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Summary
Patients with hepatic cirrhosis show normal serum tryptophan but increased brain levels, suggesting elevated serotonin. Hepatic coma did not alter CSF tryptophan but showed increased 5-HIAA, which normalized after probenecid treatment.
Area of Science:
- Neurochemistry
- Hepatology
- Biochemical Psychiatry
Background:
- Hepatic cirrhosis can affect neurotransmitter metabolism.
- Altered tryptophan and serotonin levels are implicated in hepatic encephalopathy.
Purpose of the Study:
- To investigate tryptophan and 5-hydroxyindoleacetic acid (5-HIAA) concentrations in serum and cerebrospinal fluid (CSF) in patients with hepatic cirrhosis.
- To explore the relationship between these metabolites and hepatic coma.
Main Methods:
- Measurement of serum and CSF tryptophan concentrations.
- Measurement of CSF 5-HIAA concentrations.
- Analysis of metabolite levels in cirrhotic patients with and without hepatic coma, and in control groups.
- Assessment following probenecid administration to block 5-HIAA egress.
Main Results:
- Cirrhotic patients had normal total serum tryptophan but increased non-albumin-bound tryptophan.
- CSF tryptophan levels were significantly elevated (50-800%) in cirrhotic patients.
- No significant difference in CSF tryptophan was observed between cirrhotic patients in coma versus not in coma.
- Elevated CSF 5-HIAA in hepatic coma patients, but this difference diminished after probenecid treatment.
Conclusions:
- Elevated brain tryptophan and serotonin are suggested in hepatic cirrhosis.
- The elevated CSF 5-HIAA in hepatic coma may be linked to serotonin metabolism, but probenecid data suggest complex regulation.
- Further research is needed to fully elucidate the role of these metabolites in hepatic encephalopathy.