EFFECTS OF 1,3-1,6 ß-GLUCAN FEED INCLUSION ON CAUDAL FIN REGENERATION PERFORMANCES OF ZEBRAFISH Danio rerio

Zebrafish (Danio rerio) are considered an interesting animal model for studying the tissue regeneration mechanisms because able to regrow amputated fins. Neutrophils and macrophages have shown functionally important role in tissue repair. Macrophages appear to act as the key regulatory cells for skin repair by removing dead tissues and killing pathogens. Macrophages also produce growth factors that stimulate other cells involved in wound healing. Since β-glucans may "activate" immune cells and macrophages in particular, our hypothesis is that they may positively affect the tissue regeneration process. For these reasons, we investigated the effect 1,3-1,6 β-glucan (extract form yeast cell wall) on caudal fin regeneration in zebrafish. Ninety fish were distributed into 3 groups (3 replicates). Two products were used as source of 1,3-1,6 ß-glucan: MacroGard® and new MacroGard (Biorigin©), MI and MII, respectively. Fish daily feed intake was estimated in advance (3.75% BW) and both MI and MII included into the feed for reaching the dose of 12.5 mg kg-1 BW. Feeding treatment with MI and MII was started just after amputation. The fin regeneration process was observed and described by measuring the fin regenerated area (RA=(x dpa fin area/pre-amputation fin area)*100) and calculating the daily regenerated area (DRA=(x dpa fin area-x+1 dpa fin area)/pre-amputation fin area)*100). The fin regeneration process is also described by a quadratic equation. MacroGard® showed a significantly (P<0.05) positive effect on the fin regeneration process already after 6 days of treatment; in particular these differences were significantly for both RA and DRA for group MI, and for DRA only for group MII, always in comparison to control group. During all the experimental period, no statistically significant differences (P>0.05) were observed between the two experimental groups. Further studies are necessary for understanding the mode of action of 1,3-1,6 ß-glucan on fin regeneration.