RT-PCR AND IMMUNOISTOCHEMISTRY IDENTIFY LEPTIN RECEPTOR IN THE SKIN AND ITS APPENDAGES IN THE CANINE SPECIES.

Leptin is a polypeptide secreted by adipose tissue regulating appetite and energy consumption. It acts by binding with a specific receptor (Ob-R) that is expressed in various tissues. The wide distribution of the Ob-R suggests that leptin might exert diverse biological functions other than regulating energy metabolism. Accordingly, leptin acts as a mitogen in many cell types, including the epidermis where it was detected together with its receptor in human and laboratory animals. In this work, the presence and localization of Ob-R was investigated in the skin of the dog using RT-PCR and immunohistochemical techniques. RT-PCR revealed the presence of Ob-R m-RNA in the specimens evaluated. Through immunohistochemistry, the expression of the receptor was observed in the basal layer of the epidermis, in the hair follicles as well as in the apocrine sweat and sebaceous glands. No staining for Ob-R was detected in the suprabasal skin layers. Strong positive signals were observed in many cells of the outer root sheath both in growing and regressive phase of hair follicles. The identification of the Ob-R suggests that leptin may have a role in the regulation of cyclic renewal of skin and its appendages also in the canine species.