[Substance P is not involved in SII descending modulation of the nucleus centrum medianum of the thalamus in cats].

It was investigated that the effects of electrical stimulation of the somatosensory area II (SII) of the cerebral cortex and electroacupuncture on substance P (SP) concentration in the perfusate from the nucleus centrum medianum (CM) of the thalamus, in order to probe into if SP participates in the SII descending modulation of the nucleus CM and this mechanism of acupuncture analgesia. Adult cats were randomly divided into three groups: control, electroacupuncture and electrical stimulation of SII. Push-pull perfusion technique was used to collect the perfusate from the nucleus CM. SP contents in the perfusate were determined by radioimmunoassay. The results showed that SP contents in the perfusate have not statistically significant changes before and after the electrical stimulation of SII or electroacupuncture, suggesting that the SP release from the nucleus CM was not influenced by the stimulation of SII or electroacupuncture. It is indicated that SP may not associate with the SII descending modulation of the nucleus CM and this mechanism of acupuncture analgesia.