EFFECT OF METABOLIC CAGE HOUSING ON METABOLIC CHANGES IN THE LIVER OF YOUNG MALE LABORATORY RATS

Abstract

The aim of this study is to investigate if a metabolic cage housing is appropriate for studies of metabolic changes in rat liver. Metabolic cages are intended for separately collecting animal urine and feces and for measuring of feed and water consumption. They are often used in biomedical research, especially in studies involving metabolism and nutrition, where it is necessary to control the total intake of feed and water. In numerous studies, researchers have found that housing in a condition similar to housing in metabolic cages i.e. grid floor, lack of bedding, lack of movement, and single housing, could cause stress and thus alter the results and influence the research. Two months old male Wistar rats were randomly assigned to two different housing systems for a three week period. One group of rats was housed individually in metabolic cages and rats in the other group were paired and housed in polycarbonate type IV cages with wood shavings bedding material. The body mass and feed consumption were monitored daily. At the end of the study, four rats from each group were anesthetized and the liver and blood samples were taken. The rest of the rats were used for primary hepatocytes cell culture to determinate glucose production. Metabolic cage housing conditions in our study did not cause stress of sufficient impact to alter the test parameters. Key words: metabolic cage; hepatocytes; insulin resistance; plasma lipids VPLIV BIVANJA V PRESNOVNI KLETKI NA SPREMEMBE V PRESNOVI JETER PRI MLADIH PODGANJIH SAMCIH Povzetek: Cilj študije je bil raziskati ali je bivanje v presnovnih kletkah primerno za proučevanje presnovnih sprememb v podganjih jetrih. Presnovne kletke so namenjene ločenemu zbiranju živalskega urina in blata ter merjenju porabe krme in vode. Pogosto se uporabljajo v biomedicinskih raziskavah, zlasti v študijah presnove in prehrane, kjer je potrebno nadzorovati skupni vnos krme in vode. V številnih študijah so raziskovalci ugotovili, da lahko bivanje v pogojih, ki so podobni metabolnim kletkam tj. na tleh, ki so sestavljena iz mrež, pomanjkanju nastilja, pomanjkanju gibanja in posamičnem bivanju živali povzroča stres in lahko vpliva na rezultate raziskav. Dva meseca stare samce podgan Wistar smo naključno razporedili v dva različna sistema za nastanitev za obdobje treh tednov. Ena skupina podgan je bila nameščena posamično v presnovnih kletkah, podgane druge skupine pa so bile nastanjene v parih v klasičnih polikarbonatnih kletkah tipa IV s steljo iz lesnih ostružkov. Dnevno smo spremljali njihovo telesno maso in porabo krme. Na koncu študije smo štiri podgane iz vsake skupine anestezirali in odvzeli vzorce jeter in krvi. Preostale podgane smo uporabili za pridobivanje primarnih jetrnih celic z namenom določanja proizvodnje glukoze. Pogoji bivanja v presnovnih kletkah v študiji niso povzročili stresa, ki bi imel značilen vpliv na proučevane spremenljivke. Ključne besede: presnovna kletka; jetrne celice; odpornost na inzulin; plazemske maščobe