Probes for INS

Abstract

BACKGROUND:

Drug memories become labile and reconsolidated after retrieval by presentation of environmental cues (conditioned stimulus, CS) or drugs (unconditioned stimulus, US). Whether CS- and US-retrieval trigger different memory reconsolidation processes is not clear.

METHODS:

Protein synthesis inhibitor or β-AR antagonist was systemically administrated or intra-central amygdala (CeA) infused immediately after cocaine re-exposure in cocaine-conditioned place preference (CPP) or self-administration (SA) mice models. β-ARs were conditional knockout in the CeA to further confirm the role of β-AR in cocaine re-exposure-induced memory reconsolidation of cocaine-CPP.

RESULTS:

Cocaine re-exposure triggered de novo protein synthesis dependent memory reconsolidation of cocaine-CPP. Cocaine-priming-induced reinstatement was also impaired with post cocaine-retrieval manipulation, in contrast to the relapse behavior with post context-retrieval manipulation. Cocaine-retrieval, but not context-retrieval, induced CeA activation. Protein synthesis inhibitor or β1-AR antagonist infused in the CeA after cocaine-retrieval, but not context-retrieval, inhibited memory reconsolidation and reinstatement. β1-AR conditional knockout in the CeA suppressed cocaine-retrieval triggered memory reconsolidation and reinstatement of cocaine-CPP. β1-AR antagonism after cocaine-retrieval also impaired reconsolidation and reinstatement of cocaine-SA.

CONCLUSIONS:

Cocaine reward memory triggered by US-retrieval is distinct from CS-retrieval. US-retrieval induced reconsolidation of cocaine reward memory depends on β1-adrenergic signaling in the CeA. Post US-retrieval manipulation can prevent drug memory reconsolidation and relapse to cocaine, thus providing a potential strategy for the prevention of substance addiction.

Abstract

Introduction

Placental insufficiency, arising from abnormal trophoblast differentiation and function, is a major cause of fetal growth restriction. Sirtuin-1 (Sirt1) is a ubiquitously-expressed NAD-dependent protein deacetylase which plays a key role in numerous cellular processes, including cellular differentiation and metabolism. Though Sirt1 has been widely studied, its role in placentation and trophoblast differentiation is unclear.

Method

Sirt1-heterozygous mice were mated and evaluated at various points during embryogenesis. In situ hybridization and immunohistochemistry were used to further characterize the placental phenotype of Sirt1-null mice. Wild-type (WT) and Sirt1-null mouse trophoblast stem cell (TSC) lines were derived from e3.5 littermate blastocysts. These cells were then evaluated at various points following differentiation. Differentiation was evaluated by expression of lineage specific markers using qPCR and flow cytometry, as well as Matrigel invasion assays. Global gene expression changes were evaluated using microarray-based RNA profiling; changes in specific pathways were validated using qPCR and western blot.

Results

In the absence of Sirt1, both embryos and placentas were small, with placentas showing abnormalities in both the labyrinthine layer and junctional zone. Sirt1-null TSCs exhibited an altered phenotype in both undifferentiated and differentiated states, phenotypes which corresponded to changes in pathways relevant to both TSC maintenance and differentiation. Specifically, Sirt1-null TSC showed blunted differentiation, and appeared to be suspended in an Epcam^high trophoblast progenitor state.

Discussion

Our results suggest that Sirt1 is required for proper TSC differentiation and placental development.

In the arcuate nucleus of the hypothalamus (ARH) satiety signaling (anorexigenic) pro-opiomelanocortin (POMC)-expressing and hunger signaling (orexigenic) agouti-related peptide (AgRP)-expressing neurons are key components of the neuronal circuits that control food intake and energy homeostasis. Here, we assessed whether the catecholamine noradrenalin directly modulates the activity of these neurons in mice. Perforated patch clamp recordings showed that noradrenalin changes the activity of these functionally antagonistic neurons in opposite ways, increasing the activity of the orexigenic NPY/AgRP neurons and decreasing the activity of the anorexigenic POMC neurons. Cell type-specific transcriptomics and pharmacological experiments revealed that the opposing effect on these neurons is mediated by the activation of excitatory α1A - and β- adrenergic receptors in NPY/AgRP neurons, while POMC neurons are inhibited via α2A - adrenergic receptors. Thus, the coordinated differential modulation of the key hypothalamic neurons in control of energy homeostasis assigns noradrenalin an important role to promote feeding.

The insulin receptor substrate of 53 kDa, IRSp53, is an adaptor protein that works with activated GTPases, Cdc42 and Rac, to modulate actin dynamics and generate membrane protrusions in response to cell signaling. Adult mice that lack IRSp53 fail to regulate synaptic plasticity and exhibit hippocampus-associated learning deficiencies. Here, we show that 60% of IRSp53 null embryos die at mid to late gestation, indicating a vital IRSp53 function in embryonic development. We find that IRSp53 KO embryos displayed pleiotropic phenotypes such as developmental delay, oligodactyly and subcutaneous edema, and died of severely impaired cardiac and placental development. We further show that double knockout of IRSp53 and its closest family member, IRTKS, resulted in exacerbated placental abnormalities, particularly in spongiotrophoblast differentiation and development, giving rise to complete embryonic lethality. Hence, our findings demonstrate a hitherto under-appreciated IRSp53 function in embryonic development, and further establish an essential genetic interaction between IRSp53 and IRTKS in placental formation.