Objective: To study the specific correlation between "Jinggu" (BL 64) and "Dazhong" (KI 4) in the nervous system by using a double-labeling of cholera toxin subunit B conjugated with Alexa Fluor 488 and 594 (CTB-Alexa 488, 594) in rats, so as to investigate its neuroanatomical basis for clinical joint-application of Yuan-Source and Luo acupoints.
Methods: Three male SD rats were used in the present study. Under anesthesia (10% urethane), 0.1% CTB-Alexa 488 (5 microL) and CTB-Alexa 594 (5 microL) were respectively injected into the border area between the red and white flesh, distal to the tuberosity of the fifth metatarsal bone, and the depression anterior to the medial attachment of the calcaneal tendon, the corresponding sites of the acupoints Jinggu (BL 64) and Dazhong (KI 4) in the human body. After 3 surviving days, the rat's brain, spinal cord and dorsal root ganglia (DRGs) of L3-L6 were dissected following perfusion with 4% paraformaldehyde, cut into sections and observed under fluorescent microscope equipped with a digital camera. The labeled neurons were recorded and counted.
Results: It was found under fluorescent microscope that the single-labeled neurons and the dual-labeled neurons were ipsilaterally located on the injected side. Among the single-labeled neurons, the labeled sensory neurons related to "Jinggu" (BL 64) and "Dazhong" (KI 4) were found to be in the DRGs of L3-L6, with a higher concentration in the DRGs of L.4 (27/162, 102/332) and L5 (130/162, 204/332). The dual-labeled 7 neurons were found to be in DRGs of L4 and L5. In addition, the labeled motoneurons related to "Jinggu" (BL 64) and "Dazhong" (KI 4) distributed in the dorsolateral portion of lamina IX, forming a longitudianal column from L3-L6 with a higher concentration at L4 and L5.
Conclusion: The labeled sensory and motor neurons innervating Yuan-acupoint "Jinggu" (BL 64) and Luo-acupoint "Dazhong" (KI 4) distribute in DRGs of the same spinal segments and spinal ventral horns from L3-L6.