Morphological Analysis of Human Acupuncture Points Through Immunohistochemistry

Abstract

At present, the functional mechanism of acupuncture is not yet fully understood. Analysis of the subanatomic morphology of acupuncture points (APs) could help compensate for this shortcoming. In immunohistochemistry, the use of specific antibodies enables in situ characterization of the molecular profile of tissue microenvironments. Thus, as proof in principle for the utility of immunohistochemistry, we determined whether the nerve density in biopsies of autopsied skin of a selected standard AP differed from that of a control point (CP). We analyzed pairs of skin samples from nine autopsy cases and studied the presence and density of soluble protein 100 (S-100), neuron-specific enolase (NSE), and neurofilament (NF) as markers of peripheral nerve structures. Cross-sections of nerves were counted by conventional microscopy and normalized to millimeters squared of subcutaneous fat, followed by statistical analyses for formal comparisons. Immunohistochemistry could clearly identify myelinated peripheral nerves. The number of nerve structures expressing S-100 protein was significantly reduced in APs compared with CPs (0.020 1 0.005 vs. 0.061 +/- 0.014; P < 0.006). The same pattern was seen in staining of NSE (AP: 0.011 +/- 0.003 vs. CP: 0.045 +/- 0.011) and NF (AP: 0.011 +/- 0.004 vs. CP: 0.054 +/- 0.015; both P < 0.007). In this study, we introduce immunohistochemistry as a suitable technology for acupuncture research. In addition, our findings demonstrate that a human AP is not necessarily associated with an increased but, rather, a significantly decreased number and density of subcutaneous nerve structures compared with skin biopsies from locations not recognized as effective for acupuncture. This pilot study, executed on a limited number of individuals and skin samples, justifies the application of immunohistochemistry on a larger collection of biopsy material.