Spinogenesis and Plastic Changes in the Dendritic Spines of Spinal Cord Motoneurons after Traumatic Injury in Rats.

BACKGROUND:Spinal cord injury (SCI) is highly incapacitating, and the neurobiological factors involved in an eventual functional recovery remain uncertain. Plastic changes to dendritic spines are closely related with the functional modifications of behavior.AIM OF THE STUDY:To explore the plastic response of dendritic spines in motoneurons after SCI.METHODS:Female rats were assigned to either of three groups: Intact (no manipulations), Sham (T9 laminectomy), and SCI (T9 laminectomy and spinal cord contusion).RESULTS:Motor function according to a BBBscale was progressively recovered from 2 week through 8 week postinjury, reaching a plateau through week 16. Dendritic spine density was greater in SCI vs. control groups, rostral as well as caudal to the lesion, at 8 and 16 weeks postinjury. Thin and stubby/wide spines were more abundant at both locations and time points, whereas mushroom spines predominated at 2 and 4 months in rostral to the lesion. Filopodia and atypical structures resembling dendritic spines were observed. Synaptophysin expression was lower in SCI at the caudal portion at 8 weeks, and was higher at week 16.CONCLUSION:Spinogenesis in spinal motoneurons may be a crucial plastic response to favor spontaneous recovery after SCI.