Rapid photoperiod-induced increase in detectable GnRH mRNA-containing cells in Siberian hamster

Taeja Porkka-Heiskanen, Naherin Khoshaba, Kathryn Scarbrough, Janice H. Urban, Martha H. Vitaterna, Jon E. Levine, Fred W. Turek, Teresa H. Horton*

*Corresponding author for this work

Research output: Contribution to journalArticle

30 Scopus citations

Abstract

To determine whether changes in gonadotropin-releasing hormone (GnRH) neurons are early indicators of photostimulation, Siberian hamsters were placed in short days (6:18-h light-dark) at 3 (experiment 1) or 6 (experiment 2) wk of age where they were held for 3 (experiment 1) or 4 (experiment 2) wk. Hamsters were then moved to long photoperiod (16:8-h light-dark). In experiment 1, brains were collected 1-21 days after transfer from short to long days. In experiment 2, brains were collected only on the second morning of long day exposure. Long and short day controls were included in both experiments. Cells containing GnRH mRNA, as visualized by in situ hybridization, were counted. As expected, there were no differences in the number of detectable GnRH mRNA-containing cells among animals chronically exposed to long or short photoperiods. However, on the second morning after transfer from short to long photoperiod, a positive shift in the distribution of GnRH mRNA-containing cells occurred relative to the respective controls in the two experiments. Increases in follicle-stimulating hormone secretion and gonadal growth occurred days later. In conclusion, a rapid but transient increase in the distribution of detectable GnRH mRNA-containing cells is an early step in the photostimulation of the hypothalamic-pituitary-gonadal axis.

Original languageEnglish (US)
Pages (from-to)R2032-R2039
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume273
Issue number6 42-6
StatePublished - Dec 1 1997

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Keywords

  • Gonadotropin-releasing hormone
  • In situ hybridization
  • Luteinizing hormone releasing hormone
  • Reproduction
  • Seasonality

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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