Increased expression of proenkephalin and prodynorphin mRNAs in the nucleus accumbens of compulsive methamphetamine taking rats
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ABSTRACT: Addiction to psychostimulants is associated with neuroadaptive changes in various brain regions. In this experiment we use a model of methamphetamine self-administration during which we use footshocks as adverse consequences to divide rats into animals that continue to press an active lever to get the drug (shock-resistant) whereas other rats stop or significantly reduce pressing the lever (shock-sensitive) in the presence of these adverse consequences. To investigate potential molecular bases for the divergent phenotype, we performed a whole rat transcriptome study using Affymetrix rat arrays that cover more than 24,000 coding transcripts. The array experiments revealed that there were 24 differentially expressed genes between the resistant and sensitive rats, with 15 up- and 9 downregulated transcripts. Ingenuity pathway analysis revealed that these transcripts belong in a network of genes involved in nervous system development and function, cell signaling, behavior, and disorders of the basal ganglia. These genes included proenkephalin (PENK) and prodynorphin (PDYN), among others. Because PDYN and PENK are expressed in dopamine D1- and D2-containing NAc neurons, respectively, these findings suggest that mechanisms that impact both cell types may play a role in the regulation of compulsive methamphetamine taking by rats.
Project description:Methamphetamine (METH) is a powerful stimulant that has caused addiction (compulsive drug seeking and taking behavior) in millions of people world-wide. METH abuse is also associated with negative impact on the brain. One feature of addiction is uncontrollable drug seeking despite adverse consequences and becomes habitual. To mimic this in a rat model, rats with a history of METH use are given the opportunity to earn METH accompanied by aversive shocks on their feet. Rats that continue to take METH are shock-resistant (SR) and rats that reduce their METH intake are shock-sensitive (SS ).Rats that self-administered saline are controls (CT). In addition, we used controls for shock paradigm. For this purpose, when METH SA rat received a shock, the saline SA rat was also shocked. The separate groups of rats that were yoked (Y) to the corresponding METH shock-resistant (SR) and shock-sensitive (SS) rats are termed YSR and YSS, respectively.
Project description:Methamphetamine (METH) is a powerful stimulant that has caused addiction (compulsive drug seeking and taking behavior) in millions of people world-wide. METH abuse is also associated with negative impact on the brain. One feature of addiction is uncontrollable drug seeking despite adverse consequences and becomes habitual. To mimic this in a rat model, rats with a history of METH use are given the opportunity to earn METH accompanied by aversive shocks on their feet. Rats that continue to take METH are shock-resistant (SR) and rats that reduce their METH intake are shock-sensitive (SS ).Rats that self-administered saline are controls (CT). Thereafter, rats were injected intraperitoneally with the dopamine D1 receptor antagonist, SCH23390. SCH23390 caused substantial reduction of METH taking in a dose-dependent fashion. Stopping SCH23390 administration led to re-emergence of compulsive METH taking in the shock-resistant rats.
Project description:Methamphetamine addiction is mimicked in rats that self-administer the drug and accelerate their intake when given long access to it. Self-administration (SA) models do not include adverse consequences that are necessary to reach a diagnosis of addiction in humans. Here, we studied transcriptional consequences of methamphetamine SA and repeated foot-shocks in rat brain.
Project description:Methamphetamine addiction is mimicked in rats that self-administer the drug and accelerate their intake when given long access to it. Self-administration (SA) models do not include adverse consequences that are necessary to reach a diagnosis of addiction in humans. Here, we studied transcriptional consequences of methamphetamine SA and repeated foot-shocks in rat brain.
Project description:Methamphetamine (METH) use disorder (MUD) is a neuropsychiatric disorder with loss of self-control over drug intake despite of negative consequences. The behavioral consequences of long-term METH intake on compulsive and non-compulsive individuals remain unclear. Herein we trained rats to self-administered METH 1st for 22 days than 8 days of foot-shock and 15 days of abstinence. Which was followed by 12 days of reinstatement to METH self-administration then 3 days of foot-shock and 15 days of abstinence. After 1st foot-shock phase we found two phenotypes based on their METH intake i.e., shock resistance (SR, compulsive), and shock sensitive (SS, non-compulsive). Interestingly during reinstatement of METH self-administration then foot-shock, some (resurgent shock resistance, RSR) non-compulsive rats, displayed compulsive METH intake behavior. During both abstinence period rats were tested for drug seeking behavior and SR rats displayed higher METH seeking then RSR and SS. 24 hour after 2nd withdrawal day testing, we compared transcriptional and epigenetic changes in dorsal striatum.
Project description:We studied the brain mechanisms of ‘social problem’ where a worker’s credit is exploited in a group setting. A stable ‘worker-parasite’ relationship developed when three individually operant-conditioned rats were placed together in a Skinner box equipped with response lever and food dispenser on opposite sides. Specifically, one rat, the ‘worker,’ engaged in lever-pressing while the other ‘parasitic’ rats profited by crowding the feeder in anticipation. c-Fos expression in the anterior cingulate cortex (ACC) was significantly higher in worker rats than in parasite rats. ACC inactivation suppressed the worker’s lever-press behavior under the social dilemma settings. Importantly, our RNA sequencing and the differential expression analysis showed that GABA- and potassium channel-related mRNA expressions decreased in the worker’s ACC. In contrast, network disinhibition induced-activity responsive genes such as Cyr61, Arc, and Klf are upregulated. These results suggest that downregulation and upregulation of network inhibitory and excitatory factors, respectively, in the ACC of the worker compared to parasite rats.
Project description:Estrogen receptor a (ERa) signaling in the ventromedial hypothalamus (VMH) contributes to energy homeostasis by modulating physical activity and thermogenesis. However, the precise neuronal populations involved remain undefined. Using single-cell RNA transcriptomics and in situ hybridization, we describe six neuronal populations in the mouse VMH. ERa is enriched in populations showing sex biased expression of reprimo (Rprm), tachykinin 1 (Tac1), and prodynorphin (Pdyn). Female biased expression of Tac1 and Rprm is patterned by ERa-dependent repression during male development, whereas male biased expression of Pdyn is maintained by circulating testicular hormone in adulthood. Chemogenetic activation of ERa+ VMH neurons stimulates heat generation and movement in both sexes. However, silencing Rprm gene function increases core temperature selectively in females and ectopic Rprm expression in males is associated with reduced core temperature. Together these findings reveal a role for Rprm in temperature regulation and ERa in the masculinization of neuron populations that underlie energy expenditure.
Project description:Prodynorphine-expressing neurons were targeted by eGFP-RPL10a, a transgene that is expressed under the control of the Pdyn promoter in a BAC containing the Pdyn backbone. Trangenic mice were made with FvB embryos via pro-nuclear injection. Transgene-positive progenies were bred to C57BL/6J for more than five generations before being used in the current experiment. Triplicates of 6-8 hypothalami were collected per sample from wild-type and ob/ob adult mice. Polysomal IP RNA and total Input RNA were purified from each sample. Affymetrix GeneChip Mouse 430 2.0 arrays (900495) were used to identify transcripts that are specifically expressed in Pdyn neurons with a fold change (IP vs. Input) of >=2 in wild-type mice. The same microarrays were also used to identify Pdyn-specific transcripts that are differentially regulated transcriptionally by leptin deficiency with a fold change (ob IP vs. wt IP) of >=1.5.
Project description:Motherhood involves a switch in natural rewards, whereby offspring become highly rewarding. Nucleus accumbens (NAC) is a key CNS region for natural rewards and addictions, but to date no study has evaluated on a large scale the events in NAC that underlie the maternal change in natural rewards. In this study we utilized microarray and bioinformatics approaches to evaluate postpartum NAC gene expression changes in mice. Modular Single-set Enrichment Test (MSET) indicated that postpartum (relative to virgin) NAC gene expression profile was significantly enriched for genes related to addiction and reward in 5 of 5 independently curated databases (e.g., Malacards, Phenopedia). Over 100 addiction/reward related genes were identified and these included: Per1, Per2, Arc, Homer2, Creb1, Grm3, Fosb, Gabrb3, Adra2a, Ntrk2, Cry1, Penk, Cartpt, Adcy1, Npy1r, Htr1a, Drd1a, Gria1, and Pdyn. ToppCluster analysis found maternal NAC expression profile to be significantly enriched for genes related to the drug action of nicotine, ketamine, and dronabinol. Pathway analysis indicated postpartum NAC as enriched for RNA processing, CNS development/differentiation, and transcriptional regulation. Weighted Gene Coexpression Network Analysis identified possible networks for transcription factors, including Nr1d1, Per2, Fosb, Egr1, and Nr4a1. The postpartum state involves increased risk for mental health disorders and MSET analysis indicated postpartum NAC to be enriched for genes related to depression, bipolar disorder, and schizophrenia. Mental health related genes included: Fabp7, Grm3, Penk, and Nr1d1. We confirmed via quantitative PCR Nr1d1, Per2, Grm3, Penk, Drd1a, and Pdyn. This study indicates for the first time that postpartum NAC involves large scale gene expression alterations linked to addiction and reward. Because the postpartum state also involves decreased response to drugs, the findings could provide insights into how to mitigate addictions.