title: Female sex hormones and rat dural vasodilatation to CGRP, periarterial electrical stimulation and capsaicin.
abstract: BACKGROUND
  The prevalence of migraine is 2 to 3-fold higher in females than in males, and it is intricately related to the levels of female sex hormones. These hormones may regulate the synthesis and receptor expression of calcitonin gene-related peptide (CGRP), which mediates neurogenic dural vasodilatation and is implicated in migraine pathogenesis.
  
  
  OBJECTIVE
  To investigate the effects of the female sex steroids, 17beta-estradiol and progesterone, separately and in combination, on dural vasodilatation induced by alphaCGRP, periarterial electrical stimulation and capsaicin in ovariectomized rats, using intravital microscopy.
  
  
  METHODS
  Sprague-Dawley rats were ovariectomized and, 7 days later, subcutaneously implanted with 21-day release pellets of 17beta-estradiol, progesterone, their combination or placebo. On day 19 to 21, the animals were anesthetized, overlying bone thinned to visualize the middle meningeal artery and vasodilator responses to alphaCGRP (10 to 3000 ng kg(-1)), periarterial electrical stimulation (25 to 125 microA) and capsaicin (0.3 to 18 microg kg(-1)) elicited.
  
  
  RESULTS
  There were no significant differences in the vasodilator potency or efficacy of alphaCGRP or capsaicin in the different groups studied. In contrast, the vasodilator response to electrical stimulation was significantly higher in rats treated with 17beta-estradiol (Emax:157 +/- 19%) as compared to those observed after placebo treatment (Emax:93 +/- 11%).
  
  
  CONCLUSIONS
  Our results show that, in contrast to CGRP- or capsaicin-induced dural vasodilatation, 17beta-estradiol enhanced neurogenic vasodilatation, suggesting increased CGRP release from perivascular nerves. This may be one of the mechanisms through which 17beta-estradiol exacerbates migraine in women.
authors.affiliation: Department of Pharmacology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands.
authors.forename: Saurabh
authors.initials: S
authors.lastname: Gupta
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Villalón
authors.forename: Suneet
authors.initials: S
authors.lastname: Mehrotra
authors.forename: René
authors.initials: R
authors.lastname: de Vries
authors.forename: Ingrid M
authors.initials: IM
authors.lastname: Garrelds
authors.forename: Pramod R
authors.initials: PR
authors.lastname: Saxena
authors.forename: Antoinette
authors.initials: A
authors.lastname: MaassenVanDenbrink
mesh_terms: D018712:Analgesics, Non-Narcotic / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D015740:Calcitonin Gene-Related Peptide / Q000494:pharmacology*; D002211:Capsaicin / Q000494:pharmacology*; D004388:Dura Mater / Q000098:blood supply*; D004558:Electric Stimulation; D004958:Estradiol / Q000097:blood / Q000494:pharmacology*; D005260:Female; D008576:Meningeal Arteries / Q000502:physiology; D008881:Migraine Disorders / Q000503:physiopathology*; D010052:Ovariectomy; D011374:Progesterone / Q000097:blood / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014664:Vasodilation / Q000187:drug effects* / Q000502:physiology; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D018712:Analgesics, Non-Narcotic; D014665:Vasodilator Agents; D011374:Progesterone; D004958:Estradiol; D015740:Calcitonin Gene-Related Peptide; D002211:Capsaicin