Circadian regulation of hydroxyindole-O-methyltransferase mRNA levels in rat pineal and retina. 1996

F Gauer, and C M Craft
Mary D Allen Laboratory for Vision Research, Doheny Eye Institute, Department of Cell and Neurobiology, University of Southern California School of Medicine, Los Angeles 90033, USA.

Hydroxyindole-O-methyltransferase (HIOMT, EC 2.1.1.4) catalyzes the methylation of acetylserotonin to complete the synthesis of melatonin in the pineal and retina. A complete 1728 nucleotide cDNA encoding rat pineal HIOMT was isolated, characterized, and used to evaluate day/night levels of HIOMT mRNA. As previously reported for HIOMT enzyme activity, HIOMT mRNA levels were also greater in the pineal than in the retina. Northern blot analysis and in situ hybridization were useful for detection of HIOMT mRNA in the pineal but not the retina, whereas the reverse transcriptase-polymerase chain reaction or RNase protection assay revealed transcripts for HIOMT both in the pineal and retina. Investigating HIOMT mRNA levels in rat pineal and retina at 6 time-points throughout a 24 h period revealed higher levels of HIOMT message during darkness. The daily fluctuation in HIOMT mRNA persisted in constant darkness, verifying an endogenous circadian rhythm both in the pineal and retina. In mammalian pineals, sympathetic innervation, synthesizing norepinephrine that activates beta (beta) adrenergic receptors, entrain several circadian bodily functions through the synthesis and release of melatonin. A single injection of the beta-adrenergic agonist, isoproterenol, induced a dramatic increase of HIOMT mRNA levels in the light-adapted pineal, in vivo. Moreover, a single injection of the beta-adrenergic antagonist, propranolol, prevented the nocturnal increase of pineal HIOMT mRNA. Using a combination of methods, it has been shown that the level of HIOMT mRNA fluctuates daily in both the pineal gland and retina. This day/night rhythm can be modulated either by beta receptor agonists or antagonists when applied appropriately during the circadian cycle, suggesting that the mRNA changes in HIOMT may be controlled at the transcriptional level.

UI MeSH Term Description Entries
D008297 Male Males
D008550 Melatonin A biogenic amine that is found in animals and plants. In mammals, melatonin is produced by the PINEAL GLAND. Its secretion increases in darkness and decreases during exposure to light. Melatonin is implicated in the regulation of SLEEP, mood, and REPRODUCTION. Melatonin is also an effective antioxidant.
D008969 Molecular Sequence Data Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories. Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D010870 Pineal Gland A light-sensitive neuroendocrine organ attached to the roof of the THIRD VENTRICLE of the brain. The pineal gland secretes MELATONIN, other BIOGENIC AMINES and NEUROPEPTIDES. Epiphysis Cerebri,Pineal Body,Corpus Pineale,Gland, Pineal,Pineal Bodies,Pineal Glands
D012160 Retina The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent. Ora Serrata
D002940 Circadian Rhythm The regular recurrence, in cycles of about 24 hours, of biological processes or activities, such as sensitivity to drugs or environmental and physiological stimuli. Diurnal Rhythm,Nyctohemeral Rhythm,Twenty-Four Hour Rhythm,Nycthemeral Rhythm,Circadian Rhythms,Diurnal Rhythms,Nycthemeral Rhythms,Nyctohemeral Rhythms,Rhythm, Circadian,Rhythm, Diurnal,Rhythm, Nycthemeral,Rhythm, Nyctohemeral,Rhythm, Twenty-Four Hour,Rhythms, Circadian,Rhythms, Diurnal,Rhythms, Nycthemeral,Rhythms, Nyctohemeral,Rhythms, Twenty-Four Hour,Twenty Four Hour Rhythm,Twenty-Four Hour Rhythms
D003623 Dark Adaptation Adjustment of the eyes under conditions of low light. The sensitivity of the eye to light is increased during dark adaptation. Scotopic Adaptation,Adaptation, Dark,Adaptation, Scotopic
D000121 Acetylserotonin O-Methyltransferase An enzyme that catalyzes the transfer of a methyl group from S-adenosylmethionine to N-acetylserotonin to form N-acetyl-5-methoxytryptamine (MELATONIN). Hydroxyindole O-Methyltransferase,Acetylserotonin Methyltransferase,HIOMT,Oxyindol-O-Methyltransferase,Acetylserotonin O Methyltransferase,Hydroxyindole O Methyltransferase,Methyltransferase, Acetylserotonin,O-Methyltransferase, Acetylserotonin,O-Methyltransferase, Hydroxyindole,Oxyindol O Methyltransferase
D000221 Adaptation, Ocular The adjustment of the eye to variations in the intensity of light. Light adaptation is the adjustment of the eye when the light threshold is increased; DARK ADAPTATION when the light is greatly reduced. (From Cline et al., Dictionary of Visual Science, 4th ed) Light Adaptation,Adaptation, Light,Adaptations, Light,Adaptations, Ocular,Light Adaptations,Ocular Adaptation,Ocular Adaptations
D000318 Adrenergic beta-Agonists Drugs that selectively bind to and activate beta-adrenergic receptors. Adrenergic beta-Receptor Agonists,beta-Adrenergic Agonists,beta-Adrenergic Receptor Agonists,Adrenergic beta-Agonist,Adrenergic beta-Receptor Agonist,Betamimetics,Receptor Agonists, beta-Adrenergic,Receptors Agonists, Adrenergic beta,beta-Adrenergic Agonist,beta-Adrenergic Receptor Agonist,Adrenergic beta Agonist,Adrenergic beta Agonists,Adrenergic beta Receptor Agonist,Adrenergic beta Receptor Agonists,Agonist, Adrenergic beta-Receptor,Agonist, beta-Adrenergic,Agonist, beta-Adrenergic Receptor,Agonists, Adrenergic beta-Receptor,Agonists, beta-Adrenergic,Agonists, beta-Adrenergic Receptor,Receptor Agonist, beta-Adrenergic,Receptor Agonists, beta Adrenergic,beta Adrenergic Agonist,beta Adrenergic Agonists,beta Adrenergic Receptor Agonist,beta Adrenergic Receptor Agonists,beta-Agonist, Adrenergic,beta-Agonists, Adrenergic,beta-Receptor Agonist, Adrenergic,beta-Receptor Agonists, Adrenergic

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