NMDA induced glutamate release from the suprachiasmatic nucleus: an in vitro study in the rat.
The suprachiasmatic nucleus (SCN) has been identified as a pacemaker for mammalian circadian rhythms. Excitatory amino acid receptors, especially N-methyl-D-aspartate (NMDA) receptors, have been considered to play an important role in the transmission of light information from the retina to the circadian clocks in the SCN. In the present study, we showed that application of NMDA at circadian time (CT) 12-15 induced significant glutamate release from the SCN region in vitro. The NMDA-induced glutamate release was blocked by co-application of the NMDA receptor antagonist MK-801, but not by that of tetrodotoxin. These results suggested that glutamate stimulated its own release by activating NMDA receptors. This NMDA-induced glutamate release through NMDA receptor-mediated mechanisms might be involved in NMDA-induced potent phase shifts.
Hamada
T
T
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Kyushu University 62, Fukuoka, Japan.
Sonoda
R
R
Watanabe
A
A
Ono
M
M
Shibata
S
S
Watanabe
S
S
D000818:Animals; D002940:Circadian Rhythm; D016291:Dizocilpine Maleate / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D015353:Eye Enucleation; D018698:Glutamic Acid / Q000378:metabolism*; D066298:In Vitro Techniques; D008274:Magnesium / Q000378:metabolism; D016202:N-Methylaspartate / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000378:metabolism; D013493:Suprachiasmatic Nucleus / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology; D013997:Time Factors
D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D018698:Glutamic Acid; D013779:Tetrodotoxin; D016202:N-Methylaspartate; D016291:Dizocilpine Maleate; D008274:Magnesium