Altered parabrachial nucleus nociceptive processing may underlie central pain in Parkinson’s disease

Histology

Three experimental groups were defined according to the extent of the DA lesion induced by the toxin 6-hydroxydopamine (6-OHDA) in the SNc: Sham, Partial and Total DA lesions. The lesion was assessed by immunohistochemistry against tyrosine hydroxylase (TH) at both striatal and SNc levels. The sham group was composed of rats in which sterile saline had been injected unilaterally in the SNc instead of the toxin (Sham, n = 23). In the Partial DA lesion rats, TH-labeling was reduced to an average of 53.97 ± 4.06% (mean ± SEM) in the SNc and 68.06 ± 4.30% in the…