Conditional Lpar1 gene targeting identifies cell types mediating neuropathic pain

Abstract

LPA1 is one of the six known receptors (LPA1-6) for lysophosphatidic acid (LPA). Constitutive Lpar1 null mutant mice have been instrumental in identifying roles for LPA-LPA1 signaling in neurobiological processes, brain development, and behavior as well as modelling human neurological diseases like neuropathic pain. Constitutive Lpar1 null mutant mice are protected from partial sciatic nerve ligation (PSNL)-induced neuropathic pain, however Lpar1 expressing cell types that are functionally responsible for mediating this protective effect are unknown. Here we report generation of a Lpar1flox/flox conditional null mutant mouse that allows cre-mediated conditional deletion combined with its use in a PSNL pain model. Lpar1flox/flox mice were crossed with cre transgenic lines driven by neural gene promoters for nestin (all neural cells), synapsin (neurons), or P0 (Schwann cells). CD11b-cre transgenic mice were also used to delete Lpar1 in microglia. PSNL-initiated pain responses were reduced following cre-mediated Lpar1 deletion with all 3 neural promoters but not the microglial promoter, supporting involvement of Schwann cells and central and/or peripheral neurons in mediating pain. Interestingly, rescue responses that were due to conditional deletion were non-identical, implicating distinct roles for Lpar1-expressing cell types. Our results with a new Lpar1 conditional mouse mutant expand an understanding of LPA1 signaling in the PSNL model of neuropathic pain.