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Lee SJ, Liu T, Chattoraj A, Zhang SL, Wang L, Lee TM, Wang MM, Borjigin J. Posttranscriptional regulation of pineal melatonin synthesis in Octodon degus. J Pineal Res 2009; 47:75-81. [PMID: 19538336 PMCID: PMC2837936 DOI: 10.1111/j.1600-079x.2009.00690.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Small laboratory animals have provided significant information about melatonin regulation, yet most of these organisms are nocturnal and regulate melatonin synthesis by mechanisms that diverge from those of humans. For example, in all rodents examined, melatonin secretion occurs with a time lag of several hours after the onset of darkness; in addition, arylalkylamine N-acetyltransferase (AANAT), the key enzyme in melatonin synthesis, displays dynamic transcriptional activation specifically at night in all rodents studied to date. In ungulates and primates including humans, on the other hand, melatonin secretion occurs immediately during the early night and is controlled by circadian posttranscriptional regulation of AANAT. We hypothesize that the diurnal Octodon degus (an Hystricognath rodent) could serve as an improved experimental model for studies of human melatonin regulation. To test this, we monitored melatonin production in degus using pineal microdialysis and characterized the regulation of melatonin synthesis by analyzing degu Aanat. Degu pineal melatonin rises with little latency at night, as in ungulates and primates. In addition, degu Aanat mRNA expression displays no detectable diurnal variation, suggesting that, like ungulates and primates, melatonin in this species is regulated by a posttranscriptional mechanism. Compared with AANAT from all rodents examined to date, the predicted amino acid sequence of degu AANAT is phylogenetically more closely related to ungulate and primate AANAT. These data suggest that Octodon degus may provide an ideal model system for laboratory investigation of mechanisms of melatonin synthesis and secretion in diurnal mammals.
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Affiliation(s)
- Soo Jung Lee
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
| | - Tiecheng Liu
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Asamanja Chattoraj
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Samantha L. Zhang
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
- Department of Neuroscience Program, University of Michigan, Ann Arbor, MI, USA
| | - Lijun Wang
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Theresa M. Lee
- Department of Neuroscience Program, University of Michigan, Ann Arbor, MI, USA
- Department of Psychology, University of Michigan, Ann Arbor, MI, USA
| | - Michael M. Wang
- Department of Neurology, University of Michigan, Ann Arbor, MI, USA
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
- Department of Neuroscience Program, University of Michigan, Ann Arbor, MI, USA
| | - Jimo Borjigin
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
- Department of Neuroscience Program, University of Michigan, Ann Arbor, MI, USA
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