| Research Abstract |
Neuropeptide, substance P(SP) receptor function in the brain and spinal cord was examined in the rat with septic encephalopathy produced by cecal ligation and puncture. After surgical procedures, the rats became lethargic and their behaviors were depressed and pain threshold was increased with time. For evaluation of SP receptor function, distribution of specific binding sites of [^<125>I] Bolton Hunter SP was determined using in vitro autoradiography. Binding sites of SP in septic rats were significantly decreased to 70, 50, 60, 70, 70, 80, 60, 40% and 70% of sham-operation rats in ant. cingulate, caudate-putamen(C-P), globus pallidus, hippocampus(HIP), amygdala(AMY), septal n. (SEP), interpeduncular n. (INT), dorsal raphe(RAP) and cerebellum, Cerebellum, respectivel). For more quantitative description), the number of receptors(Bmax) and affinity constant(Ka) were calculated with the scatchard analysis in represantative sp system. When compared the septic rats with the sham-operation rats, the Bmax decreased to 60-80% in C-P, HIP, AMY, SEP, INT and RAP while Ka increased to 130-220% in C-P, HIP, INT, and spinal cord. These results suggest that septic encephalopathy is associated with decreased sensitivity to SP in the brain. This study is the first demonstration of the changes in SP receptor function in the septic rat.
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