TY - JOUR
T1 - Methylcobalamin induces a long-lasting enhancement of the field potential in rat suprachiasmatic nucleus slices
AU - Nishikawa, Yukiko
AU - Shibata, Shigenobu
AU - Shimazoe, Takao
AU - Watanabe, Shigenori
PY - 1996/12/20
Y1 - 1996/12/20
N2 - Optic nerve stimulation has been reported to evoke a field potential (FP) in rat suprachiasmatic nucleus (SCN) slices. Methylcobalamin,δ-(5,6-dymethylbenzimidazolyl)-Co-methyl-cobamide (Me-B12) enhanced this FP and the enhancement lasted more than 1 h after washing out. Maximal enhancement (143.6 ± 9.8%) was achieved at a concentration of 10 μM. By contrast, cyanocobalamin containing CN- instead of CH3- showed no enhancement of the amplitude in the FP. Me-B12 induced enhhncement of FP was strongly blocked by an N-methyl-D-aspartate (NMDA) receptor antagonist, DL-2-amino-5-phosphonovaleric acid (APV). These results indicate that CH3- in the Me-B12 is required to modulate the FP amplitude and the NMDA receptor is involved in the long-lasting FP enhancement induced by Me-B12. The present results suggest that Me-B12 modifies the photic entrainment of the circadian clock in the suprachiasmatic nucleus via an activation of NMDA receptors.
AB - Optic nerve stimulation has been reported to evoke a field potential (FP) in rat suprachiasmatic nucleus (SCN) slices. Methylcobalamin,δ-(5,6-dymethylbenzimidazolyl)-Co-methyl-cobamide (Me-B12) enhanced this FP and the enhancement lasted more than 1 h after washing out. Maximal enhancement (143.6 ± 9.8%) was achieved at a concentration of 10 μM. By contrast, cyanocobalamin containing CN- instead of CH3- showed no enhancement of the amplitude in the FP. Me-B12 induced enhhncement of FP was strongly blocked by an N-methyl-D-aspartate (NMDA) receptor antagonist, DL-2-amino-5-phosphonovaleric acid (APV). These results indicate that CH3- in the Me-B12 is required to modulate the FP amplitude and the NMDA receptor is involved in the long-lasting FP enhancement induced by Me-B12. The present results suggest that Me-B12 modifies the photic entrainment of the circadian clock in the suprachiasmatic nucleus via an activation of NMDA receptors.
KW - Circadian rhythm
KW - Methylcobalamin
KW - N-Methyl-D-aspartate
KW - Retinohypothalamic tract
KW - Suprachiasmatic nucleus
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U2 - 10.1016/S0304-3940(96)13258-4
DO - 10.1016/S0304-3940(96)13258-4
M3 - Article
C2 - 8994227
AN - SCOPUS:0030596051
SN - 0304-3940
VL - 220
SP - 199
EP - 202
JO - Neuroscience Letters
JF - Neuroscience Letters
IS - 3
ER -