Search results for "Melanopsin"
showing 6 items of 6 documents
Characterization of a new murine retinal cell line (MU-PH1) with glial, progenitor and photoreceptor characteristics
2013
Unlike fish and amphibians, mammals do not regenerate retinal neurons throughout life. However, neurogenic potential may be conserved in adult mammal retina and it is necessary to identify the factors that regulate retinal progenitor cells (RPC) proliferative capacity to scope their therapeutic potential. Müller cells can be progenitors for retinal neuronal cells and can play an essential role in the restoration of visual function after retinal injury. Some members of the Toll-like receptor (TLR) family, TLR2, TLR3 and TLR4, are related to progenitor cells proliferation. Müller cells are important in retinal regeneration and stable cell lines are useful for the study of retinal stem cell bi…
Rev-Erb modulates retinal visual processing and behavioral responses to light
2016
International audience; The circadian clock is thought to adjust retinal sensitivity to ambient light levels, yet the involvement of specific clock genes is poorly understood. We explored the potential role of the nuclear receptor subfamily 1, group D, member 1 (REV-ERB; or NR1D1) in this respect. In light-evoked behavioral tests, compared with wild-type littermates, Rev-Erb(-/-) mice showed enhanced negative masking at low light levels (0.1 lx). Rev-Erb(-/-) mouse retinas displayed significantly higher numbers of intrinsically photosensitive retinal ganglion cells (ipRGCs; 62% more compared with wild-type) and more intense melanopsin immunostaining of individual ipRGCs. In agreement with a…
Circadian gene expression patterns of melanopsin and pinopsin in the chick pineal gland
2004
The directly light-sensitive chick pineal gland contains at least two photopigments. Pinopsin seems to mediate the acute inhibitory effect of light on melatonin synthesis, whereas melanopsin may act by phase-shifting the intrapineal circadian clock. In the present study we have investigated, by means of quantitative RT-PCR, the daily rhythm of photopigment gene expression as monitored by mRNA levels. Under a 12-h light/12-h dark cycle, the mRNA levels of both pigments were 5-fold higher in the transitional phase from light to dark than at night, both in vivo and in vitro. Under constant darkness in vivo and in vitro, the peak of pinopsin mRNA levels was attenuated, whereas that of melanopsi…
Chronoendokinologia — Quo vadis?
2002
The present review deals with important new chronobiological results especially in the field of chronoendocrinology, shedding new light on the circadian organisation of mammals including man. In vitro studies have shown that the concept of the existence of a single circadian oscillator located in the suprachiasmatic nucleus has to be extended. Circadian oscillators have also been found to exist in the retina, islets of Langerhans, liver, lung, and fibroblasts. Another major result is the detection of a new photopigment, melanopsin, present in a subpopulation of retinal ganglion cells which are lightsensitive and project to the suprachiasmatic nucleus, acting as zeitgeber for the photic entr…
Indoor artificial lighting: Prediction of the circadian effects of different spectral power distributions.
2014
The study presented in this paper aims to evaluate if and how the environment affects the circadian impact of a light source by predicting circadian stimulus (CS) resulting from the exposure to different light scenes, using equations reported in studies by Rea et al. The main findings are: (1) Above 600 lx at eye level the increase of CS is little; (2) Between 50 lx and 200 lx at the eye level an increase of only 50 lx determines a significant increase of CS; (3) Light sources with correlated colour temperatures between 2900 K and 4200 K have similar impacts on the circadian system according to the calculation method used; (4) Even an almost neutral environment affects the circadian impact…
Daily Profile in Melanopsin Transcripts Depends on Seasonal Lighting Conditions in the Rat Retina
2007
The retinal photopigment melanopsin (Opn4) mediates photoentrainment of the circadian system. In the present study, seasonal regulation of the melanopsin gene was investigated in comparison with the arylalkylamine N-acetyltransferase (AA-NAT) gene as an indicator of retinal pacemaker output. For this purpose, the daily profiles in the amount of melanopsin mRNA and AA-NAT mRNA were monitored under 8 : 16 h light/dark, 12 : 12 h light/dark and 16 : 8 h light/dark photoperiods using real-time polymerase chain reaction analysis. We found that, under all of the lighting regimes, melanopsin and AA-NAT expression oscillated with a peak around dark onset and the middle of the dark phase, respective…