Research ReportDevelopmental changes in expression of inhibitory neuronal proteins in the Fragile X Syndrome mouse basolateral amygdala

•Demonstration of early postnatal developmental changes in the FXS mouse basolateral amygdala.•Developmental trajectory of key inhibitory transmission proteins is altered in FXS.•These alterations may be central to early inhibitory neurotransmission defects.

In humans, Fragile X Syndrome (FXS) is characterized by enhanced fear, hyperactivity, social anxiety, and, in a subset of individuals, autism. Many of the emotional and social deficits point to defects in the amygdala. We have previously shown defects in inhibitory neuron drive onto excitatory projection neurons in the basolateral amygdala (BLA) of juvenile Fmr1-/y knockout (KO) mice. Using pharmacological approaches, we have also previously revealed dynamic functional deficits in α1, α2, and α3 subunit-containing GABAA receptors (GABAARs α1, α2, and α3) during early postnatal development. In this study, we sought to determine whether these defects in GABAAR function are accompanied by changes in protein expression of GABAARs α1, α2, and α3 and the post-synaptic GABAAR-clustering protein gephyrin. Interestingly, we found that while the expression of these proteins did not significantly differ between wildtype (WT) and KO mice at each time point, the timing of developmental expression of GABAAR α1, α2, and gephyrin was altered. Collectively, these data reveal novel defects in inhibitory synapse protein expression during critical periods of early postnatal development that could contribute to observed inhibitory neurotransmission deficits in the KO mouse BLA.