title: Season- and gender-dependent changes in the immune function of Siberian hamsters (Phodopus sungorus).
abstract: OBJECTIVE
  Siberian hamsters are photoperiodic animals exhibiting seasonality of reproduction and other physiological functions. Thus, the influence of photoperiod on the in vitro activity of selected immune cells from male and female hamsters challenged with peritoneal inflammation was examined.
  
  
  METHODS
  Animals were housed for 8-10 weeks in LD (L:D=18:6) or SD (L:D=6:18). Peritoneal leukocytes (PTLs) and splenocytes were isolated form male and female and testicular macrophages (TMs) from male hamsters, intact or challenged with zymosan-induced peritonitis. PTL and TM activity was assessed by the level of reactive oxygen species (ROS) measured with the use of flow cytometry and splenocyte activity -- by the spontaneous and mitogen-stimulated proliferation measured with the use of 3H-tymidine incorporation test.
  
  
  RESULTS
  Results obtained indicate that the immune system of Siberian hamsters is highly sexually dimorphic. Experimentally evoked peritonitis developed differently in males and females: only in LD male hamsters an increase in PTL activity was observed after zymosan treatment. Also, in LD males, PTL activity was higher in LD than in SD. Developing peritonitis exerted in these animals a stimulatory effect on splenocyte proliferation but had no influence on cells residing in the immune privileged testes. Splenocyte proliferation, both spontaneous and PHA-stimulated, depended on the photoperiod studied: in LD it was significantly higher than in SD in animals of both sexes.
  
  
  CONCLUSIONS
  Innate immunity of Siberian hamsters studied on the peritoneal inflammation model, seems to be gender- and photoperiod dependent. Moreover, local inflammation may affect other lymphoid organs but does not influence immune-privileged sites.
authors.affiliation: Department of Vertebrate Physiology, Faculty of Biology, Warsaw University, Poland. jpawlak@biol.uw.edu.pl
authors.forename: Joanna
authors.initials: J
authors.lastname: Pawlak
authors.forename: Pawel
authors.initials: P
authors.lastname: Majewski
authors.forename: Magdalena
authors.initials: M
authors.lastname: Markowska
authors.forename: Krystyna
authors.initials: K
authors.lastname: Skwarlo-Sońta
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D006224:Cricetinae; D005260:Female; D007109:Immunity / Q000502:physiology*; D007249:Inflammation / Q000276:immunology / Q000473:pathology; D007962:Leukocytes / Q000276:immunology; D008264:Macrophages / Q000276:immunology / Q000378:metabolism; D008297:Male; D010538:Peritonitis / Q000139:chemically induced / Q000276:immunology / Q000473:pathology; D010587:Phagocytosis / Q000502:physiology; D017111:Phodopus; D017440:Photoperiod; D010835:Phytohemagglutinins / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D012621:Seasons; D012727:Sex Characteristics; D013154:Spleen / Q000166:cytology / Q000276:immunology; D013737:Testis / Q000166:cytology; D013936:Thymidine / Q000378:metabolism
chemical_list: D010835:Phytohemagglutinins; D017382:Reactive Oxygen Species; D013936:Thymidine