P-18   THE ROLE OF NEUTRAL ENDOPEPTIDASE (EC 3.4.24.11) IN REGULATING THE HAIR CYCLE

N. Tsuji, A. Ohuchi, S. Moriwaki, Y. Takema Biological Science Lab. Kao Corp. Tochigi, Japan.

Various enzyme activities have been reported to change in association with the hair cycle. We determined that the activity of neutral endopeptidase (NEP) changed in association with the hair cycle from 3 to 12 weeks age. NEP activity in the skin was elevated at early anagen (at weeks 5 and 10), and then decreased during catagen to telogen. Expression of NEP mRNA and protein was modulated similarly. Immunostaining of NEP showed changes in its localization throughout the hair cycle, from the follicular epithelium during early anagen to the dermal papilla during catagen. To determine whether NEP plays an important role in regulating the hair cycle, we used an inhibitor of NEP. Because NEP is a metalloproteinase, a Phosphoramidon derivative (NPLT) was selected and was applied daily to the dorsal skin of C3H mice, which had been depilated in advance. Areas of newly grown hair were evaluated by image analysis. Mice treated with NPLT had significantly suppressed hair growth compared with the vehicle control treated mice. These data suggest that NEP plays an important role in regulating the hair cycle by its increased expression and activity in the follicular epithelium during early anagen.