2 DISTINCT OSCILLATORS IN THE RAT SUPRACHIASMATIC NUCLEUS IN-VITRO

In the rat suprachiasmatic nucleus slice culture, circadian rhythms in the release of arginine vasopressin and vasoactive intestinal polypep tide were measured simultaneously and longitudinally. The phase relati onship between the two peptide rhythms was relatively constant in the culture without a treatment of antimitotic drugs but became diverse by an introduction of antimitotics, which is generally used to reduce th e number of glial cells. By monitoring the two rhythms continuously fo r 6 days, different periods were detected in culture with the antimito tic treatment. Furthermore, N-methyl-D-aspartate shifted the phase of the two peptide rhythms in the same culture differently. These results indicate that the arginine vasopressin and vasoactive intestinal poly peptide release are under control of different circadian oscillators.