Testosterone and photoperiod interact to affect spatial learning and memory in adult male white-footed mice (Peromyscus leucopus)

Leah M. Pyter, Brian C. Trainor, Randy J. Nelson

Research output: Contribution to journalArticle

34 Scopus citations

Abstract

Gonadal hormones affect spatial learning and memory in mammals and circulating gonadal hormone concentrations fluctuate by season. Most nontropical rodents are spring/summer breeders and males display higher testosterone concentrations during the breeding season compared with the nonbreeding season (fall/winter). Seasonal patterns of testosterone concentration (as well as many other seasonal modifications of physiology, morphology, and behaviour) are induced by manipulation of photoperiod (day length; i.e. short or long days) in the laboratory. Coincident with reducing testosterone concentration, short days also impair spatial learning and memory performance in male white-footed mice (Peromyscus leucopus) compared with long days. We hypothesized that short-day-induced reduction of testosterone concentrations inhibits spatial learning and memory performance compared with long days. Adult male white-footed mice were maintained in long (16 h light/day) or short (8 h light/day) days for 14 weeks following sham-castration, castration plus saline implant, or castration plus testosterone implant treatment. Spatial learning and memory was assessed using a water maze, and photoperiod-evoked changes in gene expression of sex steroid receptors within the hippocampus were also examined. Castrated, short-day mice with testosterone replacement displayed enhanced water maze performance compared with other short-day mice, but no differences among testosterone treatments were observed in long-day mice. Photoperiod did not affect hippocampal androgen, oestrogen α, or oestrogen β receptor gene expression. These results suggest that photoperiod modulates the effects of testosterone on spatial learning performance by mechanisms indirect of the hippocampus.

Original languageEnglish (US)
Pages (from-to)3056-3062
Number of pages7
JournalEuropean Journal of Neuroscience
Volume23
Issue number11
DOIs
StatePublished - Jun 2006
Externally publishedYes

Keywords

  • Hippocampus
  • Seasonality
  • Steroid receptors
  • Water maze

ASJC Scopus subject areas

  • Neuroscience(all)

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