Acta Biologica Hungarica

, Volume 56, Issue 3–4, pp 199–204 | Cite as

Seasonal Fluctuations of Glial Fibrillary Acidic Protein (GFAP) Immunoreactivity in the Rat Suprachiasmatic Nucleus

  • B. Gerics
  • F. Szalay
  • F. HajósEmail author


The pacemaker of the “biological clock”, the suprachiasmatic nucleus (SCN) of the hypothalamus was studied in intact male rats for glial fibrillary acidic protein (GFAP) a specific marker for astrocytes. Immunohistochemical reactions were carried out in winter (January–February) and in summer (June–July). In winter the GFAP-immunoreactivity of the SCN was found low whereas in summer it was high. Gonadectomy reduced differences. Since photic stimuli that apparently trigger the observed differences reach the SCN through identified neuronal pathways we conluded that the reaction of astrocytes is an indicator of seasonally altered neuronal function in the SCN.


GFAP biological clock immunohistochemistry SCN rat 


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© Akadémiai Kiadó, Budapest 2005

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Authors and Affiliations

  1. 1.Department of Anatomy and HistologyFaculty of Veterinary Science, Szent István UniversityBudapestHungary

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