A refined technique for sciatic denervation in a golden-mantled ground squirrel (Callospermophilus lateralis) model of disuse atrophy.

Disuse atrophy of both muscle and bone can occur rapidly during periods of inactivity. In several rodent models developed for the study of disuse atrophy, immobilization is induced by prolonged cage restraint, hind limb unloading, tenotomy, sciatic nerve block or sciatic denervation. In less tractable species such as wild-caught hibernating rodents, the sciatic denervation model is superior in terms of both animal welfare and applicability to the characteristics of natural cases of disuse atrophy. The authors describe a refined surgical approach to sciatic denervation in golden-mantled ground squirrels (Callospermophilus lateralis), a hibernating species, that improves animal welfare and reduces the incidence of post-operative complications such as autotomy.

Bone strength is maintained after 8 months of inactivity in hibernating golden-mantled ground squirrels, Spermophilus lateralis.

Prolonged inactivity leads to disuse atrophy, a loss of muscle and bone mass. Hibernating mammals are inactive for 6-9 months per year but must return to full activity immediately after completing hibernation. This necessity for immediate recovery presents an intriguing conundrum, as many mammals require two to three times the period of inactivity to recover full bone strength. Therefore, if hibernators experience typical levels of bone disuse atrophy during hibernation, there would be inadequate time available to recover during the summer active season. We examined whether there were mechanical consequences as a result of the extended inactivity of hibernation. We dissected femur and tibia bones from squirrels in various stages of the annual hibernation cycle and measured the amount of force required to fracture these bones. Three groups were investigated; summer active animals were captured during the summer and immediately killed, animals in the 1 month detraining group were captured in the summer and killed following a 1-month period of restricted mobility, hibernating animals were killed after 8 months of inactivity. A three-point bend test was employed to measure the force required to break the bones. Apparent flexural strength and apparent flexural modulus (material stiffness) were calculated for femurs. There were no differences between groups for femur fracture force, tibia fracture force, or femur flexural strength. Femur flexural modulus was significantly less for the 1 month detraining group than for the hibernation and summer active groups. Thus, hibernators seem resistant to the deleterious effects of prolonged inactivity during the winter. However, they may be susceptible to immobilization-induced bone loss during the summer.

Temporal and temperature effects on the maximum rate of rewarming from hibernation.

During hibernation animals oscillate from near ambient (T(a)) to euthermic body temperatures (T(b)). As animals arouse, the rate of rewarming (RRW) might be expected to simply increase as a function of time. We monitored the T(b) of golden-mantled ground squirrels (Spermophilus lateralis) housed at 4, 8, 12, and 16 degrees C during natural arousals. The maximum RRW, the time required to reach a maximum RRW, and the relative time index all demonstrated negative relationships with T(a). The T(b) corresponding to maximal RRW demonstrated a positive relationship with T(a). Squirrels reached maximal RRW when they had generated 30 to 40% of the heat required to reach a euthermic T(b). These data suggest that arousal is more constrained than expected and that both time and temperature influence the RRW.

Desert Survivors: the design and implementation of a television program to enhance local scientific literacy.

Outreach efforts by faculty members are oftentimes limited in scope due to hectic schedules. We developed a program to enhance science literacy in elementary school children that allows experts to reach a tremendous audience while minimizing their time commitment. The foundation of the program is a television series entitled "Desert Survivors." The episodes air on local cable access television and are available to teachers on DVD. Each episode features a guest expert who spotlights a particular organism and how that organism overcomes the myriad of hardships inherent to desert survival. Local classrooms are visited to solicit questions from students regarding the organism of interest. These videotaped questions are integrated into Desert Survivors television production and provide the guest expert with the basis to discuss the ecology, physiology, and evolutionary biology of the organism. The program is bolstered through the use of an interactive website. Assessment strategies are in place to ensure program efficacy. Herein, we describe the development of the program as a model for innovative outreach opportunities.