The extraction of SCFAs was performed following the procedure reported in the article of Cresci et al. [19] with some modifications. Briefly, 250 mg of faecal sample was weighed in a 2 ml vial, 250 µl of aqueous sulfuric acid (50 % w/w) were added and the suspension was shaken by vortex for 2 minutes in order to homogenize it. Then a solution of isohexanoic acid in ethyl ether (50 mg l -1 , 500 µl) was added to extract SCFAs by means of a vortex (2 min).
After centrifugation (5 min, 5000 rpm), the upper ethereal solution was injected directly into a gas chromatograph equipped with a flame ionization detector (GC-FID). The GC conditions used are reported in the article by Fiorini et al. [20] .
Results are expressed as means ± S.E.M. All data were submitted to one-way analysis of variance (ANOVA) in order to assess significant differences (p< 0.05) between the contents of individual results in the different rats groups, using the Paleontological Statistics Software Package (PAST) [21] . For behavioural experiments, data were analyzed by one-way ANOVA, using SYSTAT version 10.0 (Systat Software, San Jose, CA, USA).
After centrifugation (5 min, 5000 rpm), the upper ethereal solution was injected directly into a gas chromatograph equipped with a flame ionization detector (GC-FID). The GC conditions used are reported in the article by Fiorini et al. [20] .
Results are expressed as means ± S.E.M. All data were submitted to one-way analysis of variance (ANOVA) in order to assess significant differences (p< 0.05) between the contents of individual results in the different rats groups, using the Paleontological Statistics Software Package (PAST) [21] . For behavioural experiments, data were analyzed by one-way ANOVA, using SYSTAT version 10.0 (Systat Software, San Jose, CA, USA).