Cyto-, gene, and multireceptor architecture of the early postnatal mouse hippocampal complex

Neurotransmitter receptors are key molecules in signal transmission in the adult brain, and their precise spatial and temporal balance expressions also play a critical role in normal brain development. However, the specific balance expression of multiple receptors during hippocampal development is not well characterized. In this study, we used quantitative in vivo receptor autoradiography to measure the distributions and densities of 18 neurotransmitter receptor types in the mouse hippocampal complex at postnatal day 7, and compared them with the expressions of their corresponding encoding genes. We provide a novel and comprehensive characterization of the cyto-, gene, and multireceptor architecture of the developing mouse hippocampal and subicular regions during the developmental period, which typically differs from that in the adult brain. High-density receptor expressions with distinct regional and laminar distributions were observed for AMPA, Kainate, mGluR2/3, GABAA, GABAA/BZ, α2, and A1 receptors during this specific period, whereas NMDA, GABAB, α1, M1, M2, M3, nicotinic α4β2, 5-HT1A, 5-HT2, D1 and D2/D3 receptors exhibited relatively low and homogeneous expressions. This specific balance of multiple receptors aligns with regional cytoarchitecture, neurotransmitter distributions, and gene expressions. Moreover, contrasting with previous findings, we detected a high α2 receptor density, with distinct regional and laminar distribution patterns. A non-covariation differentiation phenomenon between α2 receptor distributions and corresponding gene expressions is also demonstrated in this early developmental period. The multimodal data provides new insights into understanding the hippocampal development from the perspective of cell, gene, and multireceptor levels, and contributes important resources for further interdisciplinary analyses. •Architecture of 18 receptor types in developing hippocampal complex was mapped.•Densities of multiple receptors at P7 typically differ from those in the adult brain.•Distributions of multiple receptors at P7 generally align with gene expressions.•Non-covariation was observed between α2 receptor and gene expression levels.•Mean receptor densities of hippocampal complex were mapped onto a 3D brain atlas.