Forsøksdyr: Core temperature measurements in mice using wireless telemetry system

Godkjenningsdato 25.10.2018

Godkjenningsperiode 25.10.2018-01.11.2020

Cold exposure at working places is prevalence in Norway and affect the human body functions. Precise thermoregulation in response to cold, is necessary for maintenance of normal processing of cell activities which ensure the health status. Therefore, studying the effect of cold exposure on health requires some considerations like studying the core body temperature and studying its connection to other physiological processes.

In mammals, thermoregulation and maintenance of core body temperature, which is so crucial for normal physiological functions and survival, depends on both neural and humoral regulation in awake status. Mice are small, easily housed and maintained animals, and adapt well to new surroundings. Their genetic, biological and behaviour characteristics closely resemble those of humans, and many symptoms of human conditions can be replicated in mice. This study will be done on C57BL/6 mice. Availability of genetic models of C57BL/6 mice has made them efficient research animals for further studies. In addition, the same mouse strain/age/sex is used in our cold exposure studies (FOTS ID # 11816).

Conventional core body measurements in mice are hampered by biases. Temperature measurements using rectal probes is an invasive approach and should be done under anaesthesia. Heating pad affects the core body temperature, whereas not using one may lead to hypothermia. Alternatively, rectal probes may be used on scuffed mice, but results in stress and possible hyperthermia. Furthermore, surrogate measurement of surface body temperature using infrared detection in free moving animals has several limitations due to the insulative properties of the fur and variable blood-flow in visible skin (ears and tail). Accordingly, we aimed to use a more accurate method to continuous measurement of core body temperature under different ambient temperatures. To this end, we will establish methods for core temperature measurements in mice using telemetry: wireless transmission of data from a bodily implanted electronic device and reception of measured temperature with an external receiver.

The aim of this study is ex vivo technical, and surgical validation of telemetry temperature logger application. Intraperitoneal or subcutaneous implantation of loggers will be done under anesthesia and analgesia to eliminate pain and distress. To study the functional accuracy and practicality of intraperitoneal or subcutaneous implanted loggers, real-time telemetric measurement of core body temperature will be done under exposure at different ambient temperatures within a euthermic zone (down to 4-6°C or at thermoneutral temperature 27-30 °C) with or without application of thermoregulatory modulators which is not expected to induce pain or permanent damage to animal.

This methodology will help to increase the knowledge about factors influencing thermal tolerance and sensitivity, and possible implications for health status.

This is a pilot study in which 150 C57BL/6 mice (Mus musculus) will be used. The power analyses, the results of previous experiments and literature have been used to estimate the sample size.

The aim of this experiment may not be accomplished using alternative methods. The number of mice are a minimum required. The methods have been and will be refined to avoid pain and distress.