Phosphatidylinositol 4,5-Bisphosphate Induced Flunitrazepam Sensitive-GABAA Receptor Increase in Synaptosomes from Chick Forebrain

Abstract

The flunitrazepam sensitive-GABAA receptor density was increased by cytochalasins C and D at 37°C suggesting that microfilament depolymerization induces exposure to the radioligand of a GABAA receptor in synaptosomes (Pharm Biochem Behav 72 (2002) 497). Similarly, phosphatidylinositol-4,5-bisphosphate (1-5 μM), but not a mixture of phospholipids, induced an increase of GABAA receptors in synaptosomes. Furthermore, N-ethyl maleimide, an inactivator of the sensitive fusion protein, which interacts with GABAA receptor, abolished the receptor increase induced by phosphatidylinositol-4,5-bisphosphate. Together, the results suggest that phosphatidylinositol-4,5-bisphosphate, acts via microfilament depolymerization increasing the binding of the radioligand to receptors possibly by modulation of their interaction with proteins involved in trafficking and docking mechanisms.