Chemically induced cone degeneration in the 13-lined ground squirrel.

Animal models of retinal degeneration are critical for understanding disease and testing potential therapies. Inducing degeneration commonly involves the administration of chemicals that kill photoreceptors by disrupting metabolic pathways, signaling pathways, or protein synthesis. While chemically induced degeneration has been demonstrated in a variety of animals (mice, rats, rabbits, felines, 13-lined ground squirrels (13-LGS), pigs, chicks), few studies have used noninvasive high-resolution retinal imaging to monitor the in vivo cellular effects. Here, we used longitudinal scanning light ophthalmoscopy (SLO), optical coherence tomography, and adaptive optics SLO imaging in the euthermic, cone-dominant 13-LGS (46 animals, 52 eyes) to examine retinal structure following intravitreal injections of chemicals, which were previously shown to induce photoreceptor degeneration, throughout the active season of 2019 and 2020. We found that iodoacetic acid induced severe pan-retinal damage in all but one eye, which received the lowest concentration. While sodium nitroprusside successfully induced degeneration of the outer retinal layers, the results were variable, and damage was also observed in 50% of contralateral control eyes. Adenosine triphosphate and tunicamycin induced outer retinal specific damage with varying results, while eyes injected with thapsigargin did not show signs of degeneration. Given the variability of damage we observed, follow-up studies examining the possible physiological origins of this variability are critical. These additional studies should further advance the utility of chemically induced photoreceptor degeneration models in the cone-dominant 13-LGS.

Exploring Mechanisms of Action in Exposure-Based Cognitive Behavioral Therapy for Eating Disorders: The Role of Eating-Related Fears and Body-Related Safety Behaviors.

Evidence-based cognitive behavioral therapy for eating disorders includes a component of exposure therapy, which involves patients confronting feared eating and body-related stimuli while preventing safety behaviors. With recent research demonstrating that eating-related fears and safety behaviors are central to eating disorder pathology, there is increased emphasis on improving the efficacy of exposure therapy in eating disorders. Doing so will require a better understanding of important mechanisms of action in this treatment. The present study explored how changes during treatment in eating-related fears and avoidance as well as body-related safety behaviors influence overall treatment outcomes. Individuals with eating disorders (N = 71) receiving exposure-based treatment completed measures of global eating disorder severity at admission and discharge. Hypothesized mechanisms of action were also assessed at admission and discharge as well as at a 2-week time point after beginning treatment. Path modeling analyses showed that decreased eating-related cognitions (feared concerns about eating) and emotions (anxiety about eating) at the 2-week time point were prospectively predictive of lowered global eating disorder symptom severity at discharge. Additionally, reduced body checking and avoidance behaviors after 2 weeks of treatment were also associated with lower eating disorder severity at discharge. These findings highlight the importance of exposure-based therapy in eating disorders and the need to uniquely address eating-related fears and safety behaviors.