Homocysteine affects the excitability of cultured thalamic neurons to a minor extent

Homocysteine is a naturally occurring amino acid that serves as an intermediate in the metabolism of methionine. It is involved in several physiological as well as pathological processes. Hyperhomocysteinemia is a condition characterized by elevated plasma homocysteine levels. It is accompanied by multiple neurological pathologies, including epilepsy. Excitability of thalamic neurons plays a substantial role in the development of epileptic seizures. We used a primary culture of thalamic neurons to investigate changes in excitability following acute and chronic exposure to elevated homocysteine concentrations. Homocysteine did not affect input resistance, but at high concentration, it hyperpolarized the resting membrane potential. Action potential firing activated by depolarizing current pulses was not affected, neither was altered intracellular calcium concentration. Spontaneous activity was enhanced by both acute and chronic application of homocysteine.