Irradiation of protoporphyric mice induces down-regulation of epidermal eicosanoid metabolism

Journal Article · Sun Sep 01 00:00:00 EDT 1991 · Journal of Investigative Dermatology; (United States)

DOI:https://doi.org/10.1111/1523-1747.ep12481524· OSTI ID:5229465

He, D; Lim, H W ^[1]

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1. Department of Veterans Affairs Medical Center, New York, NY (USA)

This study investigated the effect of radiation on clinical and histologic changes, and on cutaneous eicosanoid metabolism, in Skh:HR-1 hairless albino mice rendered protoporphyric by the administration of collidine. At 0.1-18 h after exposure to 12 kJ/m2 of 396-406 nm irradiation, thicknesses of back skin and ears were measured, and histologic changes were evaluated by using hematoxylin and eosin (H-E) and Giemsa's stains. Activities of eicosanoid-metabolizing enzymes in epidermal and dermal homogenates were assessed by incubating the tissue homogenates with 3H-AA, followed by quantitation of the eicosanoids generated by radio-TLC. In irradiated protoporphyric mice, an increase of back-skin thickness was noted at 0.1 h, reaching a peak at 18 h, whereas maximal increase in ear thickness was observed at 12 h. Histologic changes included dermal edema, increased mast cell degranulation, and mononuclear cells in the dermis. In these irradiated protoporphyric animals, generations of 6 keto-PGF1a, PGF2a, PGE2, PGD2, and HETE by epidermal eicosanoid-metabolizing enzymes were markedly suppressed at all the timepoints studied. Dermal eicosanoid-metabolizing enzymes of irradiated protoporphyric mice generated increased amounts of PGE2 and HETE at 18 h, probably reflecting the presence of dermal cellular infiltrates. The suppression of the activities of epidermal eicosanoid-metabolizing enzymes was prevented by intraperitoneal injection of WR-2721, a sulfhydryl group generator, prior to irradiation, suggesting that the suppression was secondary to photo-oxidative damage of the enzymes during the in vivo phototoxic response. These results suggest that the effect of protoporphyrin and radiation on cutaneous eicosanoid metabolism in this animal model in vivo is that of a down regulation of the activities of epidermal eicosanoid-metabolizing enzymes.

• OSTI ID: 5229465
• Journal Information: Journal of Investigative Dermatology; (United States), Vol. 97:3; ISSN 0022-202X
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
EICOSANOIC ACID
METABOLISM
EPIDERMIS
PATHOLOGICAL CHANGES
PROTOPORPHYRINS
BIOCHEMICAL REACTION KINETICS
ARACHIDONIC ACID
MAST CELLS
MICE
MONOCYTES
SKIN DISEASES
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ANIMAL CELLS
ANIMAL TISSUES
ANIMALS
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY
BODY FLUIDS
CARBOXYLIC ACIDS
CONNECTIVE TISSUE CELLS
DISEASES
EPITHELIUM
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
KINETICS
LEUKOCYTES
MAMMALS
MATERIALS
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PIGMENTS
PORPHYRINS
REACTION KINETICS
RODENTS
SKIN
SOMATIC CELLS
TISSUES
VERTEBRATES
550501* - Metabolism- Tracer Techniques