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A binding site for [3H]glipizide in the rat cerebral cortex
1Centre CNRS-INSERM de Pharmacologie-Endocrinologie, C.C.I.P.E., Montpellier, France.
European Journal of Pharmacology
|August 11, 1987
Summary
Glipizide, a diabetes drug, binds to specific sites in the rat brain. This binding suggests a potential central role for sulfonylureas beyond glucose regulation.
Area of Science:
- Neuroscience
- Pharmacology
- Endocrinology
Background:
- Glipizide is a second-generation sulfonylurea used to manage type 2 diabetes.
- Sulfonylureas primarily act by stimulating insulin secretion from pancreatic beta cells.
Purpose of the Study:
- To investigate the specific binding of [3H]glipizide to rat cerebral cortex membranes.
- To characterize the nature and properties of this central binding site.
Main Methods:
- Radioligand binding assays using [3H]glipizide on rat cerebral cortex membranes.
- Enzyme activity assays to assess effects on adenylate cyclase and phosphodiesterase.
- Analysis of binding kinetics (saturability, reversibility, time, and temperature dependence).
Main Results:
- Specific, saturable, and reversible binding of [3H]glipizide was observed in rat cerebral cortex membranes.
- The binding site exhibited characteristics of a lipoprotein and was sensitive to proteolytic and lipolytic enzymes.
- Binding affinity (Kd = 1.5 nM) and maximal capacity (Bmax = 110 fmol/mg protein) were determined.
- Inhibition of cAMP-dependent phosphodiesterase by sulfonylureas was observed at high concentrations, while adenylate cyclase was not stimulated.
Conclusions:
- A specific binding site for glipizide exists in the rat cerebral cortex, suggesting a potential central receptor.
- The characteristics of this binding site indicate a lipoprotein nature.
- The observed binding and effects on phosphodiesterase suggest potential central nervous system actions of sulfonylureas independent of insulin secretion.