Photic Regulation of Gene Expression and Cellular Activity in the SCN
Abstract
Since visual inputs to the light-entrainable circadian pacemaker in the suprachiasmatic nucleus (SCN) presumably trigger a cascade of cellular events locally, studies were conducted during the current budget year to examine the photic regulation of cellular activity within the SCN. Experiments examined the effect of optic nerve stimulation on peptide release and mRNA levels expressed by perifused SCN explants. Emphasis was placed on studying populations of SCN neurons containing vasoactive intestinal polypeptide (VIP) or vasopressin (VP) because sensitive antibodies for radioimmunoassay and transcripts for analyzing mRNAs that encode these peptides are readily available. Irrespective of the time of treatment, optic nerve stimulation evoked acute increases in VP release, such that VP output during stimulation was 2-4 times greater than that observed in control explants. Within 2-4 hr after stimulation, VP release declined to pre-treatment levels. The effect of optic nerve stimulation on VP mRNA content in SCN explants was dependent on the time of treatment; VP mRNA was increased by 25-40% following stimulation during the subjective day, but was unchanged after stimulation during the subjective night. Release of VIP and VIP mRNA content expressed by SCN explants was unaffected by stimulation, irrespective of the time of treatment.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 09, 1991
- Accession Number
- ADA236230
Entities
People
- David J. Earnest
Organizations
- University of Rochester