Abstract

Introduction

Materials & Methods

Results

Discussion & Conclusion

References

Discussion
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Quinpirole (LY171555) is a selective D2-like receptor agonist used extensively in vivo and in vitro. [3H]Quinpirole binds selectively to D2-like receptors in vitro (Levant et al., JPET, 262 (3) 929-935, 1992). Surprisingly, the binding of [3H]quinpirole to D2-like sites in rat striatum is competitively inhibited by the monoamine oxidase inhibitors (MAOIs) Ro 41-1049, clorgyline, (+)-deprenyl and (-)-deprenyl (Levant et al., EJP, 241:141, 1993). In addition, the MAOI clorgyline has been shown to block the development and maintenance of quinpirole-induced behavioral sensitization (Culver and Szechtman, EJP, 339:109-111, 1997) suggesting that MAOI interactions at quinpirole labeled sites have functional importance.

The function of G protein-coupled receptors, which include D2-like receptors, can be assessed by agonist-stimulated [35S]GTPgammaS binding in crude membrane preparations. This provides a measure of G protein activation, the initial step in signal transduction.

The PURPOSES of these studies were to: 1) characterize quinpirole-stimulated [35S]GTPgammaS binding in rat striatal membranes, and 2) determine if MAOIs modulate quinpirole-stimulated [35S]GTPgammaS binding.

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