Temperature Monitoring in Group Housed Rats

Transcription

1 Temperature Monitoring in Group Housed Rats A Use Case

2 Introduction The Actual Home Cage Analyser has many features that set it apart from traditional rodent monitoring systems. One of the most exciting is the ability to consistently monitor individual temperature in group-housed rats on a 24-hour basis. This use case will outline the equipment and procedures needed to achieve this and discuss some of the results. All of these data have come from the work of Dr Will Redfern at AstraZeneca, who was one of the primary developers of the original ActualHCA system. Equipment: Data Collection The first category of data to be collected is positional information and temperature where the rat is, its position and identity relative to the positions and identities of its cage mates, and its subcutaneous body temperature. This knowledge is vital to successful experimentation and study within group housing environments. First, an RFID chip smaller than a fingertip is injected subcutaneously into each rat. The baseplate RFID chip reader under the home cage then automatically acquires information about position and temperature. Useful as it is, recording position and temperature does not give us everything. The next category to be collected is behavioural data. This is captured using a high-resolution camera with an embedded sensor that offers a side view of the rats. The camera s light source comes from an infrared panel directly over the home cage. The video feed has identity information for each rat that is laid over their individual images, allowing researchers to easily tell them apart. This data is all recorded along with the position and temperature data mentioned above. The recording process is surprisingly simple. Light-dark phase video is picked up from the individual animals and transmitted to a mini-computer that, along with its power supply, is attached to the camera and sits within the cage. This mini-computer gathers all of the raw data, both from the baseplate and the camera, and uploads it to a mobile server unit every few minutes. Below, you can see what some of the raw footage looks like.

3 The video data is processed using behaviour recognition software that automatically analyses footage. The software was developed using video examples annotated by AstraZeneca and MRC Harwell, so it is able to detect a range of different movements and actions. New behaviour detection algorithms and refinements to existing algorithms are released on a four monthly cycle. Old recordings can be reanalysed using the new algorithms, providing the capacity for further analysis without any need to repeat the experiment. This reduces waste and saves a considerable amount of time and money. Top 10 Most Common Behaviours Measured Behaviour Number of events Scratching 593 Rearing 579 Walking 475 Chewing hind paw 334 Licking/chewing coat 298 Immobile 266 Face washing 205 Eating from forepaws 203 Feeding from hopper 190 Drinking 177 Equipment: Housing The rodents are housed in their social groups (or, if required, individually) in a standard home cage. This sits on top of the baseplate and within a standard individually ventilated cage rack. The rack can be wheeled around and the cage itself removed from it easily. One adjacent space in the rack houses the home cage, baseplate, and infrared lighting panel. In the other, you will find the mini-computer, power source, and the camera, which is mounted facing the cage. Continue reading to see a detailed image of the ActualHCA System.

4 Features of the home cage 24 h monitoring system BASEPLATE READER Automated acquisition of ambulatory activity Automated acquisition of subcutaneous temperature RFID data used to ID tag each animal in the video Infrared lighting panel Side-view video camera (Part of) cage rack Mini-computer and power supply IVC home cage Baseplate RFID chip reader (under home cage) Procedure The monitoring and data collection runs on a 24/7 basis. Once the data is transmitted to the server the software s behavioural analysis begins, and it is possible to see some information from that analysis within around fifteen minutes. Some core analyses and plots are produced within the package (e.g. circadian activity). For more complex visualisation and analysis, selections of data can be exported into a statistical package like Microsoft Excel. From there, you can create charts documenting fluctuations in temperature depending on time and housing situation. Effects of single-housing on subcutaneous temperature Decrease in subcutaneous temperature immediately upon housing singly after being housed in groups of 3 Single vs. Group Housed Rats Possible causes: group housing or rats enables intermittent huddling with two cage mates, and may achieve a higher ambient temperature (with two additional rats generating heat) Illustrates just one of several physiological stressors associated with single housing (not to mention the psychological stressors).

5 Results So Far Dr Will Redfern, Associate Director of the Cardiovascular and CNS Translational Centre of Expertise at AstraZeneca, has already conducted some experimentation with ActualHCA. You can see some of the results in the temperature chart above. One of the key observations made by Dr Redfern is the difference in temperature data between rats housed singly and rats housed in groups. As you can see on the chart, there is an immediate decrease in subcutaneous temperature when rats are housed singly after being housed as part of a group of three. The lowered temperature then continues over the long term, mirroring the fluctuations that occur within a group without ever reaching an equivalent baseline. It is possible that the drop in temperature is down to the lack of ability to huddle with other rats, and the ambient temperature of the cage is likely affected by only having one rat inside generating heat. The temperature change is one physiological stress factor that comes with housing rodents alone. This kind of data goes a long way towards illustrating the benefits of a system that allows rodents to be housed in groups, as factors like temperature can make a real impact on drug development studies. It s also worth noting that being housed alone places a psychological stress on rodents that can manifest itself in behaviour, further complicating the process of isolating unusual behaviours and activity. Conclusion In conclusion, ActualHCA offers a capacity for 24-hour monitoring that provides better data and, therefore, the opportunity for better science. For more information, visit the Actual Analytics website or view the webinar hosted with Inside Scientific, 24/7 Automated Behaviour Tracking for Rodent Safety Pharmacology and Phenotyping. How to buy ActualHCA Call: ActualAnalytics on +44 (0) getintouch@actualanalytics.com Visit: