Foster, "Zebrafish melanopsin
: isolation, tissue localisation and phylogenetic position," Molecular Brain Research, vol.
and mechanisms of non-visual ocular photoreception.
Now we learn about the importance of melanopsin
and our circadian rhythm.
In order to determine whether all damages to ipRGCs were caused by the injection of immunotoxin, or whether theses damages were also potentially related with age, we immunohistochemically labeled ipRGCs using antibodies against melanopsin
and compared the number of ipRGCs on flat-mounted retina among 1-, 3-, and 6-month-old rd mice (n = 6 in each age group) (the detailed methodology is described below).
Unlike rods and cones, ipRGCs contain melanopsin
, a photopigment that is sensitive to light.
The cells expressing melanopsin
were able to respond to light and send visual signals to the brain, the researchers said.
"Compared to other light-sensing cells in the eye, melanopsin
cells respond as long as the light lasts, or even a few seconds longer," said Ludovic Mure, first author of the paper.
, a short-wavelength, light-sensitive G-protein-coupled receptor located in human retinal ganglion cells, is known to transduce short-wavelength light signals into neural signals.
It has been suggested that non-visual photoreception may influence developmental processes in mammals (Rao et al., 2013), and there are findings suggesting that in mammals, melanopsin
(a family of light-sensitive proteins) expressing cells are primarily located at the level of the retina, but have been able to maintain their functional connection with neuro-endocrine cells for the control of mood, as melanopsin
gene variants and polymorphisms correlate to increased risk of developing seasonal affective disorder (SAD) (Roecklein et al., 2013).
Effect of Age and Refractive Error on the Melanopsin
Mediated Post-Illumination Pupil Response (PIPR).
(Opn4) requirement for normal light-induced circadian phase shifting.
IpRGCs express the photopigment melanopsin
.  Their input synchronizes the SCN to maintain the circadian rhythm near a 24 h cycle by driving the nocturnal synthesis of the pineal hormone melatonin and feedback loops to mediate clock information to the peripheral tissues and induce circadian phase, sleep, and maintenance of pupil diameter.