The novel endocannabinoid receptor GPR18 is expressed in the rostral ventrolateral medulla and exerts tonic restraining influence on blood pressure

Anusha Penumarti and Abdel A. Abdel-Rahman Published on January 15, 2014 as DOI:10.1124/jpet.113.209213 It has been shown previously that an agonist for GPR18, abnormal cannabidiol (ab cbn) given systemically causes decreases in blood pressure. In this article they wanted to see if GPR18 was present in the CNS. They used several techniques in order to determine if GPR18 was present in RVLM. First they functional identified GPR18 using immunofluorescence on TH expressing neurons in the RVLM. Next they looked at whether GPR18 had a functional role in the control of cardiovascular responses. So they did intra-RVLM dose response injection of ab cbn they found that it caused decreases in BP and tachycardia in a dose dependent matter. When they gave O-1918 a GPR18 antagonist it caused increases in BP and bradycardia. They showed that activation of GPR18 causes reduction in reactive oxygen species (ROS). Tissue was collected after either giving ab cbn or O-1918 and they used a protein assay in order to qualitatively determine ROS in the RVLM. They used dihydroethidium staining (DHE) was used to show that ROS was present in RVLM. The data from this study shows that GPR18 is present in the RVLM and that activation of this receptor not only cause decreases in BP but also decreases ROS. -MD