Effects of lesions in the anterolateral columns and dorsolateral funiculi on self-mutilation behavior in rats.

The possible role of the anterolateral columns (ALCs) and dorsolateral funiculi (DLF) in pain mechanisms was examined from the effects of lesions in these tracts (alone or combined) on tests for chronic deafferentation pain (autotomy) in rats. Spinal lesions alone (i.e., without denervation) in either ALC or DLF or combined DLF-ALC did not lead to any form of self-mutilation behavior. Cervical surgery, without spinal lesion, followed by limb denervation (sham) resulted in similar autotomy characteristics to those observed following limb denervation alone (control). Both results were considered as one set of controls. ALC lesions simultaneous with, or 1-2 weeks prior to limb denervation (ipsilaterally or contralaterally) produced significant delay in onset of autotomy and decrease in percentage of rats showing this behavior. DLF lesions followed by limb denervation produced significant acceleration of onset of autotomy and increase in percentage of rats showing this behavior. Combined DLF-ALC lesions with limb denervation produced intermediate effects between those observed following either ALC or DLF lesions alone. These results give further support to the concept that autotomy is related to rostral transmission of nociceptive information and that a spino-bulbo-spinal inhibitory loop involving the DLF and ALC is triggered by chronic deafferentation pain.