title: Absence of a circadian rhythm of protein synthesis in the rat suprachiasmatic nucleus.
abstract: Male Wistar rats chronically catheterized in the jugular vein were entrained to a 12 L:12 D (lights on at 07.00 h) photoperiod. [1-14C]Leucine was administered in behaving rats at either 10.00 (day) or 22.00 (night) h. After 45 min of incubation animals were sacrificed, brains frozen, sectioned, and autoradiographed. The relative amount of label in the hypothalamic suprachiasmatic nucleus (SCN) was measured as the ratio of the optical density (OD) of the image of the SCN on the autoradiograph to the OD of white matter. The relative incorporation of labelled leucine into protein did not differ in the SCN of day vs night animals. This finding is in contrast to the prominent circadian rhythm of glucose utilization which has been seen in the rat SCN at identical points in the circadian cycle.
mesh_terms: D000818:Animals; D001345:Autoradiography; D002940:Circadian Rhythm; D005947:Glucose / Q000378:metabolism; D007930:Leucine / Q000378:metabolism; D008297:Male; D009419:Nerve Tissue Proteins / Q000096:biosynthesis*; D051381:Rats; D011919:Rats, Inbred Strains; D013493:Suprachiasmatic Nucleus / Q000378:metabolism*
chemical_list: D009419:Nerve Tissue Proteins; D007930:Leucine; D005947:Glucose