The impact of housing and high-fructose diet on behavior and cardiovascular response to eucalyptus wildfire smoke in WKY rats

Diet and living conditions are modifiers of behavioral and cardiovascular health, yet the combined effect is understudied, and their potential to alter responses to environmental stressors like wildfire smoke (WS) requires characterization. The purpose of this study was to determine whether housing enrichment (1) mitigates adverse cardiometabolic and neurobehavioral effects following a high fructose diet and (2) decreases responses to WS. Male Wistar-Kyoto (WKY) rats were divided into either depleted (DH) or enriched housing (EH) and fed a normal (ND) or high-fructose (HF) diet. Body composition, metabolism, and behavior were assessed over 30-weeks and cardiac function tested after a single exposure to either filtered air (FA) or flaming eucalyptus WS. EH rats exhibited significantly lower % body fat and higher % lean mass, no difference in weight, and significantly lower respiratory exchange ratio (RER) during the light phase, indicating a shift in basal metabolism after 13 weeks. EH rats habituated faster to acoustic startle and displayed less prepulse inhibition than DH, associated with improved learning and locomotor activity. In general, the effect of housing on behavior was greater than diet, while HF worsened within-group responses. WS increased blood and left ventricular pressure and contractility in EH rats, which was blunted by HF. Thus, housing enrichment appears to (1) improve certain systemic functions and behaviors and (2) enhance cardiovascular responses following WS, but partially blunting the effect of HF. These results indicate a complex interaction between housing and diet over the long-term and potentially altered adverse health risks from environmental smoke exposures.