MT1 Melatonin Receptor mRNA Expressing Cells in the Pars Tuberalis of the European Hamster: Effect of Photoperiod

Dardente, Hugues; Klosen, Paul; Pévet, Paul; Masson‐Pévet, Mireille

doi:10.1046/j.1365-2826.2003.01060.x

Cited by 97 publications

(96 citation statements)

References 57 publications

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“…Melatonin receptors are highly expressed in the PT (Dardente et al 2003), which is consistent with the notion that melatonin mediates photoperiodic information. LD stimuli induce DIO2 expression in ependymal cells in hamsters (Watanabe et al 2004).…”

Section: Regulatory Mechanism For Mammalian Seasonal Reproductionsupporting

confidence: 85%

Molecular basis for regulating seasonal reproduction in vertebrates

Nishiwaki‐Ohkawa

Yoshimura

2016

Journal of Endocrinology

109

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Animals that inhabit mid- to high-latitude regions exhibit various adaptive behaviors, such as migration, reproduction, molting and hibernation in response to seasonal cues. These adaptive behaviors are tightly regulated by seasonal changes in photoperiod, the relative day length vs night length. Recently, the regulatory pathway of seasonal reproduction has been elucidated using quail. In birds, deep brain photoreceptors receive and transmit light information to the pars tuberalis in the pituitary gland, which induces the secretion of thyroid-stimulating hormone. Thyroid-stimulating hormone locally activates thyroid hormone via induction of type 2 deiodinase in the mediobasal hypothalamus. Thyroid hormone then induces morphological changes in the terminals of neurons that express gonadotropin-releasing hormone and facilitates gonadotropin secretion from the pituitary gland. In mammals, light information is received by photoreceptors in the retina and neurally transmitted to the pineal gland, where it inhibits the synthesis and secretion of melatonin, which is crucial for seasonal reproduction. Importantly, the signaling pathway downstream of light detection and signaling is fully conserved between mammals and birds. In fish, the regulatory components of seasonal reproduction are integrated, from light detection to neuroendocrine output, in a fish-specific organ called the saccus vasculosus. Various physiological processes in humans are also influenced by seasonal environmental changes. The findings discussed herein may provide clues to addressing human diseases, such as seasonal affective disorder.

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Section: Regulatory Mechanism For Mammalian Seasonal Reproductionsupporting

confidence: 85%

Molecular basis for regulating seasonal reproduction in vertebrates

Nishiwaki‐Ohkawa

Yoshimura

2016

Journal of Endocrinology

109

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“…Annual variation in melatonin signal duration has been shown to be a critical input signal for the annual timing mechanism [81,82] that involves the pituitary and its pars tuburalis (PT), which is densely packed with melatonin receptors [83][84][85][86][87][88][89]. Pineal melatonin release is driven by the SCN via the paraventricular nucleus (PVN), superior cervical ganglion (SCG) and intermediolateral column of the spinal cord (IML) pathway [58,69].…”

Section: Adjustment To Changing Day Length As a Selection Force For Tmentioning

confidence: 99%

Evolution of time-keeping mechanisms: early emergence and adaptation to photoperiod

Hut

Beersma

2011

Phil. Trans. R. Soc. B

183

193

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Virtually all species have developed cellular oscillations and mechanisms that synchronize these cellular oscillations to environmental cycles. Such environmental cycles in biotic (e.g. food availability and predation risk) or abiotic (e.g. temperature and light) factors may occur on a daily, annual or tidal time scale. Internal timing mechanisms may facilitate behavioural or physiological adaptation to such changes in environmental conditions. These timing mechanisms commonly involve an internal molecular oscillator (a 'clock') that is synchronized ('entrained') to the environmental cycle by receptor mechanisms responding to relevant environmental signals ('Zeitgeber', i.e. German for time-giver). To understand the evolution of such timing mechanisms, we have to understand the mechanisms leading to selective advantage. Although major advances have been made in our understanding of the physiological and molecular mechanisms driving internal cycles (proximate questions), studies identifying mechanisms of natural selection on clock systems (ultimate questions) are rather limited. Here, we discuss the selective advantage of a circadian system and how its adaptation to day length variation may have a functional role in optimizing seasonal timing. We discuss various cases where selective advantages of circadian timing mechanisms have been shown and cases where temporarily loss of circadian timing may cause selective advantage. We suggest an explanation for why a circadian timing system has emerged in primitive life forms like cyanobacteria and we evaluate a possible molecular mechanism that enabled these bacteria to adapt to seasonal variation in day length. We further discuss how the role of the circadian system in photoperiodic time measurement may explain differential selection pressures on circadian period when species are exposed to changing climatic conditions (e.g. global warming) or when they expand their geographical range to different latitudes or altitudes.

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“…There are two major subtypes of mammalian melatonin receptor, termed MT 1 and MT 2 (previously Mel 1a and Mel 1b ; reviewed in Reppert et al (1996)), of which MT 1 is the dominant pituitary subtype (Weaver et al 1996, von Gall et al 2002. Despite transient expression of MT 1 receptors in neonatal pituitary gonadotrophs (Johnston et al 2003b), co-localisation studies have shown that MT 1 is only expressed in the PT-specific thyrotroph cells in adult rodents (Klosen et al 2002, Dardente et al 2003.…”

Section: The Pars Tuberalis (Pt) and Tuberalinmentioning

confidence: 99%

Photoperiodic regulation of prolactin secretion: changes in intra-pituitary signalling and lactotroph heterogeneity

Johnston

2004

Journal of Endocrinology

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Many mammalian species utilise day-length (photoperiod) to adapt their physiology to seasonal changes in environmental conditions, via secretion of pineal melatonin. Photoperiodic regulation of prolactin secretion is believed to occur via melatonin-mediated changes in the secretion of a putative prolactin secretagogue, tuberalin, from the pituitary pars tuberalis. Despite the in vivo and in vitro evidence in support of this intra-pituitary signalling mechanism, the identity of tuberalin has yet to be elucidated. This paper reviews recent advances in the characterisation of tuberalin and the regulation of its secretion. Furthermore, the hypothesis that pituitary lactotroph cells display heterogeneity in their response to changing photoperiod and tuberalin secretion is examined.

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MT1 Melatonin Receptor mRNA Expressing Cells in the Pars Tuberalis of the European Hamster: Effect of Photoperiod

Cited by 97 publications

References 57 publications

Molecular basis for regulating seasonal reproduction in vertebrates

Molecular basis for regulating seasonal reproduction in vertebrates

Evolution of time-keeping mechanisms: early emergence and adaptation to photoperiod

Photoperiodic regulation of prolactin secretion: changes in intra-pituitary signalling and lactotroph heterogeneity

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