Removal of reproductive suppression reveals latent sex differences in brain steroid hormone receptors in naked mole-rats, Heterocephalus glaber

Biology of Sex Differences

Ashlyn Swift-Gallant¹  Kaiguo Mo¹  Deane E. Peragine¹  D. Ashley Monks²  Melissa M. Holmes³ 

[1] Department of Psychology, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga L5L 1C6, ON, Canada

[2] Department of Cell and Systems Biology, University of Toronto, 100 St. George Street, Toronto M5S 3G3, ON, Canada

[3] Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto M5S 3B2, ON, Canada

关键词: Testosterone;    Sex difference;    Reproductive suppression;    Progesterone receptor;    Naked mole-rat;    Eusocial;    Estrogen receptor;    Estradiol;    Aromatase;    Androgen receptor;   

Others  :  1234984
DOI  :  10.1186/s13293-015-0050-x

 received in 2015-10-28, accepted in 2015-12-01,  发布年份 2015

【 摘 要 】

Background

Naked mole-rats are eusocial mammals, living in large colonies with a single breeding female and 1–3 breeding males. Breeders are socially dominant, and only the breeders exhibit traditional sex differences in circulating gonadal steroid hormones and reproductive behaviors. Non-reproductive subordinates also fail to show sex differences in overall body size, external genital morphology, and non-reproductive behaviors. However, subordinates can transition to breeding status if removed from their colony and housed with an opposite-sex conspecific, suggesting the presence of latent sex differences. Here, we assessed the expression of steroid hormone receptor and aromatase messenger RNA (mRNA) in the brains of males and females as they transitioned in social and reproductive status.

Methods

We compared in-colony subordinates to opposite-sex subordinate pairs that were removed from their colony for either 1 day, 1 week, 1 month, or until they became breeders (i.e., produced a litter). Diencephalic tissue was collected and mRNA of androgen receptor (Ar), estrogen receptor alpha (Esr1), progesterone receptor (Pgr), and aromatase (Cyp19a1) was measured using qPCR. Testosterone, 17β-estradiol, and progesterone from serum were also measured.

Results

As early as 1 week post-removal, males exhibited increased diencephalic Ar mRNA and circulating testosterone, whereas females had increased Cyp19a1 mRNA in the diencephalon. At 1 month post-removal, females exhibited increased 17β-estradiol and progesterone. The largest changes in steroid hormone receptors were observed in breeders. Breeding females had a threefold increase in Cyp19a1 and fivefold increases in Esr1 and Pgr, whereas breeding males had reduced Pgr and increased Ar.

Conclusions

These data demonstrate that sex differences in circulating gonadal steroids and hypothalamic gene expression emerge weeks to months after subordinate animals are removed from reproductive suppression in their home colony.

【 授权许可】

   
2015 Swift-Gallant et al.

【 图 表 】

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