Project description:Neuroligin-4 (NL4) loss-of-function mutations are strongly associated with monogenic heritable abnormalities linked with Autism Spectrum Disorder (ASD). NL4 mutation in mice causes ASD related alterations in both, the synaptic and behavioral phenotype. Since microglia closely regulate synaptic development and are implicated as key players in ASD development and progression, we here studied microglial properties in the NL4-/- mouse model. We show that loss of NL4 caused altered behavior and impaired hippocampal gamma oscillations predominantly in male mice. In parallel, microglial density, morphology, and response to injury specifically in the CA3 region of the hippocampus were altered in NL4-deficient males only. A transcriptomic and proteomic analysis revealed a strong impact of sexual dimorphism on molecular alterations in microglia of NL4-deficient compared to wildtype mice. Estrogen application in male NL4-/- animals partially restored the impaired social behavior and the altered microglial phenotype. Together, these results indicate that loss of NL4 affects not only neuronal network activity and behavior, but changes in addition the phenotype of microglia in a sex-specific manner that could be targeted by estrogen treatment.
