title: CART peptide diurnal rhythm in brain and effect of fasting.
abstract: We have recently shown that CART peptides exhibit a diurnal rhythm in blood that is affected by food intake and glucocorticoids. In the present study, we extend our observations by demonstrating that CART peptides also exhibit a diurnal rhythm in several brain regions, notably the nucleus accumbens, hypothalamus and amygdala, but not in the midbrain. To examine whether the CART peptide rhythm was dependent on food intake, animals were food-deprived for 24 h. In regular-fed animals, CART peptide levels were lower in the morning compared to evening hours. However, this diurnal variation of CART peptide was not apparent in fasted animals, and CART peptide levels were reduced. The diurnal variation of CART mRNA in the nucleus accumbens paralleled the variation of CART peptide in this region. Similar to the peptide, the mRNA did not change in midbrain. These results show that CART peptide levels and gene expression undergo a diurnal variation in some brain regions, and the variation is altered by fasting. These findings suggest a variety of regulatory mechanisms for CART and additional considerations for CART's role in brain.
authors.affiliation: Division of Neuroscience, Yerkes National Primate Center of Emory University, 954 Gatewood Road NE, Atlanta, GA 30329, USA. avicen2@emory.edu
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Vicentic
authors.forename: Anita
authors.initials: A
authors.lastname: Lakatos
authors.forename: Richard
authors.initials: R
authors.lastname: Hunter
authors.forename: Kelly
authors.initials: K
authors.lastname: Philpot
authors.forename: Geraldina
authors.initials: G
authors.lastname: Dominguez
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Kuhar
mesh_terms: D000818:Animals; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism*; D002940:Circadian Rhythm / Q000502:physiology*; D005215:Fasting / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology*; D008297:Male; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D011863:Radioimmunoassay / Q000379:methods; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein
chemical_list: D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D000098882:Cocaine- and Amphetamine-Regulated Transcript Protein