Acute effects of L-DOPA/carbidopa/buspirone (Spinalon™) on rhythmic electrical activity of the lumbosacral spinal cord in cats

Discovered by Guertin and colleagues in 2004, Spinalon™ is a fixed-drug combination (L-DOPA, carbidopa, and buspirone) that can acutely induce temporary episodes of rhythmic locomotor-like activity in complete or near-complete spinal cord-injured (SCI) subjects. However, little is known about the mechanisms of action or the direct effects of Spinalon™ on neural elements of the central pattern generators (CPGs). Our study aims at characterizing the effects of Spinalon™ on electrical activity of the spinal cord in segmental areas known to contain key rhythmogenic elements of the CPGs (i.e., lumbosacral) for scratching and locomotion. We recorded spinal cord dorsum signals from decerebrate cats using a multielectrode array placed over the lumbosacral region. We found that a single intravenous injection of 100/25/7.5 mg/kg L-DOPA/carbidopa/buspirone (Spinalon™) specifically reduced the amplitude of electrical sinusoidal waves associated with fictive scratching and promoted the appearance of electrical sinusoidal-like waves occurring at frequencies compatible with fictive locomotion. These observations suggest a profound impact of Spinalon™ on the lumbosacral CPGs.