Hydrogen Sulphide Production in Healthy and Ulcerated Gastric Mucosa of Rats.

Hydrogen sulphide (H₂S) is produced endogenously via two enzymes dependent on pyridoxal phosphate (PLP): cystathionine beta-synthase (CBS, EC 4.2.1.22), cystathionase γ-liase (CTH, EC 4.4.1.1), and a third, 3-mercaptopyruvate sulfurtransferase (MPST, EC 2.8.1.2). H₂S strengthens the defence mechanisms of the gastric mucosal barrier, and plays an important role in gastroprotection, including the increased resistance to damage caused by various irritants and non-steroidal anti-inflammatory drugs. The study was conducted to determine the role of H₂S in ulcerated gastric mucosa of rats caused by immobilization in cold water (WRS). The activity and expression of γ-cystathionase, cystathionine β-synthase, 3-mercaptopyruvate sulfurtransferase, and rhodanese was compared with healthy mucosa, together with H₂S generation, and cysteine, glutathione, and cystathionine levels. The results showed that the defence mechanism against stress is associated with stimulation of the production of H₂S in the tissue and confirmed the observed advantageous effect of H₂S on healing of gastric ulcers. In case of animals pretreated with exogenous sources of H₂S and NaHS, and some changes observed in the ulcerated gastric mucosa tend to return to values found in the healthy tissue, a finding that is in accordance with the previously determined gastroprotective properties of H₂S. The results presented in this paper point to the possible role of rhodanese in H₂S production in the gastric mucosa of rats, together with the earlier mentioned three enzymes, which are all active in this tissue.