1000 o 5-hT are localized to colonic 8000 chromogranin A-posotive( CgA+) 600 enterochromaffin cells(ECs)(p +oo 铬粒蛋白A阳性的肠嗜铬细胞) SPF GF P21 P42 P21 P42 GFGF +Sp +Sp F+CONv.SPF十ABX +PCPA CgA+ 5-HT SPF GF 5-HT are localized to colonic chromogranin A-posotive (CgA+) enterochromaffin cells (ECs)（嗜 铬粒蛋白A阳性的肠嗜铬细胞）