12313. eCollection 2020 Apr.

Authors

Kiyohito Yano¹, Toshiya Matsuzaki^{1

2}, Takeshi Iwasa¹, Yiliyasi Mayila¹, Rie Yanagihara¹, Altankhuu Tungalagsuvd^{1

3}, Munkhsaihan Munkhzaya^{1

4}, Takako Tokui¹, Shuhei Kamada¹, Aki Hayashi¹, Rie Masaki², Hidenori Aoki¹, Kou Tamura¹, Minoru Irahara¹

Affiliations

¹ Department of Obstetrics and Gynecology Graduate School of Biomedical Sciences Tokushima University Tokushima Japan.
² Division of Obstetrics and Gynecology Yoshinogawa Medical Center Tokushima Japan.
³ Division of Obstetrics and Gynecology National Center for Maternal and Child Health Ulaanbaatar Mongolia.
⁴ Department of Gynecology The First Maternity Hospital of Mongolia Ulaanbaatar Mongolia.

Abstract

Purpose: We studied the influence of psychological stress during the early neonatal period on sexual maturation and sexual behavior in rats.

Methods: Neonatal male and female rats were divided into control (C) and maternal separation (MS) groups (n = 20-24 per group). The pups in the MS groups were placed in isolation cages for 240 minutes/d from postnatal days 2-11. Vaginal opening (VO) in females and preputial separation (PS) in males (indicators of sexual maturation) were monitored, as was the estrous cycle in females. Thereafter, sexual behavior was monitored twice at 13 and 15 weeks of age.

Results: As for sexual maturation, the onset of PS occurred significantly earlier in the MS group than in the C group, whereas the onset of VO did not differ between the groups. The length of the estrous cycle did not differ between the groups. The frequencies of sexual behaviors did not differ between the groups in either sex.

Conclusions: In conclusion, early-life psychological stress induced by MS advanced sexual maturation in male rats, whereas it did not affect sexual maturation in female rats. On the other hand, early-life psychological stress might not affect sexual behavior in adulthood in either sex.

Keywords: early‐life stress; maternal separation; psychological stress; sexual behavior; sexual maturation.