title: Impaired reproduction of histamine deficient (histidine-decarboxylase knockout) mice is caused predominantly by a decreased male mating behavior.
abstract: OBJECTIVE
  Histamine induces a Th2 shift. As successful allopregnancy is characterized by a peripheral Th2 dominance, we investigated the role of histamine in reproduction.
  
  
  METHODS
  HDC knockout (HDC-/-) or wild-type (HDC+/+) mice kept on histamine-deficient or normal diet were mated. Appearance of vaginal plugs indicated day 0.5 of pregnancy. On day 10.5 uteri were inspected. Splenic IFN-gamma production and cytotoxic activity were determined.
  
  
  RESULTS
  In HDC+/+ or HDC-/- females on normal diet, plugs appeared between 3 and 6 days. In 80% of the (HDC-/-)/(HDC-/-) matings on histamine-deficient diet, no vaginal plugs were observed for more than 1 month. After replacing males with the wild type, plugs appeared within 3 days. In HDC-/- mice, litter size was lower than in HDC+/+ animals. Cytotoxicity and IFN-gamma production were significantly increased in non-pregnant histamine-deficient mice, but not in pregnant mice.
  
  
  CONCLUSIONS
  Histamine affects male mating behavior, but is not indispensable for successful pregnancy.
authors.affiliation: Department of Medical Microbiology and Immunology, Faculty of Medicine, University of Pecs, Pecs, Hungary.
authors.forename: Gabriella
authors.initials: G
authors.lastname: Pár
authors.forename: Júlia
authors.initials: J
authors.lastname: Szekeres-Barthó
authors.forename: Edit
authors.initials: E
authors.lastname: Buzás
authors.forename: Erna
authors.initials: E
authors.lastname: Pap
authors.forename: András
authors.initials: A
authors.lastname: Falus
mesh_terms: D000818:Animals; D005260:Female; D005434:Flow Cytometry; D006632:Histamine / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D006640:Histidine Decarboxylase / Q000235:genetics; D007371:Interferon-gamma / Q000378:metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D011247:Pregnancy; D011270:Pregnancy, Animal; D012726:Sexual Behavior, Animal / Q000187:drug effects / Q000502:physiology; D013154:Spleen / Q000378:metabolism
chemical_list: D006632:Histamine; D007371:Interferon-gamma; D006640:Histidine Decarboxylase