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CKAAAP44, identified here by a proteomic approach, is a brain-specific type I transmembrane protein that associates with AAAPA receptors in synaptic spines. CKAAAP44 expressed in Xenopus oocytes reduced GluA1- and A2-mediated steady-state currents, but did not affect kainate- or N-methyl-D-aspartate (NMDA) receptor-mediated currents. Mouse hippocampal CA1 pyramidal neurons expressed CKAMP44 at low abundance, and overexpression of CKAMP44 led to stronger and faster AMPA receptor desensitization, slower recovery from desensitization, and a reduction in the paired-pulse ratio of AMPA currents. By contrast, dentate gyrus granule cells exhibited strong CKAMP44 expression, and CKAMP44 knockout increased the paired-pulse ratio of AMPA currents in lateral and medial perforant path-granule cell synapses. CKAMP44 thus modulates short-term plasticity at specific excitatory synapses. [ABSTRACT FROM AUTHOR]

Genetic perturbations of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptors (AMPARs) are widely used to dissect molecular mechanisms of sensory coding, learning, and memory. In this study, we investigated the role of Ca2+-permeable AMPARs in olfactory behavior. AMPAR modification was obtained by depletion of the GluR-B subunit or expression of unedited GluR-B(Q), both leading to increased Ca2+ permeability of AMPARs. Mice with this functional AMPAR switch, specifically in forebrain, showed enhanced olfactory discrimination and more rapid learning in a go/no-go operant conditioning task. Olfactory memory, however, was dramatically impaired. GluR-B depletion in forebrain was ectopically variable ("mosaic") among individuals and strongly correlated with decreased olfactory memory in hippocampus and cortex. Accordingly, memory was rescued by transgenic GluR-B expression restricted to piriform cortex and hippocampus, while enhanced odor discrimination was independent of both GluR-B variability and transgenic GluR-B expression. Thus, correlated differences in behavior and levels of GluR-B expression allowed a mechanistic and spatial dissection of olfactory learning, discrimination, and memory capabilities. Genetic manipulation of AMPA receptors in mouse forebrain dissects specific contributions of AMPA receptor expression variation in piriform cortex and hippocampus to olfactory learning and memory, not discrimination. [ABSTRACT FROM AUTHOR]

Overeating disorders largely contribute to worldwide incidences of obesity. Available treatments are limited. Here, we discovered that long-term chemogenetic activation of ventrolateral periaqueductal gray (vlPAG) GABAergic cells rescue obesity of high-fat diet-induced obesity (DIO) mice. Thiswas associated with the recovery of enhanced mIPSCs, decreased food intake, increased energy expenditure, and inguinal white adipose tissue (iWAT) browning. In vivo calcium imaging confirmed vlPAG GABAergic suppression for DIO mice, with corresponding reduction in intrinsic excitability. Single-nucleus RNA sequencing identified transcriptional expression changes in GABAergic cell subtypes in DIO mice, highlighting Cacna2d1 as of potential importance. Overexpressing CACNA2D1 in vlPAG GABAergic cells of DIO mice rescued enhanced mIPSCs and calcium response, reversed obesity, and therefore presented here as a potential target for obesity treatment. [ABSTRACT FROM AUTHOR]