Prostanoid receptors in anagen human hair follicles

Abstract:  Prostanoid pathway in hair follicle gained closer attention since trichogenic side-effects on hair growth has been observed concomitantly with prostaglandin F_2α receptor (FP) agonist treatment of intraocular pressure. We thus investigated prostanoid receptor distribution in anagen hair follicle and different cell types from hair and skin. Using RT-PCR, Western blot and immunohistochemistry (IHC), we found that all receptors were present in hair follicle. This data shed new light on an underestimated complex network involved in hair growth control. Indeed most of these receptors showed a wide spectrum of expression in cultured cells and the whole hair follicle. Using IHC, we observed that expression of prostaglandin E₂ receptors (EP₂, EP₃, EP₄), prostaglandin D₂ receptor (DP₂), prostanoid thromboxane A₂ receptor (TP) and to a lesser extent EP₁ involved several hair follicle compartments. On the opposite, Prostaglandin I₂ receptor (IP) and DP₁ were more specifically expressed in hair cuticle layer and outer root sheath (ORS) basal layer, respectively. FP expression was essentially restricted to ORS companion layer and dermal papilla ( DP ). Although extracting a clear functional significance from this intricate network remains open challenge, FP labelling, i.e. could explain the biological effect of PGF_{2 α} on hair regrowth, by directly modulating DP function.