Age-dependent emergence of neurophysiological and behavioral abnormalities in progranulin-deficient mice

BACKGROUND: Loss-of-function mutations in the progranulin gene cause frontotemporal dementia, a genetic, heterogeneous neurodegenerative disorder. Progranulin deficiency leads to extensive neuronal loss in the frontal and temporal lobes, altered synaptic connectivity, and behavioral alterations. METHODS: The chronological emergence of neurophysiological and behavioral phenotypes of Grn heterozygous and homozygous mice in the dorsomedial thalamic—medial prefrontal cortical pathway were evaluated by in vivo electrophysiology and reward-seeking/processing behavior, tested between ages 3 and 12.5 months. RESULTS: Electrophysiological recordings identified a clear age-dependent deficit in the thalamocortical circuit. Both heterozygous and homozygous mice exhibited impaired input-output relationships and paired-pulse depression, but evoked response latencies were only prolonged in heterozygotes. Furthermore, we demonstrate firstly an abnormal reward-seeking/processing behavior in the homozygous mice which correlates with previously reported neuroinflammation. CONCLUSION: Our findings indicate that murine progranulin deficiency causes age-dependent neurophysiological and behavioral abnormalities thereby indicating their validity in modeling aspects of human frontotemporal dementia.