Key Words:        

Microbiota, Metabolism, Type II diabetes, Obesity

Purpose:

Basic research; translational and applied research; maintenance of colonies of genetically altered animals.

Objectives:

It is now admitted that the gut microbiota plays an important role on the host energy metabolism, particularly in the context of the metabolic syndrome. In order to develop optimal personalised nutrition for energy intake, it is proposed to study the role of some specific gut bacteria on the host energy metabolism, particularly on the liver, as it is a crucial organ in glucose and lipid metabolism.

These bacteria are also suspected to influence the foetal programming of metabolic diseases such as type II diabetes. This programme of work will therefore also focus on the inheritance of a “diabetic” microbiota from the mother to its offspring and determine its impact on future health in a rodent model susceptible to developing type II diabetes.

On one hand, the development of obesity leading to metabolic syndrome is strongly associated with cardiovascular diseases in Western countries, which results in a growing number of premature deaths. On the other hand, preterm babies or malnourished populations in developing countries must optimise their energy intake.

Understanding the molecular links between gut microbiota and the host metabolism will enable the development of personalised nutrition plans that also consider the right gut microbial balance for a relatively energy efficient ecosystem adapted in a medical context.

Animals used:

We will use exclusively mouse models of type II diabetes and wild type controls. We estimate that we will need a maximum of 750 animals over the entire duration of the project.

Adverse effects:

All the procedures described in this project licence are expected to be of mild to moderate severity. This includes blood collection and oral gavage that may induce transient pain and discomfort.

Antibiotic treatment may also cause mild diarrhoea and abdominal pain. Some discomfort is also expected as a result of weight gain. All animals will be killed at the end of the experiment. Only some of the pups that have been rejected by the foster mother and assessed to be in good health will be reused as breeders.

Replacement:

This programme of work investigates the relationship between the host and its gut microbiota in the context of type II diabetes. This requires a living organism with a physiology relevant to humans in which type II diabetes can be simulated.

As mice have been extensively used over the last 50 years to investigate host-gut microbial relationships, they are considered suitable models for the purpose of this work. Two mouse models will be used: a diet-induced obesity mouse model and a genetic model of type II diabetes.

Reduction:

The primary outcome of this study is to study the impact of bacteria on hepatic metabolism assessed using a metabolic profiling approach. Previous animal experiments have suggested that 7 animals per group were sufficient to ensure statistically meaningful results in this model using similar techniques. A professional statistician will be consulted where appropriate.

Refinement:

As explained above, this programme of work requires the use of a living organism relevant to type II diabetes development in humans. Diet-induced obesity and genetically obese mice are therefore the most appropriate and most refined animal models.

We are committed to keep animal discomfort to a minimum and have refined our protocol to limit the number of invasive procedures to a minimum. Although it is necessary to control the dose of live bacteria given to each animal using oral gavage, we will ensure that this procedure is performed by an experienced technician to minimise the risk of adverse effects.

Brief inhalation anaesthesia may be used to reduce stress and discomfort as recommended if necessary. It is also planned to collect urine and fecal samples weekly. This will require a brief manipulation of the animals followed by a short isolation time in an individual cage. This will avoid the use of more restrictive and stressful individual metabolic cages.