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Neuroreport. 2002 Nov 15;13(16):2143-7.

Transforming growth factor-alpha is expressed in astrocytes of the suprachiasmatic nucleus in hamster: role of glial cells in circadian clocks.

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Department of Biology, 414 Mugar, Northeastern University, 360 Huntington Avenue, Boston, MA 02115, USA.


Transforming growth factor-alpha (TGF-alpha) is abundantly expressed in the suprachiasmatic nucleus of several rodent species. It was recently suggested to be a clock output signal regulating the activity/rest rhythm. In this study we further characterized the cellular identity of TGF-alpha-expressing cells in the suprachiasmatic nucleus of the Syrian hamster (Mesocricetus auratus). Using confocal laser scanning fluorescence imaging on brain sections immuno-histologically processed for TGF-alpha and GFAP double staining, we observed that in the suprachiasmatic nucleus, TGF-alpha staining is located mainly in GFAP-positive cells, indicating suprachiasmatic nucleus astrocytes produce TGF-alpha. Glial expression of TGF-alpha was also observed in the 3rd ventricle tanycytes of the retrochiasmatic area. In other brain regions where the TGF-alpha message is abundant, such as in the piriform cortex, we observed that TGF-alpha staining is mainly located in neurons. Our results provide the first evidence that glial cells are involved in the regulation of output from the suprachiasmatic nucleus circadian clock through a diffusible mechanism.

[Indexed for MEDLINE]

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