In vitro stimulation of c-Fos protein expression in the suprachiasmatic nucleus of hypothalamic slices.
Light regulates the c-fos protooncogene in the suprachiasmatic nucleus (SCN), with increased expression after animals are exposed to light during the dark phase of a light-dark cycle or during the subjective night in constant darkness. To determine whether this phase-dependent activation of c-Fos persists in an acute in vitro preparation, we prepared horizontal slices of hamster ventral hypothalamus, electrically stimulated the still-attached optic nerves, recorded the resulting evoked potentials in the SCN, and examined c-Fos protein levels in the nucleus by immunohistochemistry. The number of SCN cells labeled for immunoreactive c-Fos was significantly increased in slices stimulated during projected night, but not during projected day, compared to matched, sham-stimulated control slices. These results imply that the phase-dependent mechanism that gates c-Fos photoinduction in vivo is intrinsic to SCN tissue, and they suggest that an in vitro slice preparation will provide a useful model for dissecting the responsible signal transduction elements.
Department of Neurology, University of Massachusetts Medical School, Worcester 01655, USA.
M R
MR
Bennett
N
N
Aronin
W J
WJ
Schwartz
D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D006224:Cricetinae; D004558:Electric Stimulation; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008027:Light; D008297:Male; D008647:Mesocricetus; D009900:Optic Nerve / Q000502:physiology*; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis* / Q000528:radiation effects; D013493:Suprachiasmatic Nucleus / Q000378:metabolism* / Q000528:radiation effects
D016760:Proto-Oncogene Proteins c-fos