( I) Acute induction of Per1 mRNA (Mean ± SEM) induced by AMPA or vehicle microinjection, detected by in situ hybridization using -labeled riboprobes. ** p<0.01 (one-way ANOVA, followed by Scheffe's multiple comparisons). Numbers at the bars denote sample sizes for each condition. ( H) Summary of phase delays (Mean ± SEM) induced by microinjection of drugs at CT14. The magnitude of the phase delays was calculated by comparing eye-fitted lines drawn according to the onset of the locomotor activity before and after the microinjection. Mice were maintained in constant darkness and microinjections were given at CT14 (marked by asterisks) under dim red light illumination. ( B–G) Representative double-plotted actograms of circadian locomotor activity rhythms in mice injected with either ( B) vehicle, ( C) AMPA, ( D) AMPA + NBQX, ( E) AMPA + AP5, ( F) NBQX or ( G) AP5. ( A) Topographic analysis of AMPA receptor mRNA expressions ( GluR1-4) in the mouse SCN by in situ hybridization using digoxigenin-labeled riboprobes. These data demonstrate that activation of AMPAR is capable of phase-shifting the circadian clock both in vivo and in vitro, and are consistent with the hypothesis that activation of AMPA receptors is a critical step in the transmission of photic information to the SCN. In the organotypic SCN slice culture, AMPA application induces phase-dependent phase-shifts of core-clock gene transcription rhythms. In vivo microinjection of AMPA in the SCN during the early subjective night phase-delays the behavioral rhythm. Here we show that, in the mouse SCN, GluR2 and GluR4 AMPAR subtypes are abundantly expressed in the retinorecipient area. Although the glutamatergic effect operating via NMDAR (N-methyl D-aspartate receptor) is well elucidated, much less is known about a role of AMPAR (alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor) in circadian entrainment. The glutamatergic neurotransmission in the suprachiasmatic nucleus (SCN) plays a central role in the entrainment of the circadian rhythms to environmental light-dark cycles.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |