Blockade of Glutamatergic Neurotransmission in the Suprachiasmatic Nucleus Prevents Cellular and Behavioural Responses of the Circadian System to Light.

摘要: The aim of this study was to test the role glutamatergic neurotransmission in photic entrainment circadian oscillator suprachiasmatic nuclei (SCN) Syrian hamster. response a brief pulse light assessed using two independent indices, phase shift free-running activity rhythm, and photically induced expression immediate-early gene c-fos within neurons SCN. behavioural cellular responses were compared animals which received intracerebroventricular (icv) infusions into region SCN either vehicle solution or gammad-glutamyl-glycine (DGG), competitive antagonist at both N-methyl-d-aspartate (NMDA) non-NMDA types glutamate receptor. Infusions DGG (200 nmol) given 10 min before presentation 15-min time (CT) 14 CT20 (onset defined as CT12). As anticipated, treated with CT14 exhibited delays whereas advances. Central infusion prior blocked phase-delaying effect light, delivered markedly attenuated phase-advancing light. In separate group animals, by immunocytochemical staining for its protein product Fos. Exposure vehicle-infused caused extensive throughout retinorecipient However, when preceded icv fusion dose would block phase-shifting total number immunopositive Fos significantly reduced ( approximately 50%) confined restricted area dorsolateral precise correlation between effects blockade upon system demonstrates that effective adjacent is necessary component mechanism mediates clock. results further demonstrate pharmacological anatomical compartmentalization zone SCN, consistent view retinal afferents ventral employ transmitter, more dorsal input may be dependent non-glutamatergic (DGG-insensitive) pathways.