Brain protein metabolism in epilepsy.

Area of Science:

• Neuroscience
• Molecular Biology
• Biochemistry

Background:

• Generalized and focal seizures disrupt brain polyribosomes, inhibiting protein synthesis.
• This inhibition occurs independently of systemic changes like hypoxemia or hypoxia.
• Previous studies indicate focal inhibition of protein synthesis during seizures in animal models.

Purpose of the Study:

• To investigate the impact of seizures on brain protein synthesis.
• To explore the relationship between local cerebral blood flow, glucose metabolism, and protein synthesis inhibition during seizures.
• To elucidate the molecular mechanisms underlying translational regulation during seizures.

Main Methods:

• Autoradiography was used to study protein synthesis, glucose metabolism, and cerebral blood flow in animal models (rats and marmoset monkeys).
• Animals were subjected to generalized seizures, with some being artificially ventilated to control systemic factors.
• Analysis focused on the correlation between regional protein synthesis inhibition and the mismatch between local glucose metabolism and blood flow.

Main Results:

• Generalized seizures caused focal inhibition of brain protein synthesis.
• A significant mismatch between increased local glucose metabolism and limited increase in local cerebral blood flow was observed during seizures.
• Regions with the most severe protein synthesis inhibition showed the greatest mismatch between blood flow and metabolism.
• Evidence suggests that translational regulation, particularly at the initiation step, is involved, potentially via altered GDP/GTP ratios affecting ternary complex formation.

Conclusions:

• Seizures directly inhibit brain protein synthesis, with regional variations.
• The observed mismatch between cerebral metabolism and blood flow during seizures is linked to protein synthesis inhibition.
• Altered cellular energy charge, leading to increased GDP/GTP ratios, may inhibit protein synthesis initiation during seizures.
• Protein biosynthesis regulation during seizures is complex and likely involves multiple regulatory sites.