Time-Dependent Effects of Stress on Cocaine Conditioned Place Preference Using a Rat Model of Posttraumatic Stress Disorder

Posttraumatic Stress Disorder (PTSD) affects approximately 8% of the entire population within their lifetimes. A startling trend of co-occurring PTSD and cocaine use has surfaced among humans who express these disorders. The present study employed the rat model of PTSD, Single Prolonged Stress, to examine the effects of stress on the rewarding properties of cocaine. Place conditioning was used to specifically evaluate differences between animals that had undergone a post-stress delay of conditioning in comparison to animals that were not delayed. This delay before conditioning, or incubation period, is a time spent undisturbed in the home cage for 10-days post-stress and has been implicated as the phase in which many of the physiological, neurochemical and behavioral changes observed in humans who have experienced stress take place. Although cocaine conditioned place preference was observed, no significant differences were detected between animals that were not stressed, stressed but not incubated, or stressed and then incubated. These results suggest that it is possible that the changes that are understood to take place within this incubation period did not directly influence cocaine reward, or that they did not take place. Future work should focus on examining different drugs, in addition to including additional testing intervals, and varying drug dose

Animal Spirits: Affective and Deliberative Processes in Economic Behavior

The economic conception of human behavior assumes that a person has a single set of well-defined goals, and that the person's behavior is chosen to best achieve those goals. We develop a model in which a person's behavior is the outcome of an interaction between two systems: a deliberative system that assesses options with a broad, goal-based perspective, and an affective system that encompasses emotions and motivational drives. Our model provides a framework for understanding many departures from full rationality discussed in the behavioral-economics literature, and captures the familiar feeling of being "of two minds." And by focusing on factors that moderate the relative influence of the two systems, our model also generates a variety of novel testable predictions.

Cannabidiol regulation of emotion and emotional memory processing: relevance for treating anxiety-related and substance abuse disorders

Learning to associate cues or contexts with potential threats or rewards is adaptive and enhances survival. Both aversive and appetitive memories are therefore powerful drivers of behaviour, but the inappropriate expression of conditioned responding to fear- and drug-related stimuli can develop into anxiety-related and substance abuse disorders respectively. These disorders are associated with abnormally persistent emotional memories and inadequate treatment, often leading to symptom relapse. Studies show that cannabidiol, the main non-psychotomimetic phytocannabinoid found in Cannabis sativa, reduces anxiety via 5-HT1A and (indirect) cannabinoid receptor activation in paradigms assessing innate responses to threat. There is also accumulating evidence from animal studies investigating the effects of cannabidiol on fear memory processing indicating that it reduces learned fear in paradigms that are translationally relevant to phobias and post-traumatic stress disorder. Cannabidiol does so by reducing fear expression acutely and by disrupting fear memory reconsolidation and enhancing fear extinction, both of which can result in a lasting reduction of learned fear. Recent studies have also begun to elucidate the effects of cannabidiol on drug memory expression using paradigms with translational relevance to addiction. The findings suggest that cannabidiol reduces the expression of drug memories acutely and by disrupting their reconsolidation. Here, we review the literature demonstrating the anxiolytic effects of cannabidiol before focusing on studies investigating its effects on various fear and drug memory processes. Understanding how cannabidiol regulates emotion and emotional memory processing may eventually lead to its use as a treatment for anxiety-related and substance abuse disorders

Neuroeconomics: How Neuroscience Can Inform Economics

Neuroeconomics uses knowledge about brain mechanisms to inform economic analysis, and roots economics in biology. It opens up the "black box" of the brain, much as organizational economics adds detail to the theory of the firm. Neuroscientists use many tools— including brain imaging, behavior of patients with localized brain lesions, animal behavior, and recording single neuron activity. The key insight for economics is that the brain is composed of multiple systems which interact. Controlled systems ("executive function") interrupt automatic ones. Emotions and cognition both guide decisions. Just as prices and allocations emerge from the interaction of two processes—supply and demand— individual decisions can be modeled as the result of two (or more) processes interacting. Indeed, "dual-process" models of this sort are better rooted in neuroscientific fact, and more empirically accurate, than single-process models (such as utility-maximization). We discuss how brain evidence complicates standard assumptions about basic preference, to include homeostasis and other kinds of state-dependence. We also discuss applications to intertemporal choice, risk and decision making, and game theory. Intertemporal choice appears to be domain-specific and heavily influenced by emotion. The simplified ß-d of quasi-hyperbolic discounting is supported by activation in distinct regions of limbic and cortical systems. In risky decision, imaging data tentatively support the idea that gains and losses are coded separately, and that ambiguity is distinct from risk, because it activates fear and discomfort regions. (Ironically, lesion patients who do not receive fear signals in prefrontal cortex are "rationally" neutral toward ambiguity.) Game theory studies show the effect of brain regions implicated in "theory of mind", correlates of strategic skill, and effects of hormones and other biological variables. Finally, economics can contribute to neuroscience because simple rational-choice models are useful for understanding highly-evolved behavior like motor actions that earn rewards, and Bayesian integration of sensorimotor information

Mechanisms of attention for cues associated with rewarding and aversive outcomes

Attentional biases arising from classical conditioning processes may contribute to the maintenance of drug addictions and anxiety disorders. This thesis examined whether attentional mechanisms for conditioned stimuli (CS) would be dominated by affective properties (Lang, Greenwald, Bradley, & Hamm, 1993), or the uncertainty of the stimulus in predicting the outcome (Pearce & Hall, 1980). In chapter one affective and uncertainty-driven mechanisms of attention are discussed in relation to rewarding and aversive outcomes. In experimental chapter 2 methodological issues are addressed. In experimental chapters three and four attentional mechanisms are tested using a discriminative conditioning procedure with visual stimuli of varying predictive certainty (CS+,CS+/-,CS-) for a monetary or noise outcome (US). Attention was measured using an eye-tracker, and emotional conditioning and learning were measured using Likert scales. It was found that attention was mediated by uncertainty (chapter 3), but increasing the intensity of the outcome switched attention to affective-driven mechanisms for the noise outcome (chapter 4). In a further experiment this effect on attention remained for the noise outcome even under conditions promoting uncertainty-driven mechanisms (chapter 6). When cigarettes were the unconditioned stimuli instead of money in the appetitive conditioning, attention was also mediated by stimulus affect (chapter 5). In chapter 7 the data are discussed and it is concluded that when the outcome is highly emotionally salient, affective-driven mechanisms of attention dominate over uncertainty

Mechanisms of attention for cues associated with rewarding and aversive outcomes

Attentional biases arising from classical conditioning processes may contribute to the maintenance of drug addictions and anxiety disorders. This thesis examined whether attentional mechanisms for conditioned stimuli (CS) would be dominated by affective properties (Lang, Greenwald, Bradley, & Hamm, 1993), or the uncertainty of the stimulus in predicting the outcome (Pearce & Hall, 1980). In chapter one affective and uncertainty-driven mechanisms of attention are discussed in relation to rewarding and aversive outcomes. In experimental chapter 2 methodological issues are addressed. In experimental chapters three and four attentional mechanisms are tested using a discriminative conditioning procedure with visual stimuli of varying predictive certainty (CS+,CS+/-,CS-) for a monetary or noise outcome (US). Attention was measured using an eye-tracker, and emotional conditioning and learning were measured using Likert scales. It was found that attention was mediated by uncertainty (chapter 3), but increasing the intensity of the outcome switched attention to affective-driven mechanisms for the noise outcome (chapter 4). In a further experiment this effect on attention remained for the noise outcome even under conditions promoting uncertainty-driven mechanisms (chapter 6). When cigarettes were the unconditioned stimuli instead of money in the appetitive conditioning, attention was also mediated by stimulus affect (chapter 5). In chapter 7 the data are discussed and it is concluded that when the outcome is highly emotionally salient, affective-driven mechanisms of attention dominate over uncertainty

The Role of NMDA Receptors in Extinction of Cocaine Self-Administration

Relapse is highly prevalent among recovering addicts, and can be triggered by associations made between the rewarding effects of the drug and cues, such as drug paraphernalia or contexts. Inhibiting these associations, through new extinction learning, could help reduce relapse rates. Extinction is formed in phases, like other types of memory. The memory first is acquired in short-term memory, then is consolidated into long-term storage from which it can be retrieved at a later time (Quirk & Mueller, 2008). NMDA receptors are necessary for extinction in other paradigms (Santini, Muller, & Quirk, 2001), and we previously found that blocking NMDA receptors before four 45-minute extinction sessions disrupts retention when tested during a subsequent full extinction session. However, it is unclear which learning phase was disrupted. To determine how NMDA receptors affect extinction of cocaine self-administration, rats were trained to lever press for i.v. infusions of cocaine. Following training, rats underwent four 45-minute extinction sessions and received post-extinction session systemic injections of either the NMDA receptor antagonist CPP or the NMDA receptor coagonist D-serine. I hypothesized that CPP would disrupt extinction learning, and D-serine would facilitate extinction learning. Post-extinction session injections of CPP did not disrupt the consolidation of extinction, but instead appears to facilitate extinction. Alternative explanations such as pharmacological side effects or disrupted reconsolidation could explain these results. Post-session injections of D-serine facilitated consolidation of extinction compared to controls. These studies indicate that NMDA receptors are necessary for acquisition and maybe consolidation of extinction, and potentiating NMDA receptors will facilitate extinction learning. Additionally, western blotting was conducted on ventral medial prefrontal cortex (vmPFC) and nucleus accumbens (NAc) tissue to determine glutamate receptor expression following extinction of cocaine self-administration, withdrawal from cocaine, or extinction of sucrose reinforcement. Results indicated a trend for increased NR2B-containing NMDA receptor expression in the vmPFC after extinction of sucrose reinforcement and increased expression of NR2A- and NR2B-containing NMDA receptors in the NAc following cocaine withdrawal compared to expression following extinction of sucrose reinforcement. Thus, these studies indicate that cocaine use and extinction learning can induce changes with NMDA receptors in the NAc and possibly vmPFC

Effects of functional disconnection of the basolateral mygdala and dorsal hippocampus following cocaine memory eactivation on subsequent drug context-induced cocaine-seeking behavior in rats

Stimulus control over instrumental drug seeking relies on the reconsolidation of context-response-drug associations into long-term memory following retrieval-induced destabilization. According to previous studies, the basolateral amygdala (BLA) and dorsal hippocampus (DH) regulate cocaine-related memory reconsolidation; however, it is not known whether these brain regions interact or independently control this phenomenon. In the present study, using the contextual rodent extinction-reinstatement paradigm, we demonstrate that disruption of intrahemispheric (disconnection), but not interhemispheric (ipsilateral control), interactions between the BLA and DH following cocaine-related memory reactivation impaired subsequent drug context-induced cocaine-seeking behavior in rats. Furthermore, post-reactivation BLA/DH disconnection inhibited the development of a time-dependent increase, or incubation, of drug context-induced cocaine seeking following an extended delay, despite some recovery of cocaine-seeking behavior. Thus, the BLA and DH interact to regulate the reconsolidation of cocaine-related memories, thereby facilitating the ability of drug-paired contexts to trigger cocaine seeking and contributing to the incubation of cocaine seeking

Cognitive Processes in Acquiring Food Preferences: Evaluative Conditioning Studies with Food-Related Stimuli

In this thesis, 1 we explored the potential of EC interventions with food-related stimuli to form and modify food preferences. The main research questions within this dissertation revolve around the role of memory in EC, the potential preparedness effect for smell-taste combinations and the hypothesized differential learning patterns between normal weight and obese participants in processing high-calorie palatable foods. In Chapter 2, we present evidence for the relevance of memory and the preparedness of smell-taste pairings in EC. In Experiment 1, we tested the role of memory in smell-taste EC. In Experiment 2, we investigated the role of memory more conclusively and tested for the presence of the preparedness of smell-taste combinations. The results show that both in Experiment 1 and in Experiment 2 we found EC effects only in the presence of memory. Furthermore, the results of Experiment 2 support the preparedness hypothesis for smell-taste pairings in EC. In Chapter 3, we tested the role of memory for food CS-US pairings and looked at the preparedness hypothesis for smell-taste combinations in an EC study with real foods as CSs. We measured EC effects in the explicit evaluative ratings and in food consumption of food CSs. The results showed no overall EC effects neither in the explicit evaluative ratings, nor in food consumption. Nonetheless, we found that participants consumed more of food CSs that had previously been paired with pleasant USs, but only when participants remembered CS-US pairings. Interestingly, for non-remembered pairings the pattern of the results was reversed. In Chapter 4, we investigated the hypothesized differences in learning effects between normal weight and obese participants in a computerized EC procedure with high-calorie and tasty-looking foods as CSs. We compared the magnitude of EC effects measured in the explicit evaluative ratings (Experiment 4, 5) and in the intention to consume food CSs (Experiment 4) between the two groups. We also looked at group differences in the accuracy at the guessing trials within the implemented EC paradigm. The results showed overall EC effects measured both in the explicit evaluative ratings and in the intention to consume foods. These learning effects were moderated by valence memory. We did not, however, find any evidence to support the hypothesized differences in the magnitude of learning effects between normal weight and obese individuals. Together, the research findings described in this dissertation make significant contribution to the existing body of knowledge on the role of memory in EC, especially in EC studies with food-related stimuli. We also provide first evidence for the preparedness of smells and tastes which has a yet to-be-explored applied value in the domain of forming food preferences

MOLECULAR AND CELLULAR MECHANISMS UNDERLYING COGNITIVE NEUROADAPTATION IN ADDICTION: AN IN VIVO-VITRO INTEGRATIVE APPROACH

Il fumo di tabacco \ue8 la principale causa di morte prevenibile nel mondo industrializzato. L\u2019effetto farmacologico della nicotina gioca un ruolo fondamentale nella dipendenza da fumo di tabacco. La nicotina ha propriet\ue0 di rinforzo positivo e negativo, e induce condizionamento operante (comportamento motivato al consumo di nicotina) durante la fase di acquisizione della dipendenza. Vari studi pre-clinici e clinici hanno dimostrato l\u2019importanza di alcuni fattori non farmacologici, come gli stimoli ambientali, nel mantenimento della dipendenza da nicotina e nell\u2019induzione della ricaduta. Questi stimoli inizialmente neutri, ripetutamente associati alla nicotina (es. accendino) assumono un nuovo valore condizionato alla nicotina (CS) attraverso il condizionamento Pavloviano, ed acquisiscono la capacit\ue0 di indurre \u201ccraving\u201d (voglia di fumare) in assenza della droga. Considerata l\u2019importanza delle associazioni CS-nicotina consolidate nella memoria del fumatore nel fenomeno della ricaduta, \ue8 stato proposto che trattamenti atti a distruggere le memorie formate ed associate alla nicotina potrebbero agire da pro-astinenti e anti-ricaduta nel trattamento della dipendenza da fumo di tabacco. Dopo una fase di apprendimento le memorie sono immagazzinate tramite un processo chiamato consolidamento. Il condizionamento operante (anche detto strumentale) e il condizionamento pavloviano portano alla formazione di diversi tipi di memorie associate alla droga e responsabili della ricaduta dopo lunga astinenza. Evidenze provenienti da studi sull\u2019animale e sull\u2019uomo dimostrano che le memorie, una volta richiamate/riattivate, tornano in uno stato labile durante il quale possono venire aggiornate e reimmagazzinate oppure distrutte. Il richiamo delle memorie dunque le destabilizza ed innesca un fenomeno detto di riconsolidamento necessario affinch\ue8 la memoria venga mantenuta. Vi \ue8 una certa evidenza che le memorie pavloviane possano subire riattivazione e riconsolidamento ed \ue8 stato proposto che trattamenti che intervengono per distruggere il riconsolidamento di queste memorie possono rendersi utili nella inibizione delle memorie associate alla paura e anche delle memorie associate alle droghe. La distruzione delle memorie associate alle droghe \ue8 stato proposto come potenziale trattamento per prevenire la ricaduta al consumo di droga indotta dai CS nei tossicodipendenti. Molti studi condotti nell\u2019animale da laboratorio hanno dimostrato che il riconsolidamento delle memorie associate alle droghe pu\uf2 essere prevenuto attraverso la somministrazione di farmaci amnesici, che agiscono a specifici livelli molecolari (es., sistema adrenergico e glutamatergico), prima o dopo la loro riattivazione. Ad oggi non \ue8 ancora chiaro se tutte le memorie, o solo alcune, possono essere riattivate e riconsolidate. Ad esempio la possibilit\ue0 che la memoria strumentale possa essere riattivata e riconsolidata o distrutta \ue8 ancora molto discussa ed esperimenti comportamentali volti a studiare la pura memoria strumentale potrebbero chiarire questa questione. Lo scopo di questo lavoro di tesi era di studiare se fosse possibile distruggere le memorie pavloviane e strumentali associate alla nicotina somministrando propranololo, antagonista del recettore \u3b2-adrenergico, o MK-801, antagonista del recettore N-methyl-d-aspartato (NMDARs). Inoltre abbiamo verificato la possibilit\ue0 di utilizzare la tecnica dell\u2019immunoistochimica per determinare il livello di espressione di Zif268, un marker molecolare specificamente coinvolto nel riconsolidamento della memoria, dopo la riattivazione di memorie pavloviane associate alla nicotina nel ratto. E\u2019 stato utilizzato il modello di laboratorio della autosomministrazione di nicotina, basato sul paradigma del condizionamento operante e pavloviano, alla nicotina e ai CS associati alla nicotina. Abbiamo condotto due studi nei quali il trattamento farmacologico (propranololo o MK-801) veniva somministrato prima o dopo la riattivazione delle memorie pavloviane o strumentali associate alla nicotina. Abbiamo quindi testato l\u2019effetto del trattamento farmacologico sulla ricaduta al comportamento di ricerca di nicotina. La riattivazione della memoria pavloviana \ue8 consistita nella presentazione dei CS in assenza della nicotina. La riattivazione della memoria strumentale \ue8 consistita nel permettere all\u2019animale di premere la leva precedentemente associata all\u2019infusione di nicotina, senza che la nicotina venisse somministrata. Abbiamo inoltre effettuato un esperimento di immunoistochimica su fettine di cervello di ratto per determinare l\u2019espressione di Zif268 in amigdala basolaterale, regione maggiormente coinvolta nel risonsolidamento della memoria, dopo la presentazione dei CS associati alla nicotina. I risultati hanno dimostrato che il propranololo somministrato dopo la riattivazione della memoria pavloviana associata alla nicotina (30 CS) non \ue8 stato in grado di prevenire la ricaduta al comportamento di ricerca di nicotina. Un\u2019ipotesi plausibile potrebbe essere che la memoria strumentale ancora presente non possa essere riattivata e riconsolidata, e quindi non possa essere nemmeno distrutta. Per verificare questa ipotesi abbiamo testato l\u2019effetto dell\u2019MK-801, dimostrato essere pi\uf9 efficace nella distruzione del riconsolidamento di diversi tipi di memoria, somministrato 30 minuti prima della riattivazione della memoria strumentale. I risultati hanno dimostrato che la somministrazione di MK-801 prima della riattivazione non previene la ricaduta al comportamento di ricerca di nicotina. Questi dati suggeriscono una prevenzione della destabilizzazione della memoria strumentale, che la blocca in una fase stabile, piuttosto che una distruzione del riconsolidamento. Un altro studio in cui MK-801 \ue8 stato somministrato dopo che la destabilizzazione della memoria strumentale ha avuto luogo (es., somministrato dopo la sessione di riattivazione) ha dimostrato che MK-801 \ue8 stato in grado di prevenire la ricaduta al comportamento di ricerca di nicotina. Infine l\u2019immunoistochimica ha consentito di individuare un aumento del livello di espresione di Zif268 in amigdala basolaterale nei ratti sottoposti a riattivazione della memoria pavloviana associata alla nicotina. Questi dati confermano la validit\ue0 della tecnica nella determinazione dell\u2019espressione di markers molecolari specificamente coinvolti nel riconsolidamento della memoria. In conclusione, i nostri dati suggeriscono che: i) propranololo non distrugge il riconsolidamento della memoria pavloviana associata alla nicotina nelle nostre condizioni, ii) MK-801 somministrato prima della riattivazione potrebbe prevenire la destabilizzazione della memoria strumentale associata alla nicotina ma non ne distrugge il riconsolidatemnto nelle nostre condizioni, iii) MK-801 somministrato dopo la riattivazione della memoria strumentale associata alla nicotina ne distrugge il riconsolidamento nelle nostre condizioni, iiii) l\u2019immunoistochimica \ue8 una tecnica adatta ad investigare l\u2019espressione di markers molecolari specifiamente coinvolti nel riconsolidamento della memoria come Zif268, e potr\ue0 dunque essere utilizzata per dimostrare direttamente il riconsolidamento della memoria e suppoortare i risultati degli esperimenti comportamentali. Questi dati suggeriscono che la memoria strumentale potrebbe essere responsabile della mancanza di effetto di alcuni trattamenti farmacologici anti-ricaduta e che comunque questo tipo di memoria pu\uf2 essere distrutta se contrastata opportunamente. Lo sviluppo di nuovi farmaci capaci di agire a livello dei diversi meccanismi molecolari che sottostanno ai differenti tipi di memorie associate alle droghe potrebbere consentire una terapia coadiuvante alle attuali terapie anti-fumo e anti-ricaduta in grado di garantire una astinenza a lungo termine agli ex fumatori.Tobacco use through cigarette smoking is the leading preventable cause of death in the developed world. The pharmacological effect of nicotine plays a crucial role in tobacco addiction. Nicotine is positively and negatively reinforcing and leads to the development of \u201coperant conditioning\u201d (motivated behaviour to nicotine consumption) in smokers during the acquisition phase of addiction. Several preclinical and clinical studies have also underlined the importance of non-pharmacological factors, such as environmental stimuli, in maintaining smoking behaviour and promoting relapse. Initially neutral stimuli that are repeatedly paired with a reinforcing drug (e.g. lighter) acquire a new conditioned value (conditioned stimuli, CS) through \u201cPavlovian conditioning\u201d and become able to elicit craving even in the absence of the drug. Given the importance of the learned association between stimuli and nicotine in the phenomenon of relapse to nicotine-seeking behaviour, it has been proposed that treatment that disrupts the nicotine-associated memories could act as a pro-abstinent and anti-relapse therapy. After learning experience, memories are stored by a process called consolidation. Operant conditioning (also called instrumental learning) and Pavlovian conditioning lead to different drug-related memories formation (instrumental memories and Pavlovian memories) responsible for the relapse even after prolonged abstinence. However converging evidence from animal and human studies have revealed that memories may return to a vulnerable phase during which they can be updated, maintained and even disrupted. The retrieval of a memory indeed may destabilize the consolidated memory that requires a new process to be maintained. This hypothetical process is called reconsolidation. There is strong evidence that Pavlovian fear memories undergo reconsolidation and it was proposed that interventions to disrupt reconsolidation may help for specific and selective inhibition of fear related memories and, similarly, appetitive memories (i.e., for drug addiction). The disruption of drug-related memories reconsolidation has been proposed as a potential therapeutic target to prevent the CS-induced relapse in ex drug-addicts. Several animal studies have shown that the reconsolidation of some drug-related memories can be disrupted by the administration of an amnestic drug contingently upon retrieval of the memory acting at specific molecular levels (i.e. adrenergic and glutamatergic systems). However it is not known if all memories or only certain kind of memories could be retrieved and reconsolidated or disrupted. To date reconsolidation of instrumental memories is still under discussion and behavioural experiments targeting the pure instrumental memory reconsolidation disruption are needed to clarify this issue. The main objective of the present thesis was to study if it is possible to disrupt Pavlovian and instrumental nicotine-related memories reconsolidation by \u3b2-adrenergic receptor antagonist propranolol, or N-methyl-d-aspartate receptors (NMDARs) antagonist MK-801 respectively. We also verified the feasibility and reliability of Zif268 (a specific marker of memory reconsolidation) expression assessment by immunohistochemistry after retrieval of Palovian memory in rodents. The experimental approach used to address this issue was the laboratory model of nicotine self-administration in rats, based on the paradigms of operant and Pavlovian conditioning to nicotine and nicotine-associated cues. We performed two studies in which the pharmacological treatment (propranolol or MK-801) was associated to retrieval of Pavlovian or instrumental nicotine-related memories. We therefore assessed the effect of these pharmacological treatments on relapse to nicotine seeking behaviour. Retrieval of Pavlovian memories consists in presenting the CS in the absence of US. Retrieval of instrumental memories consists in allowing the animal to press the lever previously paired to nicotine reinforcement, without nicotine infusion. We also performed an immunohistochemistry assay in which the Zif268 level of expression was determined in basolateral amygdala (the most important region involved in memory reconsolidation) after nicotine CS presentation. Results showed that propranolol given after retrieval of Pavlovian memories (30 CS presentations) did not reduce the relapse to nicotine seeking behaviour compared to control groups that received vehicle injection in both retrieved or no-retrieved groups. It could be possible that instrumental memories, still present, do not undergo reconsolidation and could not be disrupted. To address this issue we tested the effect of MK-801, known to be more effective against instrumental memory than propranolol, given 30 minutes before the retrieval of instrumental memories. Results showed that pre-retrieval MK-801 injection did not prevent the relapse to nicotine-seeking behaviour when compared to control groups. This effect suggests a potential role of MK-801 in inhibition of the memory destabilization process instead of reconsolidation disruption. Further experiments in which MK-801 was given after memory destabilization was engaged (i.e. given after memory retrieval) showed that MK-801 prevented the relapse to nicotine-seeking behaviour. Finally immunohistochemistry showed an increased level of Zif268 expression in basolateral amygdala after retrieval of Pavlovian nicotine-related memories. These data confirm the validity and feasibility of immunohistochemistry to assess the expression of molecular markers correlating reconsolidation such as Zif268 after memory retrieval. In conclusion, our findings suggest that: i) propranolol did not disrupt Pavlovian memory reconsolidation in our conditions, ii) MK-801 given prior to retrieval session could prevent instrumental memory destabilization, but did not disrupt memory reconsolidation in our conditions, iii) MK-801 given after retrieval session disrupted memory reconsolidation in our conditions, iiii) immunohistochemistry is a feasible technique to investigate the expression of molecular markers correlating reconsolidation such as Zif268, thus it can be used to support our future behavioural studies. These data suggest that instrumental memory could be responsible for the lack of effect of some anti-relapse pharmacological treatments and that this kind of memory can be disrupted. New and specific pharmacological intervention, acting at specific molecular mechanisms that underlies reconsolidation of different kind of memories (i.e. Pavlovian but also instrumental memories), could be used as a potential co-adjuvant to current therapeutic interventions for smoking cessation and abstinence maintenance