Endogenous neuropeptide Y (NPY) and corticotrophin-releasing factor (CRF) modulate the responses of the basolateral amygdala (BLA) to stress and are associated with the development of stress resilience and vulnerability, respectively. We characterized persistent effects of repeated NPY and CRF treatment on the structure and function of BLA principal neurons in a novel organotypic slice culture (OTC) model of male rat BLA, and examined the contributions of specific NPY receptor subtypes to these neural and behavioral effects. In BLA principal neurons within the OTCs, repeated NPY treatment caused persistent attenuation of excitatory input and induced dendritic hypotrophy via Y 5 receptor activation; conversely, CRF increased excitatory input and induced hypertrophy of BLA principal neurons. Repeated treatment of OTCs with NPY followed by an identical treatment with CRF, or vice versa, inhibited or reversed all structural changes in OTCs. These structural responses to NPY or CRF required calcineurin or CaMKII, respectively. Finally, repeated intra-BLA injections of NPY or a Y 5 receptor agonist increased social interaction, a validated behavior for anxiety, and recapitulated structural changes in BLA neurons seen in OTCs, while a Y 5 receptor antagonist prevented NPY's effects both on behavior and on structure. These results implicate the Y 5 receptor in the long-term, anxiolytic-like effects of NPY in the BLA, consistent with an intrinsic role in stress buffering, and highlight a remarkable mechanism by which BLA neurons may adapt to different levels of stress. Moreover, BLA OTCs offer a robust model to study mechanisms associated with resilience and vulnerability to stress in BLA.

23Basolateral amygdala (BLA) responses to stress are regulated by endogenous neuropeptide 24 Y (NPY) and corticotrophin-releasing factor (CRF), associated respectively with resilience and 25 vulnerability to stress. We studied mechanisms underlying effects of repeated NPY and CRF 26 treatment on structure and function of BLA principal neurons (PN) in organotypic slice cultures 27 (OTC) of rat BLA. NPY attenuated excitatory input and induced dendritic hypotrophy via Y5-28 receptors, while CRF increased excitatory input and induced hypertrophy of BLA PNs. Structural 29 responses to NPY and CRF required calcineurin and CaMKII, respectively. Finally, repeated in 30 vivo treatment of BLA with NPY or a Y5 receptor agonist increased social interaction and 31 recapitulated structural changes in BLA neurons seen in OTCs. These results implicate the Y5 32 receptor in the long-term, anxiolytic-like effects of NPY in the BLA. Moreover, BLA OTCs offer 33 a robust model to study mechanisms associated with resilience and vulnerability to stress in BLA. 34 35

When energy balance is altered by aerobic exercise, starvation, and cold exposure, for example, there appears to be coordination of the responses of skeletal muscle, white adipose (WAT), and brown adipose (BAT) tissues. We hypothesized that WAT, BAT, and skeletal muscle may share an integrated regulation by the central nervous system (CNS); specifically, that neurons in brain regions associated with energy balance would possess neuroanatomical connections to permit coordination of multiple, complementary responses in these downstream tissues. To study this, we used trans‐neuronal viral retrograde tract tracing, using isogenic strains of pseudorabies virus (PRV) with distinct fluorescent reporters (either eGFP or mRFP), injected pairwise into male rat gastrocnemius, subcutaneous WAT and interscapular BAT, coupled with neurochemical characterization of specific cell populations for cocaine‐ and amphetamine‐related transcript (CART), oxytocin (OX), corticotrophin releasing hormone (CRH) and calcitonin gene‐related peptide (CGRP). Cells in the paraventricular (PVN) and parabrachial (PBN) nuclei and brainstem showed dual projections to muscle + WAT, muscle + BAT, and WAT + BAT. Dual PRV‐labeled cells were found in parvocellular, magnocellular and descending/pre‐autonomic regions of the PVN, and multiple structural divisions of the PBN and brainstem. In most PBN subdivisions, more than 50% of CGRP cells dually projected to muscle + WAT and muscle + BAT. Similarly, 31–68% of CGRP cells projected both to WAT + BAT. However, dual PRV‐labeled cells in PVN only occasionally expressed OX or CRH but not CART. These studies reveal for the first time both separate and shared outflow circuitries among skeletal muscle and subcutaneous WAT and BAT.