Sex differences in testosterone reactivity and sensitivity in a non-model gerbil

Devorah Matas, Tirza Doniger, Shani Sarid, Mustafa Asfur, Gal Yadid, Irina S. Khokhlova, Boris R. Krasnov, Michael Kam, A. Allan Degen, Lee Koren

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Although testosterone (T) is a key regulator in vertebrate development, physiology, and behaviour in both sexes, studies suggest that its regulation may be sex-specific. We measured circulating T levels in Baluchistan gerbils (Gerbillus nanus) in the field and in the lab all year round and found no significant sex differences. However, we observed sex differences in circulating T levels following gonadotropin-releasing hormone (GnRH) challenge and T implants in this non-model species. Whereas only males elevated T following a GnRH challenge, females had higher serum T concentrations following T implant insertion. These differences may be a result of different points of regulation along the hypothalamic-pituitary–gonadal (HPG) axis. Consequently, we examined sex differences in the mRNA expression of the androgen receptor (AR) in multiple brain regions. We identified AR and β-actin sequences in assembled genomic sequences of members of the Gerbillinae, which were analogous to rat sequences, and designed primers for them. The distribution of the AR in G. nanus brain regions was similar to documented expression profiles in rodents. We found lower AR mRNA levels in females in the striatum. Additionally, G. nanus that experienced housing in mixed-sex pairs had higher adrenal AR expression than G. nanus that were housed alone. Regulation of the gerbil HPG axis may reflect evolutionary sex differences in life-history strategies, with males ready to reproduce when receptive females are available, while the possible reproductive costs associated with female T direct its regulation upstream.

Original languageEnglish
Article number113418
JournalGeneral and Comparative Endocrinology
Volume291
DOIs
StatePublished - 15 May 2020

Keywords

  • Androgen receptor
  • GnRH challenge
  • Testosterone implants

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Endocrinology

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