Photoperiodic regulation of compensatory testicular hypertrophy in hamsters

Matthew J. Paul*, Jin Ho Park, Teresa H. Horton, Maria I. Alvarez, Morgan K. Burke, Ned J. Place, Irving Zucker

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


In mammals, removal of one testis results in compensatory testicular hypertrophy (CTH) of the remaining gonad. Although CTH is ubiquitous among juveniles of many species, laboratory rats, laboratory mice, and humans unilaterally castrated in adulthood fail to display CTH. We documented CTH in pre- and postpubertally hemi-castrated Syrian and Siberian hamsters and tested whether day length affects CTH in juvenile and adult Siberian hamsters. Robust CTH was evident in long-day hemi-castrates of both species and was preceded by increased serum FSH concentrations in juvenile Siberian hamsters. In sharp contrast, CTH was undetectable in short-day hemi-castrated Siberian hamsters for several months and only made its appearance with the development of neuroendocrine refractoriness to short day lengths; serum FSH concentrations of juveniles also did not increase above sham-castrate values until the onset of refractoriness. Long-day hemi-castrated Siberian hamsters with hypertrophied testes underwent complete gonadal regression after transfer to short days, albeit at a reduced rate for the first 3 weeks of treatment. Blood testosterone concentrations of adult hamsters did not differ between long-day hemicastrates and sham-castrates 9-12 weeks after surgery. We conclude that CTH is suppressed by short day lengths in Siberian hamsters at all ages and stages of reproductive development; in short day lengths, but not long day lengths, the remaining testis produces sufficient negative feedback inhibition to restrain FSH hypersecretion and prevent CTH.

Original languageEnglish (US)
Pages (from-to)261-269
Number of pages9
JournalBiology of reproduction
Issue number2
StatePublished - Aug 2006


  • Compensatory testicular hypertrophy
  • Follicle-stimulating hormone
  • Inhibin
  • Photoperiodism
  • Reproductive axis
  • Seasonal reproduction
  • Testis
  • Testosterone
  • Unilateral castration

ASJC Scopus subject areas

  • Cell Biology
  • Reproductive Medicine


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