References: Hair growth and hair loss
Plant J. 1997 Aug;12(2):427-39.
Cytoplasmic free calcium distributions during the development of root hairs of Arabidopsis thaliana.
Wymer CL, Bibikova TN, Gilroy S.
Department of Biology, Mueller Lab, Pennsylvania State University, University Park 16802, USA.
In this study, confocal ratio analysis was used to image the relationship between cytoplasmic free calcium concentration ([Ca2+]c) and the development of root hairs of Arabidopsis thaliana. Although a localized change in [Ca2+]c that preceded or predicted the site of root hair initiation could not be detected, once initiated the majority of emerging root hairs showed an elevated [Ca2+]c (> 1 microM) in their apical cytoplasm, compared with 100-200 nM in the rest of the cell. These emerging root hairs then moved into a 3-5 h phase of sustained elongation during which they showed variable growth rates. Root hairs that were rapidly elongating exhibited a highly localized, elevated [Ca2+]c at the tip. Non-growing root hairs did not exhibit the [Ca2+]c gradient. The rhd-2 mutant, which is defective in sustained root hair growth, showed an altered [Ca2+]c distribution compared with wild-type. These results implicate [Ca2+]c in regulating the tip growth process. Treatment of elongating wild-type root hairs with the Ca2+ channel blocker verapamil (50 microM) caused dissipation of the elevated [Ca2+]c at the tip and cessation of growth, suggesting a requirement for Ca2+ channel activity at the root hair tip to maintain growth. Manganese treatment also preferentially quenched Indo-1 fluorescence in the apical cytoplasm of the root hair. As manganese is thought to enter cells through Ca(2+)-permeable channels, this result also suggests increased Ca2+ channel activity at the tip of the growing hair. Taken together, these data suggest that although Ca2+ does not trigger the initiation of root hairs, Ca2+ influx at the tip of the root hair leads to an elevated [Ca2+]c that may be required to sustain root hair elongation.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9301093&dopt=Abstract
J Comp Neurol. 1997 Sep 29;386(3):379-95.
Hair cycle-dependent plasticity of skin and hair follicle innervation in normal murine skin.
Botchkarev VA, Eichmuller S, Johansson O, Paus R.
Department of Dermatology, Charite, Humboldt-Universitat zu Berlin, Germany.
The innervation of normal, mature mammalian skin is widely thought to be constant. However, the extensive skin remodeling accompanying the transformation of hair follicles from resting stage through growth and regression back to resting (telogen-anagen-catagen-telogen) may also be associated with alteration of skin innervation. We, therefore, have investigated the innervation of the back skin of adolescent C57BL/6 mice at various stages of the depilation-induced hair cycle. By using antisera against neuronal (protein gene product 9.5 [PGP 9.5], neurofilament 150) and Schwann cell (S-100, myelin basic protein) markers, as well as against neural cell adhesion molecule (NCAM) and growth-associated protein-43 (GAP-43), we found a dramatic increase of single fibers within the dermis and subcutis during early anagen. This was paralleled by an increase in the number of anastomoses between the cutaneous nerve plexuses and by distinct changes in the nerve fiber supply of anagen vs. telogen hair follicles. The follicular isthmus, including the bulge, the seat of epithelial follicle stem cells, was found to be the most densely innervated skin area. Here, a defined subpopulation of nerve fibers increased in number during anagen and declined during catagen, accompanied by dynamic alterations in the expression of NCAM and GAP-43. Thus, our study provides evidence for a surprising degree of plasticity of murine skin innervation. Because hair cycle-associated tissue remodeling evidently is associated with tightly regulated sprouting and regression of nerve fibers, hair cycle-dependent alterations in murine skin and hair follicle innervation offer an intriguing model for studying the controlled rearrangement of neuronal networks in peripheral tissues under physiological conditions.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9303424&dopt=Abstract
Biochim Biophys Acta. 1997 Aug 29;1336(2):315-22.
Identification and measurement of beta-endorphin levels in the skin during induced hair growth in mice.
Furkert J, Klug U, Slominski A, Eichmuller S, Mehlis B, Kertscher U, Paus R.
Research Institute for Molecular Pharmacology, Berlin, Germany.
We describe new and effective techniques for extracting proopiomelanocortin (POMC)-derived peptides from mammaliar skin. Using this methodology (hot-acid extraction) and two independent HPLC-controlled RIA systems, we identify beta-endorphin peptide in mammalian skin and demonstrate significant hair cycle-dependent fluctuations in both the skin concentration and the in situ expression pattern of beta-endorphin (sebaceous glands) during the entire murine hair cycle. The observed anagen (growth phase) associated increase in beta-endorphin concentration and its decline during the follicle involution (catagen) or resting (telogen) phase raise the possibility of a regulatory function of this neuropeptide in cyclic changes of skin physiology.
online pharmacy ref. source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9305804&dopt=Abstract
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