Cutaneous lesions in capsaicin-pretreated rats. A trophic role of capsaicin-sensitive afferents?
1. The time course and regional distribution of 'spontaneous' cutaneous lesions in rats desensitized to capsaicin as newborns was correlated to behavioural observations and regional distribution of substance P-like immunoreactivity (SP-LI) and tachykinin-like immunoreactivity (TK-LI) in various skin areas. 2. 'Spontaneous' skin lesions in the form of wounds, scabs and areas of alopecia were observed in 80-90% of rats desensitized to capsaicin. No major sex-related differences were observed with regard to incidence and distribution of the lesions with the possible exception of a lesser tendency to bilateral lesions in female rats. 3. 'Spontaneous' skin lesions were almost restricted to the head: the areas most frequently affected were snouts, periocular and retroauricular regions and ventral area of the neck. 4. No major differences were observed between capsaicin- or vehicle-treated animals in spontaneous or novelty-induced grooming as well as in open-field gross behaviour. Likewise, no differences were observed in the mouse-killing behaviour. 5. Both SP-LI and TK-LI in various skin areas were significantly reduced by systemic capsaicin pretreatment. The rank order of various skin areas for SP-LI or TK-LI levels was: snouts greater than thigh greater than neck greater than abdomen approximately equal to retroauricular region. 6. Intradermal injection of Arg-neurokinin B, a potent and water soluble derivative of neurokinin B, produced a similar plasma extravasation (Evans blue leakage technique) in the skin of vehicle- or capsaicin-pretreated rats. 7. In capsaicin-desensitized rats fur regrowth (measured at abdominal level, 28 days after shaving) was significantly less than in vehicle-treated animals.(ABSTRACT TRUNCATED AT 250 WORDS)
D000818:Animals; D000831:Animals, Newborn; D001522:Behavior, Animal / Q000187:drug effects; D002199:Capillary Permeability; D002211:Capsaicin / Q000008:administration & dosage / Q000633:toxicity*; D005260:Female; D006197:Hair / Q000254:growth & development; D006851:Hydrochloric Acid / Q000633:toxicity; D008297:Male; D009475:Neurons, Afferent / Q000187:drug effects*; D009479:Neuropeptides / Q000032:analysis / Q000276:immunology; D051381:Rats; D012867:Skin / Q000032:analysis / Q000098:blood supply / Q000294:innervation*; D012871:Skin Diseases / Q000139:chemically induced* / Q000473:pathology; D012883:Skin Ulcer / Q000139:chemically induced / Q000473:pathology; D013373:Substance P / Q000032:analysis / Q000276:immunology; D015320:Tachykinins
D009479:Neuropeptides; D015320:Tachykinins; D013373:Substance P; D006851:Hydrochloric Acid; D002211:Capsaicin