| Natural gas containing hydrogen sulphide (H2S) is termed "sour gas", an environmental and occupational toxicant. The toxicity of sour gas has generally been attributed to the presence of H2S. At high concentrations, H2S causes central nervous system (CNS) effects; e.g. fatigue, dizziness, anxiety, headache, convulsions and unconsciousness. However, the effects of low concentrations of H2S are not well understood; low-level exposures are associated with anxiety, cognitive dysfunction, fatigue and memory loss, but no direct evidence for these effects exists. The purpose of this research was to determine the effects of low concentrations of sour gas and H2S on synaptic transmission in the in vitro rat hippocampal slice and examine possible mechanisms of action. Low concentrations of sour gas and H2S cause long-lasting enhancement of synaptic transmission that is NMDA receptor-dependent. These effects may provide support for the CNS symptoms reported in humans following exposure to low-level sour gas and H2S. |
