Rhythmic Melatonin Biosynthesis in a Photoreceptive Pineal Organ: A Study in the Pike

Falcón, Jacky; Guerlotté, Jérôme; Voisin, Pierre; Collin, Jean-Pierre H.

doi:10.1159/000124778

Cited by 76 publications

(39 citation statements)

References 27 publications

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“…In most species investigated, Aanat2 gene expression is controlled by intrapineal circadian clocks (Appelbaum and Gothilf, 2006;Coon et al, 1999;Gothilf et al, 1999), while light and temperature modulate AANAT2 protein amount and activity (Falcón et al, 2001;Falcón et al, 1987;Falcón et al, 1989). The result of these interactions shapes the pineal melatonin oscillations: photoperiod dictates the duration of the nocturnal surge, while temperature controls its amplitude (Falcón, 1999).…”

Section: Introductionmentioning

confidence: 99%

Unique arylalkylamine N-acetyltransferase-2 polymorphism in Salmonids and profound variations in thermal stability and catalytic efficiency conferred by two residues

Cazaméa-Catalan

Magnanou

Helland

et al. 2013

Journal of Experimental Biology

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SUMMARYMelatonin contributes to synchronizing major biological and behavioral functions with cyclic changes in the environment. Arylalkylamine N-acetyltransferase (AANAT) is responsible for a daily rhythm in melatonin secretion. Teleost possess two enzyme forms, AANAT1 and AANAT2, preferentially expressed in the retina and the pineal gland, respectively. The concomitant action of light and temperature shapes the daily and seasonal changes in melatonin secretion: the former controls duration while the latter modulates amplitude. Investigating the respective roles of light and temperature is particularly relevant in the context of global warming, which is likely to affect the way fish decode and anticipate seasonal changes, with dramatic consequences on their physiology and behavior. Here we investigated the impact of temperature on pineal melatonin secretion of a migratory species, the Arctic charr (Salvelinus alpinus), the northernmost living and cold-adapted salmonid. We show that temperature directly impacts melatonin production in cultured pineal glands. We also show that one organ expresses two AANAT2 transcripts displaying high similarity between them and with trout Oncorhynchus mykiss AANAT2, differing by only two amino acid sites. We compared the kinetics and 3D models of these enzymes as well as of a chimeric construct, particularly with regard to their response to temperature. Our study brings interesting and new information on the evolutionary diversity of AANAT enzymes in teleosts and the role played by specific residues in the catalytic properties of the enzymes.

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Section: Introductionmentioning

confidence: 99%

Unique arylalkylamine N-acetyltransferase-2 polymorphism in Salmonids and profound variations in thermal stability and catalytic efficiency conferred by two residues

Cazaméa-Catalan

Magnanou

Helland

et al. 2013

Journal of Experimental Biology

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“…In freshwater fish, in vivo, melatonin levels in the blood follow a 24h rhythm (Gem et al 1978;Falc6n et al 1987;Kezuka et al 1992;Zachmann et al 1992b). Although the hormone also can be produced by the retina, there is indication that the pineal is the major source of plasma melatonin levels (Falc6n and Collin 1991;Kezuka et al 1992;Zachmann et al 1992b).…”

Section: Introductionmentioning

confidence: 99%

Production of melatonin by the gilthead sea bream pineal: anin vivo andin vitro study

Molina‐Borja

Falcón

Ravault

1996

Fish Physiol Biochem

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This study deals with the variations of plasma melatonin content and ofin vitro pineal melatonin secretion, in one year-old male sea bream. Plasma melatonin levels varied from almost undetectable levels during the day to 150-200 pg ml(-1) during the night, in animals maintained under a light/dark (12L/12D) cycle. The duration of the nocturnal surge corresponded to the duration of the night. A similar pattern of melatonin secretion was obtainedin vitro, with pineals cultured under a 24h L/D cycle. When the photoperiod cycle was advanced by 8h, the first nocturnal peak in melatonin secretion was more acute compared to the profile described above, but the rhythmic variations were immediately synchronized to the new L/D conditions. Under constant darkness (D/D), circadian variations in melatonin release were observed for no more than two 24h cycles. No melatonin was detected in the culture media from retinas cultured under L/D or under D/D. These results strongly suggest that the pineal is the major source of plasma melatonin in the gilthead sea bream, and that the 24h photoperiod cycle is a powerful synchronizer of the rhythmic production of melatonin by this organ.

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“…Most investigations in vertebrates show that the endocrine role of the pineal organ is mediated through melatonin, the secretion of which is influenced by changes in external photoperiod (Reiter 1982;Ralph 1983). The teleost pineal organ secretes melatonin with a nocturnal surge (Gern et al 1978;Falcon et al 1987). The administration of melatonin is reported to have varied effects on gonadal activity depending on season, photoperiod, temperature, and the dose administered (see de Vlaming and Olcese 1981;Joy and Khan 1991).…”

Section: Introductionmentioning

confidence: 99%

Effects of melatonin, p-chlorophenylalanine, and ?-methylparatyrosine on plasma gonadotropin level and ovarian activity in the catfish, Heteropneustes fossilis: A study correlating changes in hypothalamic monoamines

Senthilkumaran

Joy

1995

Fish Physiol Biochem

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The effects of (ip, 10 injections over 20 days) of melatonin (75 μg 100 g(-1) BW), the serotonin (5-HT)-synthesis blocker, para-cholorophenylalanine (p-CPA, 10 mg 100g(-1 BW)) and the catecholamine-synthesis blocker, α-methylparatyrosine (α-MPT, 10 mg 100 g(-1) BW) on gonadotropin (GTH) secretion and ovarian activity were studied in (Heteropneustes fossilis) during late preparatory to early prespawning (April-May). The treatments resulted in significant reductions of plasma GTH and estradiol-17β levels, the gonadosomatic index, frequency distribution of vitellogenic and postvitellogenic oocytes, and ovarian and serum (32)p-labelled alkali-labile phosphoprotein (a marker of vitellogenic activity). Most of the oocytes were nonvitellogenic or had undergone atretic changes. The hepatic (32)-phosphoprotein content increased significantly over the saline control value. The effects were similar and pronounced in the p-CPA and melatonin-treated groups but were moderate in the α-MPT-treated group. Hypothalamic 5-HT content and turnover were significantly inhibited in the p-CPA and melatonin-treated groups but the content and turnover of catecholamines were not. The α-MPT treatment decreased significantly the content and turnover of dopamine (DA), noradrenaline (NA), and adrenaline (A) but did not influence the 5-HT content or turnover. These results suggest that 5-HT, NA and A are stimulatory to GTH secretion and that melatonin may act on the serotonergic system to inhibit the pituitary-gonadal axis.

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Rhythmic Melatonin Biosynthesis in a Photoreceptive Pineal Organ: A Study in the Pike

Cited by 76 publications

References 27 publications

Unique arylalkylamine N-acetyltransferase-2 polymorphism in Salmonids and profound variations in thermal stability and catalytic efficiency conferred by two residues

Unique arylalkylamine N-acetyltransferase-2 polymorphism in Salmonids and profound variations in thermal stability and catalytic efficiency conferred by two residues

Production of melatonin by the gilthead sea bream pineal: anin vivo andin vitro study

Effects of melatonin, p-chlorophenylalanine, and ?-methylparatyrosine on plasma gonadotropin level and ovarian activity in the catfish, Heteropneustes fossilis: A study correlating changes in hypothalamic monoamines

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