Fig. 1.

Experimental timeline and procedures. Adolescent Lewis rats (PND21) were grouped based on body weight and acoustic startle reactivity and assigned to either a Western-like high-saturated fat diet or a purified control diet with matched ingredients. These diets were consumed for four weeks, after which the rats were divided into four groups through random selection at PND49: (1) control diet, unexposed (CDU); (2) control diet, exposed (CDE); (3) Western diet, unexposed (WDU); (4) Western diet, exposed (WDE); each group comprising n = 14 rats. Exposed groups underwent a well-established 31-day psychosocial stress (PSS) model involving predator encounters and social instability. At PND82, the effects of WD and PSS were evaluated using a comprehensive battery of standard behavioral tests and various measures of stress and inflammation markers. Subsequently, all rats were euthanized, and plasma and brain tissue samples were collected. Abbreviations: ASR, Acoustic startle reflex, EPM, Elevated plus maze; SYM, Social Y-Maze; FPS, Fear-potentiated startle.