The main environmental source for skin damage is ultraviolet (UV) radiation. Many adverse effects have been recognized as the result of prolonged cutaneous exposure to solar ultraviolet radiation, such as erythema, edema, apoptosis, hyperplastic responses, photo-aging, and skin cancer development. Green tea provides photo-protection against UV radiation through many mechanisms including anti-inflammatory, immunomodulatory, and antioxidant properties. The aim of this study was to evaluate the effect of green tea in reducing epidermal thickness on mouse's skin exposed to UVB irradiation. Thirty mice (Mus musculus species, BALB/c strain) underwent this study and were divided into 3 groups: control group ( = 10 mice), without UVB exposure and green tea administration; exposure group ( = 10 mice), which were exposed to UVB light only; and treatment group ( = 10 mice), which were exposed to UVB light and treated with 1 mL of green tea through oral gavage. Mice from both groups (exposure and treatment) were subjected to UVB irradiation 4 days/week (20 minutes/day, 4 weeks). It concluded that oral administration of green tea was provided photo-protection against UVB induced hyperplasia; therefore, it can be regarded as a natural alternative for photo-protection.

Background:Ultraviolet B (UVB) is the most damaging component of sunlight. It rapidly activates the epidermal growth factor receptor (EGFR) and generates reactive oxygen species (ROS) in excessive quantities that quickly overwhelm tissue antioxidants.Setting and Design:To demonstrate the effects of UVB radiation on EGFR expression in mice skin and to evaluate the role of antioxidants in the exposed group.Materials and Methods:After obtaining the approval of the ethical committee, forty mice from BALB/c strain were used in this experiment and were allocated into 3 groups; 10 (control group); 15 (exposure group); and 15 (exposed and treated with antioxidants). Antioxidants were administered through subcutaneous injection. Skin biopsies from all groups were stained with EGFR antibodies. Total antioxidant status (TAS) was evaluated in all groups.Statistical Analysis:The data obtained were analyzed using ANOVA, Duncan's test, and Pearson's Correlation.Results:The highest EGFR expression in exposure group was of score 3+ (53%). The highest EGFR expression in treatment group was score 0 (40%). Apoptotic bodies and dermal mast cells increased in exposure group while decreased in treatment group. The mean values for TAS were measured for each group; control group = 1.2 mmol/l; exposure group = 0.87 mmol/l; treatment group =1.3 mmol/l.Conclusions:UVB led to Seborrheic Keratosis (SK) in mice through enhancement of EGFR expression. Antioxidants effectively reduced UVB-induced SK, reduced epidermal changes, apoptotic bodies, and decreased dermal mast cells. TAS measurement declined in exposure group, while it was within normal range in most treated cases.

The present study was designed to investigate the pathological lesions in different organs induced by chronic Ultraviolet type B (UVB) and Xylene exposure in mice. Forty mice were used in this study and divided into four groups; Group A (Control group, n=10) not exposed to UVB and Xylene, Group B (n=10) exposed to Xylene through painting the mouse's back skin, Group C (n=10) which were exposed to UVB light only, while the remainder group (Group D, n=10) were exposed to Xylene and UVB. The dorsal skin of mice from group B and D were painted with 1ml of Xylene whereas the animals in the group C and D exposed to UVB light for 30 minutes 4 days/week (6 weeks). The result showed that Xylene exposure in group B produced chronic tracheitis, bronchitis with some degenerative lesions in the neurons and glial cells of the brain, no specific lesions were found in the liver, spleen and kidney. UVB exposure in group C caused chronic tracheitis, lesions like lobar pneumonia, bronchopneumonia, and atelectasis, cellular swelling in the liver and kidney and follicular depletion in the spleen. In group D, the lesions became more prominent when animals exposed to both Xylene and UVB. We concluded that Xylene exposure has an adverse effect in some internal organs of mice, but not to all, when combined with UVB exposure it exaggerates its adverse effects on all of the examined organs.

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Background  Exposure to ultraviolet type B (UVB) radiation induces a number of pathologic changes in skin, including erythema, edema, epidermal hyperplasia, sunburn cell formation, immune suppression and eventually leads to cancer development. Objective To elucidate the differences in histological appearances of mast cells and apoptotic bodies between the two species (mice and human) among hyperkeratotic and acanthotic types of seborrheic keratosis (SK). Materials and Methods Thirty paraffin blocks were used in this study;  fifteen histologically con rmed acanthotic and hyperkeratotic SK cases in human (9 acanthotic and 6 hyperkeratotic) and  fifteen blocks from both types acanthotic and hyperkeratotic SK cases in mice induced by UVB light (9 acanthotic and 6 hyperkeratotic). Results Our results revealed that there was a signi cant correlation between mast cells and apoptotic bodies for both groups according to Pearson Correlation test. In human cases mast cells counting ranged between 2-10 with a mean number of 5.2/1HPF, while the total number of apoptotic bodies ranged from 1-4 with a mean number of 2.6/10HPF. When compared to mice cases, the number of mast cells were increased with a range of 12-23 and with a mean number of 19.067/1HPF, while apoptotic bodies were decreased with a range of 3-20/10HPF and with a mean number of 9.4/10HPF. Conclusion Dermal mast cells in ltration were remarkably increased in mice skin specimens which were exposed to UVB. The number of apoptotic bodies in UVB induced cases were more than in human sporadic cases.