title: The CB(2) cannabinoid receptor regulates human sperm cell motility.
abstract: OBJECTIVE
  To analyze the expression and distribution of cannabinoid receptors in human sperm cells and evaluate the effects of activation of receptors by specific agonists and antagonists, with a special emphasis on the CB(2) receptor.
  
  
  METHODS
  We performed expression assays for CB(1) and CB(2) by reverse transcriptase PCR, Western blot, and immunofluorescence techniques in spermatozoa and performed motility analysis after incubation of semen samples with cannabinoid agonists and CB(2) antagonist SR144528.
  
  
  METHODS
  Academic research laboratory.
  
  
  METHODS
  Semen from 50 normozoospermic, healthy human donors.
  
  
  METHODS
  Spermatozoa isolated from semen by two consecutive swim-ups were used for all techniques.
  
  
  METHODS
  Reverse transcriptase PCR amplification gels, immunoblots, indirect immunofluorescence antibody assays, and percentage of motile sperm.
  
  
  RESULTS
  We have verified the presence of CB(1) and CB(2) receptors in human spermatozoa. The distribution of both of these receptors was distinct. Incubation with selective cannabinoid receptor agonists induced a significant reduction in the proportion of rapidly progressive motile spermatozoa, and whereas the CB(1) agonist increased the proportion of immobile sperm cells, the CB(2) receptor agonist increased the slow/sluggish progressive sperm cell population. The effect of the CB(2) agonist was antagonized by the CB(2)-specific antagonist.
  
  
  CONCLUSIONS
  The functional CB(2) cannabinoid receptor is present in human spermatozoa and regulates the sperm motility in a more distinct manner than CB(1).
authors.affiliation: Department of Physiology, Faculty of Medicine and Dentistry, University of the Basque Country, Leioa, P.O. Box 699, E-48080, Bilbao, Biscay, Spain. e.agirregoitia@ehu.es
authors.forename: Ekaitz
authors.initials: E
authors.lastname: Agirregoitia
authors.forename: Arkaitz
authors.initials: A
authors.lastname: Carracedo
authors.forename: Nerea
authors.initials: N
authors.lastname: Subirán
authors.forename: Asier
authors.initials: A
authors.lastname: Valdivia
authors.forename: Naiara
authors.initials: N
authors.lastname: Agirregoitia
authors.forename: Laura
authors.initials: L
authors.lastname: Peralta
authors.forename: Guillermo
authors.initials: G
authors.lastname: Velasco
authors.forename: Jon
authors.initials: J
authors.lastname: Irazusta