562 Neuroendocrinology of human scalp hair follicles: Growth hormone-releasing hormone (GHRH) stimulates hair growth and controls a fully functional intrafollicular hypothalamic-pituitary-somatotropic (HPS) signaling axis

Human scalp hair follicles (HFs) are a major non-classical site of neurohormone production. While we had previously shown that growth hormone (GH), unexpectedly, inhibits female human HFs ex vivo, it is unknown whether also produce key HPS axis neurohormones themselves, i.e. GH, its upstream regulator, GHRH, and/or the negative feedback control, somatostatin (SST), and GHRH modulates growth. To answer these questions, were organ-cultured stimulated with GH (100 or 300ng/mL), vehicle for mRNA protein analysis elements. This revealed HF expression both, receptor as well their cognate ligands. Moreover, stimulation significantly upregulated both SST in matrix outer root sheath (ORS) keratinocytes vivo. After treatment 6 days, test remained longer anagen than vehicle-treated showed increased IGF-1 ORS. downregulated expression, SST, exhibiting control hormones. Taken together, this introduces novel endogenous modulator demonstrates operate fully functional peripheral equivalent central neuroendocrine signaling axis. Since insufficient/excessive serum levels can cause abnormalities, newly identified system skin clinically relevant invites intervention strategies target hormones receptors.