Rapid effects of estradiol on male aggression depend on photoperiod in reproductively non-responsive mice

Brian C. Trainor, M. Sima Finy, Randy J. Nelson

Research output: Contribution to journalArticlepeer-review

91 Scopus citations


In three genuses and four species of rodents, housing in winter-like short days (8L:16D) increases male aggressive behavior. In all of these species, males undergo short-day induced regression of the reproductive system. Some studies, however, suggest that the effect of photoperiod on aggression may be independent of reproductive responses. We examined the effects of photoperiod on aggressive behavior in California mice (Peromyscus californicus), which do not display reproductive responsiveness to short days. As expected, short days had no effect on plasma testosterone. Estrogen receptor alpha and estrogen receptor beta immunostaining did not differ in the lateral septum, medial preoptic area, bed nucleus of the stria terminalis, or medial amygdala. However, males housed in short days were significantly more aggressive than males housed in long days. Similar to previous work in beach mice (Peromyscus polionotus), estradiol rapidly increased aggression when male California mice were housed in short days but not when housed in long days. These data suggest that the effects of photoperiod on aggression and estrogen signaling are independent of reproductive responses. The rapid action of estradiol on aggression in short-day mice also suggests that nongenomic mechanisms mediate the effects of estrogens in short days.

Original languageEnglish (US)
Pages (from-to)192-199
Number of pages8
JournalHormones and Behavior
Issue number1
StatePublished - Jan 2008


  • Aggressive behavior
  • c-fos
  • California mouse
  • Estrogen receptor alpha
  • Estrogen receptor beta
  • Nongenomic effects
  • Peromyscus californicus

ASJC Scopus subject areas

  • Endocrinology
  • Behavioral Neuroscience
  • Neurology
  • Psychology(all)


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