Preference assessments as a tool to evaluate environmental enrichment.

Environmental enrichment is an important tool utilized to improve animal welfare in zoological institutions through opportunity for mental and physical stimulation. Many past studies have focused on the impact enrichment has on animal behavior; however, none have conducted preference assessments on enrichment items to examine the relationship between animals' preferences and interaction with enrichment over a 24-hr period. Ten-minute free operant, paired-choice preference assessments were implemented in Study 1 to determine the enrichment preferences of African lions (N = 3). Following Study 1, Study 2 was conducted, which examined the behavior of African lions with enrichment items over the course of 30, 24-hr trials to evaluate the relationship between preferences established in Study 1 and long-term interaction with the enrichment. Generalized estimating equations revealed a statistically significant relationship between the percentage of time the enrichment was approached first and the average duration of interaction in Study 1 to the total duration of interaction and the percent of hours interacted with the item in Study 2. Additionally, the first 2 min of the preference data resulted in comparable statistically significant findings, demonstrating shorter preference assessments can produce similar results. The results support our prediction that preference assessments can be used to estimate the amount of interaction with enrichment over the course of time, with preferred items being interacted with more frequently and in longer duration. Information gained from this study suggests preference assessments can be a time and cost-effective tool to evaluate enrichment preference and predicted efficacy.

Cardiac-specific overexpression of metallothionein rescues against cigarette smoking exposure-induced myocardial contractile and mitochondrial damage.

OBJECTIVES: Second hand cigarette smoke is an independent risk factor for cardiovascular disease. Although a tie between smoking and cardiovascular disease is well established, the underlying mechanisms still remains elusive due to the lack of adequate animal models. This study was designed to use a mouse model of exposure to cigarette smoke, a surrogate of environmental tobacco smoke, to evaluate the impact of cardiac overexpression of heavy metal scavenger metallothionein on myocardial geometry, contractile and intracellular Ca(2+) properties and apoptosis following side-stream smoke exposure. METHODS: Adult male wild-type FVB and metallothionein transgenic mice were placed in a chamber exposed to cigarette smoke for 1 hour daily for 40 days. Echocardiographic, cardiomyocyte contractile and intracellular Ca(2+) properties, fibrosis, apoptosis and mitochondrial damage were examined. RESULTS: Our data revealed that smoke exposure enlarged ventricular end systolic and diastolic diameters, reduced myocardial and cardiomyocyte contractile function, disrupted intracellular Ca(2+) homeostasis, facilitated fibrosis, apoptosis and mitochondrial damage (cytochrome C release and aconitase activity), the effects of which were attenuated or mitigated by metallothionein. In addition, side-stream smoke expose enhanced phosphorylation of Akt and GSK3ß without affecting pan protein expression in the heart, the effect of which was abolished or ameliorated by metallothionein. Cigarette smoke extract interrupted cardiomyocyte contractile function and intracellular Ca(2+) properties, the effect of which was mitigated by wortmannin and NAC. CONCLUSIONS: These data suggest that side-stream smoke exposure led to myocardial dysfunction, intracellular Ca(2+) mishandling, apoptosis, fibrosis and mitochondrial damage, indicating the therapeutic potential of antioxidant against in second smoking-induced cardiac defects possibly via mitochondrial damage and apoptosis.