Substance P receptors in primary cultures of cortical astrocytes from the mouse.
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.
D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000378:metabolism*; D001345:Autoradiography; D001667:Binding, Competitive; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D007700:Kinetics; D051379:Mice; D009479:Neuropeptides / Q000378:metabolism; D009638:Norepinephrine / Q000494:pharmacology; D010716:Phosphatidylinositols / Q000378:metabolism; D018040:Receptors, Neurokinin-1; D017981:Receptors, Neurotransmitter / Q000378:metabolism*; D013373:Substance P / Q000378:metabolism*; D015320:Tachykinins
D009479:Neuropeptides; D010716:Phosphatidylinositols; D018040:Receptors, Neurokinin-1; D017981:Receptors, Neurotransmitter; D015320:Tachykinins; D013373:Substance P; D000242:Cyclic AMP; D009638:Norepinephrine