title: Sexual dimorphism in endothelin-1 induced mechanical hyperalgesia in the rat.
abstract: While the onset of mechanical hyperalgesia induced by endothelin-1 was delayed in female rats, compared to males, the duration was much longer. Given that the repeated test stimulus used to assess nociceptive threshold enhances hyperalgesia, a phenomenon we have referred to as stimulus-induced enhancement of hyperalgesia, we also evaluated for sexual dimorphism in the impact of repeated application of the mechanical test stimulus on endothelin-1 hyperalgesia. In male and female rats, endothelin-1 induced hyperalgesia is already maximal at 30 min. At this time stimulus-induced enhancement of hyperalgesia, which is observed only in male rats, persisted for 3-4h. In contrast, in females, it develops only after a very long (15 day) delay, and is still present, without attenuation, at 45 days. Ovariectomy eliminated these differences between male and female rats. These findings suggest marked, ovarian-dependent sexual dimorphism in endothelin-1 induced mechanical hyperalgesia and its enhancement by repeated mechanical stimulation.
authors.affiliation: Department of Medicine and Oral and Maxillofacial Surgery, University of California, San Francisco, CA 94143-0440, USA.
authors.forename: Elizabeth K
authors.initials: EK
authors.lastname: Joseph
authors.forename: Jon D
authors.initials: JD
authors.lastname: Levine
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D019332:Endothelin-1 / Q000009:adverse effects*; D005260:Female; D006930:Hyperalgesia / Q000139:chemically induced*; D008297:Male; D010052:Ovariectomy; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012727:Sex Characteristics; D013997:Time Factors
chemical_list: D019332:Endothelin-1