294EVALUATION OF 9- AND 13-HYDROXY-OCTADECADIENOIC ACIDS (HODES) AS POTENTIAL ENDOVANILLOIDS: SELECTIVITY AND ACTIVITY ON TRP CHANNELSThis study investigated the potential of 9- and 13-hydroxy-octadecadienoic acids (HODEs) as endovanilloids, focusing on their selectivity and activity on transient receptor potential (TRP) channels, particularly TRPV1 and TRPV2. HODEs, oxidation products of linoleic acid, act as endogenous agonists of TRPV1 channels, similar to the well-established endovanilloid anandamide. Using recombinant forms of rat or human TRPV1 and TRPV2 receptors expressed in various cell types, intracellular calcium levels ([Ca2+]i) were measured in response to HODEs and anandamide. Results demonstrated that human TRPV1 was most responsive to anandamide and 15(S)-hydroxyanandamide, while 9(S)-HODE showed about threefold lower potency and efficacy. Interestingly, (+/-)13-HODE was inactive at TRPV1. Further investigations revealed that HODEs could activate rat TRPV2 and rat TRPA1, while antagonizing rat TRPM8. However, they did not activate rat TRPA1 or antagonize rat TRPV1 at concentrations required to activate TRPV1. In rat dorsal root ganglion (DRG) neurons, 9(S)-HODE primarily increased [Ca2+]i in capsaicin-sensitive cells at specific concentrations. Overall, HODEs exhibited differences in selectivity profiles across TRP channels compared to anandamide. Anandamide demonstrated greater potency and efficacy at TRPV1, suggesting its prominence as an endovanilloid. These findings shed light on the specific effects and selectivity of HODEs on TRP channels, contributing to our understanding of their pharmacological activity in sensory neuronsDr. Ravindra Kumar@gmail.comResearch922019HODEs, Endovanilloids, TRP channels, Anandamide, Sensory neuronsDr. Ravindra KumarAssistant Professor, Department of Pharmacology, Lord Buddha Koshi Medical College and Hospital, Saharsa, Bihar, India