IN-SITU HYBRIDIZATION OF ANTISENSE MESSENGER-RNA OLIGONUCLEOTIDES FORAMPA, NMDA AND METABOTROPIC GLUTAMATE-RECEPTOR SUBTYPES IN THE RAT SUPRACHIASMATIC NUCLEUS AT DIFFERENT PHASES OF THE CIRCADIAN CYCLE

Eleven oligonucleotides directed against mRNA for AMPA, NMDA and metab otropic glutamate receptor subtypes were hybridized to rat coronal bra in sections containing the suprachiasmatic nucleus (SCN). These oligon ucleotides were hybridized to tissue samples collected at midday and m idnight phases of the circadian cycle. Glutamate receptor mRNA for the AMPA subunits GluR1, GluR2 and GluR4, and the NMDA receptor subtype N MDAR1, were heavily expressed in the SCN and surrounding areas. The mR NA for the metabotropic glutamate subunit mGluR1 was only lightly expr essed in the SCN. In contrast, mRNA for NMDAR2A, NMDAR2B, NMDAR2C and GluR3 was not detected in the SCN. The mRNA found to be expressed in t he rat SCN was similar in samples collected at midday and midnight, su ggesting no circadian variation in endogenous SCN glutamate receptors at these two times of the light-dark cycle.