HTR1A and small intestine disorder: Rats with NSAID-induced small intestinal disease showed lower levels of NOS1(P < 0.05), and higher levels of HTR4, HTR1a, F2RL3, CALCA, NPY, CRHR2, IL1b, P2RX3, TPH1, HMOX1, TRPV1, VIP, F2RL1, SLC6A4, TFF2, AQP8(P < 0.05).