抄録
The locus coeruleus (LC) has been demonstrated to play an important role in the regulation of sleep-wake cycle. We recently reported the application of quinelorane (a D2 agonist), but not that of 7OH-DPAT(D3/D2 agonist), into LC had a significant effect in increasing SWS. From these results we hypothesized that the inhibitory effect on wakefulness of DA agonist in LC is mediated through presynaptic D2 receptor on the terminals of excitatory neurons, which are supposed to be glutamatergic. The purpose of the present study was verification of this working hypothesis.Twelve adult LD rats were implanted with the standard sleep-recording electrodes and the guide cannulae for microdialysis probes into the locus coeruleus (LC) and the thalamus. Using reverse dialysis method, D2 dopamine agonist, quinelorane (0.0, 0.1, 1.0 mM), was applied into the LC nucleus. Simultaneously dialysates from the LC and the thalamus were collected every 10 min under sleep monitoring. The amino acids concentrations in the LC and norepinephrine (NE) concentrations in the thalamus were analyzed using a HPLC system.The application of quinelorane decreases the NE in the thalamus and induced a dose-dependent increase in SWS period. Glutamate concentration in the LC decreased significantly (76.0 + 9.1%; p = 0.027, t-test) (n = 8) with a dose of 1 mM quinelorane application. With the same dose there was no significant change in GABA release (105.6 + 10.1%; p = 0.52, t-test)(n = 8). This result indicates that the disfacilitatory mechanism in LC is important to induce SWS.(Supported by MEXT 14570958.) [Jpn J Physiol 55 Suppl:S198 (2005)]
