5-Hydroxytryptamine2A (5-HT2A) receptor desensitization can occur without down-regulation.

摘要: The connection between agonist-induced desensitization and down-regulation of 5-hydroxytryptamine2A (5-HT2A) receptors was examined in a clonal cell line that stably expresses the 5-HT2A receptor. Brief (2-hr) prolonged (24-hr) exposure to agonist quipazine or 4-iodo-(2,5-dimethoxy)- phenylisopropylamine (DOI) diminished receptor-mediated phosphoinositide hydrolysis; no change receptor number affinity measured after 24 hr DOI quipazine. Immunohistochemical studies demonstrated 24-hr did not alter surface immunoreactivity. Western blot analysis with G alpha q- 11-selective antibodies indicate levels phospholipase C-dependent proteins. These results suggest can occur via process independent C-coupled Studies mutant (F340L) indicated binding per se is sufficient for desensitization. Down-regulation protein kinase C isozymes epsilon by overnight phorbol-12,13-dibutyrate attenuated intermediate phase (i.e., 2-6 exposure) DOI- quipazine-induced DOI-induced mediated alpha- and/or epsilon-protein but neither involved later desensitization.(ABSTRACT TRUNCATED AT 250 WORDS)