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Acute and Sub-chronic
Effects of Co-treatment of Female SKH-1 Mice with Alpha- and Beta-Hydroxy
Acids and/or Simulated Solar Light
Sams, Reeder1,2,
Couch, Letha1,2, Miller, Barbara1,2,
Okerberg, Carlin3, Beer, Janusz4,
Wamer, Wayne5 and Howard, Paul1,2
National Center for Toxicological Research, Food and Drug Administration,
Jefferson, AR, USA1
National Toxicology Program Center for Phototoxicology, NCTR, Jefferson,
AR, USA2
Pathology Associates International, Jefferson, AR, USA3
Center for Devices and Radiological Health, Food and Drug Administration,
Bethesda, MD, USA4
Center for Food Safety and Applied Nutrition, Food and Drug Administration,
Washington, DC, USA5
Abstract-
Glycolic acid (GA) and salicylic acid (SA) are commonly used alpha-
and beta-hydroxy acids present in over-the-counter skin care lotions
and creams. We have characterized the effects of treatment of female
SKH-1 mice with creams containing GA and SA on simulated solar light
(SSL)-induced skin edema and epidermal cell proliferation. The dose
of SSL was quantified by multiplying the incident spectrum by the CIE
erythema action spectrum (mJ CIE/cm2).
Naive and GA treated mice (5 days/week) were exposed to 0, 14, 46, 91,
137, 182, and 227 mJCIE/cm2
SSL and the skin thickness was measured 48 hrs afterward to determine
the minimal amount of light required for edema (MEdD). In naive mice
we observed a MEdD of 91 mJCIE/cm2,
while mice which received a daily treatment of 10% GA cream for 6 weeks
required an increased amount of SSL (137 mJCIE/cm2)
to produce edema. Daily exposure for 6 weeks to 14 mJCIE/cm2
(SSL) resulted in an increase of the MEdD to 182 mJCIE/cm2.
Combination of daily exposure to GA or SA and SSL resulted in a MEdD
of (GA) 227 mJCIE/cm2
and (SA) 182 mJCIE/cm2,
respectively. Epidermal proliferation data closely resembled the MedD
determinations. Sub-chronic studies were performed in which female SKH-1
mice were treated with SSL (14 mJCIE/cm2)
and GA or SA for 13 weeks. Animals were observed daily and displayed
no signs of adverse effects. All treatment groups were compared based
upon the morphological characteristics of whole skin samples. No significant
difference (p<0.01) was observed in average body weights of untreated
control animals versus treated animals. These results demonstrate that
daily treatment with GA or SA does not increase the acute or sub-chronic
sensitivity of female SKH-1 mice to daily treatments with 14 mJCIE/cm2
of SSL.
Keywords: ultraviolet
light, SKH-1 mice, edema, glycolic acid
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