Effects of melatonin on dopamine metabolism in the hypothalamus and the pituitary of the rainbow trout,Oncorhynchus mykiss

Hernandez-Rauda, Roberto; Míguez, Jesús M.; Ruibal, C.; Aldegunde, M.

doi:10.1002/1097-010x(20001101)287:6<440::aid-jez5>3.0.co;2-s

Cited by 26 publications

(3 citation statements)

References 24 publications

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“…The melatonin dose used in the present study was in the range of those chosen in previous studies carried out in fish [9,48,49]. Our experimental design consisted in a single intraperitoneal injection of melatonin during the late-light phase of the day–night cycle, to coincide with the natural nocturnal rise of melatonin [7,32].…”

Section: Discussionmentioning

confidence: 99%

Melatonin Inhibits GnRH-1, GnRH-3 and GnRH Receptor Expression in the Brain of the European Sea Bass, Dicentrarchus labrax

Servili

Herrera-Pérez

Rendón

et al. 2013

IJMS

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Several evidences supported the existence of melatonin effects on reproductive system in fish. In order to investigate whether melatonin is involved in the modulation of GnRH systems in the European sea bass, we have injected melatonin (0.5 μg/g body mass) in male specimens. The brain mRNA transcript levels of the three GnRH forms and the five GnRH receptors present in this species were determined by real time quantitative PCR. Our findings revealed day–night variations in the brain expression of GnRH-1, GnRH-3 and several GnRH receptors (dlGnRHR-II-1c, -2a), which exhibited higher transcript levels at mid-light compared to mid-dark phase of the photocycle. Moreover, an inhibitory effect of melatonin on the nocturnal expression of GnRH-1, GnRH-3, and GnRH receptors subtypes 1c, 2a and 2b was also demonstrated. Interestingly, the inhibitory effect of melatonin affected the expression of hypophysiotrophic GnRH forms and GnRH receptors that exhibit day–night fluctuations, suggesting that exogenous melatonin reinforce physiological mechanisms already established. These interactions between melatoninergic and GnRH systems could be mediating photoperiod effects on reproductive and other rhythmic physiological events in the European sea bass.

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Section: Discussionmentioning

confidence: 99%

Melatonin Inhibits GnRH-1, GnRH-3 and GnRH Receptor Expression in the Brain of the European Sea Bass, Dicentrarchus labrax

Servili

Herrera-Pérez

Rendón

et al. 2013

IJMS

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show abstract

“…Hernández‐Rauda et al. [52] found that a single melatonin injection reduces dopaminergic metabolism in hypothalamus of the rainbow trout, but feeding behavior was not evaluated. Nevertheless, it cannot be discounted that the reduction of DOPAC clearance may also contribute to the DOPAC increase found in the present study.…”

Section: Discussionmentioning

confidence: 99%

Melatonin reduces body weight in goldfish (Carassius auratus): effects on metabolic resources and some feeding regulators

Pedro

Martínez‐Álvarez

Delgado

2008

Journal of Pineal Research

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The objective of the present study was to analyze the effects of chronic melatonin (10 microg/g body weight) on body weight and the main energetic reserves, particularly hepatic and muscle content of proteins, lipids and glycogen in goldfish. In addition, we studied plasma leptin and ghrelin, and hypothalamic content of neuropeptide Y (NPY) and monoamines after chronic melatonin treatment in order to elucidate a possible interplay between melatonin and these feeding regulators on the body weight regulation in this species. Body weight gain and specific growth rate were reduced (74% and 76%, respectively) after chronic (10 days) intraperitoneal (i.p.) treatment with melatonin. The carbohydrate and lipid metabolism was regulated by melatonin in goldfish, because this indoleamine reduced muscle glycogen stores and increased lipid mobilization. A suppressive trend, but not statistically significant, in circulating ghrelin was observed after chronic treatment with melatonin. Chronic melatonin administration significantly reduced noradrenergic metabolism and increased dihydroxiphenylacetic acid content in the hypothalamus, without significant modifications in the serotoninergic system. Thus, it could be suggested that melatonin may mediate its action on energy balance in fish, at least in part, via interactions with hypothalamic catecholaminergic system. Plasma leptin and hypothalamic NPY remained unaltered after melatonin treatment, suggesting that these feeding regulators may not be involved in the effects of melatonin on energy homeostasis in fish.

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“…The in vivo inhibition of dopamine release was registered during the spawning period in summer, but not during sexual regression in winter, suggesting that the effect of melatonin on the dopaminergic system might depend of the maturation stage. Inhibiting effects of melatonin on the dopaminergic systems were also observed in other species, including the threespot wrasse ( Halichoeres trimaculatus ), where intraperitoneal melatonin injections downregulate brain dopamine content ( 136 ), and rainbow trout ( Oncorhynchus mykiss ), where melatonin decreases the hypothalamic-pituitary dopamine turnover ( 122 ). In preovulatory female catfish ( Heteropneustes fossilis ), melatonin injections for three days inhibit tyrosine hydroxylase enzymatic activity in the hypothalamus ( 120 ).…”

Section: Brain-mediated Effects Of Melatonin On Anterior Pituitary Enmentioning

confidence: 88%

Effects of Melatonin on Anterior Pituitary Plasticity: A Comparison Between Mammals and Teleosts

et al. 2021

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Melatonin is a key hormone involved in the photoperiodic signaling pathway. In both teleosts and mammals, melatonin produced in the pineal gland at night is released into the blood and cerebrospinal fluid, providing rhythmic information to the whole organism. Melatonin acts via specific receptors, allowing the synchronization of daily and annual physiological rhythms to environmental conditions. The pituitary gland, which produces several hormones involved in a variety of physiological processes such as growth, metabolism, stress and reproduction, is an important target of melatonin. Melatonin modulates pituitary cellular activities, adjusting the synthesis and release of the different pituitary hormones to the functional demands, which changes during the day, seasons and life stages. It is, however, not always clear whether melatonin acts directly or indirectly on the pituitary. Indeed, melatonin also acts both upstream, on brain centers that control the pituitary hormone production and release, as well as downstream, on the tissues targeted by the pituitary hormones, which provide positive and negative feedback to the pituitary gland. In this review, we describe the known pathways through which melatonin modulates anterior pituitary hormonal production, distinguishing indirect effects mediated by brain centers from direct effects on the anterior pituitary. We also highlight similarities and differences between teleosts and mammals, drawing attention to knowledge gaps, and suggesting aims for future research.

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Effects of melatonin on dopamine metabolism in the hypothalamus and the pituitary of the rainbow trout,Oncorhynchus mykiss

Cited by 26 publications

References 24 publications

Melatonin Inhibits GnRH-1, GnRH-3 and GnRH Receptor Expression in the Brain of the European Sea Bass, Dicentrarchus labrax

Melatonin Inhibits GnRH-1, GnRH-3 and GnRH Receptor Expression in the Brain of the European Sea Bass, Dicentrarchus labrax

Melatonin reduces body weight in goldfish (Carassius auratus): effects on metabolic resources and some feeding regulators

Effects of Melatonin on Anterior Pituitary Plasticity: A Comparison Between Mammals and Teleosts

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