Development of mechanisms associated with neurogenic-mediated skin inflammation during the growth of rats.
Neurogenic-mediated inflammation may be associated with several inflammatory skin diseases including atopic dermatitis. However, age-dependent differences in neurogenic-mediated skin responses are not fully understood. We compared skin plasma leakage in rats aged 2 and 8 wk, which was induced by topical capsaicin, topical formalin, and intracutaneous substance P, whose effects are mediated via tachykinin NK1 receptors. Evans blue dye extravasation served as an index of the increase in skin vascular permeability. Capsaicin, formalin, and substance P caused a skin response in a dose-dependent manner in both age groups. However, the skin response was much greater in adults than in pups. In addition, the localization of sensory C-fibers and tachykinin NK1 receptors in the skin was investigated by immunofluorescent staining with antisubstance P and antitachykinin NK1 receptor antibodies, respectively. Substance P-immunoreactive nerves were detected throughout the dermis and tachykinin NK1 receptors were mainly detected in blood vessel walls in the dermis in both age groups. However, they were more sparsely distributed in pups. In conclusion, the weak neurogenic-mediated skin inflammation in pups is probably because of immature neural mechanisms associated with skin inflammation such as reduced innervation of sensory C-fibers and low expression of tachykinin NK1 receptors.
Ohshima
Mihoko
M
Department of Pediatrics, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan.
Miyake
Mio
M
Takeda
Masanori
M
Muto
Taichiro
T
Ueda
Norishi
N
Ito
Komei
K
Sakamoto
Tatsuo
T
D000367:Age Factors; D000818:Animals; D002211:Capsaicin / Q000494:pharmacology; D015550:Cell Degranulation / Q000187:drug effects; D005260:Female; D005404:Fixatives / Q000494:pharmacology; D005557:Formaldehyde / Q000494:pharmacology; D008297:Male; D008407:Mast Cells / Q000187:drug effects / Q000378:metabolism; D036421:Nerve Fibers, Unmyelinated / Q000378:metabolism; D020078:Neurogenic Inflammation / Q000378:metabolism / Q000473:pathology; D018377:Neurotransmitter Agents / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D018040:Receptors, Neurokinin-1 / Q000378:metabolism; D018689:Sensory System Agents / Q000494:pharmacology; D012867:Skin / Q000033:anatomy & histology / Q000187:drug effects / Q000254:growth & development* / Q000473:pathology*; D013373:Substance P / Q000378:metabolism / Q000494:pharmacology
D005404:Fixatives; D018377:Neurotransmitter Agents; D018040:Receptors, Neurokinin-1; D018689:Sensory System Agents; D005557:Formaldehyde; D013373:Substance P; D002211:Capsaicin