Ocular Melatonin Rhythms in the Goldfish, Carassius auratus

Iigo, Masayuki; Furukawa, Kiyoshi; Hattori, Atsuhiko; Ohtani-Kaneko, Ritsuko; Hara, Masayuki; Suzuki, Takuro; Tabata, Mitsuo; Aida, Katsumi

doi:10.1177/074873049701200209

Cited by 35 publications

(37 citation statements)

References 58 publications

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“…These low expression levels are in agreement with the general acceptance that AANAT-2 is preferentially expressed in the pineal, whereas the most abundant isoform in the retina is the AANAT-1 (Klein, 2007;. Nevertheless, our results indicate that in the goldfish retina an AANAT-2, with parallel rhythmic expression to ocular MEL rhythms (Iigo et al, 1997) could eventually produce MEL, in addition to a possible role on reduction of cytotoxic compounds formation, as suggested (Klein, 2006). Further information on gAANAT-1 is needed to delve into the role of both enzymes in the retina of this species.…”

Section: Daily Rhythmic Expression and Transcriptional Regulationsupporting

confidence: 76%

“…The functional role played by AANAT-2 in these locations, is of great interest and several possibilities, apart from the MEL synthesis, can be suggested, as the reduction of the oxidative formation of aldehydes of serotonin and other arylalkylamines (Bernard et al, 1995;Coon et al, 2002) and/or a detoxification role, as it is considered the original function of this enzyme Klein, 2007). Nevertheless, in addition to the expected Hiomt expression in goldfish pineal and retina, where MEL synthesis is well documented in vivo and in vitro (Iigo et al, 1991;1997), we found positive signals for HIOMT transcripts in gonads and, to a lesser extent, in liver and gut. These are the first results identifying Hiomt transcripts in non photosensitive organs in fish, and accords with previous studies in rat (Stefulj et al, 2001) and quail (Fu et al, 2001).…”

Section: Distribution Of Aanat-2 and Hiomt-2 Mrna In Goldfishmentioning

confidence: 99%

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MELATONIN-SYNTHESIZING ENZYMES IN PINEAL, RETINA, LIVER, AND GUT OF THE GOLDFISH (CARASSIUS): mRNA EXPRESSION PATTERN AND REGULATION OF DAILY RHYTHMS BY LIGHTING CONDITIONS

Velarde

Cerdá‐Reverter

Alonso-Gómez

et al. 2010

Chronobiology International

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(MAX 350 WORDS)Melatonin is currently proposed to be synthesized in non-photosensitive organs of vertebrates, besides its well-known sites of synthesis, the pineal gland and the retina.However, very few studies have demonstrated gene expression of MEL synthesizing enzymes in extrapineal and extraretinal locations. In the present study, present study focuses on the circadian expression of the two key enzymes of the melatoninergic pathway, the AANAT and the HIOMT in central and peripheral locations of the goldfish we give report of the full-length cloning of the two enzymes catalyzing the final steps of melatonin biosynthesis, the arylalkylamine N-acetyltransferase (AANAT) and the hydroxyindole-Omethyltransferase (HIOMT), in a teleosts fish, the goldfish (Carassius auratus). Both enzymes showed high similarity with other teleost sequences, corresponding to the goldfish AANAT-2 and HIOMT-2. Two forms of AANATs were widely known to exist in teleosts, but this is the first time that two isoforms of HIOMT are deduced from a phylogenetic analysis.Both enzymes were detected in several peripheral locations, including liver and gut, being present results the first to find HIOMT in non-photosensitive structures of a fish species. No studies exist on transcriptional regulation of the expression of MEL biosynthesis enzymes in non photosensitive structures in fish The daily expression pattern of both genes in pineal gland, retina, liver and gut was investigated using quantitative real time RT-PCR and cosinor analysis. This is the first time that a rhythmic expression of AANAT and HIOMT are found in digestive tissues of a vertebrate species, supporting a functional melatonin synthesis pathway in liver and gut of the goldfish. Besides, the transcriptional regulation of Aanat-2 in pineal and peripheral locations of goldfish maintained under different lighting conditions was investigated expression of gAANAT-2 is analyzed under different lighting conditions including continuous light and darkness, revealing, as expected, light-dependent rhythms in pineal gland and retina, but also in liver. Nevertheless, the persistence in hindgut of these Aanat-2 rhythms in constant conditions suggests that the expression of this transcript is under circadian clock and entrained by non-photic cues. Our results reinforce the existence of melatonin synthesis in gut and liver of the goldfish, while the rhythmic expression profiles reported point to a regulation of both genes in gut and liver by peripheral oscillators entrainable to non-photic cues.

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Section: Daily Rhythmic Expression and Transcriptional Regulationsupporting

confidence: 76%

Section: Distribution Of Aanat-2 and Hiomt-2 Mrna In Goldfishmentioning

confidence: 99%

MELATONIN-SYNTHESIZING ENZYMES IN PINEAL, RETINA, LIVER, AND GUT OF THE GOLDFISH (CARASSIUS): mRNA EXPRESSION PATTERN AND REGULATION OF DAILY RHYTHMS BY LIGHTING CONDITIONS

Velarde

Cerdá‐Reverter

Alonso-Gómez

et al. 2010

Chronobiology International

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“…The retina shares many chronobiological characteristics with the pineal gland and can be considered a melatoninsynthesising molecular clock in some, but not all, fish species. In the cyprinids zebrafish and goldfish, retinal melatonin rhythms are light sensitive and parallel those of the pineal gland (Cahill 1996, Iigo et al 1997a. However, in rainbow trout (Besseau et al 2006) and European sea bass (Dicentrarchus labrax; Iigo et al 1997b), retinal melatonin production peaks during the daytime.…”

Section: Melatoninmentioning

confidence: 99%

Interplay between the endocrine and circadian systems in fishes

Isorna

Pedro

Valenciano

et al. 2017

Journal of Endocrinology

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The circadian system is responsible for the temporal organisation of physiological functions which, in part, involves daily cycles of hormonal activity. In this review, we analyse the interplay between the circadian and endocrine systems in fishes. We first describe the current model of fish circadian system organisation and the basis of the molecular clockwork that enables different tissues to act as internal pacemakers. This system consists of a net of central and peripherally located oscillators and can be synchronised by the light-darkness and feeding-fasting cycles. We then focus on two central neuroendocrine transducers (melatonin and orexin) and three peripheral hormones (leptin, ghrelin and cortisol), which are involved in the synchronisation of the circadian system in mammals and/or energy status signalling. We review the role of each of these as overt rhythms (i.e. outputs of the circadian system) and, for the first time, as key internal temporal messengers that act as inputs for other endogenous oscillators. Based on acute changes in clock gene expression, we describe the currently accepted model of endogenous oscillator entrainment by the light-darkness cycle and propose a new model for non-photic (endocrine) entrainment, highlighting the importance of the bidirectional cross-talking between the endocrine and circadian systems in fishes. The flexibility of the fish circadian system combined with the absence of a master clock makes these vertebrates a very attractive model for studying communication among oscillators to drive functionally coordinated outputs.

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“…As the melatonin concentration in the fish retina is higher than in plasma, e.g. 9-100 times higher in C. auratus (Iigo et al 1997), it may be a signal that dipostomula respond to upon contact with the retina. Whether they can also localize the retina following a concentration gradient of melatonin is difficult to evaluate, as ocular melatonin acts in an autocrine or paracrine manner and seems to accumulate in the eye.…”

Section: Discussionmentioning

confidence: 99%

Navigation within host tissues: cues for orientation of Diplostomum spathaceum (Trematoda) in fish towards veins, head and eye

et al. 2007

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Cercariae of Diplostomum spathaceum penetrate the skin of fish, and then migrate along blood vessels and tissues towards the head and the eye-lens. We studied their orientation behaviour in tail fins of guppies and in chemical concentration gradients within agar-filled choice chambers. In fins, they entered veins and orientated cranially, independent of the blood flow and living cells. In choice chambers, they were attracted by a small molecular fraction of fish serum, D-glucose (at 1, 10, and 1000 mM), D-mannose, D-maltotriose and Cl-ions, whereas D-glucosamine repelled them (even at 1 . 0 nM). Amino acids were not attractive, but arginine in tetrapeptides attracted at concentrations as low as 1 mM and melatonin at 0 . 4-4 . 3 pM. We suggest a preliminary model for the behaviour of diplostomula in fish fins and attracting (+) or repelling (x) host cues: (1) migration towards deeper skin layers and avoidance of skin surface, cues: Cl-ions (+ and x), glucose (+), glucosamine (x), light radiation (x); (2) orientation in cranial direction, cue: Cl-ions (+) ; (3) localization of blood vessels, cues : glucose (+), arginine-residues (+); (4) localization of the retina, cue: melatonin (+). A comparison with the navigation mechanisms of tissue-migrating schistosomules and hookworm larvae reveals an enormous diversity of strategies.

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Ocular Melatonin Rhythms in the Goldfish, Carassius auratus

Cited by 35 publications

References 58 publications

MELATONIN-SYNTHESIZING ENZYMES IN PINEAL, RETINA, LIVER, AND GUT OF THE GOLDFISH (CARASSIUS): mRNA EXPRESSION PATTERN AND REGULATION OF DAILY RHYTHMS BY LIGHTING CONDITIONS

MELATONIN-SYNTHESIZING ENZYMES IN PINEAL, RETINA, LIVER, AND GUT OF THE GOLDFISH (CARASSIUS): mRNA EXPRESSION PATTERN AND REGULATION OF DAILY RHYTHMS BY LIGHTING CONDITIONS

Interplay between the endocrine and circadian systems in fishes

Navigation within host tissues: cues for orientation of Diplostomum spathaceum (Trematoda) in fish towards veins, head and eye

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