Early Rod Dysfunction Influences Cone Development in a Rhodopsin P23H Mouse Model of Retinitis Pigmentosa.

Area of Science:

• Ophthalmology
• Neuroscience
• Genetics

Background:

• Autosomal dominant retinitis pigmentosa (RP) is often studied in RhoP23H/WT mice, focusing on later retinal changes.
• Early postnatal retinal development in RP models is understudied, particularly concerning compensatory mechanisms.
• Previous research noted inner retinal thickening in response to rod degeneration.

Purpose of the Study:

• Investigate early retinal responses to rod dysfunction in a novel RhoP23H.GFP reporter mouse line.
• Analyze the impact of rhodopsin P23H mutation on cone photoreceptors during postnatal development (P8-P24).
• Determine if cone photoreceptors exhibit compensatory changes in response to early rod degeneration.

Main Methods:

• Utilized a novel RhoP23H.GFP reporter mouse line expressing GFP in cone photoreceptors.
• Conducted histological analysis to assess retinal thickness and morphology.
• Employed flow cytometry to quantify cone photoreceptor numbers at various postnatal ages (P12, P16, P24).

Main Results:

• No significant difference in overall retinal thickness was observed between RhoP23H.GFP mice and controls.
• Rhodopsin mislocalization to rod cell bodies was transient, normalizing by P24.
• Significantly increased cone photoreceptor numbers were found in RhoP23H.GFP mice at P12, P16, and P24.
• Alterations in cone morphology were noted in diseased retinas.

Conclusions:

• Cone photoreceptors may undergo developmental compensatory adaptation in response to early rod dysfunction.
• These findings offer new insights into the early disease mechanisms of retinitis pigmentosa.
• The RhoP23H.GFP model is valuable for studying cone responses in RP during development.