Distinct Roles for Nerve Growth Factor and Brain-Derived Neurotrophic Factor in Controlling the Rate of Hair Follicle Morphogenesis  Natalia V. Botchkareva, Vladimir A. Botchkarev, Kathryn M. Albers, Martin Metz, Ralf Paus  Journal of Investigative Dermatology  Volume 114, Issue 2, Pages 314-320 (February 2000) DOI: 10.1046/j.1523-1747.2000.00864.x Copyright © 2002 The Society for Investigative Dermatology, Inc Terms and Conditions

Figure 1 NGF and TrkA expressions in murine back skin during HF morphogenesis. Cryosections (8 μm) of back skin of embryonic and neonatal C57BL/6 mice (E18.5–P10) were immunostained with antibodies against NGF and TrkA. A schematic summary of expression patterns is given in (A), (D), and (G). (A–C) Stages 1–2 of HF morphogenesis. Expression of NGF- and TrkA-IR in the hair plug KC (B, C, arrows) and in epidermis (B, C, arrowheads). (D–F) Stages 5–6. NGF-IR in the distal ORS (E, arrow), and in the epidermal KC (E, small arrowhead). Prominent TrkA-IR in the epidermal KC (F, small arrowhead), developing ORS (F, arrow), and weak expression in the hair matrix (F, large arrowhead). (G–I) Stages 7–8. Prominent NGF-IR and TrkA-IR in the distal ORS (H, I, arrows), and in the epidermal KC (H, I, arrowheads). DC, dermal condensation; EP, epidermis; HM, hair matrix; HP, hair plug. Scale bars: 50 μm. Journal of Investigative Dermatology 2000 114, 314-320DOI: (10.1046/j.1523-1747.2000.00864.x) Copyright © 2002 The Society for Investigative Dermatology, Inc Terms and Conditions

Figure 2 BDNF and TrkB expression in murine back skin during HF morphogenesis. Cryosections (8 μm) of back skin of embryonic and neonatal C57BL/6 mice (E18.5–P10) were immunostained with antibodies against BDNF and TrkB. A schematic summary of expression patterns is given in (A), (D), and (G). (A–C) Stages 1–2 of HF morphogenesis. Expression of BDNF-IR in the hair plug KC (B, arrow), in basal epidermal KC (B, arrowhead); TrkB-IR in the KC of hair plug (B, arrow), and in the epidermis (C, arrowheads). (D–F) Stages 5–6. BDNF-IR in the developing ORS (E, arrow), hair matrix (E, large arrowhead), and in the epidermal KC (E, small arrowhead). TrkB-IR in the developing ORS (F, arrow). (G–I) Stages 7–8. Prominent BDNF-IR in the distal part of ORS (H, arrows); TrkB-IR in the ORS (I, small arrowheads), in the dermal papilla fibroblasts (I, arrows), and weak expression in the hair matrix (I, large arrowhead). DC, dermal condensation; DER, dermis; DP, dermal papilla; EP, epidermis; HM, hair matrix; HP, hair plug, HS, hair shaft; IRS inner root sheath; ORS, outer root sheath; SG, subcutaneous gland. Scale bars: 50 μm. Journal of Investigative Dermatology 2000 114, 314-320DOI: (10.1046/j.1523-1747.2000.00864.x) Copyright © 2002 The Society for Investigative Dermatology, Inc Terms and Conditions

Figure 3 Hair follicle morphogenesis is accelerated in NGF overexpressing mice, but not in BDNF overexpressing mice. The percentage of HF in the defined stages of morphogenesis was evaluated in paraffin sections of the skin of homozygous NGF or BDNF overexpressing mice (promoter: K14) and in the corresponding wild-type mice at P0 by quantitative histomorphometry using established morphological criteria (Hardy 1992;Philpott & Paus 1998). (A, B) Representative skin examples of wild-type (A) and NGF overexpressing mice (B) at P0. HF at different stages of development are indicated by arabic numbers. (C) Significant increase in the percentage of HF at stages 5–6 in NGF transgenics (p < 0.05), compared with wild-type animals. (D) Skin thickness in NGF overexpressing mice is significantly enhanced at P0 (p < 0.05), compared with wild-type mice. (E) Absence of any significant differences in the rate of HF development between BDNF transgenic (promotor: K14) and wild-type mice. Mean ± SEM, asterisks indicate significant differences between the same parameters in NGF overexpressing and wild-type mice, *p < 0.05, Student’s t test. Abbreviations: DER, dermis; EP, epidermis; PCM, panniculus carnosus muscle. Scale bars: 100 μm. Journal of Investigative Dermatology 2000 114, 314-320DOI: (10.1046/j.1523-1747.2000.00864.x) Copyright © 2002 The Society for Investigative Dermatology, Inc Terms and Conditions

Figure 4 NGF and BDNF differentially influence HF development in murine skin organ culture. Four millimeter skin biopsies were obtained from C57BL/6 mouse back skin 1 d after birth (P1), to be cultured for 48 h in the presence of 50 ng NGF per ml or 50 ng BDNF per ml, and the percentage of HF in distinct stages of HF morphogenesis was evaluated. (A, B) Representative examples of skin fragments from the vehicle control group (A) and from the NGF group (B). Scale bar: 100 μm. (C) Compared with vehicle controls, a significant decrease of stage 6 HF, and increase of stage 8 HF were seen in skin biopsies, incubated with NGF (mean ± SEM, n = 8–10 biopsies per group, asterisks indicate significant differences from the controls: *p < 0.05, **p < 0.005). (D) Incubation with BDNF resulted only in decline in the percentage of stage 5 HF, compared with control biopsies (mean ± SEM, n = 8–10 biopsies per group, asterisk indicates significant differences from the controls: *p < 0.05). Journal of Investigative Dermatology 2000 114, 314-320DOI: (10.1046/j.1523-1747.2000.00864.x) Copyright © 2002 The Society for Investigative Dermatology, Inc Terms and Conditions