Heart rate variability: A primer for alcohol researchers.

Problem alcohol drinking remains a major cost and burden for society. Also, rates of problem drinking in women have dramatically increased in recent decades, and women are at risk for more alcohol problems and comorbidities. The purpose of this commentary is to discuss the potential utility of cardiac measures, including heart rate (HR) and HR variability (HRV), as markers of individual and sex differences in the drive to drink alcohol. We recently used cardiac telemetry in female and male adult rats to determine whether different cardiac markers, including HR and HRV, would differently predict alcohol and anxiety-like behavior across the sexes. Indeed, female behaviors related to HRV measures that indicate more parasympathetic (PNS) influence (the "rest and digest" system). In contrast, male behaviors are associated more with sympathetic (SNS) indicators (the activation system). Remarkably, similar sex differences in PNS versus SNS engagement under challenge are seen in human studies, suggesting strong cross-species convergence in differential autonomic regulation in females and males. Here, we describe the larger challenges that alcohol addiction presents, and how HRV measures may provide new biomarkers to help enhance development of more individualized and sex-specific treatments. We briefly explain the physiological systems underlying cardiac PNS and SNS states, and how specific HRV metrics are defined and validated, especially why particular HRV measures are considered to reflect more PNS versus SNS influence. Finally, we describe hormonal influences and sex differences in brain circuits related to cardiac autonomic regulation. Together, these findings show that HR and HRV have potential for uncovering key underlying mechanisms of sex and individual differences in autonomic drivers, which could guide more personalized treatment.

Sex differences in heart rate variability measures that predict alcohol drinking in rats.

Problem alcohol drinking continues to be a substantial cost and burden. In addition, alcohol consumption in women has increased in recent decades, and women can have greater alcohol problems and comorbidities. Thus, there is a significant need for novel therapeutics to enhance sex-specific, individualized treatment. Heart rate (HR) and HR variability (HRV) are of broad interest because they may be both biomarkers for and drivers of pathological states. HRV reflects the dynamic balance between sympathetic (SNS, 'fight or flight') and parasympathetic (PNS, 'rest and digest') systems. Evidence from human studies suggest PNS predominance in women and SNS in men during autonomic regulation, indicating the possibility of sex differences in risk factors and physiological drivers of problem drinking. To better understand the association between HRV sex differences and alcohol drinking, we examined whether alcohol consumption levels correlated with time domain HRV measures (SDNN and rMSSD) at baseline, at alcohol drinking onset, and across 10 min of drinking, in adult female and male Wistar rats. In particular, we compared both HRV and HR measures under alcohol-only and compulsion-like conditions (alcohol + 10 mg/L quinine), because compulsion can often be a significant barrier to treatment of alcohol misuse. Importantly, previous work supports the possibility that different HRV measures could be interpreted to reflect PNS versus SNS influences. Here, we show that females with higher putative PNS indicators at baseline and at drinking onset had greater alcohol consumption. In contrast, male intake levels related to increased potential SNS measures at drinking onset. Once alcohol was consumed, HR predicted intake level in females, perhaps a pharmacological effect of alcohol. However, HRV changes were greater during compulsion-like intake versus alcohol-only, suggesting HRV changes (reduced SNS in females, reduced PNS and increased HR in males) specifically related to aversion-resistant intake. We find novel and likely clinically relevant autonomic differences associated with biological sex and alcohol drinking, suggesting that different autonomic mechanisms may promote differing aspects of female and male alcohol consumption.

Neural Activity in the Anterior Insula at Drinking Onset and Licking Relates to Compulsion-Like Alcohol Consumption.

Much remains unknown about the etiology of compulsion-like alcohol drinking, where consumption persists despite adverse consequences. The role of the anterior insula (AIC) in emotion, motivation, and interoception makes this brain region a likely candidate to drive challenge-resistant behavior, including compulsive drinking. Indeed, subcortical projections from the AIC promote compulsion-like intake in rats and are recruited in heavy-drinking humans during compulsion for alcohol, highlighting the importance of and need for more information about AIC activity patterns that support aversion-resistant responding. Single-unit activity was recorded in the AIC from 15 male rats during alcohol-only and compulsion-like consumption. We found three sustained firing phenotypes, sustained-increase, sustained-decrease, and drinking-onset cells, as well as several firing patterns synchronized with licking. While many AIC neurons had session-long activity changes, only neurons with firing increases at drinking onset had greater activity under compulsion-like conditions. Further, only cells with persistent firing increases maintained activity during pauses in licking, suggesting roles in maintaining drive for alcohol during breaks. AIC firing was not elevated during saccharin drinking, similar to lack of effect of AIC inhibition on sweet fluid intake in many studies. In addition, we observed subsecond changes in AIC neural activity tightly entrained to licking. One lick-synched firing pattern (determined for all licks in a session) predicted compulsion-like drinking, while a separate lick-associated pattern correlated with greater consumption across alcohol intake conditions. Collectively, these data provide a more integrated model for the role of AIC firing in compulsion-like drinking, with important relevance for how the AIC promotes sustained motivated responding more generally.

Engagement for alcohol escalates in the 5-choice serial reaction time task after intermittent access.

Excessive intake plays a significant role in the development of alcohol use disorder and impacts 15 million Americans annually, with approximately 88 000 dying from alcohol related deaths. Several facets we contribute to alcohol use disorder include impulsivity, motivation, and attention. Previous studies have used the 5-Choice Serial Reaction Time Task (5-Choice) to analyze these types of behaviors using sugar, but recently we have published using 10% alcohol as the reward. This study analyzed 48 mice that were trained to respond for alcohol in the 5-Choice. All mice distributed and analyzed first by alcohol preference and then by consumption. Here, we became interested in a new classification called "engagement". High-engaged and low-engaged mice were determined by the number of correct responses during final Late-Stage training sessions. Interestingly, during Early-Stage training, the mice began to separate themselves into two groups based on their interaction with the task. Throughout both training stages, high-engaged mice displayed a greater number of trials and correct responses, as well as a lower percentage of omissions compared to low-engaged mice. Following three weeks of intermittent access homecage drinking, low-engaged mice showed greater increase in perseverative responding relative to high-engaged. Additionally, low-engaged mice decreased their reward and correct latencies compared to high-engaged mice suggesting an increase in motivation for alcohol. Overall, engagement analysis presents two clearly different groups, with only one being motivated to work for alcohol. These two distinct phenotypes in the 5-Choice could be used to model alcohol motivated behavior, which could help us further understand alcohol use disorder.

Heart rate variability measures indicating sex differences in autonomic regulation during anxiety-like behavior in rats.

Introduction: Mental health conditions remain a substantial and costly challenge to society, especially in women since they have nearly twice the prevalence of anxiety disorders. However, critical mechanisms underlying sex differences remain incompletely understood. Measures of cardiac function, including heart rate (HR) and HR variability (HRV), reflect balance between sympathetic (SNS) and parasympathetic (PNS) systems and are potential biomarkers for pathological states. Methods: To better understand sex differences in anxiety-related autonomic mechanisms, we examined HR/HRV telemetry in food-restricted adult rats during novelty suppression of feeding (NSF), with conflict between food under bright light in the arena center. To assess HRV, we calculated the SDNN (reflective of both SNS and PNS contribution) and rMSSD (reflective of PNS contribution) and compared these metrics to behaviors within the anxiety task. Results: Females had greater HR and lower SNS indicators at baseline, as in humans. Further, females (but not males) with higher basal HR carried this state into NSF, delaying first approach to center. In contrast, males with lower SNS measures approached and spent more time in the brightly-lit center. Further, females with lower SNS indicators consumed significantly more food. In males, a high-SNS subpopulation consumed no food. Among consumers, males with greater SNS ate more food. Discussion: Together, these are congruent with human findings suggesting women engage PNS more, and men SNS more. Our previous behavior-only work also observed female differences from males during initial movement and food intake. Thus, high basal SNS in females reduced behavior early in NSF, while subsequent reduced SNS allowed greater food intake. In males, lower SNS increased engagement with arena center, but greater SNS predicted higher consumption. Our findings show novel and likely clinically relevant sex differences in HRV-behavior relationships.

A Corticotropin Releasing Factor Network in the Extended Amygdala for Anxiety.

The central amygdala (CeA) is important for fear responses to discrete cues. Recent findings indicate that the CeA also contributes to states of sustained apprehension that characterize anxiety, although little is known about the neural circuitry involved. The stress neuropeptide corticotropin releasing factor (CRF) is anxiogenic and is produced by subpopulations of neurons in the lateral CeA and the dorsolateral bed nucleus of the stria terminalis (dlBST). Here we investigated the function of these CRF neurons in stress-induced anxiety using chemogenetics in male rats that express Cre recombinase from a Crh promoter. Anxiety-like behavior was mediated by CRF projections from the CeA to the dlBST and depended on activation of CRF1 receptors and CRF neurons within the dlBST. Our findings identify a CRFCeA→CRFdlBST circuit for generating anxiety-like behavior and provide mechanistic support for recent human and primate data suggesting that the CeA and BST act together to generate states of anxiety.SIGNIFICANCE STATEMENT Anxiety is a negative emotional state critical to survival, but persistent, exaggerated apprehension causes substantial morbidity. Identifying brain regions and neurotransmitter systems that drive anxiety can help in developing effective treatment. Much evidence in rodents indicates that neurons in the bed nucleus of the stria terminalis (BST) generate anxiety-like behaviors, but more recent findings also implicate neurons of the CeA. The neuronal subpopulations and circuitry that generate anxiety are currently subjects of intense investigation. Here we show that CeA neurons that release the stress neuropeptide corticotropin-releasing factor (CRF) drive anxiety-like behaviors in rats via a pathway to dorsal BST that activates local BST CRF neurons. Thus, our findings identify a CeA→BST CRF neuropeptide circuit that generates anxiety-like behavior.

In vivo cell type-specific CRISPR knockdown of dopamine beta hydroxylase reduces locus coeruleus evoked wakefulness.

Locus coeruleus (LC) neurons in the brainstem have long been associated with attention and arousal. Optogenetic stimulation of LC-NE neurons induces immediate sleep-to-wake transitions. However, LC neurons also secrete other neurotransmitters in addition to NE. To interrogate the role of NE derived from the LC in regulating wakefulness, we applied in vivo cell type-specific CRISPR/Cas9 technology to disrupt the dopamine beta hydroxylase (dbh) gene selectively in adult LC-NE neurons. Unilateral dbh gene disruption abolished immediate arousal following optogenetic stimulation of LC. Bilateral LC-specific dbh disruption significantly reduced NE concentration in LC projection areas and reduced wake length even in the presence of salient stimuli. These results suggest that NE may be crucial for the awakening effect of LC stimulation and serve as proof-of-principle that CRISPR gene editing in adult neurons can be used to interrogate gene function within genetically-defined neuronal circuitry associated with complex behaviors.

Do Alcohol-Related AMPA-Type Glutamate Receptor Adaptations Promote Intake?

Ionotropic glutamate receptors (AMPA, NMDA, and kainate receptors) play a central role in excitatory glutamatergic signaling throughout the brain. As a result, functional changes, especially long-lasting forms of plasticity, have the potential to profoundly alter neuronal function and the expression of adaptive and pathological behaviors. Thus, alcohol-related adaptations in ionotropic glutamate receptors are of great interest, since they could promote excessive alcohol consumption, even after long-term abstinence. Alcohol- and drug-related adaptations in NMDARs have been recently reviewed, while less is known about kainate receptor adaptations. Thus, we focus here on functional changes in AMPARs, tetramers composed of GluA1-4 subunits. Long-lasting increases or decreases in AMPAR function, the so-called long-term potentiation or depression, have widely been considered to contribute to normal and pathological memory states. In addition, a great deal has been learned about the acute regulation of AMPARs by signaling pathways, scaffolding and auxiliary proteins, intracellular trafficking, and other mechanisms. One important common adaptation is a shift in AMPAR subunit composition from GluA2-containing, calcium-impermeable AMPARs (CIARs) to GluA2-lacking, calcium-permeable AMPARs (CPARs), which is observed under a broad range of conditions including intoxicant exposure or intake, stress, novelty, food deprivation, and ischemia. This shift has the potential to facilitate AMPAR currents, since CPARs have much greater single-channel currents than CIARs, as well as faster AMPAR activation kinetics (although with faster inactivation) and calcium-related activity. Many tools have been developed to interrogate particular aspects of AMPAR signaling, including compounds that selectively inhibit CPARs, raising exciting translational possibilities. In addition, recent studies have used transgenic animals and/or optogenetics to identify AMPAR adaptations in particular cell types and glutamatergic projections, which will provide critical information about the specific circuits that CPARs act within. Also, less is known about the specific nature of alcohol-related AMPAR adaptations, and thus we use other examples that illustrate more fully how particular AMPAR changes might influence intoxicant-related behavior. Thus, by identifying alcohol-related AMPAR adaptations, the specific molecular events that underlie them, and the cells and projections in which they occur, we hope to better inform the development of new therapeutic interventions for addiction.

Do specific NMDA receptor subunits act as gateways for addictive behaviors?

Addiction to alcohol and drugs is a major social and economic problem, and there is considerable interest in understanding the molecular mechanisms that promote addictive drives. A number of proteins have been identified that contribute to expression of addictive behaviors. NMDA receptors (NMDARs), a subclass of ionotropic glutamate receptors, have been of particular interest because their physiological properties make them an attractive candidate for gating induction of synaptic plasticity, a molecular change thought to mediate learning and memory. NMDARs are generally inactive at the hyperpolarized resting potentials of many neurons. However, given sufficient depolarization, NMDARs are activated and exhibit long-lasting currents with significant calcium permeability. Also, in addition to stimulating neurons by direct depolarization, NMDARs and their calcium signaling can allow strong and/or synchronized inputs to produce long-term changes in other molecules (such as AMPA-type glutamate receptors) which can last from days to years, binding internal and external stimuli in a long-term memory trace. Such memories could allow salient drug-related stimuli to exert strong control over future behaviors and thus promote addictive drives. Finally, NMDARs may themselves undergo plasticity, which can alter subsequent neuronal stimulation and/or the ability to induce plasticity. This review will address recent and past findings suggesting that NMDAR activity promotes drug- and alcohol-related behaviors, with a particular focus on GluN2B subunits as possible central regulators of many addictive behaviors, as well as newer studies examining the importance of non-canonical NMDAR subunits and endogenous NMDAR cofactors.

A single alcohol drinking session is sufficient to enable subsequent aversion-resistant consumption in mice.

Addiction is mediated in large part by pathological motivation for rewarding, addictive substances, and alcohol-use disorders (AUDs) continue to extract a very high physical and economic toll on society. Compulsive alcohol drinking, where intake continues despite negative consequences, is considered a particular obstacle during treatment of AUDs. Aversion-resistant drives for alcohol have been modeled in rodents, where animals continue to consume even when alcohol is adulterated with the bitter tastant quinine, or is paired with another aversive consequence. Here, we describe a two-bottle choice paradigm where C57BL/6 mice first had 24-h access to 15% alcohol or water. Afterward, they drank quinine-free alcohol (alcohol-only) or alcohol with quinine (100 µM), in a limited daily access (LDA) two-bottle-choice paradigm (2 h/day, 5 days/week, starting 3 h into the dark cycle), and achieved nearly binge-level blood alcohol concentrations. Interestingly, a single, initial 24-h experience with alcohol-only enhanced subsequent quinine-resistant drinking. In contrast, mice that drank alcohol-quinine in the 24-h session showed significantly reduced alcohol-quinine intake and preference during the subsequent LDA sessions, relative to mice that drank alcohol-only in the initial 24-h session and alcohol-quinine in LDA sessions. Thus, mice could find the concentration of quinine we used aversive, but were able to disregard the quinine after a single alcohol-only drinking session. Finally, mice had low intake and preference for quinine in water, both before and after weeks of alcohol-drinking sessions, suggesting that quinine resistance was not a consequence of increased quinine preference after weeks of drinking of alcohol-quinine. Together, we demonstrate that a single alcohol-only session was sufficient to enable subsequent aversion-resistant consumption in C57BL/6 mice, which did not reflect changes in quinine taste palatability. Given the rapid development of quinine-resistant alcohol drinking patterns, this model provides a simple, quick, and robust method for uncovering the mechanisms that promote aversion-resistant consumption.

Nicotine regulates activity of lateral habenula neurons via presynaptic and postsynaptic mechanisms.

There is much interest in brain regions that drive nicotine intake in smokers. Interestingly, both the rewarding and aversive effects of nicotine are probably critical for sustaining nicotine addiction. The medial and lateral habenular (LHb) nuclei play important roles in processing aversion, and recent work has focused on the critical involvement of the LHb in encoding and responding to aversive stimuli. Several neurotransmitter systems are implicated in nicotine's actions, but very little is known about how nicotinic acetylcholine receptors (nAChRs) regulate LHb activity. Here we report in brain slices that activation of nAChRs depolarizes LHb cells and robustly increases firing, and also potentiates glutamate release in LHb. These effects were blocked by selective antagonists of α6-containing (α6*) nAChRs, and were absent in α6*-nAChR knockout mice. In addition, nicotine activates GABAergic inputs to LHb via α4ß2-nAChRs, at lower concentrations but with more rapid desensitization relative to α6*-nAChRs. These results demonstrate the existence of diverse functional nAChR subtypes at presynaptic and postsynaptic sites in LHb, through which nicotine could facilitate or inhibit LHb neuronal activity and thus contribute to nicotine aversion or reward.

Orexin-1 receptor blockade suppresses compulsive-like alcohol drinking in mice.

Addiction is promoted by pathological motivation for addictive substances, and, despite extensive efforts, alcohol use disorders (AUDs) continue to extract a very high social, physical, and economic toll. Compulsive drinking of alcohol, where consumption persists even when alcohol is paired with negative consequences, is considered a particular obstacle for treating AUDs. Aversion-resistant alcohol intake in rodents, e.g. where rodents drink even when alcohol is paired with the bitter tastant quinine, has been considered to model some compulsive aspects of human alcohol consumption. However, the critical mechanisms that drive compulsive-like drinking are only beginning to be identified. The neuropeptide orexin has been linked to high motivation for cocaine, preferred foods, and alcohol. Thus, we investigated the role of orexin receptors in compulsive-like alcohol drinking, where C57BL/6 mice had 2-hr daily access to 15% alcohol with or without quinine (100 µM). We found that systemic administration of the widely used selective orexin-1 receptor (OX1R) blocker, SB-334867 (SB), significantly reduced compulsive-like consumption at doses lower than those reported to reduce quinine-free alcohol intake. The dose of 3-mg/kg SB, in particular, suppressed only compulsive-like drinking. Furthermore, SB did not reduce concurrent water intake during the alcohol drinking sessions, and did not alter saccharin + quinine consumption. In addition, the OX2R antagonist TCS-OX2-29 (3 or 10 mg/kg) did not alter intake of alcohol with or without quinine. Together, our results suggest that OX1R signaling is particularly important for promoting compulsive-like alcohol drinking, and that OX1Rs might represent a novel therapy to counteract compulsive aspects of human AUDs.

[Histopathological diagnostic work-up of joint endoprosthesis-associated pathologies]. / Histopathologische Diagnostik von Gelenkendoprothesen-assoziierten Erkrankungen.

Increasing classes of joint implants and the combination of materials results in increased and wear-associated pathologies. According to the revised consensus classification, the following types can be recognized at conventional histological examination: Type I, particle-induced type; Type II, infection type; Type III, combination type; Type IV, indifferent type; Type V arthrofibrotic type; Type VI, allergic/immunological/toxic adverse reactions and Type VII, bone pathologies. Wear particles are histopathologically characterized according to the Krenn particle algorithm which focuses on a descriptive identification of wear particles and the differentiation of other nonwear-related particles. Type VII is considered histologically when there is evidence of a perivascular/interstitial lymphocytic CD20- and CD3-positive infiltrate, presence of mast cells and eosinophils, and tissue necrosis/infarction associated with implant wear material. Since wear particle-induced toxicity cannot be differentiated with certainty from hypersensitivity/allergic reaction on histological examination, immunological-allergological and clinical data should be used as supplementary criteria for the differential diagnosis. Tissue sampling should be performed from periprosthetic soft tissue with location mapping and when feasible also from bone tissue. Additional information regarding the type of implant and clinical, radiological, immunological, and microbiology data should be available to the pathologist. Further immunohistochemical studies are recommended in the following settings: infection (CD15, CD20, CD68); prosthesis-associated arthrofibrosis (ß­catenin); allergic/immunologic/toxic adverse reactions (CD20, CD3, CD4, CD8, CD117 and for T­cell characterization T­bet, GATA-3, and FOXP3).

[Supramacroparticulate polyethylene in inflammation of synovial-like interface membranes: Characterization and suggested nomenclature]. / Supramakropartikuläres Polyethylen bei Entzündungen periprothetischer Membranen: Charakterisierung und Nomenklaturvorschlag.

BACKGROUND: The identification of particles of prosthesis material components in the histopathological diagnosis of synovialitis is of great importance in the evaluation of implant failure. MATERIALS AND METHODS: In histopathological particle algorithms, polyethylene (PE) particles with a maximum length of less than 100 µm are designated with the term macroparticles; however, a systematic investigation and characterization are lacking. RESULTS: In SLIM knee specimens (n = 24) a minimum value of 210 µm and a maximum value of 2100 µm were measured; the mathematical mean length varied between 235 µm and 1416 µm. In SLIM hip specimens (n = 11) the minimum value was 290 µm and the maximum value was 1806 µm; the mean length varied between 353 and 1726 µm. Because of this conspicuous size, and to distinguish from PE macroparticles, the designation PE supra-macroparticulate is suggested. This new terminology acknowledges the fact that these PE particles are visible under magnification (e.g., × 12.5) and also macroscopically. The particles were also indirectly proven as there were completely separate and optically clear, column-shaped cavities corresponding to the shape of the PE particles (PE vacuoles). The life of the prosthesis is highly variable at between 12 and 300 months. In all cases loosening of the prosthesis, misalignment of the PE components, and/or damage to the PE inlay occurred. CONCLUSION: The cause and existence of these supra-macroparticulate PE particles (more than 100 µm) is still unclear. A mechanical malfunction seems probable and should be discussed. In prostheses with short lives the proof of supra-macroparticulate PE in SLIM could be a sign of an early mechanical problem. In the wider histopathological particle algorithm supra-macroparticulate PE was considered to fall in the category of macroparticles and should be considered in the histopathological diagnosis of implant failure.

D-Serine and D-Cycloserine Reduce Compulsive Alcohol Intake in Rats.

There is considerable interest in NMDAR modulators to enhance memory and treat neuropsychiatric disorders such as addiction, depression, and schizophrenia. D-serine and D-cycloserine, the NMDAR activators at the glycine site, are of particular interest because they have been used in humans without serious adverse effects. Interestingly, D-serine also inhibits some NMDARs active at hyperpolarized potentials (HA-NMDARs), and we previously found that HA-NMDARs within the nucleus accumbens core (NAcore) are critical for promoting compulsion-like alcohol drinking, where rats consume alcohol despite pairing with an aversive stimulus such as quinine, a paradigm considered to model compulsive aspects of human alcohol use disorders (AUDs). Here, we examined the impact of D-serine and D-cycloserine on this aversion-resistant alcohol intake (that persists despite adulteration with quinine) and consumption of quinine-free alcohol. Systemic D-serine reduced aversion-resistant alcohol drinking, without altering consumption of quinine-free alcohol or saccharin with or without quinine. Importantly, D-serine within the NAcore but not the dorsolateral striatum also selectively reduced aversion-resistant alcohol drinking. In addition, D-serine inhibited EPSCs evoked at -70 mV in vitro by optogenetic stimulation of mPFC-NAcore terminals in alcohol-drinking rats, similar to reported effects of the NMDAR blocker AP5. Further, D-serine preexposure occluded AP5 inhibition of mPFC-evoked EPSCs, suggesting that D-serine reduced EPSCs by inhibiting HA-NMDARs. Systemic D-cycloserine also selectively reduced intake of quinine-adulterated alcohol, and D-cycloserine inhibited NAcore HA-NMDARs in vitro. Our results indicate that HA-NMDAR modulators can reduce aversion-resistant alcohol drinking, and support testing of D-serine and D-cycloserine as immediately accessible, FDA-approved drugs to treat AUDs.

A Transgenic Rat for Investigating the Anatomy and Function of Corticotrophin Releasing Factor Circuits.

Corticotrophin-releasing factor (CRF) is a 41 amino acid neuropeptide that coordinates adaptive responses to stress. CRF projections from neurons in the central nucleus of the amygdala (CeA) to the brainstem are of particular interest for their role in motivated behavior. To directly examine the anatomy and function of CRF neurons, we generated a BAC transgenic Crh-Cre rat in which bacterial Cre recombinase is expressed from the Crh promoter. Using Cre-dependent reporters, we found that Cre expressing neurons in these rats are immunoreactive for CRF and are clustered in the lateral CeA (CeL) and the oval nucleus of the BNST. We detected major projections from CeA CRF neurons to parabrachial nuclei and the locus coeruleus, dorsal and ventral BNST, and more minor projections to lateral portions of the substantia nigra, ventral tegmental area, and lateral hypothalamus. Optogenetic stimulation of CeA CRF neurons evoked GABA-ergic responses in 11% of non-CRF neurons in the medial CeA (CeM) and 44% of non-CRF neurons in the CeL. Chemogenetic stimulation of CeA CRF neurons induced Fos in a similar proportion of non-CRF CeM neurons but a smaller proportion of non-CRF CeL neurons. The CRF1 receptor antagonist R121919 reduced this Fos induction by two-thirds in these regions. These results indicate that CeL CRF neurons provide both local inhibitory GABA and excitatory CRF signals to other CeA neurons, and demonstrate the value of the Crh-Cre rat as a tool for studying circuit function and physiology of CRF neurons.

[Histopathological particle algorithm. Particle identification in the synovia and the SLIM]. / Histopathologischer Partikelalgorithmus. Partikelidentifikation in der Synovialis und in der SLIM.

BACKGROUND: In the histopathological diagnostics of synovitis and the synovium-like interface membrane (SLIM) the identification of crystals and crystal-like deposits and the associated inflammatory reactions play an important role. The multitude of endogenous crystals, the range of implant materials and material combinations, and the variability in the formation process of different particles explain the high morphological particle heterogeneity which complicates the diagnostic identification of diagnostic particles. STUDY DESIGN AND METHODS: A simple histopathological particle algorithm has been designed which allows methodological particle identification based on (1) conventional transmitted light microscopy with a guide to particle size, shape and color, (2) optical polarization criteria and (3) enzyme histochemical properties (oil red staining and Prussian blue reaction). These methods, the importance for particle identification and the differential diagnostics from non-prosthetic materials are summarized in the so-called histopathological particle algorithm. RESULTS: A total of 35 cases of synovitis and SLIM were analyzed and validated according to these criteria. Based on these criteria and a dichotomous differentiation the complete spectrum of particles in the SLIM and synovia can be defined histopathologically. CONCLUSION: For histopathological diagnosis a particle score for synovitis and SLIM is recommended to evaluate (1) the predominant type of prothetic wear debris with differentiation between microparticles, and macroparticles, (2) the presence of non-prosthesis material particles and (3) the quantification of particle-association necrosis and lymphocytosis. An open, continuously updated web-based particle algorithm would be helpful to address the issue of particle heterogeneity and include all new particle materials generated in a rapidly changing field.

Rodent models for compulsive alcohol intake.

Continued seeking and drinking of alcohol despite adverse legal, health, economic, and societal consequences is a central hallmark of human alcohol use disorders. This compulsive drive for alcohol, defined by resistance to adverse and deleterious consequences, represents a major challenge when attempting to treat alcoholism clinically. Thus, there has long been interest in developing pre-clinical rodent models for the compulsive drug use that characterizes drug addiction. Here, we review recent studies that have attempted to model compulsive aspects of alcohol and cocaine intake in rodents, and consider technical and conceptual issues that need to be addressed when trying to recapitulate compulsive aspects of human addiction. Aversion-resistant alcohol intake has been examined by pairing intake or seeking with the bitter tastant quinine or with footshock, and exciting recent work has used these models to identify neuroadaptations in the amygdala, cortex, and striatal regions that promote compulsive intake. Thus, rodent models do seem to reflect important aspects of compulsive drives that sustain human addiction, and will likely provide critical insights into the molecular and circuit underpinnings of aversion-resistant intake as well as novel therapeutic interventions for compulsive aspects of addiction.

Cortical activation of accumbens hyperpolarization-active NMDARs mediates aversion-resistant alcohol intake.

Compulsive drinking despite serious adverse medical, social and economic consequences is a characteristic of alcohol use disorders in humans. Although frontal cortical areas have been implicated in alcohol use disorders, little is known about the molecular mechanisms and pathways that sustain aversion-resistant intake. Here, we show that nucleus accumbens core (NAcore) NMDA-type glutamate receptors and medial prefrontal (mPFC) and insula glutamatergic inputs to the NAcore are necessary for aversion-resistant alcohol consumption in rats. Aversion-resistant intake was associated with a new type of NMDA receptor adaptation, in which hyperpolarization-active NMDA receptors were present at mPFC and insula but not amygdalar inputs in the NAcore. Accordingly, inhibition of Grin2c NMDA receptor subunits in the NAcore reduced aversion-resistant alcohol intake. None of these manipulations altered intake when alcohol was not paired with an aversive consequence. Our results identify a mechanism by which hyperpolarization-active NMDA receptors under mPFC- and insula-to-NAcore inputs sustain aversion-resistant alcohol intake.