title: Temporal changes of light-induced proteins in the SCN following treatment with the serotonin mixed agonist/antagonist BMY7378.
abstract: The 5-HT1A mixed agonist/antagonist BMY7378 has been shown to greatly potentiate photic phase advances in hamsters. The underlying mechanism and intracellular changes in the suprachiasmatic nucleus (SCN) by which this potentiation is accomplished have yet to be fully determined. Here, we examine the effect of BMY7378 on temporal activation patterns of a number of proteins and enzymes in the SCN following light exposure in the late subjective night. BMY7378 administration increased the amount of several photo-inducible proteins in the SCN at specific time points following light exposure in the late subjective night. Relative to animals given saline before a light pulse, the number of cells immunoreactive for cFos, JunB and PER1 was all significantly greater 360 min following the light pulse in BMY7378 pretreated animals, indicating an extended action of these light-induced proteins in the SCN following BMY7378 pretreatment. Aside from a modest, nonsignificant increase in P-ERK levels at 60 min, BMY7378 did not affect light-induced P-ERK levels. The levels of light-induced P-CREB were similarly unaffected by BMY7378. Also unaffected by BMY7378 treatment were cFos expression and JunB expression at 120 and 180 min following light exposure. These findings suggest that BMY7378 may potentiate photic phase shifts at least partly by prolonging the activity of some, but not all, light-induced proteins and biochemical pathways involved in coupling the light signal to the output of the circadian clock, particularly those which are active many hours after the light signal reaches the SCN.
authors.affiliation: Department of Psychology, University of Calgary, 2500 University Drive NW, Calgary, AB, T2N 1N4, Canada.
authors.forename: Victoria M
authors.initials: VM
authors.lastname: Smith
authors.forename: Ryan T
authors.initials: RT
authors.lastname: Jeffers
authors.forename: Claire
authors.initials: C
authors.lastname: Wu
authors.forename: Jhenkruthi
authors.initials: J
authors.lastname: Vijaya Shankara
authors.forename: Michael C
authors.initials: MC
authors.lastname: Antle
mesh_terms: D000818:Animals; D064026:Calbindins / Q000378:metabolism; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D006224:Cricetinae; D005786:Gene Expression Regulation / Q000187:drug effects / Q000528:radiation effects; D008027:Light; D008297:Male; D056950:Period Circadian Proteins / Q000235:genetics / Q000378:metabolism; D010879:Piperazines / Q000494:pharmacology*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D018490:Serotonin Agents / Q000494:pharmacology*; D013493:Suprachiasmatic Nucleus / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D064026:Calbindins; D056950:Period Circadian Proteins; D010879:Piperazines; D016760:Proto-Oncogene Proteins c-fos; D018490:Serotonin Agents; D014157:Transcription Factors; C053428:BMY 7378