Substance P receptors in primary cultures of cortical astrocytes from the mouse.

Authors:
  • YTY Torrens
    Y Torrens
  • JBJ C Beaujouan
    J C Beaujouan
  • MSM Saffroy
    M Saffroy
  • MMM C Daguet de Montety
    M C Daguet de Montety
  • LBL Bergström
    L Bergström
  • JGJ Glowinski
    J Glowinski
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Abstract
Binding sites for substance P were labeled on intact cortical glial cells from newborn mice in primary culture using 125I-labeled Bolton-Hunter-labeled substance P. Maximal specific binding (95% of total binding) was reached after 2-3 weeks in culture. The binding was saturable, reversible, and temperature dependent. Scatchard and Hill analysis revealed a single population of noninteracting high-affinity binding sites (Kd, 0.33 nM; Bmax, 14.4 fmol per dish). Competition studies made with tachykinins and substance P analogues indicated that the characteristics of the 125I-labeled Bolton-Hunter labeled substance P binding sites on glial cells were identical to those on rat brain synaptosomes. 125I-labeled Bolton-Hunter labeled substance P binding sites were visualized by autoradiography, and differences in the intensity of labeling were seen among astrocytes. Substance P was found to stimulate phosphatidylinositol turnover; the EC50 value (0.36 nM) was identical to the IC50 value (0.38 nM) determined in binding studies. 125I-labeled Bolton-Hunter labeled substance P binding sites were also found on astrocytes derived from other brain structures and from the spinal cord of mice.

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