Neural pathway interference by retained acupuncture: a functional MRI study of a dog model of Parkinson's disease.

OBJECTIVE: The aims of this study were to investigate the interference of the brain activation during a passive movement task (PMT) by retained acupuncture at the ST 36 acupoint and to compare these effects between normal brain and Parkinson's disease (PD) brain.
METHODS: Functional magnetic resonance imaging (fMRI) techniques have been used to study neurophysiology in animals. Eight healthy beagle dogs were divided into two groups of four dogs each, a normal control group and a PD model group. PD was induced by intravenous injection of 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-HCl. During fMRI, the PMT was performed in the right tarsal joint during three different sessions, which consisted of PMT only, PMT while an acupuncture needle was inserted at the ST 36 acupoint, and PMT while needle was inserted at a sham point. RESULTS AND DISCUSSION: Standard veterinary neurological examination was performed on dogs with MPTP-induced PD. A homogeneous grade similar to human PD patients was evident in all dogs. The fMRI study showed that insertion of the acupuncture needle at acupoint ST 36 significantly affected the proprioceptive brain activation by decreasing blood oxygenation level-dependent signal intensity in basal ganglia, limbic system, and cerebellum. Compared with normal and PD brain, we suggest that acupuncture at ST 36 has different modulation effects depending on the pathologic condition of the brain. The study provides evidence of the potential clinical applications of retained acupuncture at ST 36 for rehabilitation therapy of PD patients.