Project description:Animals must learn through experience which foods are nutritious and should be consumed, and which are toxic and should be avoided. Enteroendocrine cells (EECs) are the principal chemosensors in the GI tract, but investigation of their role in behavior has been limited by the difficulty of selectively targeting these cells in vivo. Here we describe an intersectional genetic approach for manipulating EEC subtypes in behaving mice. We show that multiple EEC subtypes inhibit food intake but have different effects on learning. Conditioned flavor preference is driven by release of cholecystokinin whereas conditioned taste aversion is mediated by serotonin and substance P. These positive and negative valence signals are transmitted by vagal and spinal afferents, respectively. These findings establish a cellular basis for how chemosensing in the gut drives learning about food.
Project description:A substantial proportion of basal amygdala (BA) glutamate neurons project to nucleus accumbens (NAc). The evidence that these neurons are activated by reward and/or aversion is equivocal. Social stimuli are highly salient, and in male mice we conducted a detailed analysis of the responsiveness of BA-NAc neurons to estrous female (social reward, SR) or aggressive male (social aversion, SA). Both SR and SA activated c-Fos expression in a relatively high number of BA-NAc neurons in intermediate (int) BA. Using Fos-TRAP2 mice, the majority of social int-BA-NAc neurons were activated by either SR or SA, i.e. were monovalent, and in similar numbers. Fiber photometry provided corroborative evidence that int-BA-NAc neural pathway activity was similar in response to SR or SA. These findings contribute substantially to understanding the topography and valence-specificity of BA-NAc neurons with respect to highly salient stimuli, and to identifying molecular targets for treatment of reward- or aversion-specific psychopathologies.
Project description:The nucleus accumbens (NAc) plays an important role in motivation and reward processing. Recent studies suggest that different NAc subnuclei differentially contribute to reward-related behaviors. However, how reward is encoded in individual NAc neurons remains unclear. Using in vivo single-cell resolution calcium imaging, we discovered diverse patterns of reward encoding in the medial and lateral shell subdivision of the NAc (NAcMed and NAcLat, respectively). Reward consumption increases NAcLat activity but decreases NAcMed activity, albeit with high variability among neurons. The heterogeneity in reward encoding could be attributed to differences in their synaptic inputs and transcriptional profiles. Specific optogenetic activation of Nts-positive neurons in the NAcLat promotes positive reinforcement, while activation of Cartpt-positive neurons in the NAcMed induces behaviour aversion. Collectively, our study reveals organizational and transcriptional differences in NAc subregions, and provides a framework for future dissection of NAc subregions in physiological and pathological conditions.
Project description:We generated knock-in mice expressing GFP under the control of the endogenous GIP (Glucose-dependent Insulinotropic Polypeptide) promoter that enable the isolation of a purified population of small intestine K cells. Using RNA-Seq, we comprehensively characterized the transcriptomes of GIP-GFP cells as well as the entire enteroendocrine lineage derived from Neurogenin3 (Ngn3)-expressing progenitors. We interrogated the whole transcriptome of FACS-isolated small intestine GIPGFP cells using high-throughput mRNA sequencing. We also obtained the global gene expression patterns of the entire enteroendocrine cell lineage as well as the non-enteroendocrine cell population, comprising enterocytes, goblet cells and Paneth cells. To achieve this, small intestine epithelial cells from male mice resulting from the breeding of Neurogenin3 (Ngn3)-Cre mice with ROSA26-LoxP-STOP-LoxP-tomato indicator mice were isolated based on Tomato fluorescence and negative staining for CD45. Due to the small cell numbers, we constructed each of the three RNA-Seq libraries (GIPGFP, Ngn3TOMATO, and Ngn3-) using a pool of equal amounts of individual RNA samples without RNA amplification.
Project description:The ability of honey bees to evaluate differences in food type and value is crucial for colony success, but these assessments are made by individuals who bring food to the hive, eating little, if any, of it themselves. We tested the hypothesis that responses to food type (pollen or nectar) and value involve different subsets of brain regions, and genes responsive to food. mRNA in situ hybridization of c‐jun revealed that brain regions responsive to differences in food type were mostly different from regions responsive to differences in food value, except those dorsal and lateral to the mushroom body calyces, which responded to all three. Transcriptomic profiles of the mushroom bodies generated by RNA sequencing gave the following results: (1) responses to differences in food type or value included a subset of molecular pathways involved in the response to food reward; (2) genes responsive to food reward, food type and food value were enriched for (the Gene Ontology categories) mitochondrial and endoplasmic reticulum activity; (3) genes responsive to only food and food type were enriched for regulation of transcription and translation; and (4) genes responsive to only food and food value were enriched for regulation of neuronal signaling. These results reveal how activities necessary for colony survival are channeled through the reward system of individual honey bees.
Project description:Reduced reward interest/learning and reward-to-effort valuation are distinct, common symptoms in neuropsychiatric disorders for which chronic stress is a major aetiological factor. Pyramidal glutamate neurons in the basal amygdala (BA) project to various brain regions including nucleus accumbens (NAc). The BA-NAc neural pathway is activated by reward and aversion, with many neurons being monovalent. In adult male mice, chronic social stress (CSS) led to both reduced discriminative reward learning (DRL) associated with decreased BA-NAc Ca2+ activity, and reduced sucrose reward-to-effort valuation (REV) associated, in contrast, with increased BA-NAc Ca2+ activity. Chronic tetanus toxin inhibition of BA-NAc neurons replicated the CSS-DRL effect whilst causing only a mild REV reduction, whilst chronic DREADDs activation of BA-NAc neurons replicated the CSS effect on REV without affecting DRL. This study provides novel evidence that chronic stress disruption of reward processing involves the BA-NAc neural pathway; the bi-directional effects implicate activity changes in BA-NAc reward (learning) and aversion (effort) neurons, with the net overall direction of stress-induced change in activity dependent on on-going stimulus processing and behaviour.
Project description:Reduced reward interest/learning and reward-to-effort valuation are distinct, common symptoms in neuropsychiatric disorders for which chronic stress is a major aetiological factor. Pyramidal glutamate neurons in the basal amygdala (BA) project to various brain regions including nucleus accumbens (NAc). The BA-NAc neural pathway is activated by reward and aversion, with many neurons being monovalent. In adult male mice, chronic social stress (CSS) led to both reduced discriminative reward learning (DRL) associated with decreased BA-NAc Ca2+ activity, and reduced sucrose reward-to-effort valuation (REV) associated, in contrast, with increased BA-NAc Ca2+ activity. Chronic tetanus toxin inhibition of BA-NAc neurons replicated the CSS-DRL effect whilst causing only a mild REV reduction, whilst chronic DREADDs activation of BA-NAc neurons replicated the CSS effect on REV without affecting DRL. This study provides novel evidence that chronic stress disruption of reward processing involves the BA-NAc neural pathway; the bi-directional effects implicate activity changes in BA-NAc reward (learning) and aversion (effort) neurons, with the net overall direction of stress-induced change in activity dependent on on-going stimulus processing and behaviour.