Intrinsic Neuronal Rhythms in the Suprachiasmatic Nuclei and their Adjustment
- 28 September 2007
- book chapter
- Published by Wiley
- Vol. 183, 134-153
- https://doi.org/10.1002/9780470514597.ch8
Abstract
The central role of the suprachiasmatic nuclei in regulating mammalian circadian rhythms is well established. We study the temporal organization of neuronal properties in the suprachiasmatic nucleus (SCN) using a rat hypothalamic brain slice preparation. Electrical properties of single neurons are monitored by extra‐cellular and whole‐cell patch recording techniques. The ensemble of neurons in the SCN undergoes circadian changes in spontaneous activity, membrane properties and sensitivity to phase adjustment. At any point in this cycle, diversity is observed in individual neurons' electrical properties, including firing rate, firing pattern and response to injected current. Nevertheless, the SCN generate stable, near 24 h oscillations in ensemble neuronal firing rate for at least three days in vitro. The rhythm is sinusoidal, with peak activity, a marker of phase, appearing near midday. In addition to these electrophysiological changes, the SCN undergoes sequential changes in vitro in sensitivities to adjustment. During subjective day, the SCN progresses through periods of sensitivity to cyclic AMP, serotonin, neuropeptide Y, and then to melatonin at dusk. During the subjective night, sensitivities to glutamate, cyclic GMP and then neuropeptide Y are followed by a second period of sensitivity to melatonin at dawn. Because the SCN, when maintained in vitro, is under constant conditions and isolated from afferents, these changes must be generated within the clock in the SCN. The changing sensitivities reflect underlying temporal domains that are characterized by specific sets of biochemical and molecular relationships which occur in an ordered sequence over the circadian cycle.Keywords
This publication has 42 references indexed in Scilit:
- Phospholipases and melatonin signal transduction in the ovine pars tuberalisMolecular and Cellular Endocrinology, 1994
- Potassium Channels in Samanea saman Protoplasts Controlled by Phytochrome and the Biological ClockScience, 1993
- Serotonin and the Mammalian Circadian System: I. In Vitro Phase Shifts by Serotonergic Agonists and AntagonistsJournal of Biological Rhythms, 1993
- Phase-resetting efect of 8-OH-DPAT, a serotonin1A receptor agonist, on the circadian rhythm of firing rate in the rat suprachiasmatic nuclei in vitroBrain Research, 1992
- Cyclic changes in cAMP concentration and phosphodiesterase activity in a mammalian circadian clock studied in vitroBrain Research, 1991
- Melatonin Inhibits the Activation of Cyclic AMP‐Dependent Protein Kinase in Cultured Pars Tuberalis Cells from Ovine PituitaryJournal of Neuroendocrinology, 1991
- An immunohistochemical and chromatographic analysis of the distribution and processing of proneuropeptide Y in the rat suprachiasmatic nucleusPeptides, 1991
- Behavioural entrainment of circadian rhythmsCellular and Molecular Life Sciences, 1989
- An autoradiographic analysis of the differential ascending projections of the dorsal and median raphe nuclei in the ratJournal of Comparative Neurology, 1978
- Analogs of cyclic AMP and cyclic GMP: General methods of synthesis and the relationship of structure to enzymic activityLife Sciences, 1974