Correlations between main variables.

<p>Correlational analysis of impulsive responses during the first long ITI session in the 5-CSRTT and the data from the 5^th session of the Pavlovian conditioned approach task: Impulsivity and goal-tracking responses (number of magazine nose-pokes) (a); impulsive responses and sign-tracking responses (number of lever presses) (b); goal-tracking and sign-tracking responses (c); goal-tracking responses and time spent nose-poking in the food magazine during the first long ITI session in the 5-CSRTT) (d). P(closed circles), NP (open circles).</p

Intermittent access two-bottle choice procedure.

<p>Data represent the mean ± SE of alcohol preference (a) and alcohol intake (g/kg/day) (b) during the 12 sessions of intermittent access to alcohol in alcohol-preferring rats (P, closed squares) and alcohol-non-preferring rats (NP, open circles). All p<0.05 (adjusted after Bonferroni correction): (*) significant group differences, (•) vs session 1.</p

Pavlovian conditioned approach.

<p>Acquisition of Pavlovian conditioned approach in alcohol-preferring rats (P, closed squares) and alcohol-non-preferring rats (NP, open circles). Data are means ± SE of total lever presses (sign-tracking responses, a), total magazine nose-pokes during the CS-lever presentations (goal-tracking responses, b), and total time spent nose-poking during the CS-lever presentations (c). All p<0.05: (*) significant group differences, (•) versus session 1 in NP rats.</p

5-CSRTT.

<p>Performance of alcohol-preferring rats (P, closed squares) and alcohol-non-preferring rats (NP, open circles) in the 5-CSRTT, during baseline sessions (ITI = 5s) and during the long ITI challenge session (ITI = 7s) before and after the 4-week alcohol intake. Data are means ± SE of % premature responding (a), attentional accuracy (b), % omissions (c), correct response latency (d), food magazine latency (e) and time spend nose-poking in the food magazine (f). All p<0.05: (≠) vs baseline A, (σ) vs previous sessions; (*) significant difference between P and NP rats in the same session; (•) vs baseline A in P rats, (∞) vs baseline A and B; (x) versus pre-alcohol sessions in NP rats.</p

Reduced p-p38 staining in the colon of Boc2-treated C57BL/6 and <i>Fpr2/3</i>^-/- mice.

<p>Immunofluorescence (top panel) of phospho-p38 of intestinal whole mount preparations (as described in Material and Methods) in either PBS-vehicle treated, Boc2 treated or <i>Fpr2/3</i>^-/- intestinal mucosa. The middle and bottom panel show the bright field and the overlay pictures of the same samples.</p

Reduced anxiety-like behaviour of <i>Fpr2/3</i>^-/- mice in the open field test.

<p>The bar graphs and images show total number of squares crossed, rears and centre crossings during a 5-minute session. Values are expressed as median ± S.E.M. and representative of four experiments, each involving 6–9 mice per group. * <i>P</i><0.05 indicate significant values compared with wild-type (WT) control mice (Mann–Whitney <i>U</i>-test).</p

Increased discriminatory activity of <i>Fpr2/3</i>^-/- mice in the novel object recognition test.

<p>The bar graph in <b>A</b> shows the total time (seconds) spent exploring the objects used in the test (shown in the top picture) during the 10-minute acquisition phase (left panel) and the % of time spent on the novel object (shown in the bottom picture) in the subsequent 5-minute test phase (right panel). The bar graphs in <b>B</b> show the total number of arm entries and spontaneous alternation percentage (calculated as described in material and Methods section) in the Y-maze during a 5-minute trial. Values are expressed as median ± S.E.M. and representative of n = 4 different experiments involving 6–9 mice per group. ** <i>P</i><0.05 indicates significant values compared with wild-type (WT) control mice (Mann–Whitney <i>U</i>-test).</p

Boc2-treatment increases the recognition of a novel object in C57BL/6 mice.

<p>The bar graphs show the total time (seconds) spent exploring the objects used in the test during the 10-minute acquisition phase (left panel) and the % of time spent on the novel object in the subsequent 5-minute test phase (right panel) of Boc2-treated mice compared to PBS vehicle-treated mice. Values are expressed as median ± S.E.M. and representative of four different experiments involving 6 mice per group. ** <i>P</i><0.01 indicates significant values compared to PBS-vehicle treated mice (Mann–Whitney <i>U</i>-test).</p

Hypothetical schema of the role of Fpr2/3 at the interface of the gut-brain axis.

<p>Non-pathogenic gut microbiota releases physiological levels of formylated peptides that activate FPR signalling in the gut epithelium. This homeostatic level of protective inflammation influences brain function maintaining a physiological level of focus and attention. The blockage of FPR signalling by an antagonist or the absence of gut microbiota causes a reduction in FPR activation and a parallel increase in the state of alertness, as observed in <i>Fpr2/3</i>^-/- and Boc2-treated mice.</p

Increased exploratory behaviour of <i>Fpr2/3</i>^-/- mice in the climbing test.

<p>The bar graphs show the number of climbing events and total time (seconds) spent on the climbing mesh during a 5-minute trial. Values are expressed as median ± S.E.M. and representative of three different experiments, each involving 6–9 mice per group. * <i>P</i><0.05 indicate significant values compared with wild-type (WT) control mice (Mann–Whitney <i>U</i>-test).</p