Abstract
The rodent pineal organ transduces a photoneural input into a hormonal output. This photoneuroendocrine transduction leads to highly elevated levels of the hormone melatonin at night-time which serves as a message for darkness. The melatonin rhythm depends on transcriptional, translational and posttranslational regulation of the arylalkylamine-N-acetyltransferase, the key enzyme of melatonin biosynthesis. These regulatory mechanisms are fundamentally linked to two second messenger systems, namely the cAMP- and the Ca(2+)-signal transduction pathways. Our data gained by molecular biology, immunohistochemistry and single-cell imaging demonstrate a time- and substance-specific activation of these signaling pathways and provide a framework for the understanding of the complex signal transduction cascades in the rodent pineal gland which in concert not only regulate the basic profile but also fine-tune the circadian rhythm in melatonin synthesis.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Arylamine N-Acetyltransferase / genetics
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Calcium / physiology
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Cell Membrane / physiology*
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Cell Nucleus / physiology*
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Cyclic AMP / physiology
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Cyclic AMP Response Element Modulator
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Cyclic AMP Response Element-Binding Protein / metabolism
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Cyclic AMP-Dependent Protein Kinases / genetics
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Cyclic AMP-Dependent Protein Kinases / metabolism
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DNA-Binding Proteins / genetics
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GTP-Binding Protein alpha Subunits, Gs / genetics
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Male
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Melatonin / biosynthesis*
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Mice
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Mice, Inbred C3H
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Organ Culture Techniques
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Pineal Gland / physiology*
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Rats
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Rats, Wistar
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Receptors, Adrenergic, alpha-1 / genetics
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Repressor Proteins*
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Second Messenger Systems
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Signal Transduction*
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Transcription, Genetic
Substances
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Cyclic AMP Response Element-Binding Protein
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DNA-Binding Proteins
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Receptors, Adrenergic, alpha-1
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Repressor Proteins
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Cyclic AMP Response Element Modulator
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Cyclic AMP
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Arylamine N-Acetyltransferase
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Cyclic AMP-Dependent Protein Kinases
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GTP-Binding Protein alpha Subunits, Gs
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Melatonin
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Calcium