GABAergic deficits in absence of LPA1 receptor, associated anxiety-like and coping behaviors, and amelioration by interneuron precursor transplants into the dorsal hippocampus

Defects in GABAergic function can cause anxiety- and depression-like behaviors among other neuropsychiatric disorders. Therapeutic strategies using the transplantation of GABAergic interneuron progenitors derived from the medial ganglionic eminence (MGE) into the adult hippocampus reversed the symptomatology in multiple rodent models of interneuron-related pathologies. In turn, the lysophosphatidic acid receptor LPA has been reported to be essential for hippocampal function. Converging evidence suggests that deficits in LPA receptor signaling represent a core feature underlying comparable hippocampal dysfunction and behaviors manifested in common neuropsychiatric conditions. Here, we first analyzed the GABAergic interneurons in the hippocampus of wild-type and maLPA-null mice, lacking the LPA receptor. Our data revealed a reduction in the number of neurons expressing GABA, calcium-binding proteins, and neuropeptides such as somatostatin and neuropeptide Y in the hippocampus of maLPA-null mice. Then, we used interneuron precursor transplants to test links between hippocampal GABAergic interneuron deficit, cell-based therapy, and LPA receptor-dependent psychiatric disease-like phenotypes. For this purpose, we transplanted MGE-derived interneuron precursors into the adult hippocampus of maLPA-null mice, to test their effects on GABAergic deficit and behavioral symptoms associated with the absence of the LPA receptor. Transplant studies in maLPA-null mice showed that grafted cells were able to restore the hippocampal host environment, decrease the anxiety-like behaviors and neutralize passive coping, with no abnormal effects on motor activity. Furthermore, grafted MGE-derived cells maintained their normal differentiation program. These findings reinforce the use of cell-based strategies for brain disorders and suggest that the LPA receptor represents a potential target for interneuron-related neuropsychiatric disorders.This work was supported by grants from the Spanish Ministry of Science, Innovation and Universities, co-funded by the European Regional Development Fund (ERDF, EU), (PSI2017-82604R, to LJS; PSI2017-83408-P to CP; SAF09-07746, to MAD; PI16/01510, to GET) and Andalusian Regional Ministries of Economy, Knowledge, Business and University (SEJ-4515 -to LJS; SEJ1863 to CP) and of Health and Families (Nicolas Monardes Programme to GET)