In vivo EEDQ dose-dependently inactivates rat brain 5-HT receptors but not 5-HT uptake sites.

Abstract

The present study investigates the inactivation and recovery of brain serotonin (5-HT) recognition sites by EEDQ (N-ethoxycarbonyl-2-ethoxy-1,2,-dihydroquinoline). Adult male Sprague-Dawley rats were given a single s.c. injection of vehicle (1:1 EtOH/H2O) or EEDQ (1-20 mg kg-1) and sacrificed at 4 h and 7 days (10 mg kg-1 dose) post-injection. EEDQ dose-dependently reduced the Bmax of 5-HT1A(3H-DPAT),5-HT1B(125I-CYP),5-HT2(3H-ketanserin) and 5-HT2/1C(125I-DOI) receptors in cortical homogenates. In contrast, EEDQ was without effect on the 5-HT transporter recognition site (3H-paroxetine). No significant changes in affinity were observed for 5-HT1B, 5-HT2 or 5-HT2/1C receptors. The rank order of sensitivity to EEDQ inactivation was: 5-HT1A > 5-HT1B > 5-HT2 approximately 5-HT2/1C >>> 5-HT uptake sites. This study demonstrates: (1) differential EEDQ inactivation and recovery of 5-HT receptors and (2) lack of EEDQ inactivation of the 5-HT transporter.