Figure 3.

Serotonergic Signal is Functionally Sufficient for Overcoming the Loser Effect

(A) Expression patterns of 12F-Gal4/UAS-mCD8:GFP (A1-A2′) and expression patterns of 12F-Gal4 driving UAS-GFP in the presence of Tsh-Gal80 (A3-A4′).

(B) Photoactivation of 12F-Gal4-labeled 5-HT neurons promoted attacks in losers (n = 22–24).

(C) Expression pattern of SPN-split-Gal4/UAS-mCD8:GFP.

(D and E) Optogenetic activation of SPNs induced aggression (D) and rendered short latency to fight (E) in losers (n = 20–25).

(F and G) Activation of P1 neurons promoted aggression with increased attack intensity (F) and reduced latency to fight (G) in losers (n = 21–22).

(H and I) Elevated 5-HT levels in 5-HT neurons induced aggressive actions (H) and reduce the latency to fight (I) in loser pairs (n = 21–28).

(J and K) Pharmacologically increasing the 5-HT levels promoted aggression (J) and decreased the latency to fight (K) in losers (n = 19–22).

(L and M) Elevating the serotonin level in SPNs promoted aggression (L) and decreased the latency to fight (M) in losers (n = 21–24).

(N and O) Simultaneously activating Tph-GAL4 neurons and reducing the serotonin level in the same neurons blocked the loser from gaining aggression (N) and shortening the latency to fight (O) (n = 21–23). The Kruskal-Wallis test was performed for (B), (D)-(I), and (L)-(O); the Mann-Whitney test was performed for (J) and (K). ∗∗P < 0.01; ∗∗∗P < 0.001. Scale bar, 100 μm.

See also Figures S5–S6.