N-acetyltransferase activity responds to environmental lighting in the eye as well as in the pineal gland

Binkley, Sue; Hryshchyshyn, Michael; Reilly, Kathleen B.

doi:10.1038/281479a0

Cited by 131 publications

(54 citation statements)

References 17 publications

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“…The crest at the end of the day is similar to that reported for HIOMT in the retina [21 ] and not inconsistent with the day-night differ ences in NAT in the retina [3]. Under conditions of LD 2:22 retinal melatonin fails to exhibit a 24-hour cycle and, in ad dition, the levels of melatonin are reduced to the levels seen at the trough of the normal cycle.…”

Section: Discussionsupporting

confidence: 63%

“…In the rat, serum melatonin appears to come mainly from the pineal since pinealectomy markedly reduces serum melatonin levels [19,22]. In the retina, both enzymes necessary for melatonin synthesis from serotonin (N-acetyltransferase, NAT; hydroxyindole-o-methyltransferase, HIOMT) have been identified [3,8,9] suggesting that melatonin is probably synthesized there [10,28]. Bubenik et al [7] reported that retinal melatonin determined immunohistochemically was not altered by pinealectomy.…”

mentioning

confidence: 99%

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24-Hour Rhythm of Hypothalamic Melatonin Immunofluorescence Correlates with Serum and Retinal Melatonin Rhythms

1982

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The 24-hour rhythm of retinal and hypothalamic melatonin immunofluorescence was determined in male albino rats and compared to the 24-hour rhythm of serum melatonin determined by radioimmunoassay. Under a 12-hour (0:00–12:00):12-hour dark cycle, the 24-hour rhythm of melatonin immunocytochemical fluorescence in the retina was bio-modal (crests at 1:00 and 10:00–13:00). In serum, melatonin has a single crest late in the dark period (18:00). In the hypothalamus melatonin immunofluorescence showed increments corresponding to the crests in retina (13:00) and serum (18:00). In a 2-hour light: 22-hour dark cycle, the retinal rhythm was suppressed, the serum rhythm unchanged, and the hypothalamic rhythm had a single crest corresponding to the crest of the serum melatonin rhythm. These data indicate that the 24-hour hypothalamic rhythm of melatonin immunofluorescence may be secondary to the serum and retinal 24-hour rhythms of melatonin.

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Section: Discussionsupporting

confidence: 63%

mentioning

confidence: 99%

24-Hour Rhythm of Hypothalamic Melatonin Immunofluorescence Correlates with Serum and Retinal Melatonin Rhythms

1982

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“…Our results strongly indicate that the input of the circadian signal to GnRH neurons shows sexually dimorphic development, and this occurs independent of the effect of gonadal hormones. In birds, three oscillator systems are known to be involved in the generation of circadian rhythms: the retina, the pineal organ and the SCN [37][38][39][40][41] . The circadian pacemaker responsible for determining appropriate ovulation timing as well as the neural circuit that mediates this circadian signalling to GnRH neurons have not yet been elucidated.…”

Section: Discussionmentioning

confidence: 99%

A genetically female brain is required for a regular reproductive cycle in chicken brain chimeras

et al. 2013

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Sexual differentiation leads to structural and behavioural differences between males and females. Here we investigate the intrinsic sex identity of the brain by constructing chicken chimeras in which the brain primordium is switched between male and female identities before gonadal development. We find that the female chimeras with male brains display delayed sexual maturation and irregular oviposition cycles, although their behaviour, plasma concentrations of sex steroids and luteinizing hormone levels are normal. The male chimeras with female brains show phenotypes similar to typical cocks. In the perinatal period, oestrogen concentrations in the genetically male brain are higher than those in the genetically female brain. Our study demonstrates that male brain cells retain male sex identity and do not differentiate into female cells to drive the normal oestrous cycle, even when situated in the female hormonal milieu. This is clear evidence for a sex-specific feature that develops independent of gonadal steroids.

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“…It mimics darkness in its effects on rod photoreceptor disc shedding (2), cone myoid length (3), movement of pigment granules in the pigment epithelium (4)(5)(6), and retinal dopamine release (7). Melatonin synthesis in the retina, as in the pineal gland, is elevated at night as a result of regulation by light and a circadian oscillator (1,(8)(9)(10)(11)(12)(13). Melatonin may therefore be a circadian signal for night in the retina.…”

mentioning

confidence: 99%

Retinal melatonin is metabolized within the eye of xenopus laevis.

Cahill

Besharse

1989

Proc. Natl. Acad. Sci. U.S.A.

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N-acetyltransferase activity responds to environmental lighting in the eye as well as in the pineal gland

Cited by 131 publications

References 17 publications

24-Hour Rhythm of Hypothalamic Melatonin Immunofluorescence Correlates with Serum and Retinal Melatonin Rhythms

24-Hour Rhythm of Hypothalamic Melatonin Immunofluorescence Correlates with Serum and Retinal Melatonin Rhythms

A genetically female brain is required for a regular reproductive cycle in chicken brain chimeras

Retinal melatonin is metabolized within the eye of xenopus laevis.

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