Abstract
Housing rats under continuous illumination (LL) disrupts circadian rhythms controlled by a pacemaker located in the hypothalamic suprachiasmatic nucleus (SCN). The neural mechanisms underlying this effect are not well understood. The present study examined the effects of LL on circadian rhythms and on light-induced expression of Fos protein in the SCN, intergeniculate leaflet (IGL), and ventrolateral geniculate nucleus (vLGN) in adult rats treated neonatally with monosodium glutamate (MSG). Such treatment is known to lead to acute degeneration of retinal ganglion cells. Despite degeneration of the optic nerve, neonatal MSG treatment (2 mg/g SC on postnatal days 1,3,5,7, and 9) had no effect on daily temperature rhythms in the adult animal under a light-dark cycle. However, the disintegration of circadian rhythms under LL conditions observed in adult rats treated neonatally with 10% saline was prevented in MSG-treated rats. Furthermore, neonatal MSG treatment attenuated light-induced expression of Fos protein in the IGL and vLGN, but not in the SCN. These data suggest that neonatal MSG treatment alters the response of the circadian system to LL and that cells within the IGL/vLGN region may mediate this response.
| Original language | English |
|---|---|
| Pages (from-to) | 135-142 |
| Number of pages | 8 |
| Journal | Brain Research |
| Volume | 675 |
| Issue number | 1-2 |
| DOIs | |
| Publication status | Published - Mar 27 1995 |
Bibliographical note
Funding Information:Engineering Research Council of Canada to S.A. and J.G.P., and from the Medical Research Council of Canada to B.R.
Funding Information:
We thank Donna Goguen for technical advice on the immunocytochemical procedures. This study was supported by grants from the Natural Sciences and
ASJC Scopus Subject Areas
- General Neuroscience
- Molecular Biology
- Clinical Neurology
- Developmental Biology