Methods for Establishment and Maintenance of Germ-Free Rat Models

Abstract

Numerous studies have demonstrated that the gut microbiota plays a vital role in human health and disease development. Although the number of studies on host-microbiota interactions have increased in recent years, the underlying pathogenesis of dysbiosisrelated diseases are still largely unknown. Germ-free (GF) rodent models, with the animals housed in sterile isolators and completely free of microbiota, are useful tools to advance our understanding of host-microbiota relationship in vivo. Although protocols concerning the establishment and maintenance of GF mouse models have previously been reported, the establishment, maintenance and monitoring of GF rodents are laborintensive, tedious and take experience and skills. The aim of our study was to establish a GF rat model for the following microbiota-related researches and provide an easy-touse protocol for the establishment and maintenance of GF rat model in detail, including steps to set up the isolator, sterilize the flexible isolator bubble, import food, water and other supplies, and methods to acquire newborn GF rats, hand rearing of suckling GF rats and reproduction of GF offspring. During the hand feeding period, the body weight of suckling GF rats was weighed once a day to ascertain the amount of artificial milk was given. Based on our results, the body weight of suckling GF rats decreased 1 week after birth and then began to increase. Methods for verifying the quality of the model like assessing the sterile status of the rat colony are also described. Moreover, possible difficulties and challenges, especially during gavage, and suggestions to avoid contamination will be discussed. The protocol presented will facilitate the establishment of GF rat models and downstream microbiota-related researches.

Improved functionality of Ligilactobacillus salivarius Li01 in alleviating colonic inflammation by layer-by-layer microencapsulation

“…The dynamics of bacterial colonization with Li01 in the intestines were investigated in a germ-free SD rat model. Ten male germ-free rats (6-8 weeks old) were maintained according to the methods we established previously 58 . Germ-free rats were fed through gavage with 200 µL of solution containing 10 9 CFU/mL of non-encapsulated Li01 (n = 5) or LbL Li01 (n = 5).…”

“…npj Biofilms and Microbiomes (2021)58 Published in partnership with Nanyang Technological University…”

The effect of Sennoside A on the improvement of lipopolysaccharide -associated encephalopathy through gut microbiota

“…More interestingly, in GF rats, Sennoside A did not lower the ratio of abnormal EEG, or lower TNF-α, IL-1β, and IL-6 levels in rat cortexes. Abnormal EEG and elevated in ammatory mediators indicate the degree of SAE [14] . The present results support the hypothesis that gut microbiota is involved in the pathogenesis of LPS-associated encephalopathy and that Sennoside A exerts its brain protective effects through gut microbiota alteration.…”

“…The animals were housed under a 12-h light/dark cycle in a temperature-controlled room at 24±1°C with free access to food and water. Germ free rats were given free access to germ free food and water (all food, water, bedding and other supplies that were put in the isolator were sterilized in advance) [14] .…”

Oxidized Linoleic Acid Interacts With Gut Microbiota to Promote Colitis and Colorectal Cancer

“…We found that oxidized LA diet altered gut microbiota and failed to promote colitis in antibiotic-treated mice. In our study we did not use the approach of germ-free mice, because it usually requires irradiation to create sterile feed for germ-free mice 25 ; but during this process, the prepared experimental oils (e.g., puri ed corn oil and oxidized corn oil) added in the diets would be degraded and/or oxidized. In addition, we found that oxidized LA diet activated TLR4 signaling in vivo and failed to promote colitis in Tlr4 -/mice.…”