Melatonin and the Brain in Photoperiodic Mammals

Hastings, Michael H.; Herbert, J.; Martensz, N. D.; Roberts, Angela

doi:10.1002/9780470720981.ch5

Cited by 11 publications

(6 citation statements)

References 41 publications

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“…Since the 60's, it has been known that the pineal hormone melatonin is a major signal for the synchronization of reproduction with the seasons. Indeed, melatonin synthesis and release occurs only during the night and, therefore, the nocturnal production of melatonin is longer in the autumn/winter SD as compared to spring/summer LD (115). Hoffman and Reiter were the first to demonstrate that the elimination of this neuroendocrine calendar by pinealectomy abolishes the reproductive response of Syrian hamsters to the photoperiod signal (116).…”

Section: Rfrp-3 Plays a Role In Seasonal Reproductionmentioning

confidence: 99%

Functional Implications of RFRP-3 in the Central Control of Daily and Seasonal Rhythms in Reproduction

et al. 2019

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Adaptation of reproductive activity to environmental changes is essential for breeding success and offspring survival. In mammals, the reproductive system displays regular cycles of activation and inactivation which are synchronized with seasonal and/or daily rhythms in environmental factors, notably light intensity and duration. Thus, most species adapt their breeding activity along the year to ensure that birth and weaning of the offspring occur at a time when resources are optimal. Additionally, female reproductive activity is highest at the beginning of the active phase during the period of full oocyte maturation, in order to improve breeding success. In reproductive physiology, it is therefore fundamental to delineate how geophysical signals are integrated in the hypothalamo-pituitary-gonadal axis, notably by the neurons expressing gonadotropin releasing hormone (GnRH). Several neurochemicals have been reported to regulate GnRH neuronal activity, but recently two hypothalamic neuropeptides belonging to the superfamily of (Arg)(Phe)-amide peptides, RFRP-3 and kisspeptin, have emerged as critical for the integration of environmental cues within the reproductive axis. The goal of this review is to survey the current understanding of the role played by RFRP-3 in the temporal regulation of reproduction, and consider how its effect might combine with that of kisspeptin to improve the synchronization of reproduction to environmental challenges.

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Section: Rfrp-3 Plays a Role In Seasonal Reproductionmentioning

confidence: 99%

Functional Implications of RFRP-3 in the Central Control of Daily and Seasonal Rhythms in Reproduction

et al. 2019

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“…In vertebrates, melatonin also serves as the signalling molecule to transduce environmental photoperiodic information to their neuroendocrine system (13)(14)(15). Thus, the animals can synchronize their daily or seasonal physiological activities coupled to their environments.…”

Section: Introductionmentioning

confidence: 99%

Mitochondria: the birth place, battle ground and the site of melatonin metabolism in cells

2019

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It was a surprising discovery when mitochondria, as the power houses of cells, were also found to synthesize the potent mitochondrial targeted antioxidant, melatonin. The melatonin synthetic enzyme serotonin N-acetyltransferase (SNAT) was found in matrix and also in the intermembrane space of mitochondria. We hypothesize that the melatonin synthesis occurs in the matrix due to substrate (N-acetyl co-enzyme A) availability while the intermembrane space may serve as the recycling pool of SNAT to regulate the melatonin circadian rhythm. Another surprise was that the melatonin membrane receptors, including MT1 and MT2, were also present in mitochondria. The protective effects of melatonin against neuronal injury induced by brain ischemia/reperfusion were proven to be mainly mediated by mitochondrial melatonin receptors rather than the cell surface membrane receptors which is contrary to the classical principle. In addition, melatonin metabolic enzyme has also been identified in the mitochondria. This enzyme can convert melatonin to N-acetylserotonin to strengthen the antitumor effects of melatonin. Thus, mitochondria are the generator, battle ground and metabolic sites of melatonin. The biological significance of the strong association between mitochondria and melatonin should be intensively investigated.

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“…These fibers originate in the lateral hypothalamus and descend through the brainstem and the cervical cord to the intermediolateral cell column in the upper thoracic cord, then return as sympathetic nerves to the pineal body through the upper cervical ganglion and the diencephalon. 3,4 Damage to cervical tracts may decrease the normal nocturnal melatonin secretion and thereby cause sleep abnormalities. [5][6][7] Other clinical phenomena may also be related to 'biological clock' disturbances following cervical SCL.…”

Section: Introductionmentioning

confidence: 99%

The feasibility of sleep assessment by actigraph in patients with tetraplegia

2007

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Background: Sleep disturbances are frequent in patients with high spinal cord lesions, and are difficult to diagnose by means of polysomnography (PSG). Design: Retrospective cohort study. Objective: Examine the feasibility of sleep assessment by actigraph in patients with tetraplegia. Setting: A rehabilitation center in Israel. Subjects: Twenty-one patients with tetraplegia and 20 healthy persons. Interventions: Sleep assessment by actigraphs attached to the head and the wrist. Main outcome measures: The actigraphic movement index (MI), total sleep time (TST), sleep efficiency (SE), wake after sleep onset (WASO), sleep latency (SL), and number of awakenings (NOA). Results: In the control group actigraphy showed that during sleep the hand moves more than the head but that the movements were highly correlated. In patients with tetraplegia below C 5 -C 7 the hand also moved more than the head, but in patients with tetraplegia below C 4 , the head moved more (Po0.05). No significant differences were found between patients with C 5 -C 7 tetraplegia and healthy controls in the sleep indices obtained by hand movements, or between patients with C 4 tetraplegia and healthy controls in the indices obtained by head movements. Control subjects and patients showed similar subjective assessment of sleep quality. Conclusions: These preliminary findings support the validity of wrist actigraphy for sleep assessment in patients with C 5 -C 7 tetraplegia, and suggest that head-mounted actigraphy is a feasible alternative for sleep assessment in patients with tetraplegia below C 4 . To establish these findings, further investigations are required, with a larger number of patients and comparison with PSG.

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Melatonin and the Brain in Photoperiodic Mammals

Cited by 11 publications

References 41 publications

Functional Implications of RFRP-3 in the Central Control of Daily and Seasonal Rhythms in Reproduction

Functional Implications of RFRP-3 in the Central Control of Daily and Seasonal Rhythms in Reproduction

Mitochondria: the birth place, battle ground and the site of melatonin metabolism in cells

The feasibility of sleep assessment by actigraph in patients with tetraplegia

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