Laminar distribution of cortical interneurons is impaired in postnatal CB1-R deficient mice

SAEZ T; CALTANA L; ARONNE MP; BRUSCO A

Cancun

Congreso; I Congreso FALAN; 2012

IBRO

Recent evidence indicates that the endocannabinoid (eCB) system plays a modulatory role in specific processes of brain development, such as neural progenitor proliferation, neuronal migration, phenotypic pyramidal specification of immature neurons and axonal navigation. Disruptions in the development and function of diverse interneuron classes contribute to major neuropsychiatric diseases, namely schizophrenia, depression, and anxiety disorders. Previous work described that cannabinoid receptor 1 (CB1-R) is predominantly expressed in interneurons during late gestation and early postnatal life, although the role of the eCB system in the laminar organization of cortical interneurons subpopulation in postnatal cerebral cortex has not been extensively examined. We used CB1-R deficientmice to investigate the role of the CB1-R in the distribution of three subtypes of interneuron in different cortical layers. We examined subpopulations of interneurons which can be identified by specific neurochemical markers: calretinin (CR), calbindin (CB) and reelin (Re). CB1-R did not affect the total number of GABA-ergic interneurons in the cerebral cortex in any of these interneuron subsets. However, the laminar distribution of CB-, CRand Re-positive cells in the different cortical layers is impaired. We divided de cerebral cortex into ten bins to facilitate the laminar analysis of the interneurons. Quantitative analysis revealed that in CB1-R knockout mice there is a significant differences of the percentage of CR cells in bin 3 (layer III) and Re cells in bin 7 (layer IV). Here we present new evidence indicating that eCB signaling plays an important role in interneuron migration and laminar positioning in the postnatal cerebral cortex.