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Category: Essays

Disruption of cocaine-associated memory

Increasing lines of evidence suggest that retrieval of previously consolidated memories is a dynamic process that either reinforces or alters memory. Memory retrieval may initiate two potentially opposing but distinguishable processes: reconsolidation and extinction (Suzuki et al., 2004). Memory reconsolidation acts to stabilize retrieved memories whereas extinction tends to weaken the expression of the original […]

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NO-dependent and NO-independent cocaine-associated memory

The CPP paradigm which employs the principles of Pavlovian learning is often used to investigate the incentive value of drugs of abuse. One caveat to conditioned reward studies is the use of a fixed daily dose of the addictive drug during training. However, the transition from drug use to addiction in human addicts involves an […]

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Corticosterone levels and stress-induced reinstatement

One possible explanation for attenuation of stress-induced reinstatement of Fix-C CPP is that pre-treatment with MK-801, 7-NI or antalarmin may have suppressed HPA activity and thereby prevented activation of the stress response. This explanation is unlikely since we found that none of the abovementioned pharmacological modulators attenuated swim-induced increases in corticosterone levels indicating an activation […]

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Discussion (Stress-induced reinstatement of Fix-C and Esc-C CPP)

Stress is known to precipitate relapse to drug use (Sinha, 2008) but the exact signaling molecules that govern these behavioral responses are unclear. The FST is one stressor that can be used to model stress-induced reinstatement outside the conditioning context in animal models (Kreibich & Blendy, 2004). The present study shows that exposure to FST […]

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Measurement of corticosterone levels

Plasma corticosterone levels were determined before and after FST. One hundred microliters whole blood was collected from mouse superficial temporal vein. The vein was punctured using a 26G needle and blood was collected in heparin coated capillary tubes. Upon completion, the wound was gently patted with cotton to stop bleeding. Mice were then returned to […]

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Stress-induced reinstatement of Fix-C and Esc-C CPP

Stress-induced reinstatement was assessed using the forced swim test (FST). The FST is a common behavioral paradigm used to model stress-induced relapse to drug use (Kreibich & Blendy, 2004). Twenty-four hours after a test for CPP extinction, mice were exposed to FST. Thirty minutes prior to FST mice were injected with either a) MK-801 (0.3mg/kg), […]

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Materials and Methods (Cocaine)

Subjects Male C57BL/6J mice (8-10 weeks old) were purchased from Jackson Laboratories (Bar Harbor, Maine). Mice were housed in groups of 5/cage with food and water ad-libitum and were acclimatized to the vivarium for one week before experiments began. Animal care was in accordance with the Guide for the Care and Use of Laboratory Animals […]

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The pattern of cocaine conditioning differentially influences stress-induced reinstatement of conditioned place preference

Vulnerability to relapse following prolonged periods of abstinence presents a major challenge to combating drug addiction. It is therefore essential that much attention be placed on understanding the neural mechanisms that sub-serve relapse to drug use. We have previously shown that the acquisition and reconsolidation of cocaine-context memory associated with conditioning by a fixed daily […]

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Discussion about CPP

The current study employed an escalating dose schedule for cocaine-induced CPP as opposed to a typical fixed schedule used in other studies. Mice conditioned by ascending doses of cocaine maintain a higher magnitude of CPP and show greater resistance to extinction compared to mice conditioned by a fixed daily dose of cocaine (Itzhak & Anderson, […]

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CPP Test, Extinction and reinstatement, Data Analysis

The expression of place preference was tested 3 days after the final training session in order to eliminate possible contributions from residual cocaine administration on the last training session and also to allow the consolidation of long-term memory of drug reward. Similar to habituation, CPP testing was carried out between 12:00 and 14:00 hours. Extinction […]

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