Abstract
Some effects of acupuncture on central nervous system activity were examined using the quantitative autoradiographic deoxyglucose (2DG) metabolic (functional) mapping technique. Eight unanesthetized, restrained rats received an intravenous injection of (14C)-2 deoxyglucose and 45 minutes of either: (1) intermittent noxious (56°C H20) thermal stimulation of the tail, (2) the same noxious stimulation and unilateral mechanical acupuncture of tsu-san-li, (3) unilateral tsu-san-li stimulation only, or (4) non-noxious (40°C H20) thermal stimulation of the tail. All animals were subsequently sacrificed and prepared for 2DG film autoradiography according to Sokoloff (J. Neurochem., 1977). Noxious thermal stimulation alone produced significantly increased functional (metabolic) labeling (24-44% above control values) in medial medullary reticular formation; rostral medullary raphe; midbrain dorsal raphe and central gray; n. cuneiformis; n. reuniens- centra! medianus complex of thalamus; intralaminar nuclei of thalamus; dorsomedial, rostromedial, dorsolateral, and lateral thalamus; and neocortex (primarily parietal regions). Tsu-san-li stimulation alone produced substantial increases (26% above control values) in functional labeling in midbrain central gray and medullary raphe, and small- to-moderate increases (7-19% above control values) in the other structures listed above. Paired noxious thermal and tsu-san-li stimulation produced in the above structures either slight increases (3-12% above control values), no change (medullary reticular formation and n. reuniens-central medianus complex), or small decreases (3-7% below control values; rostromedial and submedius nuclei of thalamus) in functional labeling.
In summary: (1) noxious thermal stimulation of the tail produced significant increases in functional (metabolic) labeling of a number of structures, some of which have been implicated in the conduction of noxious information and in the subsequent production of analgesia, (2) tsu-san-1i stimulation alone produces moderately increased functional labeling of a number of the same brain structures examined in (1), and (3) the pairing of tsu-san-li and noxious thermal stimulation of the tail resulted in an interaction, which produced significantly less brain labeling than was present following noxious or acupuncture stimulation alone. The mechanisms responsible for such an inhibitory interaction are presently under investigation.
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