Analysis of Signal Transmissions from Suprachiasmatic Nucleus in the Rat Brain Using Optical Recordings

抄録

Neuronal signal propagations from the optic nerve to the hypothalamus via the suprachiasmatic nucleus (SCN), which works as the center for generating circadian rhythm in the body, were analyzed using two-dimensional optic recording with a voltage-sensitive dye. When electric stimulation on the optic chiasma (OX) was applied to a slice preparation of rat brain including SCN, signal propagations from the vetrolateral SCN to dorsomedian SCN were successfully recorded by the optical recording system. The signals propagated dorsally along the third ventricle. The optic signals disappeared in the low Ca²⁺ and high Mg²⁺ artificial cerebrospinal fluid, which blocks synaptic transmissions. Signal propagation from the SCN to the hypothalamus was synaptically mediated. Application of the NMDA receptor blocker decreased the responses, and the application of a vasoactive intestinal polypeptide (VIP) antagonist also weakened the response. These results indicate that the NMDA receptor and VIP are involved in signal propagation in the SCN.