Fragile X Syndrome (FXS) is a neurodevelopmental disorder characterized by intellectual disability and difficulties in social interaction. This last feature is reproduced in the Fmr1 KO mouse, an animal model of FXS. In mice, the accessory olfactory bulb (AOB) is the first central region of the vomeronasal system implicated in the processing of chemical cues that trigger social and sexual behaviors.
Here, we show that the Fmr1 KO mice exhibit a reduced investigation towards conspecifics and social odors (soiled bedding and urine). We also found that the Fmr1 KO mice exhibit a higher detection threshold for urine and impaired discrimination of urine samples from different conspecifics. Accordingly, we found that mitral cells (MCs), the projection neurons of the AOB, exhibit hypo-excitability in Fmr1 KO mice and impaired spontaneous excitatory postsynaptic currents, accompanied by increased dendritic branching.
This overall decrease in activity in the AOB of the Fmr1 KO mice could partly explain their deficit in odor-mediated social behavior. We would like to thank Dr. Felipe Avello for his valuable assistance in programming some of the scripts used for behavioral analysis and Alexandra Saavedra for her help in the three-chambers test.
This study was funded by the National Agency for Research and Development (ANID) / Scholarship Program / DOCTORADO NACIONAL/2020 – 21200657, Project FONDECYT Regular 1210069, and by a National Institute of Health (NIH), National Institute of Aging (NIA), grant number R01AG088147A (RCA). Department of Biology, Faculty of Science, Universidad de Chile, Santiago, Chile Marcela P. Navarrete, Joaquín De La Rosa, Sara Fernández, Jorge Mpodozis & Alexia Nunez-Parra Department of Biology, College of Computer, Mathematical, and Natural Sciences, University of Maryland, College Park, USA Lucy C.
Irvine, Juan Zegers-Delgado & Ricardo C. Araneda Correspondence to Ricardo C. Araneda or Alexia Nunez-Parra.
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