Can cocaine by affecting A2a-D2 colocalisation in lipid rafts modify the intercellular transfer of A2a and D2 via the roamer type of volume transmission?

Our work focuses on intercellular transfer of A2a and D2 receptors (R) via microvesicles in cell cultures and on action of cocaine on intercellular transfer of GPCRs via roamer type of volume transmission. Microvesicles referred to as exosomes [vesicles segregated within multivesicular bodies (MVBs) lumen] and shedding vesicles originated by direct budding from plasma membrane (PM). Shedding vesicles can be formed from lipid raft (LR) domains of PM, preceded by budding of small cytoplasmic protrusions, which detach by fission of their stalk. While exosomes formed by MVBs allow transfer of ‘‘packets of signals’’ (RNA, proteins, trophic factors), shedding vesicles from LRs may be the vehicle for transferring signalosomes to target cells, creating new transient integrative complex molecular networks in target cells, and hence a possible redeployment of entire neural networks cocaine affects dopamine (DA) transmission, and its action at DA Rs (especially D2) is affected by activation of A2a Rs. Thus, A2aD2 interactions have been proposed as a possible new target for neuro-psychiatric disorders and drug addiction. Cocaine (150 nM; 8h) causes substantial and highly significant rise of membrane-associated D2 immunoreactivity (IR) and a small increase of membrane-associated A2a R in CHO cell cultures. Higher concentration of cocaine increases GM1 in CHO PM. GM1, a major component of LRs, involved in localisation and trafficking of GPCRs and in release of shedding vesicles. Proteins in GPCRs are associated with PM and sorted in shedding vesicles. Microvesicles can transfer competent GPCRs in HEK293T cell cultures, transiently transfected with A2a and D2 Rs. This report investigates whether cocaine at suitable concentrations (below 1 mM; 8 h) modulates release of microvesicles in cell cultures of CHO and COS-7 cells, transiently transfected with A2a and/or D2R. We will investigate whether cocaine modulates the release of microvesicles from cultures of astrocytes.