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Co-expression of two subtypes of melatonin receptor on rat M1-type intrinsically photosensitive retinal ganglion cells.

Sheng WL, Chen WY, Yang XL, Zhong YM, Weng SJ - PLoS ONE (2015)

Bottom Line: Immunoreactivity for both MT1 and MT2 receptors was clearly seen in the cytoplasm of all labeled ipRGCs, indicating that these two receptors were co-expressed in each of these neurons.Furthermore, labeling for both the receptors were found in neonatal M1 cells as early as the day of birth.It is therefore highly plausible that retinal melatonin may directly modulate the activity of ipRGCs, thus regulating non-image forming visual functions.

View Article: PubMed Central - PubMed

Affiliation: Institute of Neurobiology, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China.

ABSTRACT
Intrinsically photosensitive retinal ganglion cells (ipRGCs) are involved in circadian and other non-image forming visual responses. An open question is whether the activity of these neurons may also be under the regulation mediated by the neurohormone melatonin. In the present work, by double-staining immunohistochemical technique, we studied the expression of MT1 and MT2, two known subtypes of mammalian melatonin receptors, in rat ipRGCs. A single subset of retinal ganglion cells labeled by the specific antibody against melanopsin exhibited the morphology typical of M1-type ipRGCs. Immunoreactivity for both MT1 and MT2 receptors was clearly seen in the cytoplasm of all labeled ipRGCs, indicating that these two receptors were co-expressed in each of these neurons. Furthermore, labeling for both the receptors were found in neonatal M1 cells as early as the day of birth. It is therefore highly plausible that retinal melatonin may directly modulate the activity of ipRGCs, thus regulating non-image forming visual functions.

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Neonatal expression of melatonin receptors on rat ipRGCs.(A1-A3) Confocal fluorescence microphotographs of a rat retinal section harvested at P0, showing that MT1 receptor is immunohistochemically localized to the cytoplasm of a melanopsin-positive cell (arrow head). (B1-B3) Confocal fluorescence microphotographs of P0 rat retina, double labeled by melanopsin and MT2. MT2 immunoreactivity was detected in the cytoplasm of a melanopsin-expressing cell (arrow head). Scale bar = 20 μm.
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pone.0117967.g004: Neonatal expression of melatonin receptors on rat ipRGCs.(A1-A3) Confocal fluorescence microphotographs of a rat retinal section harvested at P0, showing that MT1 receptor is immunohistochemically localized to the cytoplasm of a melanopsin-positive cell (arrow head). (B1-B3) Confocal fluorescence microphotographs of P0 rat retina, double labeled by melanopsin and MT2. MT2 immunoreactivity was detected in the cytoplasm of a melanopsin-expressing cell (arrow head). Scale bar = 20 μm.

Mentions: ipRGCs are likely the first functional photosensitive neurons in the retina, sensing light immediately after the birth [48,49]. There is convergent evidence that ipRGCs mediate a number of light-driven developmental functions during the early postnatal stage (see Discussion). It is plausible that these functions may be subject to melatonin-mediated modulation even in neonatal animals. To explore this possibility, we performed double-labeling analysis on retinal sections harvested from P0 rats. In these rats the melanopsin antibody stained a small set of cells with their somata located in the GCL (Fig. 4A1 and B1). Double-labeling analysis revealed that these melanopsin-positive neonatal ipRGCs were invariably double-labeled by MT1 (Fig. 4A2, A3) or MT2 (Fig. 4B2, B3), even though most of them were not yet showing dendritic stratifying feature typical of M1 cells. Quantitative analysis was also made for the expression of these two receptors on neonatal M1 cells (30 sections, 127 cells for MT1; 30 sections, 69 cells for MT2). It is likely that MT1 and MT2 receptors are co-expressed in ipRGCs in neonatal animals, as early as the day of birth.


Co-expression of two subtypes of melatonin receptor on rat M1-type intrinsically photosensitive retinal ganglion cells.

Sheng WL, Chen WY, Yang XL, Zhong YM, Weng SJ - PLoS ONE (2015)

Neonatal expression of melatonin receptors on rat ipRGCs.(A1-A3) Confocal fluorescence microphotographs of a rat retinal section harvested at P0, showing that MT1 receptor is immunohistochemically localized to the cytoplasm of a melanopsin-positive cell (arrow head). (B1-B3) Confocal fluorescence microphotographs of P0 rat retina, double labeled by melanopsin and MT2. MT2 immunoreactivity was detected in the cytoplasm of a melanopsin-expressing cell (arrow head). Scale bar = 20 μm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4340921&req=5

pone.0117967.g004: Neonatal expression of melatonin receptors on rat ipRGCs.(A1-A3) Confocal fluorescence microphotographs of a rat retinal section harvested at P0, showing that MT1 receptor is immunohistochemically localized to the cytoplasm of a melanopsin-positive cell (arrow head). (B1-B3) Confocal fluorescence microphotographs of P0 rat retina, double labeled by melanopsin and MT2. MT2 immunoreactivity was detected in the cytoplasm of a melanopsin-expressing cell (arrow head). Scale bar = 20 μm.
Mentions: ipRGCs are likely the first functional photosensitive neurons in the retina, sensing light immediately after the birth [48,49]. There is convergent evidence that ipRGCs mediate a number of light-driven developmental functions during the early postnatal stage (see Discussion). It is plausible that these functions may be subject to melatonin-mediated modulation even in neonatal animals. To explore this possibility, we performed double-labeling analysis on retinal sections harvested from P0 rats. In these rats the melanopsin antibody stained a small set of cells with their somata located in the GCL (Fig. 4A1 and B1). Double-labeling analysis revealed that these melanopsin-positive neonatal ipRGCs were invariably double-labeled by MT1 (Fig. 4A2, A3) or MT2 (Fig. 4B2, B3), even though most of them were not yet showing dendritic stratifying feature typical of M1 cells. Quantitative analysis was also made for the expression of these two receptors on neonatal M1 cells (30 sections, 127 cells for MT1; 30 sections, 69 cells for MT2). It is likely that MT1 and MT2 receptors are co-expressed in ipRGCs in neonatal animals, as early as the day of birth.

Bottom Line: Immunoreactivity for both MT1 and MT2 receptors was clearly seen in the cytoplasm of all labeled ipRGCs, indicating that these two receptors were co-expressed in each of these neurons.Furthermore, labeling for both the receptors were found in neonatal M1 cells as early as the day of birth.It is therefore highly plausible that retinal melatonin may directly modulate the activity of ipRGCs, thus regulating non-image forming visual functions.

View Article: PubMed Central - PubMed

Affiliation: Institute of Neurobiology, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, China.

ABSTRACT
Intrinsically photosensitive retinal ganglion cells (ipRGCs) are involved in circadian and other non-image forming visual responses. An open question is whether the activity of these neurons may also be under the regulation mediated by the neurohormone melatonin. In the present work, by double-staining immunohistochemical technique, we studied the expression of MT1 and MT2, two known subtypes of mammalian melatonin receptors, in rat ipRGCs. A single subset of retinal ganglion cells labeled by the specific antibody against melanopsin exhibited the morphology typical of M1-type ipRGCs. Immunoreactivity for both MT1 and MT2 receptors was clearly seen in the cytoplasm of all labeled ipRGCs, indicating that these two receptors were co-expressed in each of these neurons. Furthermore, labeling for both the receptors were found in neonatal M1 cells as early as the day of birth. It is therefore highly plausible that retinal melatonin may directly modulate the activity of ipRGCs, thus regulating non-image forming visual functions.

Show MeSH
Related in: MedlinePlus