Effects of diazepam and levodopa single doses on motor cortex plasticity modulation in healthy human subjects: A TMS study

Srpski Arhiv za Celokupno Lekarstvo

关键词: transcranial magnetic stimulation;    paired associative stimulation;    motor cortex;    cortical plasticity;   

DOI  :  10.2298/SARH1202014I

来源: DOAJ

【 摘 要 】

Introduction. Administration of pharmacological agents with specific actionson neurotransmitter systems is a powerful driver of functional corticalreorganization. Plastic reorganization of the motor cortex in humans studiesby the use of non-invasive stimulation protocols, which mimic the Hebbianmodel of associative plasticity. Objective. Aiming to explore pharmacologicalmodulation on human motor cortex plasticity, we tested healthy subjects aftereach dosage of diazepam, levodopa i placebo administration, using pairedassociative stimulation protocol (PAS) that induce fenomena similar to along-term potentiation and depression, as defined on the synaptic level.Methods. We analyzed effects of benzodiazepines (10 mg), levodopa (200 mg)and placebo on PAS protocol in 14 healthy volunteers, using a double-blindplacebo-controlled study design. PAS consisted of electrical stimuli pairs atn.medianus and magnetic pulses over the scalp (transcranial magneticstimulation) in precisely defined intervals (ISI was 10 and 25 ms) for atotal of about 15 minutes (200 pairs). MEP amplitudes before and after (0,10, 20 and 30 minutes later) interventional protocols were compared. Results.When protocols were applied with placebo depending on ISI (10 ms -inhibitory, 25 ms - facilitatory effects), MEP amplitudes decreased orincreased, while values in the postinterventional period (0, 10, 20 and 30min) were compared with initial values before the use of SAS. The use ofbenzodiazepines caused the occlusion of LTP-like effect, in contrast toamplification effects recorded after the administration of levodopa. Withrespect to the LTD-like protocol, the reverse was true (ANOVA for repeatmeasurements p<0.001). Conclusion. Administration of GABA-ergic agonistdiazepam interferes with the induction of associative plasticity in the motorcortex of healthy individuals, as opposed to the use of levodopa, whichstimulates these processes. The observed effects point at a potential role ofpharmacological modulation of plasticity in humans.

【 授权许可】

Unknown