Pregabalin exerts oppositional effects on different inhibitory circuits in human motor cortex: a double-blind, placebo-controlled transcranial magnetic stimulation study.
OBJECTIVE
To explore acute effects of pregabalin (PGB) on human motor cortex excitability with transcranial magnetic stimulation (TMS).


METHODS
PGB, 600 mg/day, was orally administered in 19 healthy subjects twice daily in a randomized, double-blind, placebo-controlled crossover design. Several measures of motor cortex excitability were tested with single- and paired-pulse TMS.


RESULTS
Mean short-interval intracortical inhibition (SICI) was reduced after PGB (74 +/- 7% of unconditioned response) compared with placebo (60 +/- 6% of unconditioned response). In contrast, mean long-interval intracortical inhibition (LICI) was increased by PGB (26 +/- 4% of unconditioned response) compared with placebo (45 +/- 8% of unconditioned response), and mean cortical silent period (CSP) showed an increase from 139 +/- 8 ms or 145 +/- 8 ms after placebo to 162 +/- 7 ms or 161 +/- 10 ms after PGB. Motor thresholds, intracortical facilitation, and corticospinal excitability were unaffected.


CONCLUSIONS
The observed excitability changes with oppositional effects on SICI and LICI or CSP suggest gamma-aminobutyric acid (GABA)B-receptor activation. They are markedly distinct from those induced by gabapentin, although both PGB and gabapentin are thought to mediate their function by binding to the alpha2-delta subunit of voltage-gated calcium channels. Conversely, the TMS profile of PGB shows striking similarities with the pattern evoked by the GABA-reuptake inhibitor tiagabine.
Lang
Nicolas
N
Department of Clinical Neurophysiology, Georg-August-University, Goettingen, Germany. nlang@gwdg.de
Sueske
Elke
E
Hasan
Alkomiet
A
Paulus
Walter
W
Tergau
Frithjof
F