Role of dopaminergic and serotonergic systems on behavioral stimulatory effects of low-dose alprazolam and lorazepam

Severe Alprazolam Withdrawal With Delirium and Psychosis: A Case Report and Literature Review

ABSTRACT

In our report, and review of the literature, we present an important clinical lesson for the recognition and treatment of alprazolam withdrawal with complicated delirium and psychosis, and present a strong case for future treatment algorithms. Our case is unique due to the severity of behavioral disturbance associated with acute psychosis secondary to alprazolam withdrawal and the significant quantity of alprazolam consumed. The use of high cumulative doses of longer-acting benzodiazepines resulted in rapid improvement in symptoms with full resolution of psychosis. Within 4 days of treatment in hospital, delirium and psychosis had fully resolved. Detoxification continued in the community and the patient was followed up in clinic for monitoring of mental state. There was no recurrence of psychotic symptoms.

Alprazolam misuse: Analysis of French Addictovigilance Network data from 2011 to 2020

OBJECTIVES

Alprazolam, a high-potency and short-acting anxiolytic benzodiazepine, is one of the most misused benzodiazepines in France. In the context of various reports on alprazolam misuse during the COVID-19 pandemic, the objective of this study was to assess alprazolam abuse potential by analyzing French addictovigilance and international data.

METHODS

Data collected from 2011 to 2020 using the following epidemiological tools of the French Addictovigilance Network were analyzed: spontaneous reports (SRs), OPPIDUM (addiction care center data), OSIAP (falsified prescriptions), DRAMES (substance-related deaths), and chemical submission surveys. Moreover, the VigiBase™ database was analyzed to evaluate alprazolam abuse liability worldwide.

RESULTS

During the study period, 675 SRs concerning alprazolam misuse were recorded (sex ratio: ̴1; median age: 39 years). The desired effects were intensification of the therapeutic anxiolytic effect, euphoric effect, and management of substance withdrawal. Alprazolam was the third and first benzodiazepine listed in OPPIDUM and OSIAP surveys. Analysis of the SR and OPPIDUM data showed a recent increase in the alprazolam-opioid combination. In DRAMES data, alprazolam was directly linked to 11 deaths (associated with opioids in 10/11). VigiBase™ data analysis highlighted that France was the third country with the most cases of alprazolam misuse. The disproportionality analysis showed that in France, alprazolam was associated with higher risk of misuse and dependence compared with other benzodiazepines: reporting odds ratio=1.43, (95% CI: 1.04-1.95) and=1.97 (95% CI:1.50-2.59), respectively.

CONCLUSIONS

This study highlighted an increase in various signals of alprazolam abuse in France, and an increased use of the alprazolam-opioid combination that was also linked to most of the recorded alprazolam-linked deaths. These signals have been reported also in the international literature, and should be thoroughly investigated.

Dopaminergic and norepinephrinergic modulation of endogenous event-related potentials: A systematic review and meta-analysis

Event-related potentials (ERPs) represent the cortical processing of sensory, motor or cognitive functions invoked by particular events or stimuli. A current theory posits that the catecholaminergic neurotransmitters dopamine (DA) and norepinephrine (NE) modulate a number of endogenous ERPs during various cognitive processes. This manuscript aims to evaluate a leading neurotransmitter hypothesis with a systematic overview and meta-analysis of pharmacologic DA and NE manipulation of specific ERPs in healthy subjects during executive function. Specifically, the frontally-distributed P3a, N2, and Ne/ERN (or error-related negativity) are supposedly modulated primarily by DA, whereas the parietally-distributed P3b is thought to be modulated by NE. Based on preceding research, we refer to this distinction between frontally-distributed DA-sensitive and parietally-distributed NE-sensitive ERP components as the Extended Neurobiological Polich (ENP) hypothesis. Our systematic review and meta-analysis indicate that this distinction is too simplistic and many factors interact with DA and NE to influence these specific ERPs. These may include genetic factors, the specific cognitive processes engaged, or elements of study design, i.e. session or sequence effects or data-analysis strategies.

Alprazolam modulates persistence energy during emotion processing in first-degree relatives of individuals with schizophrenia: a network control study

Schizophrenia is marked by deficits in facial affect processing associated with abnormalities in GABAergic circuitry, deficits also found in first-degree relatives. Facial affect processing involves a distributed network of brain regions including limbic regions like amygdala and visual processing areas like fusiform cortex. Pharmacological modulation of GABAergic circuitry using benzodiazepines like alprazolam can be useful for studying this facial affect processing network and associated GABAergic abnormalities in schizophrenia. Here, we use pharmacological modulation and computational modeling to study the contribution of GABAergic abnormalities toward emotion processing deficits in schizophrenia. Specifically, we apply principles from network control theory to model persistence energy - the control energy required to maintain brain activation states - during emotion identification and recall tasks, with and without administration of alprazolam, in a sample of first-degree relatives and healthy controls. Here, persistence energy quantifies the magnitude of theoretical external inputs during the task. We find that alprazolam increases persistence energy in relatives but not in controls during threatening face processing, suggesting a compensatory mechanism given the relative absence of behavioral abnormalities in this sample of unaffected relatives. Further, we demonstrate that regions in the fusiform and occipital cortices are important for facilitating state transitions during facial affect processing. Finally, we uncover spatial relationships (i) between regional variation in differential control energy (alprazolam versus placebo) and (ii) both serotonin and dopamine neurotransmitter systems, indicating that alprazolam may exert its effects by altering neuromodulatory systems. Together, these findings provide a new perspective on the distributed emotion processing network and the effect of GABAergic modulation on this network, in addition to identifying an association between schizophrenia risk and abnormal GABAergic effects on persistence energy during threat processing.

Alprazolam: Good for Some, Not Good for All!

BACKGROUND

Although alprazolam is approved only for use in panic disorder and generalized anxiety disorder, it is used for numerous other conditions, not only by psychiatrists but also by medical professionals in general. This commentary critically analyzes the use of alprazolam.

METHODS

A narrative review approach was adopted, using relevant articles and textbooks, to compile pertinent literature for the aforementioned topic.

RESULTS

Among all its adverse reactions, the most bothersome concern about the use of alprazolam is its potential for abuse and dependence. This can be attributed to certain unique pharmacokinetic and pharmacodynamic properties of this benzodiazepine. Also, the withdrawal triggered by use of alprazolam is challenging to treat. Alternate pharmacological and non-pharmacological strategies for use in anxiety and insomnia are available, which might be safer than alprazolam. Also, policy changes can serve as an answer to curb alprazolam abuse to some extent. Alprazolam might still be a good choice for individuals who do not have a history of abuse of other substances, with adequate psychoeducation and close monitoring of their usage pattern.

CONCLUSION

There is a need to reconsider the need for long-term use of benzodiazepines in general, and alprazolam in particular. However, they still might be an appropriate choice in individuals where abuse and dependence are less likely.

BDZs, designer BDZs, and Z-drugs: pharmacology and misuse insights

Benzodiazepines (BZDs) are a widely prescribed class of sedative-hypnotics compounds for the treatment of a broad range of conditions as anxiety and obsessive-compulsive disorders, phobias, sleep related problems associated with insomnia and for the management of alcohol and GHB withdrawal. Zolpidem, zopiclone and zaleplon, commonly known as Z-drugs are non-benzodiazepine hypnotic drug with pharmacology similar to BDZs. Despite their usefulness, BDZs and Z-drugs present a potential for abuse and dependence. Moreover, the non-medical use of BDZs is a well-known phenomenon and represents an increasingly widespread public health problem since is associated with an elevated risk of serious health consequences or fatal overdose, especially among specific group of users. The spectrum of BDZs and Z-drugs misuse is extended by new synthetic BDZs, which may pose high risks to users, since the majority have never undergone clinical trials or tests and consequently their pharmacology and toxicology is largely unknown.

Axonal Modulation of Striatal Dopamine Release by Local γ-Aminobutyric Acid (GABA) Signalling

Striatal dopamine (DA) release is critical for motivated actions and reinforcement learning, and is locally influenced at the level of DA axons by other striatal neurotransmitters. Here, we review a wealth of historical and more recently refined evidence indicating that DA output is inhibited by striatal γ-aminobutyric acid (GABA) acting via GABAA and GABAB receptors. We review evidence supporting the localisation of GABAA and GABAB receptors to DA axons, as well as the identity of the striatal sources of GABA that likely contribute to GABAergic modulation of DA release. We discuss emerging data outlining the mechanisms through which GABAA and GABAB receptors inhibit the amplitude as well as modulate the short-term plasticity of DA release. Furthermore, we highlight recent data showing that DA release is governed by plasma membrane GABA uptake transporters on striatal astrocytes, which determine ambient striatal GABA tone and, by extension, the tonic inhibition of DA release. Finally, we discuss how the regulation of striatal GABA-DA interactions represents an axis for dysfunction in psychomotor disorders associated with dysregulated DA signalling, including Parkinson's disease, and could be a novel therapeutic target for drugs to modify striatal DA output.

Prevalence and socioeconomic factors in the prescription of concurrent amphetamine and alprazolam

OBJECTIVE

Goals were to determine the prevalence of concurrent prescription of amphetamine and alprazolam, and examine variation by socioeconomic factors.

METHODS

Washington State's Prescription Monitoring Program was reviewed for calendar years 2013 through 2017. Individuals receiving more than 180 days of amphetamine, alprazolam or both were tabulated for each zip code. Prescription rates were compared between zip codes with variation in rural/urban setting and fraction of low and high income households using a multiple regression.

RESULTS

One in 3920 individuals in the general population of Washington State were taking a combination of alprazolam and amphetamine. The statewide prevalence of this combination increased 40.2% between 2013 and 2017. The prevalence of the combination in each zip code is significantly positively correlated with the fraction of high income households, p < 0.001, and urban area, p < 0.05. In contrast, the prevalence of amphetamine increased with both the fraction of high income, p < 0.001, and low income households, p < 0.01, with an incremental increase over twice as large with fraction of high income (b = 232 (25)) than low income households (b = 102 (38)). In contrast, alprazolam decreased in prevalence with the fraction of high income households, p < 0.05.

CONCLUSIONS

The prevalence of concurrent prescription of alprazolam and amphetamine correlates with local socioeconomic factors, including greater household income, instead of the prevalence of FDA indications, including anxiety disorders or ADHD. More clinical studies are required to establish efficacy and guidelines for safe use to mitigate the increased risk of accidents in patients taking concurrent amphetamine and alprazolam.

A Review of Alprazolam Use, Misuse, and Withdrawal

: Alprazolam is one of the most widely prescribed benzodiazepines for the treatment of generalized anxiety disorder and panic disorder. Its clinical use has been a point of contention as most addiction specialists consider it to be highly addictive, given its unique psychodynamic properties which limit its clinical usefulness, whereas many primary care physicians continue to prescribe it for longer periods than recommended. Clinical research data has not fully shed light on its "abuse liability," yet it is one of the most frequently prescribed benzodiazepines. "Abuse liability" is the degree to which a psychoactive drug has properties that facilitate people misusing it, or becoming addicted to it, and is commonly used in the literature. We have replaced it in our manuscript with "misuse liability" as it reflects a more updated terminology consistent with the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). In this paper, we have reviewed alprazolam's indications for use, its effect on pregnant women, misuse liability, withdrawal syndrome, pharmacodynamic properties, and suggest better clinical prescription practice of alprazolam by presenting an indepth theory of its clinical effects with use and withdrawal.

Illicit and prescription drug misuse as reported to the Maine Diversion Alert Program

BACKGROUND

The opioid epidemic is rapidly evolving and new tools are needed to combat drug abuse. The Maine Diversion Alert Program (DAP) is an informational resource that facilitates communication about drug arrests between the criminal justice and healthcare fields. The objectives of this report were to: (1) describe the illegal and prescription pharmaceuticals reported to the DAP; (2) determine if the drugs implicated in arrests changed from the first to latter half of 2016; (3) identify the demographic and other characteristics of arrestees; and (4) outline the strengths and limitations of the DAP for other areas considering implementing similar programs.

METHODS

The arrests (N=2,368, 31.4% female, mean age=33.7, SD=9.9, Min=18, Max=71.5) reported to the DAP were examined. Drugs were classified by Drug Enforcement Administration Schedule (I-V, non-controlled prescription) and into families (opioids, stimulants, sedatives, hallucinogens, and other). A comparison between the first and second half of 2016 and arrest by county was completed.

RESULTS

Arrests involved 2,957 substances (drugs and paraphernalia). Most arrests (80.6%) involved a single drug. One-third (33.2%) of arrests involved illicit drugs (i.e. Schedule I) and three-fifths (59.8%) were for controlled prescription medical drugs (i.e. Schedule II-V), and a minority (6.8%) involved non-controlled prescription drugs (e.g. gabapentin, bupropion). Opioids (e.g. heroin, buprenorphine, and oxycodone) accounted for over-half (51.3%) of arrests followed by stimulants (29.0%, e.g. cocaine), and sedatives (7.6%). Arrests for oxycodone significantly decreased (51.9%) and alprazolam increased (89.3%) during 2016. Arrestees for non-controlled prescription drugs were older than arrestees for illegal drugs. Arrests, correcting for population, were most common in more urban (e.g. Androscoggin and Cumberland) counties.

CONCLUSIONS

Opioids (illicit and prescription) account for over half of all arrests. However, arrests for oxycodone decreased while arrests for benzodiazepines, and especially alprazolam, increased in 2016. The DAP is a novel source of information for healthcare decisions and can empirically inform law enforcement about drug misuse and addiction.

Diazepam Concurrently Increases the Frequency and Decreases the Amplitude of Transient Dopamine Release Events in the Nucleus Accumbens

Benzodiazepines are commonly prescribed anxiolytics that pose abuse liability in susceptible individuals. Although it is well established that all drugs of abuse increase brain dopamine levels, and benzodiazepines are allosteric modulators of the GABA_A receptor, it remains unclear how they alter dopamine release. Using in vivo fast-scan cyclic voltammetry, we measured diazepam-induced changes in the frequency and amplitude of transient dopamine release events. We found that diazepam concurrently increases the frequency and decreases the amplitude of transient dopamine release events in the awake and freely moving rat. The time course during which diazepam altered the frequency and amplitude of dopamine release events diverged, with the decreased amplitude effect being shorter lived than the increase in frequency, but both showing similar rates of onset. We conclude that diazepam increases the frequency of accumbal dopamine release events by disinhibiting dopamine neurons, but also decreases their amplitude. We speculate that the modest abuse liability of benzodiazepines is due to their ability to decrease the amplitude of dopamine release events in addition to increasing their frequency.

Diazepam Inhibits Electrically Evoked and Tonic Dopamine Release in the Nucleus Accumbens and Reverses the Effect of Amphetamine

Diazepam is a benzodiazepine receptor agonist with anxiolytic and addictive properties. Although most drugs of abuse increase the level of release of dopamine in the nucleus accumbens, here we show that diazepam not only causes the opposite effect but also prevents amphetamine from enhancing dopamine release. We used 20 min sampling in vivo microdialysis and subsecond fast-scan cyclic voltammetry recordings at carbon-fiber microelectrodes to show that diazepam caused a dose-dependent decrease in the level of tonic and electrically evoked dopamine release in the nucleus accumbens of urethane-anesthetized adult male Swiss mice. In fast-scan cyclic voltammetry assays, dopamine release was evoked by electrical stimulation of the ventral tegmental area. We observed that 2 and 3 mg of diazepam/kg reduced the level of electrically evoked dopamine release, and this effect was reversed by administration of the benzodiazepine receptor antagonist flumazenil in doses of 2.5 and 5 mg/kg, respectively. No significant effects on measures of dopamine re-uptake were observed. Cyclic voltammetry experiments further showed that amphetamine (5 mg/kg, intraperitoneally) caused a significant increase in the level of dopamine release and in the half-life for dopamine re-uptake. Diazepam (2 mg/kg) significantly weakened the effect of amphetamine on dopamine release without affecting dopamine re-uptake. These results suggest that the pharmacological effects of benzodiazepines have a dopaminergic component. In addition, our findings challenge the classic view that all drugs of abuse cause dopamine release in the nucleus accumbens and suggest that benzodiazepines could be useful in the treatment of addiction to other drugs that increase the level of dopamine release, such as cocaine, amphetamines, and nicotine.

Incongruent reduction of dopamine transporter availability in different subgroups of alcohol dependence

The dopamine transporter (DAT) plays a crucial role in the pathogenesis of alcohol dependence (AD) and major depression (MD), and males have more risk factors for the development of AD. However, imaging studies on brain DAT availability in males with AD comorbid with MD (AD/MD) are limited, and the association of DAT availability with cognitive function and depressive scores in patients with AD/MD has not been analyzed. Hence, this study examined the relationship between brain DAT availability, cognitive function, and depressive symptoms in different subgroups of males with AD.Single-photon emission computed tomography imaging with Tc-TRODAT-1 as a ligand was used to measure striatal DAT availability in 49 patients with AD (28 pure AD and 21 AD/MD) and 24 age- and sex-matched healthy volunteers. The Wisconsin Card Sorting Test (WCST) and 17-item Hamilton Depression Rating Scale were used to assess neurocognitive function and depressive scores, respectively. Patients with AD showed a significant reduction of DAT availability in 3 brain regions (P < 0.001), and this reduction was more pronounced in the patients with pure AD compared to healthy controls. The patients with AD showed significantly poorer performance on the WCST, but only in the control group was DAT availability significantly negatively correlated with total errors and perseverative errors (P < 0.001).These preliminary findings suggest that DAT availability is associated with neurocognitive function, and incongruent reduction of DAT may play a pathophysiological role in different subgroups of AD. In addition, decreased DAT availability may be associated with the severity of depressive symptoms in patients with AD/MD.

Apolipoprotein E (APOE) genotype and the pesticide chlorpyrifos modulate attention, motivation and impulsivity in female mice in the 5-choice serial reaction time task

Organophosphate pesticides - and chlorpyrifos (CPF) in particular - contribute to a wide range of neurobehavioural disorders. Most experimental research focuses on learning and memory processes, while other behaviours remain understudied. The isoforms of the human apolipoprotein E (apoE) confer different cognitive skills on their carriers, but data on this topic are still limited. The current study was performed to assess whether the APOE genotypic variability differently modulates the effects of CPF on attentional performance, inhibitory control and motivation. Human apoE targeted replacement adult female mice (apoE2, apoE3 and apoE4) were trained to stably perform the 5-choice serial reaction time task (5-CSRTT). Animals were then subjected to daily dietary CPF (3.75 mg/kg body weight) for 4 weeks. After CPF exposure, we established a 4-week CPF-free period to assess recovery. All individuals acquired the task, apoE2 mice showed enhanced learning, while apoE4 mice displayed increased premature and perseverative responding. This genotype-dependent lack of inhibitory control was reversed by CPF. Overall, the pesticide induced protracted impairments in sustained attention and motivation, and it reduced anticipatory responding. ApoE3 mice exhibited delayed attentional disruptions throughout the wash-out period. Taken together, these findings provide notable evidence on the emergence of CPF-related attentional and motivational deficits.

Reduced Dopamine Transporter Availability and Neurocognitive Deficits in Male Patients with Alcohol Dependence

Dopamine plays an important role in the development of alcohol dependence, cognitive dysfunction, and is regulated via dopamine transporter activity. Although dopamine transporter activity is critically involved in alcohol dependence, studies observing this relationship are limited. Thus the current study examined whether dopamine transporter availability is associated with developing of alcohol dependence and cognitive dysfunction. Brain imaging with ^99mTc-TRODAT-1 as a ligand was used to measure dopamine transporter availability among 26 male patients with pure alcohol dependence and 22 age- and sex- matched healthy volunteers. The Wisconsin Card Sorting Test (WCST) and Tridimensional Personality Questionnaire (TPQ) were administered to assess neurocognitive functioning and personality traits, respectively. Compared to healthy controls, patients with alcohol dependence showed a significant reduction in dopamine transporter availability (p < 0.001), as well as diminished performance on the WCST (p < 0.001). Dopamine transporter availability was negatively correlated with both total and perseverative WCST errors among healthy controls, but only patients with alcohol dependence showed a positive correlation between dopamine transporter availability and a harm avoidance personality profile. Thus, reductions in dopamine transporter availability may play a pathophysiological role in the development of pure alcohol dependence, given its association with neurocognitive deficits. Moreover, personality may influence the development of pure alcohol dependence; however, additional clinical subgroups should be examined to confirm this possibility.

Effects of chronic flunitrazepam treatment schedule on therapy-induced sedation and motor impairment in mice

BACKGROUND

The aim of the present study was to examine whether different treatment schedules could be associated with tolerance development to the ataxic and sedative effects of flunitrazepam in mice.

METHODS

Effects of repeated flunitrazepam administration were studied in the rotarod and the chimney test for motor coordination and in a photocell apparatus for locomotor activity in mice. Flunitrazepam doses varied in particular types of injections or in different experiment duration periods.

RESULTS

Repeated flunitrazepam administration (1 mg/kg, sc and 2 mg/kg, ip) for 8 consecutive days induced tolerance to the motor impairing effects of flunitrazepam in mice, both in the rotarod and the chimney test. In turn, no tolerance developed to sedative flunitrazepam effects, regarding either dose level, injection type or treatment duration.

CONCLUSIONS

Those findings confirmed the previous observations that tolerance to benzodiazepines was not simultaneous for each pharmacological property of the drugs. Interestingly enough, an acute dose of flunitrazepam (1 mg/kg, sc) in our study enhanced locomotor activity of mice.

The role of alprazolam for the treatment of panic disorder in Australia

OBJECTIVE

To investigate the potential impact of increasing prescription rates of alprazolam for the treatment of panic disorder (PD) in Australia through a review of efficacy, tolerability and adverse outcome literature.

METHODS

Data were sourced by a literature search using MEDLINE, Embase, PsycINFO and a manual search of scientific journals to identify relevant articles. Clinical practice guidelines from the American Psychiatric Association, National Institute of Clinical Excellence, Royal Australian and New Zealand College of Psychiatrists and World Federation of Societies of Biological Psychiatry were sourced. Prescription data were sourced from Australian governmental sources.

RESULTS

Alprazolam has shown efficacy for control of PD symptoms, particularly in short-term controlled clinical trials, but is no longer recommended as a first-line pharmacological treatment due to concerns about the risks of developing tolerance, dependence and abuse potential. Almost no evidence is available comparing alprazolam to current first-line pharmacological treatment. Despite this, prescription rates are increasing. A number of potential issues including use in overdose and impact on car accidents are noted. conclusion: Although effective for PD symptoms in clinical trials, a number of potential issues may exist with use. Consideration of its future place in PD treatment in Australia may be warranted.

Evidence for a role of inhibition of orexinergic neurons in the anxiolytic and sedative effects of diazepam: A c-Fos study

The classical benzodiazepine diazepam (DZ) induces anxiolysis at low doses and sedation and hypnosis at higher doses. Different brain areas and neuronal populations most likely mediate these different behavioral effects. We used c-Fos immunohistochemistry as an indirect way to study neuronal activation or inhibition induced by DZ at anxiolytic and sedative doses (0.5 and 5mg/kg, respectively) in various brain areas involved in anxiety, arousal, sedation and addiction in C57BL/6J mice. We also focused on the two neuronal populations, orexinergic and dopaminergic neuronal populations, with the help of double-immunohistochemistry using c-Fos and orexin-A antibodies and c-Fos and tyrosine hydroxylase antibodies. We found that different brain areas of unhabituated mice reacted differently to the mild stress induced by vehicle injection. Also the response to anxiolytic or sedative doses of DZ differed between the areas, suggesting that distinct brain areas mediate the behavioral effects of low and high DZ doses. Our findings propose a role for inhibition of orexin neurons in the anxiolytic and sleep-promoting effects of DZ. In addition, the activation of central amygdala neurons by DZ treatment was associated with anxiolytic and sedative effects. On the other hand, the ventral hippocampus, basolateral amygdala, ventral tegmental area and prefrontal cortex were sensitive even to the mild injection stress, but not to the anxiolytic dose of DZ.

Availability of the serotonin transporter in patients with alcohol dependence

OBJECTIVES

Evidence has suggested that the serotonin transporter (SERT) plays a role in the pathogenesis of alcohol dependence, anxiety and depression and that polymorphisms of the serotonin-transporter-linked promoter region (5-HTTLPR) may influence the SERT. This study evaluated the differences in SERT availability between healthy controls and alcoholic patients and the impact of 5-HTTLPR polymorphisms on SERT availability.

METHODS

Eleven healthy controls and 28 alcoholic patients were recruited. SERT availability was measured in vivo with single photon emission computed tomography and (123)I-labelled 2-((2-((dimethyl-amino)methyl)phenyl)thio)-5-iodophenylamine in the midbrain, thalamus and striatum. Each subject was genotyped for the 5-HTTLPR polymorphism.

RESULTS

Compared to healthy controls, there was a significantly lower availability of SERT in the midbrain among patients with pure alcohol dependence (pure ALC). Of patients with anxiety, depression and alcohol dependence (ANX/DEPALC), the carriers of one L(A) allele showed a significantly higher availability of SERT in the striatum compared to non-L(A) carriers. After Bonferroni correction, these significances vanished. There were no significant differences in SERT availability between controls and ANX/DEP ALC.

CONCLUSIONS

The results suggest that pure alcoholics may have lower SERT availability in the midbrain; the 5HTTLPR polymorphism may influence SERT availability in ANX/DEP ALC. These findings may serve as a springboard for future large-scale studies.

The effects of lorazepam on extrastriatal dopamine D(2/3)-receptors-A double-blind randomized placebo-controlled PET study

Lorazepam is a widely used anxiolytic drug of the benzodiazepine class. The clinical actions of benzodiazepines are thought to be mediated via specific allosteric benzodiazepine binding sites and enhancement of GABAergic neurotransmission in the brain. However, the indirect effects of benzodiazepines on other neurotransmitter systems have not been extensively studied. Previous experimental evidence suggests that benzodiazepines inhibit striatal dopamine release by enhancing the GABAergic inhibitory effect on dopamine neurons whereas very little is known about cortical or thalamic gamma-amino-butyric (GABA)-dopamine interactions during benzodiazepine administration. We explored the effects of lorazepam (a single 2.5 mg dose) on cortical and thalamic D(2/3) receptor binding using Positron-Emission Tomography (PET) and the high-affinity D(2/3)-receptor ligand [(11)C]FLB 457 in 12 healthy male volunteers. We used a randomized, double-blind and placebo-controlled study design. Dopamine D(2)/D(3) receptor binding potential was measured with the reference tissue method in several extrastriatal D(2)-receptor areas including frontal, parietal, temporal cortices and thalamus. The main subjective effect of lorazepam was sedation. Lorazepam induced a statistically significant decrease of D(2)/D(3) receptor BP(ND) in medial temporal and dorsolateral prefrontal cortex (DLPFC) that was also confirmed by a voxel-level analysis. The sedative effect of lorazepam was associated with a decrease in D(2)/D(3) receptor BP(ND) in the DLPFC. In conclusion, lorazepam decreased [(11)C]FLB 457 binding in frontal and temporal cortex, suggesting that cortical GABA-dopamine interaction may be involved in the central actions of lorazepam in healthy volunteers. The correlation between lorazepam-induced sedation and D(2)/D(3) receptor binding potential (BP) change further supports this hypothesis.

Oxidative metabolism of limbic structures after acute administration of diazepam, alprazolam and zolpidem

The effects of acute administration of two benzodiazepines and a non-benzodiazepine hypnotic on behavior and brain metabolism were evaluated in rats. After testing the behavioral action of the benzodiazepines on the open field and the elevated plus-maze, the effects of the three drugs on neuronal metabolism of particular limbic regions were measured using cytochrome c oxidase (CO) histochemistry. Diazepam (5 mg/kg i.p.) and alprazolam (0.5 mg/kg i.p.) induced clear anxiolytic effects and a decrease in locomotion, whereas zolpidem (2 mg/kg i.p.) caused an intense hypnotic effect. The anxiolytic effects of alprazolam were distinguishable from diazepam due to the pharmacological and clinical profile of this triazolobenzodiazepine. CO activity decreased significantly in almost all the limbic regions evaluated after zolpidem administration. However, significant prominent decreases in CO activity were found after diazepam treatment in the medial mammillary nucleus, anteroventral thalamus, cingulate cortex, dentate gyrus and basolateral amygdala. Alprazolam caused similar decreases in CO activity, with the exception of the prelimbic and cingulate cortices, where significant increases were detected. In agreement with previous studies using other functional mapping techniques, our results indicate that particular benzodiazepines and non-benzodiazepine hypnotics induce selective changes in brain oxidative metabolism.

Electrophysiological Effects of Allopregnanolone in Rats With a History of Ethanol Exposure

BACKGROUND

Sensitivity to the anticonvulsant effects of allopregnanolone (ALLO) is enhanced during the early phase of ethanol (EtOH) withdrawal. However, it is unclear whether this enhanced sensitivity generalizes to ALLO's neurobehavioral effects during protracted abstinence. The purpose of this study was to examine the neurophysiological effects of ALLO in rats with a history of chronic EtOH exposure after a protracted period of abstinence.

METHODS

Male Wistar rats were exposed to EtOH vapor for 14 hr/day for 5 weeks. Blood EtOH levels were maintained between 200 and 250 mg/dl. The effects of ALLO (0.0-10 mg/kg, intraperitoneally) on motor activity, the electroencephalogram (EEG), and auditory event-related potentials then were assessed after 6 to 8 weeks of abstinence from EtOH.

RESULTS

ALLO's effects on the EEG were consistent with previous studies and were unaffected by EtOH exposure. ALLO increased high-frequency EEG power and shifted peak EEG frequencies in a benzodiazepine- and barbiturate-like manner in both the cortex and the hippocampus. The effects of ALLO on event-related potentials were attenuated in rats with a history of EtOH exposure. Low doses of ALLO (1 and 5 mg/kg) reduced cortical P1 amplitude in response to the standard tone but only in the control group. ALLO also increased N1 amplitude in the hippocampus of the control group while having no significant effect in EtOH-exposed rats. Low doses of ALLO (1 and 5 mg/kg) were found to increase motor activity.

CONCLUSIONS

These data indicate that a history of EtOH exposure attenuates some of the neurophysiological effects of ALLO in a manner consistent with cross-tolerance. Taken together, these data suggest that increased sensitivity to ALLO's neurobehavioral effects is limited to the early phases of EtOH withdrawal and may not extend to more protracted periods of abstinence.

The neurobiology and control of anxious states

Fear is an adaptive component of the acute "stress" response to potentially-dangerous (external and internal) stimuli which threaten to perturb homeostasis. However, when disproportional in intensity, chronic and/or irreversible, or not associated with any genuine risk, it may be symptomatic of a debilitating anxious state: for example, social phobia, panic attacks or generalized anxiety disorder. In view of the importance of guaranteeing an appropriate emotional response to aversive events, it is not surprising that a diversity of mechanisms are involved in the induction and inhibition of anxious states. Apart from conventional neurotransmitters, such as monoamines, gamma-amino-butyric acid (GABA) and glutamate, many other modulators have been implicated, including: adenosine, cannabinoids, numerous neuropeptides, hormones, neurotrophins, cytokines and several cellular mediators. Accordingly, though benzodiazepines (which reinforce transmission at GABA(A) receptors), serotonin (5-HT)(1A) receptor agonists and 5-HT reuptake inhibitors are currently the principle drugs employed in the management of anxiety disorders, there is considerable scope for the development of alternative therapies. In addition to cellular, anatomical and neurochemical strategies, behavioral models are indispensable for the characterization of anxious states and their modulation. Amongst diverse paradigms, conflict procedures--in which subjects experience opposing impulses of desire and fear--are of especial conceptual and therapeutic pertinence. For example, in the Vogel Conflict Test (VCT), the ability of drugs to release punishment-suppressed drinking behavior is evaluated. In reviewing the neurobiology of anxious states, the present article focuses in particular upon: the multifarious and complex roles of individual modulators, often as a function of the specific receptor type and neuronal substrate involved in their actions; novel targets for the management of anxiety disorders; the influence of neurotransmitters and other agents upon performance in the VCT; data acquired from complementary pharmacological and genetic strategies and, finally, several open questions likely to orientate future experimental- and clinical-research. In view of the recent proliferation of mechanisms implicated in the pathogenesis, modulation and, potentially, treatment of anxiety disorders, this is an opportune moment to survey their functional and pathophysiological significance, and to assess their influence upon performance in the VCT and other models of potential anxiolytic properties.