Transcription profiling of rat circadian regulation in skeletal muscle
Ontology highlight
ABSTRACT: In intact animals, time of drug administration may be an important factor influencing drug response. Our general goal seeks to incorporate circadian time into the study of corticosteroid regulated gene expression. This study is designed to examine fluctuations in gene expression in skeletal muscle within the 24 hour circadian cycle in normal animals. Circadian time is relevant to designing optimal corticosteroid dosing regimens. Since levels of endogenous steroid exhibit circadian fluctuations, it is our hypothesis that the expression of genes controlled by corticosteroids either directly or indirectly will also exhibit a circadian pattern in normal animals. Experiment Overall Design: Our previous studies examined changes in gene expression in response to corticosteroid treatment in adrenalectomized animals, where endogenous glucocorticoids are absent. This study is designed to examine baseline patterns of gene expression in normal animals within a 24 hour cycle. This data will be used in conjunction with future studies involving treatment of animals with corticosteroids at defined times within the circadian cycle. Fifty-four male normal Wistar rats (250-350 g body weight) were housed in a strictly controlled stress free environment with light:dark cycles of 12 hr:12hr. Three animals were sacrificed at each of 18 selected time points within the 24 hour cycle. RNA was prepared from gastrocnemius muscles for gene arrays. Time point designations reflect time after lights on in hours.
Project description:In intact animals, time of drug administration may be an important factor influencing drug response. Our general goal seeks to incorporate circadian time into the study of corticosteroid regulated gene expression. This study is designed to examine fluctuations in gene expression in skeletal muscle within the 24 hour circadian cycle in normal animals. Circadian time is relevant to designing optimal corticosteroid dosing regimens. Since levels of endogenous steroid exhibit circadian fluctuations, it is our hypothesis that the expression of genes controlled by corticosteroids either directly or indirectly will also exhibit a circadian pattern in normal animals. Keywords: time series design
Project description:In intact animals, time of drug administration may be an important factor influencing drug response. Our general goal seeks to incorporate circadian time into the study of corticosteroid regulated gene expression. Since levels of endogenous steroid exhibit circadian fluctuations, it is our hypothesis that the expression of genes controlled by corticosteroids either directly or indirectly, will also exhibit a circadian pattern in normal animals. Experiment Overall Design: This study is designed to examine fluctuations in gene expression in liver within the 24 hour circadian cycle in normal animals. Fifty-four male normal Wistar rats (250-350 g body weight) were housed in a strictly controlled stress free environment with light:dark cycles of 12 hr:12hr. Three animals were sacrificed at each of 18 selected time points within the 24 hour cycle. RNA was prepared from livers for gene arrays. Time point designations reflect time after lights on in hours.
Project description:In intact animals, time of drug administration may be an important factor influencing drug response. Our general goal seeks to incorporate circadian time into the study of corticosteroid regulated gene expression. Since levels of endogenous steroid exhibit circadian fluctuations, it is our hypothesis that the expression of genes controlled by corticosteroids either directly or indirectly, will also exhibit a circadian pattern in normal animals. Keywords: time series design
Project description:Circadian rhythms are oscillations with a periodicity of 24 hours that are controlled by an endogenous clock and are observed in virtually all aspects of mammalian function from expression of genes to complex physiological processes. The master clock is present in the suprachiasmatic nucleus (SCN) in the anterior part of the hypothalamus and controls peripheral clocks present in other parts of the body . Although much is known about the mechanism of the central clock in the SCN, the regulation of clocks present in peripheral tissues is still unclear. This study is designed to examine fluctuations in gene expression in lungs within the 24 hour circadian cycle in normal animals. The objectives of this study is to identify and analyze circadian oscillation in gene expression in lungs, and to identify the role of circadian regulation in coordinating the functioning of this dynamic organ. Fifty-four male normal Wistar rats (250-350 g body weight) were housed in a strictly controlled stress free environment with light:dark cycles of 12 hr:12hr. Three animals were sacrificed at each of 18 selected time points within the 24 hour cycle. RNA was prepared from lungs for gene arrays. Time point designations reflect time after lights on in hours.
Project description:Circadian rhythms are oscillations with a periodicity of 24 hours that are controlled by an endogenous clock and are observed in virtually all aspects of mammalian function from expression of genes to complex physiological processes. The master clock is present in the suprachiasmatic nucleus (SCN) in the anterior part of the hypothalamus and controls peripheral clocks present in other parts of the body. Although much is known about the mechanism of the central clock in the SCN, the regulation of clocks present in peripheral tissues is still unclear. This study is designed to examine fluctuations in gene expression in abdominal white adipose tissue within the 24 hour circadian cycle in normal animals. The objectives of this study is to identify and analyze circadian oscillation in gene expression in white adipose tissue, and to identify the role of circadian regulation in coordinating the functioning of this dynamic tissue. Fifty-four male normal Wistar rats (250-350 g body weight) were housed in a strictly controlled stress free environment with light:dark cycles of 12 hr:12hr. Three animals were sacrificed at each of 18 selected time points within the 24 hour cycle. RNA was prepared from abdominal adipose tissue for gene arrays. Two samples were not used due to RNA degradation: Adipose .25-1 and Adipose 11-2. Time point designations reflect time after lights on in hours.
Project description:Circadian rhythms are oscillations with a periodicity of 24 hours that are controlled by an endogenous clock and are observed in virtually all aspects of mammalian function from expression of genes to complex physiological processes. The master clock is present in the suprachiasmatic nucleus (SCN) in the anterior part of the hypothalamus and controls peripheral clocks present in other parts of the body . Although much is known about the mechanism of the central clock in the SCN, the regulation of clocks present in peripheral tissues is still unclear. This study is designed to examine fluctuations in gene expression in lungs within the 24 hour circadian cycle in normal animals. The objectives of this study is to identify and analyze circadian oscillation in gene expression in lungs, and to identify the role of circadian regulation in coordinating the functioning of this dynamic organ.
Project description:Circadian rhythms are oscillations with a periodicity of 24 hours that are controlled by an endogenous clock and are observed in virtually all aspects of mammalian function from expression of genes to complex physiological processes. The master clock is present in the suprachiasmatic nucleus (SCN) in the anterior part of the hypothalamus and controls peripheral clocks present in other parts of the body. Although much is known about the mechanism of the central clock in the SCN, the regulation of clocks present in peripheral tissues is still unclear. This study is designed to examine fluctuations in gene expression in abdominal white adipose tissue within the 24 hour circadian cycle in normal animals. The objectives of this study is to identify and analyze circadian oscillation in gene expression in white adipose tissue, and to identify the role of circadian regulation in coordinating the functioning of this dynamic tissue.
Project description:Disrupted circadian activity is associated with many neuropsychiatric disorders. A major coordinator of circadian biological systems is adrenal glucocorticoid secretion which exhibits a pronounced pre-awakening peak that regulates metabolic, immune, and cardiovascular processes, as well as mood and cognitive function. Loss of this circadian rhythm during corticosteroid therapy is often associated with memory impairment. Surprisingly the mechanisms that underlie this deficit are not understood. In this study, in rats, we report that circadian regulation of the hippocampal transcriptome integrates crucial functional networks that link corticosteroid-inducible gene regulation to synaptic plasticity processes via an intra-hippocampal circadian transcriptional clock. Further, these circadian hippocampal functions were significantly impacted by corticosteroid treatment delivered in a five day oral dosing treatment protocol. Rhythmic expression of the hippocampal transcriptome, as well as the circadian regulation of synaptic plasticity were misaligned with the natural light/dark circadian entraining cues, resulting in memory impairment in hippocampal-dependent behavior. These findings provide mechanistic insights into how the transcriptional clock machinery within the hippocampus is influenced by corticosteroid exposure, leading to adverse effects on critical hippocampal functions, as well as identifying a molecular basis for memory deficits in patients treated with long-acting synthetic corticosteroids.
Project description:Disrupted circadian activity is associated with many neuropsychiatric disorders. A major coordinator of circadian biological systems is adrenal glucocorticoid secretion which exhibits a pronounced pre-awakening peak that regulates metabolic, immune, and cardiovascular processes, as well as mood and cognitive function. Loss of this circadian rhythm during corticosteroid therapy is often associated with memory impairment. Surprisingly the mechanisms that underlie this deficit are not understood. In this study, in rats, we report that circadian regulation of the hippocampal transcriptome integrates crucial functional networks that link corticosteroid-inducible gene regulation to synaptic plasticity processes via an intra-hippocampal circadian transcriptional clock. Further, these circadian hippocampal functions were significantly impacted by corticosteroid treatment delivered in a five day oral dosing treatment protocol. Rhythmic expression of the hippocampal transcriptome, as well as the circadian regulation of synaptic plasticity were misaligned with the natural light/dark circadian entraining cues, resulting in memory impairment in hippocampal-dependent behavior. These findings provide mechanistic insights into how the transcriptional clock machinery within the hippocampus is influenced by corticosteroid exposure, leading to adverse effects on critical hippocampal functions, as well as identifying a molecular basis for memory deficits in patients treated with long-acting synthetic corticosteroids.
Project description:Most higher organisms, including plants and animals, have developed a time-keeping mechanism that allows them to anticipate daily fluctuations of environmental parameters such as light and temperature. This circadian clock efficiently coordinates plant growth and metabolism with respect to time-of-day by producing self-sustained rhythms of gene expression with an approximately 24-hour period. The importance of these rhythms has in fact been demonstrated in both phytoplankton and higher plants: organisms that have an internal clock period matched to the external environment possess a competitive advantage over those that do not. We used microarrays to identify circadian-regulated genes of Arabidopsis thaliana to elucidate how the clock provides an adaptive advantage by understanding how the clock regulates outputs and determining which pathways and processes may be under circadian control. Keywords: time course