The reticular thalamic nucleus (Rt) is a sheet of neurons that surrounds the dorsal thalamus laterally, along its dorso-ventral and rostro-caudal axes. It consists of inhibitory neurons releasing gamma-aminobutyric acid (GABA). This nucleus participates in the circuitry between the thalamus and the cerebral cortex, and its impairment is associated with neuro-psychiatric disorders. In this study, we investigated the Rt anatomy of Engrailed-2 knockout mice (En2 ), a mouse model of autism spectrum disorder (ASD), using parvalbumin as an immunohistochemical marker. We compared 4- and 6-week-old wild type (WT) and En2 mice using various morphometric parameters: cell area, shape factor, circularity and cell density. Significant differences were present in 6-week-old male mice with different genetic background (WT vs. En2 ): the Rt neurons of En2 mice showed a bigger cell area, shape factor and circularity when compared with WT. Age (4 weeks vs. 6 weeks) influenced the shape factor of WT females, the circularity and cell density of En2 males, and the shape factor and circularity of En2 females. Gender affected cell density in 4-week-old WT mice, shape factor and cellularity of 6-week-old WT mice, and cell area, shape factor and cell density of En2 at 6 weeks. Intrasubject (left-right) asymmetry of Rt was never observed. These results show for the first time that sex- and age-related changes occur in the Rt GABAergic neurons of the En2 ASD mouse model.
© 2020 Anatomical Society.

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