Alterations in white matter microstructure in alcohol and alcohol‐polydrug dependence: Associations with lifetime alcohol and nicotine exposure

Evidence suggests that alcohol dependence (AD) is associated with microstructural deficits in white matter, but the relationship with lifetime alcohol exposure and the impact of polydrug dependence is not well understood. Using diffusion tensor magnetic resonance (MR) imaging, we examined white matter microstructure in relation to alcohol and polydrug dependence using data from the Imperial College Cambridge Manchester (ICCAM) platform study. Tract‐based spatial statistics were used to examine fractional anisotropy (FA) in a cohort of abstinent AD participants, most of whom had a lifetime history of dependence to nicotine. A further subgroup also had a lifetime history of dependence to cocaine and/or opiates. Individuals with AD had lower FA throughout the corpus callosum, and negative associations with alcohol and nicotine exposure were found. A group‐by‐age interaction effect was found showing greater reductions with age in the alcohol‐dependent group within corpus callosum, overlapping with the group difference. We found no evidence of recovery with abstinence. A comparison of alcohol‐only‐ and alcohol‐polydrug‐dependent groups found no differences in FA. Overall, our findings show that AD is associated with lower FA and suggest that these alterations are primarily driven by lifetime alcohol consumption and cigarette smoking, showing no relationship with exposure to other substances such as cocaine, opiates or cannabis. Reductions in FA across the adult lifespan are more pronounced in AD and offer further support for the notion of accelerated ageing in relation to alcohol dependence. These findings highlight there may be lasting structural differences in white matter in alcohol dependence, despite continued abstinence.

The Imperial College Cambridge Manchester (ICCAM) platform study: An experimental medicine platform for evaluating new drugs for relapse prevention in addiction. Part A: Study description

Drug and alcohol dependence are global problems with substantial societal costs. There are few treatments for relapse prevention and therefore a pressing need for further study of brain mechanisms underpinning relapse circuitry. The Imperial College Cambridge Manchester (ICCAM) platform study is an experimental medicine approach to this problem: using functional magnetic resonance imaging (fMRI) techniques and selective pharmacological tools, it aims to explore the neuropharmacology of putative relapse pathways in cocaine, alcohol, opiate dependent, and healthy individuals to inform future drug development. Addiction studies typically involve small samples because of recruitment difficulties and attrition. We established the platform in three centres to assess the feasibility of a multisite approach to address these issues. Pharmacological modulation of reward, impulsivity and emotional reactivity were investigated in a monetary incentive delay task, an inhibitory control task, and an evocative images task, using selective antagonists for µ-opioid, dopamine D3 receptor (DRD3) and neurokinin 1 (NK1) receptors (naltrexone, GSK598809, vofopitant/aprepitant), in a placebo-controlled, randomised, crossover design. In two years, 609 scans were performed, with 155 individuals scanned at baseline. Attrition was low and the majority of individuals were sufficiently motivated to complete all five sessions (n=87). We describe herein the study design, main aims, recruitment numbers, sample characteristics, and explain the test hypotheses and anticipated study outputs.

Childhood traumata, Dexamethasone Suppression Test and psychiatric symptoms: a trans-diagnostic approach

BACKGROUND

Childhood traumatic events and functional abnormalities of the hypothalamus-pituitary-adrenal (HPA) axis have been widely reported in psychiatric patients, although neither is specific for any diagnosis. Among the limited number of studies that have evaluated these topics, none has adopted a trans-diagnostic approach. The aim of the present research is to explore the relationship between childhood stressors, HPA axis function and psychiatric symptoms, independent of the diagnosis.

METHOD

A total of 93 moderate to severely ill psychiatric out-patients of Florence and Pisa University Psychiatric Units and 33 healthy control subjects were recruited. The assessment consisted of salivary cortisol pre- and post-low dose (0.5 mg) Dexamethasone, early and recent life events, 121 psychiatric symptoms independent of diagnosis, SCID, BPRS.

RESULTS

In total, 33.5% of patients were Dexamethasone Suppression Test (DST) non-suppressors, compared with 6.1% of controls (p=0.001). Among patients, non-suppression was associated with particular symptoms (i.e. depressive and psychotic), but not to any specific diagnosis. Early stressful life events were significantly associated with higher salivary cortisol levels, with DST non-suppression and with approximately the same subset of symptoms. A recent stressful event seemed to be associated to the HPA response only in those subjects who were exposed to early traumata.

CONCLUSIONS

Our report suggests a relationship between life stress, HPA axis and psychopathology. A cluster of specific psychiatric symptoms seems to be stress related. Moreover, it seems that an abnormal HPA response is possibly triggered by an excessive pressure in vulnerable individuals.

Bipolar Disorder: an impossible diagnosis

Following the recent debates on the discrepancy between the predominant weight of bipolar disorder (BPD) in the clinical reality and its relatively low prevalence figures emerging from epidemiological surveys, the present paper contends the ability of current operational diagnostic system to properly detect the clinical entity of bipolar disorder.

As an episode of mania/hypomania is the necessary requirement for a diagnosis of bipolar disorder to be made, in this editorial we maintain that: a) the most severe forms of mania, characterized by cloudy consciousness, mood incongruent delusions, and physical symptoms are likely to escape DSM IV criteria, that are shaped around hypomania or mild mania; b) the impossibility to diagnose mania when this occurs during antidepressant treatments impedes diagnosing those cases whose natural illness pattern is Depression followed by Mania (known as DMI pattern); c) given that approximately 50% of cases have their onset of BPD with affective episodes other than mania/hypomania any prevalence figure necessarily underestimates BPD; d) the sub-threshold forms of BPD, well described in the concept of Bipolar Spectrum, are beyond the possibility to be recognized using operational diagnoses in spite of their utmost clinical relevance.

Agoraphobia between panic and phobias: clinical epidemiology from the Sesto Fiorentino Study

In the last few decades, there has been a long debate on the existence of agoraphobia (AG) without a history of panic attacks (PAs). In the present study, the problem of the relationships between AG and PAs is addressed trough a reevaluation of the cases who had been diagnosed with AG in the community survey of Sesto Fiorentino. Forty-one of the 75 subjects who met the criterion of AG in the Sesto Fiorentino Study were reinterviewed by experienced clinical psychiatrists. The Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) and the Composite International Diagnostic Interview were used to make the diagnoses. The Mobility Inventory for Agoraphobia (MIA) and a specific adjunctive question, "why do/did you avoid?", were used to compare AG subjects with or without PD. Of the 41 subjects with a lifetime history of AG, 12 cases had original diagnosis of AG without PAs and the remaining 29 had PD with AG. After the reassessment, in 10 cases, the criteria for the diagnosis of AG without PAs were confirmed, totaling a lifetime prevalence of 0.4% (confidence interval, 0.2-0.8). Agoraphobia subjects with and without PAs were comparable as regard to sex, age, age of onset, duration of illness, family history for anxiety or mood disorders, MIA scores, number, and type of situations avoided. Thus, AG seems to exist also in absence of a history of PAs, and the one-way relationship between the occurrence of PAs and a following development of AG, postulated by DSM-IV, should be reconsidered for the future classifications.

Safinamide: From molecular targets to a new anti-Parkinson drug

Ideal treatment in Parkinson's disease (PD) aims at relieving symptoms and slowing disease progression. Of all remedies, levodopa remains the most effective for symptomatic relief, but the medical need for neuroprotectant drugs is still unfulfilled. Safinamide, currently in phase III clinical trials for the treatment of PD, is a unique molecule with multiple mechanisms of action and a very high therapeutic index. It combines potent, selective, and reversible inhibition of MAO-B with blockade of voltage-dependent Na+ and Ca2+ channels and inhibition of glutamate release. Safinamide has neuroprotective and neurorescuing effects in MPTP-treated mice, in the rat kainic acid, and in the gerbil ischemia model. Safinamide potentiates levodopa-mediated increase of DA levels in DA-depleted mice and reverses the waning motor response after prolonged levodopa treatment in 6-OHDA-lesioned rats. Safinamide has excellent bioavailability, linear kinetics, and is suitable for once-a-day administration. Therefore, safinamide may be used in PD to reduce l-dopa dosage and also represents a valuable therapeutic drug to test disease-modifying potential.

Anti-allodynic effect of NW-1029, a novel Na(+) channel blocker, in experimental animal models of inflammatory and neuropathic pain

NW-1029, a benzylamino propanamide derivative, was selected among several molecules of this chemical class on the basis of its affinity for the [(3)H]batracotoxin ligand displacement of the Na(+) channel complex and also on the basis of its voltage and use-dependent inhibitory action on the Na(+) currents of the rat DRG (dorsal root ganglia) sensory neuron. This study evaluated the analgesic activity of NW-1029 in animal models of inflammatory and neuropathic pain (formalin test in mice, complete Freund's adjuvant and chronic constriction injury in rats) as well as in acute pain test (hot-plate and tail-flick in rats). Orally administered NW-1029 dose-dependently reduced cumulative licking time in the early and late phase of the formalin test (ED(50)=10.1 mg/kg in the late phase). In the CFA model, NW-1029 reversed mechanical allodynia (von Frey test) after both i.p. and p.o. administration (ED(50)=0.57 and 0.53 mg/kg), respectively. Similarly, NW-1029 reversed mechanical allodynia in the CCI model after both i.p. and p.o. administration yielding an ED(50) of 0.89 and 0.67 mg/kg, respectively. No effects were observed in the hot-plate and tail-flick tests up to 30 mg/kg p.o. The compound orally administered (0.1-10 mg/kg) was well tolerated, without signs of neurological impairment up to high doses (ED(50)=470 and 245 mg/kg in rat and mice Rotarod test, respectively). These results indicate that NW-1029 has anti-nociceptive properties in models of inflammatory and neuropathic pain.

Biochemical and electrophysiological studies on the mechanism of action of PNU-151774E, a novel antiepileptic compound

PNU-151774E [(S)-(+)-2-(4-(3-fluorobenzyloxy)benzylamino)propanamide methanesulfonate], a new anticonvulsant that displays a wide therapeutic window, has a potency comparable or superior to that of most classic anticonvulsants. PNU-151774E is chemically unrelated to current antiepileptics. In animal seizure models it possesses a broad spectrum of action. In the present study, the action mechanism of PNU-151774E has been investigated using electrophysiological and biochemical assays. Binding studies performed with rat brain membranes show that PNU-151774E has high affinity for binding site 2 of the sodium channel receptor, which is greater than that of phenytoin or lamotrigine (IC50, 8 microM versus 47 and 185 microM, respectively). PNU-151774E reduces sustained repetitive firing in a use-dependent manner without modifying the first action potential in hippocampal cultured neurons. In the same preparation PNU-151774E inhibits tetrodotoxin-sensitive fast sodium currents and high voltage-activated calcium currents under voltage-clamp conditions. These electrophysiological activities of PNU-151774E correlate with its ability to inhibit veratrine and KCl-induced glutamate release in rat hippocampal slices (IC50, 56.4 and 185.5 microM, respectively) and calcium inward currents in mouse cortical neurons. On the other hand, PNU-151774E does not affect whole-cell gamma-aminobutryic acid- and glutamate-induced currents in cultured mouse cortical neurons. These results suggest that PNU-151774E exerts its anticonvulsant activity, at least in part, through inhibition of sodium and calcium channels, stabilizing neuronal membrane excitability and inhibiting transmitter release. The possible relevance of these pharmacological properties to its antiepileptic potential is discussed.

herg encodes a K+ current highly conserved in tumors of different histogenesis: a selective advantage for cancer cells?

The human ether-a-go-go-related gene (herg) encodes a K+ current (IHERG) that plays a fundamental role in heart excitability by regulating the action potential repolarization (IKr); mutations of this gene are responsible for the chromosome 7-linked long QT syndrome (LQT2). In this report, we show that in a variety (n = 17) of tumor cell lines of different species (human and murine) and distinct histogenesis (neuroblastoma, rhabdomyosarcoma, adenocarcinoma, lung microcytoma, pituitary tumors, insulinoma beta-cells, and monoblastic leukemia), a novel K+ inward-rectifier current (IIR), which is biophysically and pharmacologically similar to IHERG, can be recorded with the patch-clamp technique. Northern blot experiments with a human herg cDNA probe revealed that both in human and murine clones the very high expression of herg transcripts can be quantified in at least three clearly identifiable bands, suggesting an alternative splicing of HERG mRNA. Moreover, we cloned a cDNA encoding for IIR from the SH-SY5Y human neuroblastoma. The sequence of this cDNA result was practically identical to that already reported for herg, indicating a high conservation of this gene in tumors. Consistently, the expression of this clone in Xenopus oocytes showed that the encoded K+ channel had substantially all of the biophysical and pharmacological properties of the native IIR described for tumor cells. In addition, in the tumor clones studied, IIR governs the resting potential, whereas it could not be detected either by the patch clamp or the Northern blot techniques in cells obtained from primary cell cultures of parental tissues (sensory neurons and myotubes), whose resting potential is controlled by the classical K+ anomalous rectifier current. This current substitution had a profound impact on the resting potential, which was markedly depolarized in tumors as compared with normal cells. These results suggest that IIR is normally only expressed during the early stages of cell differentiation frozen by neoplastic transformation, playing an important pathophysiological role in the regulatory mechanisms of neoplastic cell survival. In fact, because of its biophysical features, IIR, besides keeping the resting potential within the depolarized values required for unlimited tumor growth, could also appear suitable to afford a selective advantage in an ischemic environment.

A novel K+ channel blocker isolated from 'hiccup nut' toxin

Combretastatin B1, a polyhydroxybibenzyl compound extracted from the fruit of Combretum kraussii, known to contain 'hiccup nut' toxin, reversibly increased the duration, but not the peak or the rate of rise, of the action potential in rat sensory neurones by approximately 300%. This effect was only seen when it was applied to the extracellular side of the membrane. No effects on the resting potential were observed. K+ delayed rectifier currents were inhibited in neurones and in human myotubes with an IC50 of about 300 microM; the HERG-type inward rectifier channels in tumour cells were inhibited to a greater degree. Due to its selective action and the similarity of its blockade to that produced by class III antiarrhythmic drugs, the toxin could be the origin of compounds of potentially significant pharmacological interest.

Soluble or bound laminin elicit in human neuroblastoma cells short- or long-term potentiation of a K+ inwardly rectifying current: relevance to neuritogenesis

Changes in the resting potential (VREST) and in the underlying ionic conductances were measured by the patch-clamp technique in SH-SY5Y human neuroblastoma cells exposed to substrate-bound or soluble Laminin (bLN; sLN), as compared to integrin-independent substrates (polylysine (PL); bovine serum albumin (BSA)). While PL and BSA were ineffective, both forms of LN caused an early (5-15 min) activation of a peculiar type of Inwardly Rectifying K+ current (IIR) characterised by a voltage-dependent inactivation in the range of membrane potentials around -50/0 mV. IIR was blocked by Cs+ ions and by the antiarrhythmic drug E-4031, a specific inhibitor of the HERG-codified channels. In cells adherent to bLN, IIR potentiation (85%) persisted for 90-120 min and was accompanied by a similar, but transient, increase in the leakage conductance (GL). Successively, the persistence of a high IIR conductance and the decrease of GL progressively bring VREST from -12 to approximately -30 mV in about 120 min. On the other hand, in cells adherent to PL, exposure to sLN produced a similar but not persistent activation of IIR, without any increase in GL: this caused a rapid, transient hyperpolarisation of VREST. The effects of bLN and sLN were mimicked by antibodies raised against the integrin beta 1 subunit, suggesting a specific integrin-mediated mechanism. In fact, when bound to the culture dishes, these antibodies simultaneously activated the IIR and GL, whereas in soluble form they only activated IIR. Cells adherent to bLN emitted neurites, a process impaired by the block of IIR by E-4031 and Cs+. On the whole data suggest that the integrin-mediated activation of IIR plays a crucial role in the commitment to neuritogenesis of neuroblastoma cells, independently on the effects of this activation on VREST.

A HERG-like K+ channel in rat F-11 DRG cell line: pharmacological identification and biophysical characterization

1. The relationships between the K+ inward rectifier current present in neuroblastoma cells (IIR) and the current encoded by the human ether-á-go-go-related gene (HERG), IHERG, and the rapidly activating repolarizing cardiac current IK(r), were investigated in a rat dorsal root ganglion (DRG) x mouse neuroblastoma hybrid cell line (F-11) using pharmacological and biophysical treatments. 2. IIR shared the pharmacological features described for IK(r), including the sensitivity to the antiarrhythmic drugs E4301 and WAY-123,398, whilst responding to Cs+, Ba2+ and La3+ in a similar way to IHERG. 3. The voltage-dependent gating properties of IIR were similar to those of IK(r) and IHERG, although IIR outward currents were negligible in comparison. 4. In high K+ extracellular solutions devoid of divalent cations, IIR deactivation kinetics were removed resulting in long-lasting currents apparently activated in hyperpolarization, with a marked (2.7-fold) increase in conductance, as recorded from the instantaneous linear current-voltage relationship at -120 mV. Re-addition of Ca2+ restored the original closure of the channel whereas re-addition of Mg2+ reduced the peak current. 5. The IIR described here, the heart IK(r) and the IHERG could be successfully predicted by a unique kinetic model where the voltage dependencies of the activation/inactivation gates were properly voltage shifted. On the whole, IIR seems to be the first example of a HERG-type current constitutively expressed and operating in mammalian cells of the neuronal lineage.

Multipotential stem cells from the adult mouse brain proliferate and self-renew in response to basic fibroblast growth factor

It has been established that the adult mouse forebrain contains multipotential (neuronal/glial) progenitor cells that can be induced to proliferate in vitro when epidermal growth factor is provided. These cells are found within the subventricular zone of the lateral ventricles, together with other progenitor cell populations, whose requirements for proliferation remain undefined. Using basic fibroblast growth factor (bFGF), we have isolated multipotential progenitors from adult mouse striatum. These progenitors proliferate and can differentiate into cells displaying the antigenic properties of astrocytes, oligodendrocytes, and neurons. The neuron-like cells possess neuronal features, exhibit neuronal electrophysiological properties, and are immunoreactive for GABA, substance P, choline acetyl-transferase, and glutamate. Clonal analysis confirmed the multipotency of these bFGF-dependent cells. Most significantly, subcloning experiments demonstrated that they were capable of self-renewal, which led to a progressive increase in population size over serial passaging. These results demonstrate that bFGF is mitogenic for multipotential cells from adult mammalian forebrain that possess stem cell properties.

A novel inward-rectifying K+ current with a cell-cycle dependence governs the resting potential of mammalian neuroblastoma cells

1. Human and murine neuroblastoma cell lines were used to investigate, by the whole-cell patch-clamp technique, the properties of a novel inward-rectifying K+ current (IIR) in the adjustment of cell resting potential (Vrest), which was in the range -40 to -20 mV. 2. When elicited from a holding potential of 0 mV, IIR was completely inactivated with time constants ranging from 13 ms at -140 mV to 4.5 s at -50 mV. The steady-state inactivation curve (h(V)) was found to be independent of [Na+]o and [K+]o (2-80 mM) and could be fitted to a Boltzmann curve with a steep slope factor of 5-6, and a V1/2 around Vrest. Divalent ion-free extracellular solutions shifted h(V) to the left by about 28 mV. 3. Peak chord conductance, whose maximal value was approximately proportional to the square root of [K+]o, could be fitted to a Boltzmann curve independently of [K+]o, with a V1/2 value around -48 mV and a slope factor of 18. Extracellular Cs+ and Ba2+ blocked the IIR in a concentration- and voltage-dependent manner, but Ba2+ was less effective than it is on classical inward-rectifier channels. 4. Under control culture conditions the values of Vrest and V1/2 of h(V) varied widely among cells. The knowledge of V1/2 proved crucial or the theoretical prediction of Vrest. After cell synchronization in the G0-G1 phase of the cell cycle, or at the G1-S boundaries, the cells reduced their variability of h(V). The same occurred after cell synchronization in G1 by treatment with retinoic acid. 5. The experimental data could be fitted to a classical model of an inward rectifier, after removing the dependence of conductance activation on (V-EK), and incorporating an inactivation with an intrinsic voltage dependence. Moreover, the model predicts, for this novel inward rectifier and in contrast with the classical inward rectifier, the incapacity of maintaining, in physiological media, a Vrest more negative than -35 to -40 mV, which is an important feature of cancer cells.