The retinal clock is altered in a mouse model of diabetic retinopathy
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1
Claude Bernard University, Lyon1, France
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2
INSERM U846, France
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3
University Caddi Ayyad, Faculty of Science Semlalia, Morocco
The mammalian retina contains an endogenous pacemaker that regulates retinal physiology and adjusts daily the temporal phase of the central circadian timing system with environmental time. This entrainment process involves rods, cones and melanopsin-expressing retinal ganglion cells.
Diabetic retinopathy is a major cause of blindness and visual impairment that affects up to 90% of patients with diabetes. Although vascular damage is considered the first clinical sign of retinopathy, several studies suggest that alterations in retinal neurons and glial cells precede these vascular signs.
Based on findings that retinal ganglion cells and photoreceptors may degenerate during the development of diabetic retinopathy, we address the question to what extent this neuronal loss will impact on the molecular machinery of the retinal clock (clock and clock-controlled gene) and opsin mRNA expression (melanopsin, MW, SW and rhodopsin)
Diabetes was induced by injection of three successive doses of streptozotocin (SZT), in 3-week-old C57/BL6 wild-type mice, which damages pancreatic β-insulin-producing cells.
At 12 weeks post-injection, freshly dissected mice retinas (n=24 diabetic mice and n=24 control mice) were collected from animals at different circadian times (CT0, CT4, CT8, CT12, CT16 and CT20). The expression of clock and clock-controlled genes, opsin and tyrosine-hydroxylase (TH) genes were assessed by real-time RT-PCR.
Our results showed in the SZT-mice 1) an over-expression of mCry1, mCry2 and mE4BP4, 2) an over-expression of melanopsin mRNA and 3) a down-regulation of TH mRNA.
In conclusion, our results show that the molecular machinery of the retinal clock is poorly affected by the development of diabetic retinopathy. The over-expression of melanopsin may induce an alteration in the entrainment process of the circadian timing system and the retinal clock by light. The decreased level of TH mRNA suggests a disruption of dopamine, the modulator of the retinal molecular clock mechanism.
Acknowledgements
RETINA-FRANCE, GDRI-Neuro, Rhône-Alpes-CMIRA.
Keywords:
Melanopsin,
Circadian Rhythm,
Clock genes.,
diabetes,
Retina
Conference:
4th Conference of the Mediterrarnean Neuroscience Society, Istanbul, Türkiye, 30 Sep - 3 Oct, 2012.
Presentation Type:
Poster Presentation
Topic:
Abstracts
Citation:
LAHOUAOUI
H,
Coutanson
C,
Cooper
H,
BENNIS
M and
Dkhiss-Benyahya
O
(2013). The retinal clock is altered in a mouse model of diabetic retinopathy.
Conference Abstract:
4th Conference of the Mediterrarnean Neuroscience Society.
doi: 10.3389/conf.fnhum.2013.210.00044
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Received:
27 Jan 2013;
Published Online:
11 Apr 2013.
*
Correspondence:
Miss. HASNA LAHOUAOUI, Claude Bernard University, Lyon1, Lyon, France, fourkane@live.fr