Melanopsin System Dysfunction in Smith-Magenis Syndrome Patients

Barboni, Mirella Telles Salgueiro; Bueno, Clarissa; Nagy, Balázs Vince; Maia, Patrícia Lobo; Vidal, Kallene Summer Moreira; Alves, Rosana Cardoso; Reíter, Russel J.; Amaral, Fernanda Gaspar do; Cipolla‐Neto, José; Ventura, Dora Fix

doi:10.1167/iovs.17-22612

Cited by 22 publications

(9 citation statements)

References 62 publications

(105 reference statements)

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“…Patients with Smith‐Magenis Syndrome, a genetic disorder, have abnormal daily rhythms with sleep disturbances (daytime sleepiness, nocturnal awakenings, difficulty falling asleep at night), and they have high melatonin levels during the day but low levels at night. These patients apparently have a deficit in melanopsin positive ipRGC photoreception (Barboni et al., ), which reinforces the importance of ipRGCs in photoentrainment.…”

Section: Melanopsin‐expressing Intrinsically Photosensitive Retinal Gmentioning

confidence: 69%

Circadian regulation in the retina: From molecules to network

2018

Eur J of Neuroscience

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The mammalian retina is the most unique tissue among those that display robust circadian/diurnal oscillations. The retina is not only a light sensing tissue that relays light information to the brain, it has its own circadian “system” independent from any influence from other circadian oscillators. While all retinal cells and retinal pigment epithelium (RPE) possess circadian oscillators, these oscillators integrate by means of neural synapses, electrical coupling (gap junctions), and released neurochemicals (such as dopamine, melatonin, adenosine, and ATP), so the whole retina functions as an integrated circadian system. Dysregulation of retinal clocks not only causes retinal or ocular diseases, it also impacts the circadian rhythm of the whole body, as the light information transmitted from the retina entrains the brain clock that governs the body circadian rhythms. In this review, how circadian oscillations in various retinal cells are integrated, and how retinal diseases affect daily rhythms.

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Section: Melanopsin‐expressing Intrinsically Photosensitive Retinal Gmentioning

confidence: 69%

Circadian regulation in the retina: From molecules to network

2018

Eur J of Neuroscience

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“…The result is a misalignment of the organism to the circadian timing domain, causing sleep/wake, metabolic and cardiovascular disturbances, among other symptoms. This syndrome is usually associated to the Smith-Magenis disease, the phase-delayed sleep-wake disorder, and as a consequence of indoors illumination during the evening/night, among others (57,58).…”

Section: Melatonin Physiology Clinical Syndromes and Therapeuticsmentioning

confidence: 99%

A brief review about melatonin, a pineal hormone

Amaral¹,

Cipolla‐Neto²

2018

Archives of Endocrinology and Metabolism

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244

148

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Melatonin is a ubiquitous molecule in nature, being locally synthesized in several cells and tissues, besides being a hormone that is centrally produced in the pineal gland of vertebrates, particularly in mammals. Its pineal synthesis is timed by the suprachiasmatic nucleus, that is synchronized to the light-dark cycle via the retinohypothalamic tract, placing melatonin synthesis at night, provided its dark. This unique trait turns melatonin into an internal synchronizer that adequately times the organism's physiology to the daily and seasonal demands. Besides being amphiphilic, melatonin presents specific mechanisms and ways of action devoted to its role as a time-giving agent, being widely spread in the organism. The present review aims to focus on melatonin as a pineal hormone with specific mechanisms and ways of action, besides presenting the clinical syndromes related to its synthesis and/or function disruptions.

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“…PIPR measurements have been made in numerous clinical conditions, including multiple sclerosis, Parkinson's disease, idiopathic intracranial hypertension, traumatic brain injury, glaucoma, diabetes, retinitis pigmentosa, Leber's hereditary optic neuropathy, Smith-Magenis syndrome, and depression. 21 – 32 …”

mentioning

confidence: 99%

Pulses of Melanopsin-Directed Contrast Produce Highly Reproducible Pupil Responses That Are Insensitive to a Change in Background Radiance

McAdams

Igdalova

Spitschan

et al. 2018

Invest. Ophthalmol. Vis. Sci.

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PurposeTo measure the pupil response to pulses of melanopsin-directed contrast, and compare this response to those evoked by cone-directed contrast and spectrally narrowband stimuli.MethodsThree-second unipolar pulses were used to elicit pupil responses in human subjects across three sessions. Thirty subjects were studied in session 1, and most returned for sessions 2 and 3. The stimuli of primary interest were “silent substitution” cone- and melanopsin-directed modulations. Red and blue narrowband pulses delivered using the post-illumination pupil response (PIPR) paradigm were also studied. Sessions 1 and 2 were identical, whereas session 3 involved modulations around higher radiance backgrounds. The pupil responses were fit by a model whose parameters described response amplitude and temporal shape.ResultsGroup average pupil responses for all stimuli overlapped extensively across sessions 1 and 2, indicating high reproducibility. Model fits indicate that the response to melanopsin-directed contrast is prolonged relative to that elicited by cone-directed contrast. The group average cone- and melanopsin-directed pupil responses from session 3 were highly similar to those from sessions 1 and 2, suggesting that these responses are insensitive to background radiance over the range studied. The increase in radiance enhanced persistent pupil constriction to blue light.ConclusionsThe group average pupil response to stimuli designed through silent substitution provides a reliable probe of the function of a melanopsin-mediated system in humans. As disruption of the melanopsin system may relate to clinical pathology, the reproducibility of response suggests that silent substitution pupillometry can test if melanopsin signals differ between clinical groups.

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Melanopsin System Dysfunction in Smith-Magenis Syndrome Patients

Cited by 22 publications

References 62 publications

Circadian regulation in the retina: From molecules to network

Circadian regulation in the retina: From molecules to network

A brief review about melatonin, a pineal hormone

Pulses of Melanopsin-Directed Contrast Produce Highly Reproducible Pupil Responses That Are Insensitive to a Change in Background Radiance

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