Effects of etretinate in epidermal metabolism and histology after abrasio of superficial layers. Mouse tail assay
Lubach, D.; Kietzmann, M.
Arzneimittel-Forschung 38(1): 54-59
1988
ISSN/ISBN: 0004-4172 PMID: 3365278 Document Number: 318372
The mouse tail assay is suitable for the histological detection of altered differentiation of the epidermis. In the present study, the stratum corneum of the tail epidermis of female mice (NMRI) was removed by means of fine sandpaper. One group of mice was treated with 2 mg of ethyl (alltrans)-9-(4-methoxy-2,3,6-trimethylphenyl)-3,7-dimethyl-2,4,6,8-nonatetraenoate (etretinate)/kg body weight daily. The untreated group served as control. After removal of the stratum corneum epidermal hyperplasia and formation of a stratum granulosum was found in the controls (peak on the third day). The alterations declined from the fourth day onwards. The histidine incorporation into protein was increased from days 4 to 6. A similar reaction sequence was observed in the animals treated with etretinate. In addition to the hyperplasia, there was an enlargement of the cells (hypertrophy). The control group showed a significant elevation of leucine incorporation and a reduction of histidine incorporation into protein on the first day after removal of the stratum corneum. The incorporation rate of thymidine triphosphate into DNA peaked on the second day. The rise of leucine incorporation into protein and the increase of thymidine triphosphate incorporation into DNA on the second day after removal of the stratum corneum could not be detected in the animals treated with etretinate. In these animals histidine metabolism could not be influenced by etretinate. In conclusion, etretinate greatly influences the alteration of basal metabolism caused by the removal of the stratum corneum. Opposite to this etretinate is not able to change the alterations observed in the uppermost epidermal layer (formation of a stratum granulosum, histidine metabolism) and the development of acanthosis.