Gnotobiotics

Abstract

This chapter provides an overview of the germfree (GF) and defined flora (DF) laboratory rat. One of the main advantages of using GF and DF laboratory rats in biomedical research is that the nutrition and physiology of many such colonies and strains have been well established. These rats have been used extensively, for example, in metabolic experiments. These animals are quite prolific in the isolator environment, notwithstanding the greatly enlarged cecum, which is thought to impair reproduction in GF guinea pigs. The other major uses and importance of GN rats are as nucleus seed stocks for the production of disease-free animals and as diagnostic tools for infectious disease studies, particularly in situations in which routinely used culture media are inadequate. The chapter also presents research applications of gnotobiotic rats. Gnotobiotic animals are particularly suitable for testing candidate viral carcinogens, because derivation by hysterectomy and gnotobiotic maintenance has been found to eliminate all known viruses from GF rats. Immunological studies with GF or DF animals enable one to distinguish primary mediation lesions from those associated with microbial infections. From work on the biological effects of radiation, it has been determined that GF rats survive larger doses of total-body X irradiation for a longer time. In basic immunological studies, GF or DF rats provide information on the role of the microbial flora in stimulating humoral and cell-mediated immune responses.