747 Human hair follicles functionally respond to growth hormone and growth hormone-releasing hormone, mimicking the central hypothalamic-pituitary-somatotropic axis

Human scalp hair follicles (HFs) are a major non-classical peripheral site of neurohormone production. However, it is unknown whether human HFs also produce the key hypothalamic-pituitary-somatotropic (HPS) axis neurohormones, its main member growth hormone (GH), and upstream hypothalamic regulator, GH-releasing (GHRH). To answer this, we treated microdissected with either GH (100 or 300 ng/mL), GHRH for mRNA by qRT-PCR protein analysis quantitative immunohistomorphometry HPS elements. Our data showed that transcribed all elements (incl. GHRH, GH), inhibitor, somatostatin (SST), receptor. stimulation increased both intrafollicular SST expression. Furthermore, significantly decreased own transcription SST, IGF-1, TGF-B2, IGF-1 binding protein, JAK2 expression while was decreased. We significant upregulation in outer root sheath matrix keratinocytes as well dermal papilla fibroblasts. These results represent first preliminary evidence operate functional equivalent system central axis, along expected negative feedback loops (including SST) factor responses. Since abnormal serum cause abnormalities, this neuroendocrine system, whose role HF physiology requires systematic exploration, clinically relevant invites novel HPS-targeting intervention strategies.