Protective effect of carnosic acid, a pro-electrophilic compound, in models of oxidative stress and light-induced retinal degeneration.
OBJECTIVE
The herb rosemary has been reported to have antioxidant and anti-inflammatory activity. We have previously shown that carnosic acid (CA), present in rosemary extract, crosses the blood-brain barrier to exert neuroprotective effects by upregulating endogenous antioxidant enzymes via the Nrf2 transcriptional pathway. Here we investigated the antioxidant and neuroprotective activity of CA in retinal cell lines exposed to oxidative stress and in a rat model of light-induced retinal degeneration (LIRD).


METHODS
Retina-derived cell lines ARPE-19 and 661W treated with hydrogen peroxide were used as in vitro models for testing the protective activity of CA. For in vivo testing, dark-adapted rats were given intraperitoneal injections of CA prior to exposure to white light to assess protection of the photoreceptor cells. Retinal damage was assessed by measuring outer nuclear layer thickness and by electroretinogram (ERG).


RESULTS
In vitro, CA significantly protected retina-derived cell lines (ARPE-19 and 661W) against H(2)O(2)-induced toxicity. CA induced antioxidant phase 2 enzymes and reduced formation of hyperoxidized peroxiredoxin (Prx)2. Similarly, we found that CA protected retinas in vivo from LIRD, producing significant improvement in outer nuclear layer thickness and ERG activity.


CONCLUSIONS
These findings suggest that CA may potentially have clinical application to diseases affecting the outer retina, including age-related macular degeneration and retinitis pigmentosa, in which oxidative stress is thought to contribute to disease progression.
Del E Web Center for Neuroscience, Aging, and Stem Cell Research, Sanford-Burnham Medical Research Institute, La Jolla, California, USA.
Tayebeh
T
Rezaie
Scott R
SR
McKercher
Kunio
K
Kosaka
Masaaki
M
Seki
Larry
L
Wheeler
Veena
V
Viswanath
Teresa
T
Chun
Rabina
R
Joshi
Marcos
M
Valencia
Shunsuke
S
Sasaki
Terumasa
T
Tozawa
Takumi
T
Satoh
Stuart A
SA
Lipton
D045784:Abietanes / Q000627:therapeutic use*; D000818:Animals; D000975:Antioxidants / Q000627:therapeutic use; D001812:Blood-Brain Barrier / Q000187:drug effects; D002460:Cell Line; D004195:Disease Models, Animal; D018450:Disease Progression; D004596:Electroretinography; D008027:Light / Q000009:adverse effects; D018384:Oxidative Stress; D020419:Photoreceptor Cells, Vertebrate / Q000187:drug effects* / Q000473:pathology / Q000528:radiation effects; D010936:Plant Extracts / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012162:Retinal Degeneration / Q000209:etiology / Q000378:metabolism / Q000517:prevention & control*; D027542:Rosmarinus
D045784:Abietanes; D000975:Antioxidants; D010936:Plant Extracts; C018381:salvin