Role of dorsomedial striatum neuronal ensembles in incubation of methamphetamine craving after voluntary abstinence

Abstract We recently developed a rat model of incubation of methamphetamine craving after choice-based voluntary abstinence. Here, we studied the role of dorsolateral striatum (DLS) and dorsomedial striatum (DMS) in this incubation. We trained rats to self-administer palatable food pellets (6 d, 6 h/d) and methamphetamine (12 d, 6 h/d). We then assessed relapse to methamphetamine seeking under extinction conditions after 1 and 21 abstinence days. Between tests, the rats underwent voluntary abstinence (using a discrete choice procedure between methamphetamine and food; 20 trials/d) for 19 d. We used in situ hybridization to measure the colabeling of the activity marker Fos with Drd1 and Drd2 in DMS and DLS after the tests. Based on the in situ hybridization colabeling results, we tested the causal role of DMS D1 and D2 family receptors, and DMS neuronal ensembles in "incubated" methamphetamine seeking, using selective dopamine receptor antagonists (SCH39166 or raclopride) and the Daun02 chemogenetic inactivation procedure, respectively. Methamphetamine seeking was higher after 21 d of voluntary abstinence than after 1 d (incubation of methamphetamine craving). The incubated response was associated with increased Fos expression in DMS but not in DLS; Fos was colabeled with both Drd1 and Drd2 DMS injections of SCH39166 or raclopride selectively decreased methamphetamine seeking after 21 abstinence days. In Fos-lacZ transgenic rats, selective inactivation of relapse test-activated Fos neurons in DMS on abstinence day 18 decreased incubated methamphetamine seeking on day 21. Results demonstrate a role of DMS dopamine D1 and D2 receptors in the incubation of methamphetamine craving after voluntary abstinence and that DMS neuronal ensembles mediate this incubation. SIGNIFICANCE STATEMENT: In human addicts, abstinence is often self-imposed and relapse can be triggered by exposure to drug-associated cues that induce drug craving. We recently developed a rat model of incubation of methamphetamine craving after choice-based voluntary abstinence. Here, we used classical pharmacology, in situ hybridization, immunohistochemistry, and the Daun02 inactivation procedure to demonstrate a critical role of dorsomedial striatum neuronal ensembles in this new form of incubation of drug craving

Blockade of adenosine A2A receptors prevents protein phosphorylation in the striatum induced by cortical stimulation

©2006 Society for NeurosciencePrevious studies have shown that cortical stimulation selectively activates extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation and immediate early gene expression in striatal GABAergic enkephalinergic neurons. In the present study, we demonstrate that blockade of adenosine A2A receptors with caffeine or a selective A2A receptor antagonist counteracts the striatal activation of cAMP– protein kinase A cascade (phosphorylation of the Ser845 residue of the glutamate receptor 1 subunit of the AMPA receptor) and mitogenactivated protein kinase (ERK1/2 phosphorylation) induced by the in vivo stimulation of corticostriatal afferents. The results indicate that A2A receptors strongly modulate the efficacy of glutamatergic synapses on striatal enkephalinergic neurons.This work was supported by the Intramural Research Program of the National Institutes of Health, National Institute on Drug Abuse, Department of Health and Human Services

Exploring the epigenetics of cocaine resistance

Drug addiction is known to have a heritable component and to run in families. However, a recent study in rats by Vassoler et al.(1) shows an unexpected result-that the sons of males who had self-administered cocaine had a reduced propensity to take this drug and a delay in their acquisition of drug-seeking behavior. The authors linked these behavioral changes to epigenetic changes in the sperm from cocaine-exposed males and in the brains of their male offspring. We asked four experts to comment on the results of this study and their implications for understanding how addictive phenotypes are inherited

Ruptured splenic artery aneurysms and the use of an adapted fast protocol in reproductive age women with hemodynamic collapse: Case series

Nontraumatic symptomatic hypotension in all patients requires prompt diagnosis and appropriate treatment for optimum outcome. The female population specifically has an expanded differential diagnosis that should be considered when these patients present with hemodynamic collapse. While the most common causes of hypotension in pregnant patients are dehydration, ruptured ectopic pregnancy, and placental and uterine abnormalities, less common nonobstetrical etiologies such as hepatic rupture and ruptured abdominal and visceral artery aneurysms should also be considered. Splenic artery aneurysms are associated with high rates of mortality and in cases of pregnancy, maternal and fetal mortality. These high rates can be attributed to the asymptomatic nature of the aneurysm, rapid deterioration after rupture, and frequent misdiagnosis. In patients with hemodynamic collapse, the role of traditional imaging is limited mainly due to the critical condition of the patient. Bedside ultrasound has emerged as a diagnostic imaging resource in patients with undifferentiated hypotension and in patients with traumatic injuries. However, its use has not been studied specifically in the female population. We present two patients with ruptured splenic artery aneurysms, discuss the role of bedside ultrasound in their management, and introduce a new ultrasound protocol for use in reproductive age female patients with hemodynamic collapse

Distinct fos-expressing neuronal ensembles in the ventromedial prefrontal cortex mediate food reward and extinction memories

In operant learning, initial reward-associated memories are thought to be distinct from subsequent extinction-associated memories. Memories formed during operant learning are thought to be stored in “neuronal ensembles.” Thus, we hypothesize that different neuronal ensembles encode reward- and extinction-associated memories. Here, we examined prefrontal cortex neuronal ensembles involved in the recall of reward and extinction memories of food self-administration.Wefirst trained rats to lever press for palatable food pellets for 7 d (1 h/d) and then exposed them to 0, 2, or 7 daily extinction sessions in which lever presses were not reinforced. Twenty-four hours after the last training or extinction session, we exposed the rats to either a short 15 min extinction test session or left them in their homecage (a control condition). We found maximal Fos (a neuronal activity marker) immunoreactivity in the ventral medial prefrontal cortex of rats that previously received 2 extinction sessions, suggesting that neuronal ensembles in this area encode extinction memories. We then used the Daun02 inactivation procedure to selectively disrupt ventral medial prefrontal cortex neuronal ensembles that were activated during the 15 min extinction session following 0 (no extinction) or 2 prior extinction sessions to determine the effects of inactivating the putative food reward and extinction ensembles, respectively, on subsequent nonreinforced food seeking 2 d later. Inactivation of the food reward ensembles decreased food seeking, whereas inactivation of the extinction ensembles increased food seeking. Our results indicate that distinct neuronal ensembles encoding operant reward and extinction memories intermingle within the same cortical area

Medial prefrontal cortex neuronal activation and synaptic alterations after stress-induced reinstatement of palatable food seeking: a study using c-fos-GFP transgenic female rats

Relapse to maladaptive eating habits during dieting is often provoked by stress and there is evidence for a role of ovarian hormones in stress responses and feeding. We studied the role of these hormones in stress-induced reinstatement of food seeking and medial prefrontal cortex (mPFC) neuronal activation in c-fos-GFP transgenic female rats, which express GFP in strongly activated neurons. Food-restricted ovariectomized or sham-operated c-fos-GFP rats were trained to lever-press for palatable food pellets. Subsequently, lever-pressing was extinguished and reinstatement of food seeking and mPFC neuronal activation was assessed after injections of the pharmacological stressor yohimbine (0.5-2 mg/kg) or pellet priming (1-4 noncontingent pellets). Estrous cycle effects on reinstatement were also assessed in wild-type rats. Yohimbine- and pellet-priming-induced reinstatement was associated with Fos and GFP induction in mPFC; both reinstatement and neuronal activation were minimally affected by ovarian hormones in both c-fos-GFP and wild-type rats. c-fos-GFP transgenic rats were then used to assess glutamatergic synaptic alterations within activated GFP-positive and nonactivated GFP-negative mPFC neurons following yohimbine-induced reinstatement of food seeking. This reinstatement was associated with reduced AMPA receptor/NMDA receptor current ratios and increased paired-pulse facilitation in activated GFP-positive but not GFP-negative neurons. While ovarian hormones do not appear to play a role in stress-induced relapse of food seeking in our rat model, this reinstatement was associated with unique synaptic alterations in strongly activated mPFC neurons. Our paper introduces the c-fos-GFP transgenic rat as a new tool to study unique synaptic changes in activated neurons during behavio

Ruptured Splenic Artery Aneurysms and the Use of an Adapted Fast Protocol in Reproductive Age Women with Hemodynamic Collapse: Case Series

Nontraumatic symptomatic hypotension in all patients requires prompt diagnosis and appropriate treatment for optimum outcome. The female population specifically has an expanded differential diagnosis that should be considered when these patients present with hemodynamic collapse. While the most common causes of hypotension in pregnant patients are dehydration, ruptured ectopic pregnancy, and placental and uterine abnormalities, less common nonobstetrical etiologies such as hepatic rupture and ruptured abdominal and visceral artery aneurysms should also be considered. Splenic artery aneurysms are associated with high rates of mortality and in cases of pregnancy, maternal and fetal mortality. These high rates can be attributed to the asymptomatic nature of the aneurysm, rapid deterioration after rupture, and frequent misdiagnosis. In patients with hemodynamic collapse, the role of traditional imaging is limited mainly due to the critical condition of the patient. Bedside ultrasound has emerged as a diagnostic imaging resource in patients with undifferentiated hypotension and in patients with traumatic injuries. However, its use has not been studied specifically in the female population. We present two patients with ruptured splenic artery aneurysms, discuss the role of bedside ultrasound in their management, and introduce a new ultrasound protocol for use in reproductive age female patients with hemodynamic collapse

Microdissection: A method developed to investigate mechanisms involved in transmissible spongiform encephalopathy pathogenesis

BACKGROUND: The transmissible spongiform encephalopathies (TSEs) are a group of neurodegenerative diseases affecting both human and animals. The neuroanatomical changes which occur in the central nervous system (CNS) of TSE infected animals include vacuolation, gliosis, neuronal loss and the deposition of a disease specific protein, PrP(Sc). Experimental murine models of scrapie, a TSE of sheep, have revealed that pathology may be confined to specific brain areas with targeting of particular neuronal subsets depending on route of injection and scrapie isolate. To assess the biochemical changes which are taking place in these targeted areas it was necessary to develop a reliable sampling procedure (microdissection) which could be used for a variety of tests such as western blotting and magnetic resonance spectroscopy. METHODS: The method described is for the microdissection of murine brains. To assess the usefulness of this dissection technique for producing similar sample types for analysis by various down-stream biochemical techniques, the areas dissected were analysed for PrP(Sc )by western blotting and compared to immunocytochemical (ICC) techniques. RESULTS: Results show that the method generates samples yielding a consistent protein content which can be analysed for PrP(Sc). The areas in which PrP(Sc )is found by western blotting compares well with localisation visualised by immunocytochemistry. CONCLUSION: The microdisssection method described can be used to generate samples suitable for a range of biochemical techniques. Using these samples a range of assays can be carried out which will help to elucidate the molecular and cellular mechanisms underlying TSE pathogenesis. The method would also be useful for any study requiring the investigation of discrete areas within the murine brain

Role of Ventral Subiculum in Context-Induced Relapse to Alcohol Seeking after Punishment-Imposed Abstinence

In many human alcoholics, abstinence is self-imposed because of the negative consequences of excessive alcohol use, and relapse is often triggered by exposure to environmental contexts associated with prior alcohol drinking. We recently developed a rat model of this human condition in which we train alcohol-preferring P rats to self-administer alcohol in one context (A), punish the alcohol-reinforced responding in a different context (B), and then test for relapse to alcohol seeking in Contexts A and B without alcohol or shock. Here, we studied the role of projections to nucleus accumbens (NAc) shell from ventral subiculum (vSub), basolateral amygdala, paraventricular thalamus, and ventral medial prefrontal cortex in context-induced relapse after punishment-imposed abstinence. First, we measured double-labeling of the neuronal activity marker Fos with the retrograde tracer cholera toxin subunit B (injected in NAc shell) and demonstrated that context-induced relapse is associated with selective activation of the vSub→NAc shell projection. Next, we reversibly inactivated the vSub with GABA receptor agonists (muscimol+baclofen) before the context-induced relapse tests and provided evidence for a causal role of vSub in this relapse. Finally, we used a dual-virus approach to restrict expression of the inhibitory κ opioid-receptor based DREADD (KORD) in vSub→NAc shell projection neurons. We found that systemic injections of the KORD agonist salvinorin B, which selectively inhibits KORD-expressing neurons, decreased context-induced relapse to alcohol seeking. Our results demonstrate a critical role of vSub in context-induced relapse after punishment-imposed abstinence and further suggest a role of the vSub→NAc projection in this relapse. SIGNIFICANCE STATEMENT In many human alcoholics, abstinence is self-imposed because of the negative consequences of excessive use, and relapse is often triggered by exposure to environmental contexts associated with prior alcohol use. Until recently, an animal model of this human condition did not exist. We developed a rat model of this human condition in which we train alcohol-preferring P rats to self-administer alcohol in one context (A), punish the alcohol-reinforced responding in a different context (B), and test for relapse to alcohol seeking in Contexts A and B. Here, we used neuroanatomical, neuropharmacological, and chemogenetic methods to demonstrate a role of ventral subiculum and potentially its projections to nucleus accumbens in context-induced relapse after punishment-imposed abstinence