Dataset Information

Food-entrained rhythmic expression of apolipoprotein E expression in the hypothalamus of rats.

ABSTRACT: Apolipoprotein E (apoE) is a protein mainly synthesized in the liver and brain. To further understand the role of brain apoE in the management of daily food intake, we have examined the circadian pattern of hypothalamic apoE gene and protein expression in freely-fed (FF) and food-restricted (RF, food provided 4 h daily between 1000 h and 1400 h) rats sacrificed at 3-h intervals throughout the light-dark cycle. In FF rats, hypothalamic apoE mRNA and protein levels fluctuated with peaks occuring during the dark phase and the nadirs occuring during the light phase. This pattern was altered in RF rats, which had a marked increase in hypothalamic apoE mRNA and protein levels during the 4-h feeding period in the light phase. Although corticosterone (CORT) levels temporally coincided with the increasing phase of apoE in the hypothalamus in both FF and RF rats, depletion of CORT by adrenalectomy (ADX) did not significantly influence the hypothalamic apoE levels during either period, implying that the circadian pattern of hypothalamic apoE is regulated by factors other than circulating CORT. The finding that hypothalamic apoE and food intake are positively associated during the normal circadian cycle as well as in the period of restricted feeding suggests that hypothalamic apoE is food-entrained and likely involved in the physiological regulation of daily food intake.

SUBMITTER: Shen L

PROVIDER: S-EPMC2757069 | biostudies-literature | 2009 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Food-entrained rhythmic expression of apolipoprotein E expression in the hypothalamus of rats.

Shen Ling L Carey Katherine K Wang David Q-H DQ Woods Stephen C SC Liu Min M

Brain research 20090409

Apolipoprotein E (apoE) is a protein mainly synthesized in the liver and brain. To further understand the role of brain apoE in the management of daily food intake, we have examined the circadian pattern of hypothalamic apoE gene and protein expression in freely-fed (FF) and food-restricted (RF, food provided 4 h daily between 1000 h and 1400 h) rats sacrificed at 3-h intervals throughout the light-dark cycle. In FF rats, hypothalamic apoE mRNA and protein levels fluctuated with peaks occuring d ...[more]

PMID: 19362542

Similar Datasets

Project description:BackgroundCircadian rhythms in behavior and physiology are the observable phenotypes from cycles in expression of, interactions between, and degradation of the underlying molecular components. In bilaterian animals, the core molecular components include Timeless-Timeout, photoreceptive cryptochromes, and several members of the basic-loop-helix-Per-ARNT-Sim (bHLH-PAS) family. While many of core circadian genes are conserved throughout the Bilateria, their specific roles vary among species. Here, we identify and experimentally study the rhythmic gene expression of conserved circadian clock members in a sea anemone in order to characterize this gene network in a member of the phylum Cnidaria and to infer critical components of the clockwork used in the last common ancestor of cnidarians and bilaterians.Methodology/principal findingsWe identified homologs of circadian regulatory genes in the sea anemone Nematostella vectensis, including a gene most similar to Timeout, three cryptochromes, and several key bHLH-PAS transcription factors. We then maintained N. vectensis either in complete darkness or in a 12 hour light: 12 hour dark cycle in three different light treatments (blue only, full spectrum, blue-depleted). Gene expression varied in response to light cycle and light treatment, with a particularly strong pattern observed for NvClock. The cryptochromes more closely related to the light-sensitive clade of cryptochromes were upregulated in light treatments that included blue wavelengths. With co-immunoprecipitation, we determined that heterodimerization between CLOCK and CYCLE is conserved within N. vectensis. Additionally, we identified E-box motifs, DNA sequences recognized by the CLOCK:CYCLE heterodimer, upstream of genes showing rhythmic expression.Conclusions/significanceThis study reveals conserved molecular and functional components of the circadian clock that were in place at the divergence of the Cnidaria and Bilateria, suggesting the animal circadian clockwork is more ancient than previous data suggest. Characterizing circadian regulation in a cnidarian provides insight into the early origins of animal circadian rhythms and molecular regulation of environmentally cued behaviors.

Dataset Information

Food-entrained rhythmic expression of apolipoprotein E expression in the hypothalamus of rats.

Publications

Food-entrained rhythmic expression of apolipoprotein E expression in the hypothalamus of rats.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets