CIRCADIAN RELEASE OF AMINO-ACIDS IN THE SUPRACHIASMATIC NUCLEUS IN-VITRO

TEMPORAL patterns of release of aspartate, glutamate and glycine, whic h are related to excitatory amino acidergic transmission, were examine d in organotypic slice cultures of rat suprachiasmatic nucleus over a 60 h period. Vasopressin release in the same culture was measured simu ltaneously to compare the temporal pattern with that of the amino acid s. Amino acids and vasopressin were measured by high performance liqui d chromatography and enzyme immunoassay, respectively. Robust circadia n rhythms were detected in release of aspartate, glutamate and glycine . Glycine levels were about 10 times higher than those of aspartate an d glutamate in the culture. Vasopressin also showed a clear circadian rhythm and the phase angle difference between each amino acid and AVP was not significantly different. The results indicate that cultured SC N cells release these amino acids and the release is under the control of the circadian pacemaker.