Locus coeruleus anchors a trisynaptic circuit controlling fear-induced suppression of feeding.

The circuit mechanisms underlying fear-induced suppression of feeding are poorly understood. To help fill this gap, mice were fear conditioned, and the resulting changes in synaptic connectivity among the locus coeruleus (LC), the parabrachial nucleus (PBN), and the central nucleus of amygdala (CeA)-all of which are implicated in fear and feeding-were studied. LC neurons co-released noradrenaline and glutamate to excite PBN neurons and suppress feeding. LC neurons also suppressed inhibitory input to PBN neurons by inducing heterosynaptic, endocannabinoid-dependent, long-term depression of CeA synapses. Blocking or knocking down endocannabinoid receptors in CeA neurons prevented fear-induced depression of CeA synaptic transmission and fear-induced suppression of feeding. Altogether, these studies demonstrate that LC neurons play a pivotal role in modulating the circuitry that underlies fear-induced suppression of feeding, pointing to new ways of alleviating stress-induced eating disorders.

Brain region-specific effects of cGMP-dependent kinase II knockout on AMPA receptor trafficking and animal behavior.

Phosphorylation of GluA1, a subunit of AMPA receptors (AMPARs), is critical for AMPAR synaptic trafficking and control of synaptic transmission. cGMP-dependent protein kinase II (cGKII) mediates this phosphorylation, and cGKII knockout (KO) affects GluA1 phosphorylation and alters animal behavior. Notably, GluA1 phosphorylation in the KO hippocampus is increased as a functional compensation for gene deletion, while such compensation is absent in the prefrontal cortex. Thus, there are brain region-specific effects of cGKII KO on AMPAR trafficking, which could affect animal behavior. Here, we show that GluA1 phosphorylation levels differ in various brain regions, and specific behaviors are altered according to region-specific changes in GluA1 phosphorylation. Moreover, we identified distinct regulations of phosphatases in different brain regions, leading to regional heterogeneity of GluA1 phosphorylation in the KO brain. Our work demonstrates region-specific changes in GluA1 phosphorylation in cGKII KO mice and corresponding effects on cognitive performance. We also reveal distinct regulation of phosphatases in different brain region in which region-specific effects of kinase gene KO arise and can selectively alter animal behavior.