Familial Danish
dementias (FDDs) are autosomal dominant
neurodegenerative disorders that are associated with visual defects. In some aspects, FDD is similar to
Alzheimer's disease (AD)- the
amyloid deposits in FDD and AD are made of short
peptides:
amyloid β (Aβ) in AD and ADan in FDD. Previously, we demonstrated an interaction between the
dementia peptides and α-
crystallin leading to lens opacification in organ culture due to impaired chaperone activity of α-
crystallin. Herein, we report the in vivo effects of ADan and Aβ on the eye. ADan [reduced (ADan-red) and oxidized (ADan-oxi)] and Aβ (Aβ1-40 and Aβ1-42) were injected intravitreally in rats. The onset of
cataract was seen after injection of all the
peptides, but the
cataract matured by 2 weeks in the case of ADan-red, 5 weeks for ADan-oxi and 6 weeks for Aβ1-40, while Aβ1-42 had minimal effect on
cataract progression. The severity of
cataract is associated with insolubilization and alterations in
crystallins and loss of chaperone activity of α-
crystallin. Further, disruption of the architecture of the retina was evident from a loss of
rhodopsin, increased
gliosis, and the thinning of the retina. These results provide a basis for the dominant heredo-otoophthalmo-
encephalopathy (HOOE)/FDD syndrome and indicate that ADan
peptides are more potent than Aβpeptides in inflicting
visual impairment.