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GABAB-ergic motor cortex dysfunction in SSADH deficiency.

Janine Reis1, Leonardo G Cohen, Phillip L Pearl

  • 1Human Cortical Physiology and Stroke Neurorehabilitation Section, NINDS, NIH, Bethesda, MD, USA. janine.reis@uniklinik-freiburg.de

Neurology
|June 23, 2012
PubMed
Summary
This summary is machine-generated.

Succinic semialdehyde dehydrogenase deficiency impairs GABA degradation, leading to reduced cortical inhibition. This study found GABA(B)-ergic motor cortex dysfunction in patients, suggesting altered inhibitory circuits.

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Area of Science:

  • Neuroscience
  • Neurogenetics
  • Metabolic Disorders

Background:

  • Succinic semialdehyde dehydrogenase (SSADH) deficiency is a rare genetic disorder affecting GABA degradation.
  • This leads to elevated levels of GABA and GHB in the brain.
  • The impact of these elevations on cortical excitability remains unclear.

Purpose of the Study:

  • To investigate the effects of chronically elevated GABA and GHB on cortical excitability in SSADH deficiency.
  • To test the hypothesis that GABA receptor downregulation promotes cortical disinhibition via presynaptic GABAergic mechanisms.

Main Methods:

  • Utilized single and paired pulse transcranial magnetic stimulation (TMS).
  • Quantified excitation and inhibition in the primary motor cortex (M1).
  • Compared patients with SSADH deficiency, heterozygotes, and healthy controls.

Main Results:

  • Patients with SSADH deficiency exhibited significantly reduced long-interval intracortical inhibition.
  • A significantly shortened cortical silent period was observed in SSADH deficiency patients.
  • These findings were compared to heterozygous parents and healthy control groups.

Conclusions:

  • Results indicate GABA(B)-ergic motor cortex dysfunction in SSADH deficiency, linked to GABA(B) receptor downregulation.
  • The findings support proposed mechanisms in animal models and suggest autoinhibition of GABAergic neurons.
  • This study provides the first evidence of altered GABA(B)-ergic function in SSADH deficiency patients, potentially explaining clinical features and offering insights into neurotransmitter disorders.