Phosphatidylinositol 4,5-bisphosphate induced flunitrazepam sensitive-GABAA receptor increase in synaptosomes from chick forebrain.

The flunitrazepam sensitive-GABA(A) receptor density was increased by cytochalasins C and D at 37 degrees C suggesting that microfilament depolymerization induces exposure to the radioligand of a GABA(A) receptor in synaptosomes (Pharm Biochem Behav 72 (2002) 497). Similarly, phosphatidylinositol-4,5-bisphosphate (1-5 microM), but not a mixture of phospholipids, induced an increase of GABA(A) receptors in synaptosomes. Furthermore, N-ethyl maleimide, an inactivator of the sensitive fusion protein, which interacts with GABA(A) 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.