Feeding Data

We are using the data from a rat feeding experiment originally described in Kramer et al. (2010) – Experiment 1, and from a small pilot experiment – Experiment 2, unpublished data. These studies were approved by the Baylor College of Dentistry Institutional Animal Care and Use Committee and conducted in accordance with the USDA and National Institutes of Health guidelines (National Research Council, 2011). The designs for Experiments 1 and 2 was identical except for the quantity of CFA injected and the duration of monitoring. Young adult male Sprague-Dawley Harlan Industries, Houston, TX rats were caged individually in sound-attenuated modules equipped with photobeam computer-activated pellet feeders (Med Assoc. Inc., East Fairfield, VT) and given food and water ad libitum. The animals were kept on a 12 h/12 h light/dark cycle with lights on at 08:00. All rats were given precision made 45 mg rodent pellet diet (Bioserv, Frenchtown, NJ). When a rat removed a pellet from a trough of the feeder this signaled the computer to drop another pellet into the trough. The computer recorded each time the pellet was released with 1 s precision. The computer record of pellet drop times provided a raw data for meal pattern analyses. It should be noted that the rats on average drop less than five pellets per day. In Experiment 1, after acclimating in the feeders for at least two days the rats received either bilateral CFA injections (250 μg/50 μL per side) or physiological saline injections (50 μL of 0.9%) into TMJ. The day of injection was taken as day 0 when 15 rats were injected with CFA and 13 with saline solution. At day 21 one saline-injected rat and two CFA-injected rat were sacrificed for tissue analysis in the previous study (Kramer et al., 2010) thus reducing the number of animals monitored. On day 22 the saline-injected animals were injected CFA (n=6) or saline (n=6) (same amounts as for TMJ injection) into the knee. The animals were monitored for a period of up to 41 days after the TMJ injection. One CFA-injected animal was removed from analysis because the animal experienced weight loss due to poor feeding and thus was not representative of the population of interest. The total number of meals per day varied from 48 to 147 in the saline group and from 54 to 126 in the CFA group. For further details of this experiment see Kramer et al. (2010). In experiment 2, ten rats were injected with either 15 μg/50 μL per side of CFA (n=6) or 50 μL physiological saline (n=4) solution into the TMJ. The animals were monitored for eight days post-injection. Other conditions were the same as in Experiment 1. The total number of meals per day varied from 16 to 28 in the saline group and from 16 to 32 in the CFA group.