951 research outputs found
Corticolimbic catecholamines in stress: A computational model of the appraisal of controllability
Appraisal of a stressful situation and the possibility to control or avoid it is thought to involve frontal-cortical mechanisms. The precise mechanism underlying this appraisal and its translation into effective stress coping (the regulation of physiological and behavioural responses) are poorly understood. Here, we propose a computational model which involves tuning motivational arousal to the appraised stressing condition. The model provides a causal explanation of the shift from active to passive coping strategies, i.e. from a condition characterised by high motivational arousal, required to deal with a situation appraised as stressful, to a condition characterised by emotional and motivational withdrawal, required when the stressful situation is appraised as uncontrollable/unavoidable. The model is motivated by results acquired via microdialysis recordings in rats and highlights the presence of two competing circuits dominated by different areas of the ventromedial prefrontal cortex: these are shown having opposite effects on several subcortical areas, affecting dopamine outflow in the striatum, and therefore controlling motivation. We start by reviewing published data supporting structure and functioning of the neural model and present the computational model itself with its essential neural mechanisms. Finally, we show the results of a new experiment, involving the condition of repeated inescapable stress, which validate most of the model's prediction
Food seeking in spite of harmful consequences is under prefrontal cortical noradrenergic control
<p>Abstract</p> <p>Background</p> <p>Eating disorders are multifactorial psychiatric disorders. Chronic stressful experiences and caloric restriction are the most powerful triggers of eating disorders in human and animals. Although compulsive behavior is considered to characterize pathological excessive food intake, to our knowledge, no evidence has been reported of continued food seeking/intake despite its possible harmful consequences, an index of compulsive behavior. Brain monoamine transmission is considered to have a key role in vulnerability to eating disorders, and norepinephrine in medial prefrontal cortex has been shown to be critical for food-related motivated behavior.</p> <p>Here, using a new paradigm of conditioned suppression, we investigated whether the ability of a foot-shock-paired conditioned stimulus to suppress chocolate-seeking behavior was reversed by previous exposure to a food restriction experience, thus modeling food seeking in spite of harmful consequences in mice. Moreover, we assessed the effects of selective norepinephrine inactivation in medial prefrontal cortex on conditioned suppression test in stressed and caloric restricted mice.</p> <p>Results</p> <p>While Control (non food deprived) animals showed a profound conditioned suppression of chocolate seeking during presentation of conditioned stimulus, previously food restricted animals showed food seeking/intake despite its possible harmful consequences. Moreover, food seeking in spite of harmful consequences was prevented by selective norepinephrine inactivation, thus showing that prefrontal cortical norepinephrine is critical also for maladaptive food-related behavior.</p> <p>Conclusions</p> <p>These findings indicate that adaptive food seeking/intake can be transformed into maladaptive behaviors and point to "top-down" influence on eating disturbances and to new targets for therapy of aberrant eating behaviors.</p
Single prazosin infusion in prelimbic cortex Fosters extinction of amphetamine-induced conditioned place preference
Exposure to drug-associated cues to induce extinction is a useful strategy to contrast cue-induced drug seeking. Norepinephrine (NE) transmission in medial prefrontal cortex has a role in the acquisition and extinction of conditioned place preference induced by amphetamine. We have reported recently that NE in prelimbic cortex delays extinction of amphetamine-induced conditioned place preference (CPP). A potential involvement of α1-adrenergic receptors in the extinction of appetitive conditioned response has been also suggested, although their role in prelimbic cortex has not been yet fully investigated. Here, we investigated the effects of the α1-adrenergic receptor antagonist prazosin infusion in the prelimbic cortex of C57BL/6J mice on expression and extinction of amphetamine-induced CPP. Acute prelimbic prazosin did not affect expression of amphetamine-induced CPP on the day of infusion, while in subsequent days it produced a clear-cut advance of extinction of preference for the compartment previously paired with amphetamine (Conditioned stimulus, CS). Moreover, prazosin-treated mice that had extinguished CS preference showed increased mRNA expression of brain-derived neurotrophic factor (BDNF) and post-synaptic density 95 (PSD-95) in the nucleus accumbens shell or core, respectively, thus suggesting that prelimbic α1-adrenergic receptor blockade triggers neural adaptations in subcortical areas that could contribute to the extinction of cue-induced drug-seeking behavior. These results show that the pharmacological blockade of α1-adrenergic receptors in prelimbic cortex by a single infusion is able to induce extinction of amphetamine-induced CPP long before control (vehicle) animals, an effect depending on contingent exposure to retrieval, since if infused far from or after reactivation it did not affect preference. Moreover, they suggest strongly that the behavioral effects depend on post-treatment neuroplasticity changes in corticolimbic network, triggered by a possible “priming” effect of prazosin, and point
to a potential therapeutic power of the antagonist for maladaptive memories
Prefrontal Dopamine in Flexible Adaptation to Environmental Changes: A Game for Two Players
Deficits in cognitive flexibility have been characterized in affective, anxiety, and neurodegenerative
disorders. This paper reviews data, mainly from studies on animal models, that support
the existence of a cortical–striatal brain circuit modulated by dopamine (DA), playing a major role in
cognitive/behavioral flexibility. Moreover, we reviewed clinical findings supporting misfunctioning
of this circuit in Parkinson’s disease that could be responsible for some important non-motoric
symptoms. The reviewed findings point to a role of catecholaminergic transmission in the medial
prefrontal cortex (mpFC) in modulating DA’s availability in the nucleus accumbens (NAc), as well
as a role of NAc DA in modulating the motivational value of natural and conditioned stimuli. The
review section is accompanied by a preliminary experiment aimed at testing weather the extinction
of a simple Pavlovian association fosters increased DA transmission in the mpFC and inhibition of
DA transmission in the NAc
Intermittent theta-burst stimulation rescues dopamine-dependent corticostriatal synaptic plasticity and motor behavior in experimental parkinsonism. Possible role of glial activity.
Background: Recent studies support the therapeutic utility of repetitive transcranial magnetic stimulation in Parkinson's disease (PD), whose progression is correlated with loss of corticostriatal long-term potentiation and long-term depression. Glial cell activation is also a feature of PD that is gaining increasing attention in the field because astrocytes play a role in chronic neuroinflammatory responses but are also able to manage dopamine (DA) levels.
Methods: Intermittent theta-burst stimulation protocol was applied to study the effect of therapeutic neuromodulation on striatal DA levels measured by means of in vivo microdialysis in 6-hydroxydopamine-hemilesioned rats. Effects on corticostriatal synaptic plasticity were studied through in vitro intracellular and whole-cell patch clamp recordings while stepping test and CatWalk were used to test motor behavior. Immunohistochemical analyses were performed to analyze morphological changes in neurons and glial cells.
Results: Acute theta-burst stimulation induced an increase in striatal DA levels in hemiparkinsonian rats, 80 minutes post-treatment, correlated with full recovery of plasticity and amelioration of motor performances. With the same timing, immediate early gene activation was restricted to striatal spiny neurons. Intense astrocytic and microglial responses were also significantly reduced 80 minutes following theta-burst stimulation.
Conclusion: Taken together, these results provide a first glimpse on physiological adaptations that occur in the parkinsonian striatum following intermittent theta-burst stimulation and may help to disclose the real potential of this technique in treating PD and preventing DA replacement therapy-associated disturbances
Dopamine neuronal loss contributes to memory and reward dysfunction in a model of Alzheimer's disease
Alterations of the dopaminergic (DAergic) system are frequently reported in Alzheimer’s disease (AD) patients and are commonly linked to cognitive and non-cognitive symptoms. However, the cause of DAergic system dysfunction in AD remains to be elucidated. We investigated alterations of the midbrain DAergic system in the Tg2576 mouse model of AD, overexpressing a mutated human amyloid precursor protein (APPswe). Here, we found an age-dependent DAergic neuron loss in the ventral tegmental area (VTA) at pre-plaque stages, although substantia nigra pars compacta (SNpc) DAergic neurons were intact. The selective VTA DAergic neuron degeneration results in lower DA outflow in the hippocampus and nucleus accumbens (NAc) shell. The progression of DAergic cell death correlates with impairments in CA1 synaptic plasticity, memory performance and food reward processing. We conclude that in this mouse model of AD, degeneration of VTA DAergic neurons at pre-plaque stages contributes to memory deficits and dysfunction of reward processing
Low Incidence Rate of Opportunistic and Viral Infections During Imatinib Treatment in Chronic Myeloid Leukemia Patients in Early and Late Chronic Phase.
<!--StartFragment--> <p class="MsoNormal" style="text-align: justify; line-height: 150%;"><span style="font-family: Arial; mso-ansi-language: EN-GB;" lang="EN-GB">Background: Imatinib has become first line therapy in chronic myeloid leukemia patients. Little is known about the infective consequences during the treatment with this drug in large series of chronic phase patients. </span></p> <p class="MsoNormal" style="text-align: justify; line-height: 150%;"><span style="font-family: Arial; mso-ansi-language: EN-GB;" lang="EN-GB">Material and methods: From January 2001 to September 2006 we treated with imatinib 250 patients in first line (early CP) or after interferon failure (late CP), out of clinical trials and recorded all the bacterial and viral infections occurred.</span></p> <p class="MsoNormal" style="text-align: justify; line-height: 150%;"><span style="font-family: Arial; mso-ansi-language: EN-GB;" lang="EN-GB">Results: We recorded a similar incidence of bacterial and viral infections both in first line and late CP patients (respectively, 16% and 13%) during 3.5 years of follow-up. Analysis of presenting features predisposing to infections revealed differences only in late CP patients, with elevated percentage of high Sokal risk patients and a more longer median time from diagnosis to start of imatinib.</span></p> <p class="MsoNormal" style="text-align: justify; line-height: 150%;"><span style="font-family: Arial; mso-ansi-language: EN-GB;" lang="EN-GB">Conclusions: Opportunistic infections and reactivation of Herpes Zoster are observed during imatinib therapy at very low incidence.</span></p> <!--EndFragment-->
Corticolimbic catecholamines in stress: a computational model of the appraisal of controllability
Appraisal of a stressful situation and the possibility to control or avoid it is thought to involve frontal-cortical mechanisms. The precise mechanism underlying this appraisal and its translation into effective stress coping (the regulation of physiological and behavioural responses) are poorly understood. Here, we propose a computational model which involves tuning motivational arousal to the appraised stressing condition. The model provides a causal explanation of the shift from active to passive coping strategies, i.e. from a condition characterised by high motivational arousal, required to deal with a situation appraised as stressful, to a condition characterised by emotional and motivational withdrawal, required when the stressful situation is appraised as uncontrollable/unavoidable. The model is motivated by results acquired via microdialysis recordings in rats and highlights the presence of two competing circuits dominated by different areas of the ventromedial prefrontal cortex: these are shown having opposite effects on several subcortical areas, affecting dopamine outflow in the striatum, and therefore controlling motivation. We start by reviewing published data supporting structure and functioning of the neural model and present the computational model itself with its essential neural mechanisms. Finally, we show the results of a new experiment, involving the condition of repeated inescapable stress, which validate most of the model\u27s predictions
A population-based study on myelodysplastic syndromes in the Lazio Region (Italy), medical miscoding and 11-year mortality follow-up. The Gruppo Romano-Laziale Mielodisplasie experience of retrospective multicentric registry
Data on Myelodysplastic Syndromes (MDS) are difficult to collect by cancer registries because of the lack of reporting and the use of different classifications of the disease. In the Lazio Region, data from patients with a confirmed diagnosis of MDS, treated by a hematology center, have been collected since 2002 by the Gruppo Romano-Laziale Mielodisplasie (GROM-L) registry, the second MDS registry existing in Italy. This study aimed at evaluating MDS medical miscoding during hospitalizations, and patients' survival. For these purposes, we selected 644 MDS patients enrolled in the GROM-L registry. This cohort was linked with two regional health information systems: the Hospital Information System (HIS) and the Mortality Information System (MIS) in the 2002-2012 period. Of the 442 patients who were hospitalized at least once during the study period, 92% had up to 12 hospitalizations. 28.5% of patients had no hospitalization episodes scored like MDS, code 238.7 of the International Classification of Disease, Ninth Revision, Clinical Modification (ICD-9-CM). The rate of death during a median follow-up of 46 months (range 0.9-130) was 45.5%. Acute myeloid leukemia (AML) was the first cause of mortality, interestingly a relevant portion of deaths is due to cerebro-cardiovascular events and second tumors. This study highlights that MDS diagnosis and treatment, which require considerable healthcare resources, tend to be under-documented in the HIS archive. Thus we need to improve the HIS to better identify information on MDS hospitalizations and outcome. Moreover, we underline the importance of comorbidity in MDS patients' survival
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