Exogenous Hydrogen Sulfide Within the Nucleus Ambiguus Inhibits Gastrointestinal Motility in Rats

Abstract

Hydrogen sulfide (H₂S) is a neuromodulator in the central nervous system. However, the physiological role of H₂S in the nucleus ambiguus (NA) has rarely been reported. This research aimed to elucidate the role of H₂S in the regulation of gastrointestinal motility in rats. Male Wistar rats were randomly assigned to sodium hydrosulfide (NaHS; 4 and 8 nmol) groups, physiological saline (PS) group, capsazepine (10 pmol) + NaHS (4 nmol) group, L703606 (4 nmol) + NaHS (4 nmol) group, and pyrrolidine dithiocarbamate (PDTC, 4 nmol) + NaHS (4 nmol) group. Gastrointestinal motility curves before and after the injection were recorded using a latex balloon attached with a pressure transducer, which was introduced into the pylorus through gastric fundus. The results demonstrated that NaHS (4 and 8 nmol), an exogenous H₂S donor, remarkably suppressed gastrointestinal motility in the NA of rats (P < 0.01). The suppressive effect of NaHS on gastrointestinal motility could be prevented by capsazepine, a transient receptor potential vanilloid 1 (TRPV1) antagonist, and PDTC, a NF-κB inhibitor. However, the same amount of PS did not induce significant changes in gastrointestinal motility (P > 0.05). Our findings indicate that NaHS within the NA can remarkably suppress gastrointestinal motility in rats, possibly through TRPV1 channels and NF-κB-dependent mechanism.

Keywords: NF-κB; TRPV1; gastric motility; hydrogen sulfide; nucleus ambiguus.

FIGURE 1

Effects of chemicals microinjected into the nucleus ambiguus (NA) on gastric motility. Effects of NaHS (4 nmol in 0.1 μL) microinjected into the NA on gastric motility (representing curve from a rat) (A). Effects of NaHS (8 nmol in 0.1 μL) microinjected into the NA on gastric motility (representing curve from a rat) (B). Representative curve from a rat showing the Effects of 0.1 μL physiological saline (PS) microinjected into the NA on gastric motility (representing curve from a rat) (C).

FIGURE 2

Representative data for gastric motility before and after microinjection of NaHS (4 and 8 nmol) or physiological saline (PS) into the nucleus ambiguus. Data of T.A.C.W (A). Data for T.D.C.W (B). Data for gastric motility index (C). Average inhibitory rate of T.A.C.W, T.D.C.W and gastric motility index (D). Micro: microinjection; T.A.C.W: total amplitude of contraction waves; T.D.C.W: total duration of contraction waves; ^∗∗P < 0.01, versus before microinjection.

FIGURE 3

Representative data for gastric motility in the NaHS (4 nmol in 0.1 μL) group and NaHS (4 nmol in 0.1 μL) + Capsazepine group. Gastric motility curve in NaHS + Capsazepine group (A). Data of T.A.C.W (B). Data for T.D.C.W (C). Data for gastric motility index (D). Micro: microinjection; T.A.C.W: total amplitude of contraction waves; T.D.C.W: total duration of contraction waves; ^∗∗P < 0.01, versus before microinjection.

FIGURE 4

Representative data for gastric motility in the NaHS (4 nmol in 0.1 μL) group and NaHS (4 nmol in 0.1 μL) + L703606 group. Gastric motility curve in NaHS + L703606 group (A). Data of T.A.C.W (B). Data for T.D.C.W (C). Data for gastric motility index (D). Micro: microinjection; T.A.C.W: total amplitude of contraction waves; T.D.C.W: total duration of contraction waves; ^∗∗P < 0.01, versus before microinjection.

FIGURE 5

Representative data for gastric motility in the NaHS (4 nmol in 0.1 μL) group and NaHS (4 nmol in 0.1 μL) + PDTC group. Gastric motility curve in NaHS + PDTC group (A). Data of T.A.C.W (B). Data for T.D.C.W (C). Data for gastric motility index (D). Micro: microinjection; T.A.C.W: total amplitude of contraction waves; T.D.C.W: total duration of contraction waves; PDTC: pyrrolidine dithiocarbamate; ^∗∗P < 0.01, versus before microinjection.