Metabolic changes in rat brain synaptosomes after exposure to sulfide in vivo

Effects of hydrogen sulfide on neurobehavioral function

BACKGROUND

Nineteen hydrogen sulfide (H2S)-exposed patients were compared with 202 unexposed subjects. This 1997-to-2001 case-referent series was compared with 16 previous (1991-1996) case-referent patients.

METHODS

New patients were bystanders of H2S exposure and none had been unconscious. In contrast, 13 members of the prior group were exposed at work and 7 had been unconscious. The three groups were compared on the basis of 8 physiologic and 12 psychological measurements. Observed measurements were compared with predicted ones after adjusting for age, sex, educational attainment (years), and other significant factors (observed/predicted x 100).

RESULTS

The new group performed poorly compared with unexposed controls and were similar to the first group on balance, reaction time, color discrimination, visual performance, hearing, Culture Fair, digit symbol, vocabulary, verbal recall, peg placement, trail making A and B, and information.

CONCLUSION

H2S impairments associated with H2S were similar in 19 workers (44% had been unconscious) and in 16 bystanders who had not been unconscious.

Lead as an inductor of some morphological and functional changes in synaptosomes from rat brain

1. The effect of lead (in vivo) on the uptake of GABA, dopamine, and histidine as a precursor of histamine in synaptosomes obtained from chronically lead-treated rats was studied. 2. Lead decreased the uptake of GABA, increased the uptake of dopamine, and did not change the uptake of histidine. These effects were independent of calcium concentration. 3. Lead administration to the rat changed the morphology of the synaptosomes, as manifested in the decreased number of synaptic vesicles and disturbed mitochondrial structure. 4. The results suggest the existence of several mechanisms of lead toxicity on uptake, related to individual neurotransmitters, which are not necessarily connected with a Pb2+/Ca2+ interaction.

Brain sulfide levels in anaesthesia: a comparison with hydrogen sulfide intoxication

Although sublethal concentrations of hydrogen sulfide produce a state not unlike anaesthesia, measurement of rat brain sulfide levels by gas dialysis and IC with electrochemical detection after either 1.5 g/kg urethane or 42 mg/kg pentobarbital failed to demonstrate any changes as compared with endogenous brain sulfide levels of saline-injected controls. This suggests that the mechanisms underlying anaesthesia are not directly linked to endogenous cerebral sulfide levels.

Peroxidation induced changes in synaptosomal transport of dopamine and gamma-aminobutyric acid

The effects of iron-dependent peroxidation on respiration and neurotransmitter transport of brain nerve endings has been studied. Rat brain synaptosomes were peroxidized by exposure to an ADP-Fe/ascorbate system and the protective effect of added Se, Cd, or Zn was investigated with regard to dopamine and gamma-aminobutyric acid (GABA) transport. Peroxidation impaired the respiration of synaptosomes by about 20% and caused a marked increase in dopamine uptake; but in contrast, peroxidation induced a large decrease in synaptosomal uptake of GABA. The increased dopamine transport into synaptosomes was partially prevented by the presence of Zn, Se, or Cd. The presence of Zn, Cd, or Se, in order of decreasing effectiveness, also slowed down ADP-Fe/ascorbate mediated peroxidation of synaptosomes. Peroxidation caused a significant inhibition of veratridine-dependent release of both dopamine and GABA from synaptosomes, but the KCl-dependent release of these neurotransmitters was not effected by peroxidation. These results implicate that peroxidation damage of nerve endings may lead to large changes in neurotransmitter transport thus resulting in an alteration in the function of the central nervous system.