Age and Time of Day Influences on the Expression of Transforming Growth Factor-Beta and Phosphorylated SMAD3 in the Mouse Suprachiasmatic and Paraventricular NucleiBeynon A.L. · Thome J. · Coogan A.N.
Neuroscience and Molecular Psychiatry, Institute of Life Science, School of Medicine, Swansea University, Swansea, UK
Background/Aims: The master mammalian circadian pacemaker is the suprachiasmatic nuclei (SCN) of the hypothalamus. In this study we examined the expression of transforming growth factor (TGF)-β and the associated signaller phosphorylated SMAD3 (pSMAD3) in the SCN and the paraventricular nucleus (PVN) of the hypothalamus of the young and older mouse across the diurnal cycle, in order to ascertain whether there are time-of-day and age influences on their expression in the hypothalamus. Methods: Immunohistochemistry coupled to densitometric analysis has been used to quantitate the expression of TGF-β and pSMAD3 in the SCN and PVN. Results: We have demonstrated a diurnal pattern of expression of TGF-β in the SCN of young animals, a rhythm that is lost in older mice. The PVN also shows diurnal expression of TGF-β and older mice exhibit elevated levels. Finally, we have demonstrated a novel day/night difference in the expression of pSMAD3, a part of the TGF signalling pathway, in the SCN, a rhythm that appears to be lost with age. Conclusion: We conclude that TGF-β and pSMAD3 are expressed under basal conditions in the SCN and PVN, and this expression is modulated in both a diurnal and age-dependent manner.
Andrew N. Coogan
Department of Psychology, National University of Ireland
Maynooth, Co. Kildare (Ireland)
Tel. +353 1 708 6624, Fax +353 1 708 4767
Received: October 17, 2008
Accepted after revision: January 28, 2009
Published online: July 17, 2009
Number of Print Pages : 8
Number of Figures : 5, Number of Tables : 0, Number of References : 36
Vol. 16, No. 6, Year 2009 (Cover Date: September 2009)
Journal Editor: Savino W. (Rio de Janeiro)
ISSN: 1021-7401 (Print), eISSN: 1423-0216 (Online)
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