Diurnal expressions of four subtypes of melatonin receptor genes in the optic tectum and retina of goldfish

Ikegami, Taro; Azuma, Kyoichi; Nakamura, Masahisa; Suzuki, Nobuo; Hattori, Atsuhiko; Ando, Hironori

doi:10.1016/j.cbpa.2008.09.030

Cited by 37 publications

(48 citation statements)

References 37 publications

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“…These receptors are widely distributed in the fish central nervous system and peripheral tissues (Park et al 2006, Ikegami et al 2008, Sauzet et al 2008, allowing the melatonin circadian message to be broadcast throughout the organism (Fig. 1).…”

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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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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“…In terms of their tissue distribution, all three genes were strongly expressed in the pineal gland, pituitary, optic tectum, diencephalon, cerebellum, telencephalon, and retina. The expressions of these genes in parts of the visual system, such as the retina, confirm that they play a role in visual processing (Ikegami et al 2009). Daily and circadian variations of melatonin-binding sites under LD conditions have been noted in the retina of goldfish (Iigo et al 1997) and European sea bass (Bayarri et al 2004) as well as in the whole brain of goldfish (Iigo et al 1995) and gilthead seabream Figure 5.…”

Section: Discussionmentioning

confidence: 90%

“…Melatonin is an autocrine (neural retina) and paracrine (retinal pigment epithelium) regulator of retinal functions such as cyclic biosynthesis of melatonin and circadian activity of photoreceptor cells (Sauzet et al 2008). The diurnal expression of the three genes may be important for the circadian regulation of the retinal functions (Ikegami et al 2009). Despite the low amounts of mRNAs, circadian variations were still visible under DD conditions.…”

Section: Discussionmentioning

confidence: 98%

“…MTs are distributed in the central nervous system and peripheral tissues of vertebrate species (Dubocovich 1995;Reppert et al 1996) and are believed to be expressed to mediate various physiological functions of melatonin in these tissues (Ikegami et al 2009). A variety of vertebrates reportedly express MT1 and MT2 (Reppert et al 1995b;Roca et al 1996).…”

Section: Introductionmentioning

confidence: 99%

“…In addition, Confente et al (2010) investigated the expression of three types of MT genes, comparing day-night and seasonal variations. Ikegami et al (2009) investigated the expression levels of four subtypes of MT genes in the diencephalons of puffer fish (Takifugu niphobles) with lunar-related spawning cycles. Previous studies have shown that MTs perform the important role of regulating melatonin activity according to the circadian rhythm, but knowledge of the relationship between the expression of MTs and the control of circadian rhythm is limited, i.e.…”

Section: Introductionmentioning

confidence: 99%

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Diurnal and circadian regulations by three melatonin receptors in the brain and retina of olive flounderParalichthys olivaceus: profiles following exogenous melatonin

Shin

Kim

Lee

et al. 2011

Marine and Freshwater Behaviour and Physiology

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To establish the molecular basis of circadian rhythm control by melatonin receptors (MTs), we investigated the mitochondrial ribonucleic acid (mRNA) expressions of three types of MTs in different tissues of the olive flounder (Paralichthys olivaceus). All three types of MT mRNAs were expressed in the neural tissues, while MT1 mRNA was expressed in the peripheral tissues and MT2 and MT3 mRNAs were weakly expressed or undetected in these tissues. We observed increased MT mRNA expression in the neural tissues at night under both light-dark (LD) and constant dark (DD) conditions. Although the melatonin-treated cultured pineal gland samples showed similar diurnal variations with high-MT mRNA expression levels at night compared to those of untreated cultured pineal gland samples, the expression levels were considerably higher in the melatonintreated samples. The plasma melatonin level also significantly increased at night. Under DD conditions, the expression patterns of MT mRNAs were similar to those under the LD photocycle, but the peak was lower and the circadian change patterns were less clear. These findings reinforce the hypothesis that MTs are active in processing light information, and that these genes are regulated by the circadian clock and light, thus suggesting that MTs play an important role in daily and circadian variations in the brain and retina of olive flounders.

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Melatonin receptors in the brain of the European sea bass: An in situ hybridization and autoradiographic study

Herrera-Pérez

Rendón

Besseau

et al. 2010

J of Comparative Neurology

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Melatonin is synthesized in the pineal organ and retina of vertebrates and exhibits a clear nocturnal rhythm of secretion. This hormone influences a number of important physiological processes acting through specific transmembrane G-protein-coupled receptors. Recently, we have cloned three different melatonin receptors in sea bass belonging to the MT1, MT2, and Mel1c subtypes. In this paper, we have analyzed the central expression of the MT1 gene by in situ hybridization and compared its distribution with the localization of 2-[(125)I]-iodomelatonin binding sites. In situ hybridization and autoradiographic studies provided consistent results. Melatonin receptors were mainly expressed in visually related areas of the sea bass brain, such as the pretectal area, glomerular complex, optic tectum, torus longitudinalis, and thalamus. A conspicuous expression was also detected in neuroendocrine regions including the ventral telencephalon, preoptic area, and hypothalamus. Furthermore, melatonin receptors were evident in the ganglionic cell layer of the cerebellum. The presence of iodomelatonin binding and/or MT1 mRNA-expressing cells was also observed in the hindbrain, in particular in the oculomotor and trigeminal nuclei and in the reticular formation. Our results suggest an important role of MT1 in the mediation of melatonin actions in visual/light integration, mechanoreception, somatosensation, eye-body motor coordination, and integrative and neuroendocrine functions. Remarkable differences in the number and distribution of brain nuclei expressing MT1 mRNAs in sea bass and trout, the only fish species analyzed to date, represent another piece of evidence for differences in the organization of the visual and circadian systems observed between salmoniform and perciform teleosts.

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Diurnal expressions of four subtypes of melatonin receptor genes in the optic tectum and retina of goldfish

Cited by 37 publications

References 37 publications

Interplay between the endocrine and circadian systems in fishes

Interplay between the endocrine and circadian systems in fishes

Diurnal and circadian regulations by three melatonin receptors in the brain and retina of olive flounderParalichthys olivaceus: profiles following exogenous melatonin

Melatonin receptors in the brain of the European sea bass: An in situ hybridization and autoradiographic study

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