Automated monitoring of mouse feeding and body weight for continuous health assessment.

Routine health assessment of laboratory rodents can be improved using automated home cage monitoring. Continuous, non-stressful, objective assessment of rodents unaware that they are being watched, including during their active dark period, reveals behavioural and physiological changes otherwise invisible to human caretakers. We developed an automated feeder that tracks feed intake, body weight, and physical appearance of individual radio frequency identification-tagged mice in social home cages. Here, we experimentally induce illness via lipopolysaccharide challenge and show that this automated tracking apparatus reveals sickness behaviour (reduced food intake) as early as 2-4 hours after lipopolysaccharide injection, whereas human observers conducting routine health checks fail to detect a significant difference between sick mice and saline-injected controls. Continuous automated monitoring additionally reveals pronounced circadian rhythms in both feed intake and body weight. Automated home cage monitoring is a non-invasive, reliable mode of health surveillance allowing caretakers to more efficiently detect and respond to early signs of illness in laboratory rodent populations.

Nutritional up-regulation of serotonin paradoxically induces compulsive behavior.

Dietary etiologies or treatments for complex mental disorder are highly controversial in psychiatry. Nevertheless, diet affects brain chemistry (particularly serotonin), and can reduce abnormal behavior in humans and animals. We formulated a diet that elevated brain serotonin and tested whether it would reduce hair pulling in a mouse model of trichotillomania. In a double-blind crossover trial, dietary elevation of brain serotonin unexpectedly increased hair pulling (P = 0.0006) and induced ulcerative dermatitis (UD; P = 0.001). The causative agent for UD is unknown. Therefore, we fed the treatment diet to a second group of mice to test whether UD is behavioral in origin. The diet increased scratching behavior (P < 0.0001). However, high scratching behavior (P = 0.027) and low barbering (P = 0.040) prior to treatment predicted the development of UD. Thus diet can trigger the onset of a complex disorder in the absence of an underlying metabolic deficit. Furthermore, we propose UD as model of compulsive skin-picking.