Modulation of Caffeine-Induced Behavioral Alterations by N-Acetylcysteine in a Pharmacological Challenge Model

Background: Caffeine is a widely consumed psychostimulant that may affect anxiety-like, aggression-like, and social behaviors, potentially in association with oxidative imbalance. Objectives: This study evaluated the behavioral and biochemical effects of acute caffeine exposure in adult zebrafish and investigated the potential protective effects of N-acetylcysteine (NAC). Methods: Sixty adult wild-type AB zebrafish (Danio rerio), approximately 9-10 months old, were assigned to six groups (n = 10/group): control, caffeine (25 or 60 mg/L), NAC (1 mg/L), and NAC combined with either caffeine concentration. Behavioral effects were assessed using the Social Preference Test, Mirror-Biting Test, and Novel Tank Test. Superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities were measured as oxidative stress-related markers. Results: Caffeine increased locomotor activity and induced anxiety-like and aggression-like behavioral alterations, including increased bottom-dwelling, thigmotaxis, and mirror-directed behavior, while reducing social preference. Caffeine significantly increased SOD activity at 25 mg/L (p = 0.010) and 60 mg/L (p = 0.008), and GPx activity at 25 mg/L (p = 0.008) and 60 mg/L (p = 0.006), compared with controls. NAC attenuated caffeine-induced hyperlocomotion and several anxiety-like and aggression-like alterations and modulated antioxidant enzyme responses, but did not fully restore social preference. Conclusions: Acute caffeine exposure produces behavioral alterations and changes in antioxidant enzyme activity in adult zebrafish. NAC partially attenuates these effects, particularly hyperlocomotion, anxiety-like behavior, and aggression-like responses, while showing more limited effects on caffeine-induced social alterations.