Cellular Analysis of Circadian Rhythmicity in Cultured SCN Neurons
Abstract
Circadian rhythms are generated by brain cells located in the suprachiasmatic nuclei (SCN) of the mammalian hypothalamus, but it is not clear how individual cells contribute to the operation of the circadian clock. SCN neurons dissociated from newborn rat SCN were characterized by immunocytochemistry and by patch recording of spontaneous action potentials and synaptic currents. Inhibitory synaptic interactions were prevalent among neurons, increasing progressively with time in culture. Evidence was found for presence of gap junctions between glial cells but not between neurons. To assess circadian rhythmicity, long-term multielectrode recordings of spontaneous action potentials were obtained from neurons cultured for 1-6 wks on Glass plates containing a flat array of 61 microelectrodes. Firing rates of some but not all individual neurons exhibited clear circadian rhythms with periods of nearly 24 hrs. Within a culture, cells expressing circadian rhythms showed no short-term firing synchrony. The phase of the circadian rhythm varied among cultures and, in most cases, among different cells within the same culture. With the ability to record circadian rhythms from individual SCN neurons, experimental analysis can now proceed to detailed study of circadian pacemaker neurons and their interactions. Circadian Rhythms.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 28, 1994
- Accession Number
- ADA284167
Entities
People
- David K Welsh
- Steven M. Reppert
Organizations
- Massachusetts General Hospital