Subjective (craving, stress), neuroendocrine (adrenocorticotropic

Subjective (craving, stress), neuroendocrine (adrenocorticotropic hormone (ACTH), cortisol), and physiologic responses to the presentation of neutral and E7080 in vitro marijuana cues were assessed after randomization to a stress (Trier Social Stress Task (TSST)) or non-stress control condition in marijuana-dependent individuals. Outcome measures were assessed at baseline, post-stressor/pre-neutral cue, post-neutral cue,

and post-marijuana cue.

Eighty-seven participants completed procedures (stress group, n = 45; non-stress group, n = 42). The stress group had a significant increase over the non-stress group in stress rating (p < 0.001), craving (p = 0.028), cortisol (p < 0.001), and ACTH (p PCI-32765 research buy < 0.001) after the completion of the TSST. An increased craving response for all participants was seen following the presentation of the marijuana cues (p = 0.005). Following the TSST or non-stress condition, the non-stress group had an increase in craving to marijuana cues as compared to neutral cues

(p = 0.002); an increase in craving was not observed in the stress group (p = 0.404).

Marijuana cue exposure and a social stressor increased craving in marijuana-dependent individuals. Completion of the TSST did not increase craving response to subsequent marijuana cue exposure.”
“Neuropeptide Y (NPY) and brain-derived neurotrophic factor (BDNF) have been implicated in both the stress response and alcohol addiction. However, few studies have assessed the NPY and learn more BDNF response to stress in alcohol-dependent participants and the concurrent measure of NPY and BDNF has not been reported in human participants.

The purpose of this study was to concurrently

assess serum NPY and BDNF, as well as adrenocorticotropin (ACTH) and cortisol, in control and race- and aged-matched abstinent alcohol-dependent participants in response to a stress-inducing public-speaking task.

Basal and post-stress serum values of NPY and BDNF, as well as ACTH and cortisol, were assessed in 14 abstinent alcohol-dependent and ten healthy control male participants.

Basal measures were stable over short periods of time and stress induced a significant increase in both NPY (p = 0.002) and BDNF (p = 0.006) as well as ACTH (p < 0.001) and cortisol (p < 0.007). Alcohol-dependent and control groups did not significantly differ on any basal or stress-induced measure. Basal and delta responses of NPY and BDNF were not significantly correlated, and delta peak responses of NPY and BDNF did not correlate with one another or with their respective ACTH and cortisol responses.

Results from many independent groups suggest that mouse and human

Results from many independent groups suggest that mouse and human iPS cells, once established, generally exhibit a normal karyotype, are transcriptionally and epigenetically similar to ES cells and maintain the potential to differentiate into derivatives of all germ layers. Recent developments provide optimism that safe, viral-free human iPS cells could be derived routinely

in the near future. An important next step will be to identify ways of assessing which iPS call lines are sufficiently reprogrammed buy Palbociclib and safe to use for therapeutic applications. The approach of generating patient-specific pluripotent cells will undoubtedly transform regenerative medicine in many ways.”
“Porcine circovirus 2 (PCV2) is a T=1 nonenveloped icosahedral virus that has had severe impact on the swine industry. Here we report the crystal structure of an N-terminally truncated PCV2 virus-like particle at 2.3-angstrom resolution, and the cryo-electron microscopy (cryo-EM) image reconstruction of a full-length PCV2 virus-like particle at 9.6-angstrom resolution. This is the first atomic structure of a circovirus. The crystal structure revealed that the capsid protein fold is a canonical viral

Batimastat price jelly roll. The loops connecting the strands of the jelly roll define the limited features of the surface. Sulfate ions interacting with the surface and electrostatic potential calculations strongly suggest a heparan sulfate binding site that allows PCV2 to gain entry into the cell. The crystal structure also allowed previously determined epitopes of the capsid to be visualized. The cryo-EM image reconstruction showed that the location of the N terminus, absent in the crystal structure, is inside the capsid. As the N terminus was previously shown to be antigenic,

it may externalize through viral “”breathing.”"”
“Serotonin receptor 7, i.e. 5-HT(7) protein coded by Htr7 gene, was discovered see more in supra-chiasmatic nucleus (SCN) of the hypothalamus but is widespread in the forebrain. Studies have shown that this receptor is involved in learning/memory, regulation of mood and circadian rhythms. The modulatory effects of two novel agonists, LP-211 and LP-378, were assessed in male adult CD-1 mice with a battery of behavioral tests. Exp. 1 (Black/White Boxes, BWB: Adriani et al., 2009) and Exp. 2 (Dark/Light, D/L; Novelty-seeking, N-S) show: a) that LP-211 administration (acutely, at a 0.25 mg/kg dose i.p.) increases locomotion and BWB exploration; b) that the time spent away from an aversive, lit chamber (i.e., stress-induced anxiety) and in a new environment (i.e., novelty-induced curiosity) are both reduced. Sub-chronic LP-211 (at a 2.5 mg/kg dose i.p.) reveals a sensitization of locomotor-stimulant properties over 4-5 days. In Exp. 3 (BWB), a three- to four-fold dosage (acutely, at 0.83 mg/kg i.p.) is needed with LP-378 to increase locomotion and BWB exploration. In Exp.

The demand curve (consumption

vs FR value) for KO mice d

The demand curve (consumption

vs. FR value) for KO mice decreased more steeply than that of HET or WT mice, suggesting that reinforcing effectiveness is decreased with DA D2R deletion. Prefeeding decreased, whereas extinction increased overall response rates as a proportion of baseline, with no significant genotype differences. Both (+)- and (-)-eticlopride dose-dependently decreased responding in all genotypes with (-)-eticlopride more potent than (+)-eticlopride in all but KO mice. The enantiomers were equipotent in KO mice, and similar in potency to (+)-eticlopride in WT and HET mice.

That prefeeding and extinction did not vary across genotypes indicates a lack of involvement of DA D(2)Rs in these processes. Differences between (-)-eticlopride click here effects and extinction indicate that DA D2R blockade does not mimic extinction. The maintenance of responding in KO mice indicates that the DA D2R is not necessary for reinforcement. However, the economic analysis indicates that the DA D2R contributes substantially to the effectiveness of food reinforcement.”
“Sophisticated retargeting systems for lentiviral vectors have been developed in recent years. Most seek to suppress the viral envelope’s natural tropism while modifying the

receptor-binding domain such that its tropism is determined by the specificity of the engineered ligand-binding motif. Here we took advantage of the natural tropism of Nipah virus (NiV), whose attachment envelope glycoprotein has picomolar affinity for ephrinB2, a molecule proposed as a molecular 4SC-202 cell line marker of “”stemness”" (present on embryonic, hematopoietic, and neural stem cells) as well as being implicated in tumorigenesis of specific

cancers. NiV entry Selleck BAY 1895344 requires both the fusion (F) and attachment (G) glycoproteins. Truncation of the NiV-F cytoplasmic tail (T5F) alone, combined with full-length NiV-G, resulted in optimal titers of NiV-pseudotyped particles (NiVpp) (similar to 10(6) IU/ml), even without ultracentrifugation. To further enhance the infectivity of NiVpp, we engineered a hyperfusogenic NiV-F protein lacking an N-linked glycosylation site (T5F Delta N3). T5F Delta N3/wt G particles exhibited enhanced infectivity on less permissive cell lines and efficiently targeted ephrinB2(+) cells even in a 1,000-fold excess of ephrinB2-negative cells, all without any loss of specificity, as entry was abrogated by soluble ephrinB2. NiVpp also transduced human embryonic, hematopoietic, and neural stem cell populations in an ephrinB2-dependent manner. Finally, intravenous administration of the luciferase reporter NiVpp-T5F Delta N3/G to mice resulted in signals being detected in the spleen and lung but not in the liver. Bypassing the liver sink is a critical barrier for targeted gene therapy. The extraordinary specificity of NiV-G for ephrinB2 holds promise for targeting specific ephrinB2(+) populations in vivo or in vitro.

A trivariate genetic model that included trauma exposure as a sep

A trivariate genetic model that included trauma exposure as a separate phenotype was fitted to estimate genetic and

environmental contributions to PTSD and the degree to which they overlap with those that contribute to AD, after accounting for potential confounding effects of heritable influences on trauma exposure.

Results. Additive genetic influences (A) accounted for 72% of the variance in PTSD; individual-specific environmental (E) factors accounted for the remainder. An AE model also provided the best fit for AD, for which heritability was estimated to be 71%. The genetic correlation between PTSD and AD was 0.54.

Conclusions. The heritability estimate for PTSD in our sample is higher than estimates CHIR-99021 in vitro reported in earlier studies based almost exclusively on an all-male sample in which combat exposure was the precipitating traumatic event. However, our findings are consistent with the absence of evidence for shared environmental influences on PTSD and, most importantly, the substantial overlap in genetic influences on PTSD and AD reported in these investigations.

Additional research addressing potential distinctions by gender in the relative contributions of genetic and environmental influences on PTSD is merited.”
“Disability is associated with depression in older persons, yet the effect of disability burden on the likelihood of being depressed click here is uncertain.

A total of 754 community-living persons, aged epsilon 70, underwent monthly assessments in four essential activities of daily living and assessments of depression (yes/no) every 18 months for up to 108 months. Within each 18-month

person-interval, participants’ disability burden was operationalized as none or any, and according to severity (none, mild, or severe) and chronicity (none, nonchronic, or chronic) given the highest level of severity or chronicity experienced during a given 18-month interval, respectively. A variable combining severity and chronicity (none, nonchronic mild, nonchronic severe, chronicmild, or chronicsevere) was also created. Using generalized Epacadostat ic50 estimating equations, we evaluated the association between each indicator of disability burden and subsequent depression.

Participants who had any versus no disability during the previous 18 months were 65% more likely to experience subsequent depression (OR 1.65; 95% confidence interval [CI] 1.34, 2.02). Quantifying severity (mild disability vs. none, OR 1.43; 95% CI: 1.15, 1.79; severe disability vs. none, OR 2.07; 95% CI 1.56, 2.74) and chronicity (nonchronic disability vs. none, OR 1.44; 95% CI 1.13, 1.83; chronic disability vs. none, OR 1.96; 95% CI 1.50, 2.55) indicated increasingly stronger associations with subsequent depression, with the highest likelihood of subsequent depression (OR 2.42; 95% CI 1.78, 3.30) observed among participants with chronicsevere disability.

Since K323 may secure helix 12 in the closed conformation by inte

Since K323 may secure helix 12 in the closed conformation by interacting with D198, the replacement of Lys to Arg likely induced the higher mobility of the built-in lid, resulting

in the higher activity at relatively low temperatures.”
“Objective: Late complications can develop in patients after surgery for aortic type A dissection, mandating redo surgery on the ascending aorta and arch.

Methods: From 2006 to 2010, 23 patients (aged 41-69 years) who had late complications related to previous aortic surgery for acute type A dissection underwent redo surgery. Initial surgery included ascending aorta replacement in all cases.

Results: The main indications for reoperation were progressive enlargement of the false lumen of the aortic arch or descending aorta and suture line dehiscence in 10 patients each. All patients with progressive aneurysm formation in nonresected aortic segments had persistent dissection within the aortic arch since initial surgery. Suture line dehiscence led to a localized hematoma in most cases. Three GSK923295 patients presented with graft infection and extensive perigraft hematoma. The average time interval from the initial repair to the redo procedure was 71 +/- 56 months. Exchange of the

formerly implanted Dacron graft in the ascending aorta was the most frequently used surgical procedure. Implantation of a valved conduit was deemed necessary in 4 cases, and isolated aortic valve replacement was necessary

in 2 cases. A hybrid stent graft was used in 6 patients. All patients survived surgery, and 1 EPZ5676 patient died of postoperative low output cardiac failure in hospital. Only 1 major stroke was noted.

Conclusions: Complex reoperations for repaired acute type A dissection can be performed safely. The concern for the reoperative risk should not dictate the operative strategy during the initial procedure in acute type A dissection. (J Thorac Cardiovasc Surg 2012;144:300-7)”
“Protein kinase G (PKG) has been implicated in a variety of physiological functions including synaptic plasticity in the brain. This study investigated the involvement of dopamine D3 (D3) receptors in PKG-regulated dopamine release, long-term changes in gene expression and behavioral sensitization after repeated cocaine administration. Repeated systemic injections of cocaine (20 mg/kg), once a day for seven consecutive days, increased extracellular dopamine concentrations in the dorsal striatum. Inhibition of neuronal nitric oxide synthase, cGMP or PKG, stimulation of D3 receptors, and simultaneous inhibition of each of them with D3 receptor stimulation decreased the repeated cocaine-induced increase in dopamine concentrations and locomotor activity. Similarly, inhibition of PKG and simultaneous inhibition of PKG with D3 receptor stimulation decreased Delta FosB immunoreactivity elevated by repeated cocaine administration, however stimulation of D3 receptors alone did not.

Six viral genogroups have been described, although only genogroup

Six viral genogroups have been described, although only genogroups GI, GII, and GIV are known to infect humans, with the GII viruses most commonly identified in both outbreak and sporadic settings. In contrast, infections by GIV viruses are rarely reported, and their overall prevalence in the community is unknown. Here, we report the complete genome sequence of the human GIV.1 strain Lake Macquarie virus, which caused two linked outbreaks of acute gastroenteritis PRT062607 purchase in aged-care facilities

in the Hunter region of New South Wales, Australia. The Lake Macquarie virus genome was 7,527 nucleotides (nt) in length and shared highest identity (70%) with the recently completed feline GIV.2 virus genome.”
“Little is known about mechanisms underlying female rodent aggression PD-1/PD-L1 Inhibitor 3 manufacturer during the late postpartum period with no pups present. Studies of aggression, dominance, and oxytocin (OT) response in cocaine-treated females are sparse.

This study was designed to examine dominance (drinking success) and aggression in a limited-access drinking model of water competition. Acute OT level measures were made on postpartum day (PPD) 36 in several brain regions of interest. Chronic and intermittent cocaine- and saline-treated and untreated rats 10 days post-weaning were tested (without pups) over PPDs

31-35 following cessation of cocaine treatment 10-30 days before testing.

Subjects were water-deprived overnight, and triads consisting of an untreated control (UN), a chronic continuous saline-treated (CS), and chronic continuous cocaine-treated (CC; 30 mg/kg/day throughout gestation) or a UN, an intermittent saline-treated (IS), and an intermittent cocaine-treated (IC; 30 mg/kg Bucladesine purchase two consecutive days every 4 days throughout gestation until PPD 20) female were tested for aggression and drinking behavior during 5 min sessions on five consecutive days. The amygdala, medial preoptic area (MPOA), and ventral tegmental area were assayed for OT levels.

CC and IC females were more aggressive than controls, but only IC females drank more often than controls. OT levels were lower in the MPOA of IC and CC females than in controls.


demonstrate that long after cessation of treatment, CC- and IC-treated non-lactating females (no pups present) had higher rates of aggression, altered drinking behavior, and acutely lower MPOA OT levels.”
“The removal of bilateral olfactory bulbs (OBs) can result in serious behavioral, neurochemical, neuroendocrine, and neuroimmune alterations in depressed patients. However, there is little information on how olfactory bulbectomy (OBX) leads to depression. Habenular nuclei and their connections are important in the regulation of psychomotor and psychosocial behaviors through afferent impulses of the olfactory system. Therefore, we investigated whether OB lesions lead to habenular degeneration. We used a sample of 50 rats (25 female and 25 male) for this study.

Given the known effects of metal ions on the activities of variou

Given the known effects of metal ions on the activities of various DNA and RNA polymerases, we tested if metal ions could affect selleck chemical hepadnavirus RT priming. We report here that Mn(2+), in comparison with Mg(2+), showed dramatic effects on the priming activity of MiniRT2 as well as the full-length, RT. First and foremost, MiniRT2 exhibited full polymerization activity in the presence of Mn(2+), indicating that MiniRT2 contains all sequences essential for polymerization but is unable to transition from initiation to polymerization with Mg(2+). Second,

the initiation activities of MiniRT2 and the full-length RT were much stronger with Mn(2+). Third, the nucleotide and template specificities during protein priming were decreased in the presence of Mn(2+). Fourth, polymerization was sensitive to inhibition by a pyrophosphate analog in the presence of Mn(2+) but not in the presence of Mg(2+). Finally, limited proteolysis provided direct evidence that the priming active MiniRT2 adopted distinct conformations depending on the presence of Mn(2+) versus that of Mg(2+) and that the transition from initiation to polymerization was accompanied by RT conformational change.”
“In this study, we establish that cholesterol and sphingolipid associated with hepatitis C virus (HCV) particles

click here are important for virion maturation and infectivity. In a recently developed culture system WZB117 cost enabling study of the complete life cycle of HCV, mature virions were enriched with cholesterol as assessed by the molar ratio of cholesterol to phospholipid in virion and cell membranes. Depletion of cholesterol from the virus or hydrolysis of virion-associated sphingomyelin almost completely abolished HCV infectivity. Supplementation of cholesterol-depleted virus with exogenous cholesterol enhanced infectivity to a level equivalent to that of the untreated control.

Cholesterol-depleted or sphingomyelin-hydrolyzed virus had markedly defective internalization, but no influence on cell attachment was observed. Significant portions of HCV structural proteins partitioned into cellular detergent-resistant, lipid-raft-like membranes. Combined with the observation that inhibitors of the sphingolipid biosynthetic pathway block virion production, but not RNA accumulation, in a JFH-1 isolate, our findings suggest that alteration of the lipid composition of HCV particles might be a useful approach in the design of anti-HCV therapy.”
“Manganese (Mn) is a transition metal that is essential for normal cell growth and development, but is toxic at high concentrations. While Mn deficiency is uncommon in humans, Mn toxicity is known to be readily prevalent due to occupational overexposure in miners, smelters and possibly welders.

“The aim of this study was to explore the changes evoked b

“The aim of this study was to explore the changes evoked by organ culture in the signalling pathways activated by noradrenaline in rat resistance mesenteric artery. Contractile responses and calcium signalling were significantly more sensitive to noradrenaline in arteries cultured for 48-72 h in the absence of growth factors compared to fresh arteries. Both calcium release activated see more by noradrenaline in

calcium-free solution and calcium entry measured after the addition of external calcium were higher in cultured arteries than in fresh tissue. Blockers of non-selective cation channels (SKF-96365, flufenamic acid, Gd(3+)) more potently inhibited noradrenaline contraction in cultured arteries than in fresh ones. The src kinase inhibitors genistein or PP2 normalised the increased contraction and the increased calcium release evoked by noradrenaline in cultured arteries. In cultured arteries, trpc1 (transient receptor potential canonical 1) mRNA expression

was decreased by 47 +/- 8% (n = 5, p < 0.05), while trpc6 mRNA expression was increased by 92 +/- 24% (n = 5, p < 0.05) in comparison with non-cultured arteries. Immunofluorescence analysis of protein expression confirmed the up-regulation of TRPC6 protein after culture. These results indicate that mesenteric artery culture results in src kinase-dependent increase in the responses to noradrenaline and in a change in cation channel selleckchem activity, which could contribute to the increased contraction. Copyright (C) 2009 S. Karger AG, Basel”
“Repeated, intermittent exposure to drugs of abuse results in response enhancements to subsequent drug treatments, a phenomenon referred to as sensitization. As persistent neuronal sensitization may contribute to the long-lasting consequences of drug abuse, characterizing the neuroanatomical substrates of sensitization is providing insights into addiction. It is known that the ventral tegmental area (VTA) is necessary for induction, and expression involves the nucleus accumbens (NAc). We reveal here that the ventral pallidum (VP), a brain region reciprocally

innervated by the VTA and the NAc, is a critical mediator of opiate-induced behavioral sensitization. Blockade of VP mu-opioid receptors (via intra-VP CTOP injections) negated the ability of systemic administration of the opiate, morphine to induce motor sensitization, and for sensitized rats to subsequently express enhanced responding to a morphine challenge. Intra-VP morphine was sufficient to induce motor sensitization, and this sensitization was expressed following 17 days of withdrawal. Rats with a treatment history of intra-VP morphine demonstrated cross-sensitization to a challenge injection of systemically administered morphine. Conversely, repeated systemic treatments of morphine cross-sensitized to an intra-VP morphine challenge.

All rights reserved “
“Nicotinic acetylcholine receptors (nA

All rights reserved.”
“Nicotinic acetylcholine receptors (nAChRs) containing either the alpha 4 and/or alpha 6 subunit are robustly expressed in dopaminergic nerve terminals in dorsal striatum where they are hypothesized to modulate dopamine (DA) release via acetylcholine (ACh) stimulation from cholinergic interneurons. However, pharmacological blockade of nAChRs or genetic deletion of individual nAChR subunits, including alpha 4 and alpha

6, in mice, yields little effect on motor behavior. Based on the putative role of nAChRs containing the alpha 4 subunit in modulation of DA in dorsal striatum, Elafibranor chemical structure we hypothesized that mice expressing a single point mutation in the alpha 4 nAChR subunit, Leu9′Ala, that renders nAChRs hypersensitive to agonist, would exhibit exaggerated differences in motor behavior compared to WT mice. To gain insight into these

differences, we challenged WT and Leu9′Ala mice with the alpha 4 beta 2 nAChR antagonist dihydro-beta-erythroidine (DH beta E). Interestingly, in Leu9′Ala mice, DH beta E elicited a robust, reversible motor impairment S3I-201 characterized by hypolocomotion, akinesia, catalepsy, clasping, and tremor; whereas the antagonist had little effect in WT mice at all doses tested. Pre-injection of nicotine (0.1 mg/kg) blocked DH beta E-induced motor impairment in Leu9′Ala mice confirming that the phenotype was mediated RSL3 ic50 by antagonism of nAChRs. In addition, SKF82958 (1 mg/kg)

and amphetamine (5 mg/kg) prevented the motor phenotype. DH beta E significantly activated more neurons within striatum and substantia nigra pars reticulata in Leu9′Ala mice compared to WT animals, suggesting activation of the indirect motor pathway as the circuit underlying motor dysfunction. ACh evoked DA release from Leu9′Ala striatal synaptosomes revealed agonist hypersensitivity only at alpha 4(non-alpha 6)* nAChRs. Similarly, alpha 6 nAChR subunit deletion in an alpha 4 hypersensitive nAChR (Leu9′Ala/alpha 6 KO) background had little effect on the DH beta E-induced phenotype, suggesting an alpha 4(non-alpha 6)* nAChR-dependent mechanism. Together, these data indicate that alpha 4(non-alpha 6)* nAChR have an impact on motor output and may be potential molecular targets for treatment of disorders as ociated with motor impairment. (C) 2013 Elsevier Ltd. All rights reserved.”
“Background. Medication use is a potentially reversible cause of urinary incontinence (UI). The objective of this longitudinal cohort study was to evaluate whether self-reported UI in community-dwelling older women is associated with the use of different classes of antihypertensive agents.

Methods. The sample consisted of 959 black and white women aged 7281 years without baseline (Year 1) UI from the Health, Aging, and Body Composition Study.

These results show that the core gene ac68 encodes a per os infec

These results show that the core gene ac68 encodes a per os infectivity factor (pif6). The lef3KO virus was also analyzed, and virus replication was drastically reduced compared to WT virus, but very low LGK-974 datasheet levels of lef3KO virus DNA replication and BV production could be detected. In addition, in transfected cells P143 was transported to the nucleus in the absence of LEF3. This study therefore shows for the first time that even though the loss of LEF3 severely impairs virus replication, it is not absolutely essential for P143 nuclear import or viral replication.”
“Background. Patients with obsessive-compulsive disorder (OCD) have to repeat their actions before feeling satisfied that the action

reached its intended goal. Learning theory predicts that this may be due to a failure in the processing of external feedback.

Method. We examined the performance of 29 OCD patients and 28 healthy volunteers on an associative learning task, in which initial learning is based solely on external feedback signals. Feedback valence was manipulated with monetary gains and losses.

Results. As predicted, OCD patients were impaired during initial, external feedback-driven learning but not during later learning stages. The emotional salience of the feedback modulated learning during the initial

stage in patients and controls alike. During later learning stages, however, patients approached near-normal performance with rewarding feedback but continued to produce deficient learning with punishing feedback.

Conclusion. OCD patients have a fundamental impairment in updating behavior based on the external outcome of their actions, possibly Sotrastaurin mediated by faulty error signals in response selection processes.”
“Exposure to traumatic events can lead to posttraumatic stress disorder (PTSD). Current PTSD treatments typically only produce partial improvement. Hence, there is a need for preclinical research to identify new candidate drugs and to develop novel therapeutic approaches. Animal studies

have indicated that fear memories can be weakened by blocking restabilization after retrieval, a process known as reconsolidation. Furthermore, evidence suggests that there are important alterations of the noradrenergic system in PTSD, and hence it may be of interest to study drugs that target this C188-9 molecular weight pathway. Here, we investigated the efficacy of clonidine, an alpha 2-adrenoreceptor agonist, to block reconsolidation in an animal model of persistent traumatic memories. Using an auditory fear conditioning paradigm in rats, we tested the efficacy of clonidine to weaken fear memory retention when administered systemically after retrieval. We evaluated dosage, number of treatments, and specificity in reconsolidation blockade. We found that postretrieval administration of clonidine disrupts fear-related memories in a dose-dependent manner and that two treatments are sufficient for maximal memory impairment.