Genetically Epileptic Mice Have Elevated Enkephalin — A Clue to Seizure Biology | Research

The takeaway

Met-enkephalin was significantly elevated in the cortex, hippocampus, and brainstem of genetically epileptic tg/tg mice, while beta-endorphin and dynorphin were unchanged.

Elevated met-enkephalin in 3 seizure regions
Cortex, hippocampus, and brainstem of epileptic tg/tg mice had significantly increased met-enkephalin

What the researchers found

Met-enkephalin was significantly elevated in cortex, hippocampus, and brainstem of tg/tg epileptic mice. Beta-endorphin and dynorphin were unchanged.

Why it matters

Elevated enkephalin in seizure-prone brain regions suggests the opioid system is actively involved in epilepsy. This could help develop new anti-seizure treatments targeting opioid pathways.

How the study worked

Brain regions from 15-18 week old tg/tg and control mice were dissected. Met-enkephalin, beta-endorphin, and dynorphin levels were measured by radioimmunoassay.

What this study cannot tell us

Genetic mouse model that may not represent all forms of human epilepsy. Measurements show total levels, not release rates. Cannot determine if elevated enkephalin is cause or effect of seizures.

How to read the evidence

Preliminary animal study in a single genetic epilepsy model. Cannot determine if elevated enkephalin is cause or effect.

When this study was published

Published in 1991. Opioid peptide involvement in epilepsy has been further explored.

The bigger picture

The selective enkephalin elevation in seizure-prone brain regions could represent the brain's attempt to use opioid peptides as natural anticonvulsants — or could paradoxically contribute to seizure generation. Understanding this could lead to opioid-targeted epilepsy treatments.

Questions still open

Is elevated enkephalin protective against or contributing to seizures?
Do epilepsy patients have altered opioid peptide levels?

Common questions

Are the elevated enkephalins helping or hurting?

Unclear. Met-enkephalin can have both anticonvulsant and pro-convulsant effects depending on the receptor type and brain region. The elevation could be a compensatory attempt to suppress seizures, or could contribute to seizure propagation.

Could this apply to human epilepsy?

The tg/tg mouse produces seizures similar to human generalized epilepsy. If opioid peptide changes are confirmed in epilepsy patients, it could open new treatment avenues targeting the enkephalin system.

Read the original research

Increased methionine-enkephalin levels in genetically epileptic (tg/tg) mice.

Brain research bulletin, 27(6), 849-52

View on PubMed ↗

Citation

Patel, V K; Abbott, L C; Rattan, A K; Tejwani, G A. (1991). Increased methionine-enkephalin levels in genetically epileptic (tg/tg) mice.. Brain research bulletin, 27(6), 849-52.