The preoptic nucleus: the probable location of the circadian pacemaker of the hagfish, Eptatretus burgeri

Ooka-Souda, Sadako; Kadota, Tetsuo; Kabasawa, Hiroshi

doi:10.1016/0304-3940(93)90850-k

Cited by 16 publications

(7 citation statements)

References 9 publications

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“…Uniquely among non-mammalian vertebrates, hagfish use only their eyes as circadian photoreceptors (20). They apparently have no pineal gland and the evidence, although still incomplete, suggests strongly that the circadian pacemaker that controls their surprisingly robust locomotor rhythm is located in the preoptic nucleus of the anterior hypothalamus (31). This pattern of circadian organization closely parallels that which we find in mammals and which we have attributed to their early forced nocturnality.…”

supporting

confidence: 66%

Evolution of circadian organization in vertebrates

Menaker¹,

Moreira²,

Tosini³

1997

Braz J Med Biol Res

145

104

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Circadian organization means the way in which the entire circadian system above the cellular level is put together physically and the principles and rules that determine the interactions among its component parts which produce overt rhythms of physiology and behavior. Understanding this organization and its evolution is of practical importance as well as of basic interest. The first major problem that we face is the difficulty of making sense of the apparently great diversity that we observe in circadian organization of diverse vertebrates. Some of this diversity falls neatly into place along phylogenetic lines leading to firm generalizations: i) in all vertebrates there is a "circadian axis" consisting of the retinas, the pineal gland and the suprachiasmatic nucleus (SCN), ii) in many non-mammalian vertebrates of all classes (but not in any mammals) the pineal gland is both a photoreceptor and a circadian oscillator, and iii) in all non-mammalian vertebrates (but not in any mammals) there are extraretinal (and extrapineal) circadian photoreceptors. An interesting explanation of some of these facts, especially the differences between mammals and other vertebrates, can be constructed on the assumption that early in their evolution mammals passed through a "nocturnal bottleneck". On the other hand, a good deal of the diversity among the circadian systems of vertebrates does not fall neatly into place along phylogenetic lines. In the present review we will consider how we might better understand such "phylogenetically incoherent" diversity and what sorts of new information may help to further our understanding of the evolution of circadian organization in vertebrates. Key wordsOrganisms, from unicellulars to vertebrates, are structured in time as well as in space. Many, if not most, biochemical, physiological and behavioral parameters exhibited by organisms show daily fluctuations and most of these daily rhythms persist in constant conditions, thus demonstrating that they are driven by endogenous oscillators. The rhythms that persist in constant conditions with periods close to 24 h are called circadian rhythms.By circadian organization we mean the way in which the entire circadian system above the cellular level is put together physically, and the principles and rules that determine the interactions among its component parts. Circadian organization extends both broadly and deeply into the physiology and

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supporting

confidence: 66%

Evolution of circadian organization in vertebrates

Menaker¹,

Moreira²,

Tosini³

1997

Braz J Med Biol Res

145

104

View full text Add to dashboard Cite

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“…The structure of pinealocytes in snakes resembles those of mammals, lacking photosensory anatomical features [ 328 , 329 ]. Hagfish ( Eptatretus burgeri ) appear to lack a pineal complex [ 330 , 331 ]. A pineal complex has not been identified in crocodile, and circulating melatonin rhythms are absent in free-living crocodiles ( Crocodylus johnstoni ) but are present in captive populations exposed to natural light and temperature cycles [ 332 ], suggesting an extra-pineal source of circadian melatonin in this species.…”

Section: Melatonin Signalling In Reproductionmentioning

confidence: 99%

Seasonal Reproduction in Vertebrates: Melatonin Synthesis, Binding, and Functionality Using Tinbergen’s Four Questions

viviD

Bentley

2018

Molecules

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One of the many functions of melatonin in vertebrates is seasonal reproductive timing. Longer nights in winter correspond to an extended duration of melatonin secretion. The purpose of this review is to discuss melatonin synthesis, receptor subtypes, and function in the context of seasonality across vertebrates. We conclude with Tinbergen’s Four Questions to create a comparative framework for future melatonin research in the context of seasonal reproduction.

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“…The PG is present in almost all vertebrates, with a few exceptions, e.g., an agnathan, Eptatretus burgeri (Myxinidae), whereas other agnathans possess this organ [145]. In Eptatretus, a diencephalic structure seems to represent a pineal homolog.…”

Section: Revisiting the Pineal Glandmentioning

confidence: 99%

Thymus-Pineal Gland Axis: Revisiting Its Role in Human Life and Ageing

Rezzani

Franco

Hardeland

et al. 2020

IJMS

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For years the thymus gland (TG) and the pineal gland (PG) have been subject of increasingly in-depth studies, but only recently a link that can associate the activities of the two organs has been identified. Considering, on the one hand, the well-known immune activity of thymus and, on the other, the increasingly emerging immunological roles of circadian oscillators and the rhythmically secreted main pineal product, melatonin, many studies aimed to analyse the possible existence of an interaction between these two systems. Moreover, data confirmed that the immune system is functionally associated with the nervous and endocrine systems determining an integrated dynamic network. In addition, recent researches showed a similar, characteristic involution process both in TG and PG. Since the second half of the 20th century, evidence led to the definition of an effectively interacting thymus-pineal axis (TG-PG axis), but much has to be done. In this sense, the aim of this review is to summarize what is actually known about this topic, focusing on the impact of the TG-PG axis on human life and ageing. We would like to give more emphasis to the implications of this dynamical interaction in a possible therapeutic strategy for human health. Moreover, we focused on all the products of TG and PG in order to collect what is known about the role of peptides other than melatonin. The results available today are often unclear and not linear. These peptides have not been well studied and defined over the years. In this review we hope to awake the interest of the scientific community in them and in their future pharmacological applications.

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The preoptic nucleus: the probable location of the circadian pacemaker of the hagfish, Eptatretus burgeri

Cited by 16 publications

References 9 publications

Evolution of circadian organization in vertebrates

Evolution of circadian organization in vertebrates

Seasonal Reproduction in Vertebrates: Melatonin Synthesis, Binding, and Functionality Using Tinbergen’s Four Questions

Thymus-Pineal Gland Axis: Revisiting Its Role in Human Life and Ageing

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