Serotonin (5-HT) and 5-hydroxyindole-3-acetic acid (5-HIAA) levels in neostriatum. n-3 PUFA supplementation modulates 5-HT turnover in both male and female SHR rats. Levels of (a) 5-HT and (b) 5-HIAA were used to determine (c) 5-HIAA/5-HT ratios. The data are presented as means ± SEM (n = 4–8) and the level of significance is symbolized with * (p-value ≤ 0.05), ** (p-value ≤ 0.01) or *** (p-value ≤ 0.001). The p-values are calculated by comparison with the mid bar, which represents control-fed SHRs. The analyses were performed by HPLC using electrochemical detection.