Health-Related Quality of Life after Fractures of the Distal Forearm in Children and Adolescents-Results from a Center in Switzerland in 432 Patients.

(1) Background: We aimed to evaluate the health-related quality of life (HRQoL) in children with fractures of the distal forearm and to assess if HRQoL was associated with fracture classification; (2) Methods: We followed up on 432 patients (185 girls, 247 boys) who sustained a fracture of the distal radius or forearm from 1/2007 to 6/2007, 1/2014 to 6/2014, and 11/2016 to 10/2017. Patients filled in the Quick-DASH (primary outcome) and the Peds-QL; (3) Results: The radius was fractured in 429 and the ulna in 175 cases. The most frequent injury of the radius was a buckle fracture (51%, mean age 8.5 years), followed by a complete metaphyseal fracture (22%, 9.5 years), Salter-Harris-2 fracture (14%, 11.4 years), greenstick fracture (10%, 9.3 years), Salter-Harris-1 fracture (1%, 12.6 years), and other rare injuries. The most common treatment was closed reduction and an above-elbow cast in 138 cases (32%), followed by a cast without reduction (30%), splint (28%), and K-wire fixation and cast (9%). Definite treatment was performed initially in 95.8%, a new cast or cast wedging was performed in 1.6%, and revision surgery was performed in 2.5%. There were no open reductions and no plate fixations. After a mean follow-up of 4.2 years, patients with buckle fractures had a mean Quick-DASH of 3.3 (scale of 0-100) (complete fracture: 1.5; greenstick: 1.5; SH-1: 0.9; SH-2: 4.1; others: 0.9). The mean function score of the PedsQL ranged from 93.0 for SH-2 fractures to 97.9 for complete fractures; (4) Conclusions: In this cohort of 432 children with fractures of the distal forearm, there was equally good mean mid- and long-term HRQoL when assessed by the Quick-DASH and the PedsQL. There was a trend for children with complete metaphyseal fractures reporting better HRQoL than patients with buckle fractures or patients with Salter-Harris II fractures, however, these differences were not statistically significant nor clinically relevant.

[Triple osteotomy for patients with Legg-Calve-Perthes disease]. / Tripleosteotomie bei Morbus Perthes.

OBJECTIVE: Osteotomy of iliac-pubic and ischial bone in order to cover the lateralized femoral head with the acetabulum. With the restoration of the containment of the hip joint, the acetabulum functions as a template for the femoral head, thus, allowing it to keep its sphericity during the vulnerable stages of Legg-Calve-Perthes disease. INDICATIONS: Lateralized femoral head in severe Legg-Calve-Perthes disease and visible head at risk signs on the radiographs. Prerequisite is possible concentric reduction of the femoral head (confirmed by preoperative abduction radiograph or arthrography). CONTRAINDICATIONS: Hinged abduction. Impossible concentric reduction of the femoral head. SURGICAL TECHNIQUE: Hip arthrography to confirm the indication of the triple pelvic osteotomy is recommended. Osteotomy of the ischial bone by a modified Ludloff approach. Osteotomy of pubic and iliac bone by anterior approach (Smith Peterson/bikini incision). Turning the acetabulum over the femoral head allows improvement of the containment of the hip. Fixation of the acetabulum with fully threaded Kirschner wires or 3.5 mm cortical screws. POSTOPERATIVE MANAGEMENT: Touch-down weight bearing with crutches (wheelchair in younger children) for 4-6 weeks depending on the age of the child. After radiologic evidence of consolidation, transition to full-weight bearing within 1-2 weeks. RESULTS: Promising results in our own practice. Good functional and radiological results in a to-date unpublished study of 30 patients with Legg-Calve-Perthes disease after an average 5­year follow-up.

Polymer-Conjugated Carbon Nanotubes for Biomolecule Loading.

Nanomaterials have emerged as an invaluable tool for the delivery of biomolecules such as DNA and RNA, with various applications in genetic engineering and post-transcriptional genetic manipulation. Alongside this development, there has been an increasing use of polymer-based techniques, such as polyethylenimine (PEI), to electrostatically load polynucleotide cargoes onto nanomaterial carriers. However, there remains a need to assess nanomaterial properties, conjugation conditions, and biocompatibility of these nanomaterial-polymer constructs, particularly for use in plant systems. In this work, we develop mechanisms to optimize DNA loading on single-walled carbon nanotubes (SWNTs) with a library of polymer-SWNT constructs and assess DNA loading ability, polydispersity, and both chemical and colloidal stability. Counterintuitively, we demonstrate that polymer hydrolysis from nanomaterial surfaces can occur depending on polymer properties and attachment chemistries, and we describe mitigation strategies against construct degradation. Given the growing interest in delivery applications in plant systems, we also assess the stress response of plants to polymer-based nanomaterials and provide recommendations for future design of nanomaterial-based polynucleotide delivery strategies.

Amphiphilic Copolymers for Versatile, Facile, and In Situ Tunable Surface Biofunctionalization.

Precision surface engineering is key to advanced biomaterials. A new platform of PEGylated styrene-maleic acid copolymers for adsorptive surface biofunctionalization is reported. Balanced amphiphilicity renders the copolymers water-soluble but strongly affine for surfaces. Fine-tuning of their molecular architecture provides control over adsorptive anchorage onto specific materials-which is why they are referred to as "anchor polymers" (APs)-and over structural characteristics of the adsorbed layers. Conjugatable with an array of bioactives-including cytokine-complexing glycosaminoglycans, cell-adhesion-mediating peptides and antimicrobials-APs can be applied to customize materials for demanding biotechnologies in uniquely versatile, simple, and robust ways. Moreover, homo- and heterodisplacement of adsorbed APs provide unprecedented means of in situ alteration and renewal of the functionalized surfaces. The related options are exemplified with proof-of-concept experiments of controlled bacterial adhesion, human umbilical vein endothelial cell, and induced pluripotent cell growth on AP-functionalized surfaces.

[Approaches and fixation of femoral neck fractures in children-transgluteal approach]. / Zugangswege und Fixation kindlicher Schenkelhalsfrakturen ­ transglutealer Zugang.

OBJECTIVE: Transgluteal approach for anatomical reduction of femoral neck fractures (extra-intraarticular) in children under preservation of the blood supply of the femoral head. INDICATIONS: Femoral neck fractures AO 31-M/2.1 I­III; 31-M/3.1 I­III; 31-M/3.2 I­III. CONTRAINDICATIONS: None. SURGICAL TECHNIQUE: Preparation of a muscular flap including the proximal insertion of the vastus lateralis muscle and approximately one third of the gluteus medius muscle. Elevation of the gluteus minimus muscle from the hip capsule without completely detaching it from its insertion. Exposure of the anterolateral hip capsule and capsulotomy followed by controlled reduction of the fracture fragments without compromising the retinacular vessels. POSTOPERATIVE MANAGEMENT: Touch-down weightbearing for 4-6 weeks (age dependent). To protect the healing of the abductors, active abduction or passive adduction prohibited for 4-6 weeks. Consolidation radiographs 4-6 weeks postoperatively. RESULTS: Excellent results in 29 patients subsequently treated in the last 10 years by the transgluteal approach. No cases of avascular necrosis of the femoral head by this procedure.

Stable clinical long term results after AMIC in the aligned knee.

INTRODUCTION: The aim of this study was to report a long-term follow-up of patients treated with autologous matrix-induced chondrogenesis (AMIC) for full-thickness chondral and osteochondral defects of the femoral condyle or patella combined with the correction of lower limb malalignment or patellar tracking if indicated. METHODS: Thirty-three patients (thirty-four knees) were treated surgically for chondral and osteochondral cartilage defects of the knee joint. Regarding the origin of the lesion, patients were divided into three groups. Chondral lesions were observed in the patella (cP group) in fifteen patients, whereas eight patients demonstrated a femoral condylar location (cF group). Eleven patients presented with osteochondritis dissecans of the femur (ocF group). Associated procedures involving realignment of the patella, osteotomy around the knee, or cancellous bone grafting were performed when necessary. The mean size of the lesions was 2.8 ± 1.6 cm2, and the mean patient age was 37.1 ± 11.9 years. To evaluate the clinical outcomes, the Lysholm score and the VAS pain score were imposed, as well as the reoperation rate. RESULTS: After an average of 9.3 ± 1 years, follow-up was completed in 79% of the patients. Two patients from the cohort received a total knee prosthesis. The primary outcome measures (Lysolm and VAS pain) at 9-year follow-up were 85 ± 13 for the Lysholm score and 1.9 ± 1.6 for the VAS score in the entire analyzed population. Compared to the preoperative values (Lysholm 56 ± 19, VAS 5.8 ± 2.4) and the 2-year results (Lysholm 85 ± 16, VAS 2.0 ± 2.1), there was significant improvement in the first 2 years after intervention and a stable course in the long-term observation. The same was observed in the cP and ocF subgroups, whereas patients of the cF group showed even further improvement. CONCLUSIONS: AMIC showed durable results in aligned knees. The favorable outcome was maintained after an average of 9 years when malalignment of the lower limb and patellar maltracking were corrected. Such data are particularly encouraging for young adult patients who may benefit from a procedure that circumvents early arthroplasty.

Health-related quality of life after paediatric supracondylar humeral fractures.

AIMS: We aimed to evaluate the health-related quality of life (HRQoL) in children with supracondylar humeral fractures (SCHFs), who were treated following the recommendations of the Paediatric Comprehensive AO Classification, and to assess if HRQoL was associated with AO fracture classification, or fixation with a lateral external fixator compared with closed reduction and percutaneous pinning (CRPP). METHODS: We were able to follow-up on 775 patients (395 girls, 380 boys) who sustained a SCHF from 2004 to 2017. Patients completed questionnaires including the Quick Disabilities of the Arm, Shoulder and Hand questionnaire (QuickDASH; primary outcome), and the Pediatric Quality of Life Inventory (PedsQL). RESULTS: An AO type I SCHF was most frequent (327 children; type II: 143; type III: 150; type IV: 155 children). All children with type I fractures were treated nonoperatively. Two children with a type II fracture, 136 with a type III fracture, and 141 children with a type IV fracture underwent CRPP. In the remaining 27 children with type III or IV fractures, a lateral external fixator was necessary for closed reduction. There were no open reductions. After a mean follow-up of 6.3 years (SD 3.7), patients with a type I fracture had a mean QuickDASH of 2.0 (SD 5.2), at a scale of 0 to 100, with lower values representing better HRQoL (type II: 2.8 (SD 10.7); type III: 3.3 (SD 8.0); type IV: 1.8 (SD 4.6)). The mean function score of the PedsQL ranged from 97.4 (SD 8.0) for type I to 96.1 (SD 9.1) for type III fractures, at a scale of 0 to 100, with higher values representing better HRQoL. CONCLUSION: In this cohort of 775 patients in whom nonoperative treatment was chosen for AO type I and II fractures and CRPP or a lateral external fixator was used in AO type III and IV fractures, there was equally excellent mid- and long-term HRQoL when assessed by the QuickDASH and PedsQL. These results indicate that the treatment protocol followed in this study is unambiguous, avoids open reductions, and is associated with excellent treatment outcomes. Cite this article: Bone Joint J 2020;102-B(6):755-765.

Image-Based Morphological Profiling Identifies a Lysosomotropic, Iron-Sequestering Autophagy Inhibitor.

Chemical proteomics is widely applied in small-molecule target identification. However, in general it does not identify non-protein small-molecule targets, and thus, alternative methods for target identification are in high demand. We report the discovery of the autophagy inhibitor autoquin and the identification of its molecular mode of action using image-based morphological profiling in the cell painting assay. A compound-induced fingerprint representing changes in 579 cellular parameters revealed that autoquin accumulates in lysosomes and inhibits their fusion with autophagosomes. In addition, autoquin sequesters Fe2+ in lysosomes, resulting in an increase of lysosomal reactive oxygen species and ultimately cell death. Such a mechanism of action would have been challenging to unravel by current methods. This work demonstrates the potential of the cell painting assay to deconvolute modes of action of small molecules, warranting wider application in chemical biology.

Mechanism of centromere recruitment of the CENP-A chaperone HJURP and its implications for centromere licensing.

Nucleosomes containing the histone H3 variant CENP-A are the epigenetic mark of centromeres, the kinetochore assembly sites required for chromosome segregation. HJURP is the CENP-A chaperone, which associates with Mis18α, Mis18ß, and M18BP1 to target centromeres and deposit new CENP-A. How these proteins interact to promote CENP-A deposition remains poorly understood. Here we show that two repeats in human HJURP proposed to be functionally distinct are in fact interchangeable and bind concomitantly to the 4:2:2 Mis18α:Mis18ß:M18BP1 complex without dissociating it. HJURP binds CENP-A:H4 dimers, and therefore assembly of CENP-A:H4 tetramers must be performed by two Mis18αß:M18BP1:HJURP complexes, or by the same complex in consecutive rounds. The Mis18α N-terminal tails blockade two identical HJURP-repeat binding sites near the Mis18αß C-terminal helices. These were identified by photo-cross-linking experiments and mutated to separate Mis18 from HJURP centromere recruitment. Our results identify molecular underpinnings of eukaryotic chromosome inheritance and shed light on how centromeres license CENP-A deposition.

Health-related Quality of Life After Fractures of the Lateral Third of the Clavicle in Children and Adolescents.

INTRODUCTION: The health-related quality of life after pediatric fractures of the lateral third of the clavicle is unknown. Given the trend in the literature toward surgical management of clavicular fractures in adults, we frequently receive referrals for surgical management of lateral clavicular fractures in children.Therefore, we examined (1) the health-related quality of life of patients who sustained a fracture of the lateral third of the clavicle in childhood and who were treated at a large regional pediatric trauma center, (2) if the health-related quality of life was associated with the age at the time of the injury, and (3) whether fracture and displacement patterns were associated with health-related qualify of life. METHODS: This is a retrospective case series. We were able to identify 69 patients (21 girls and 48 boys) who sustained a fracture of the lateral third of the clavicle between the period spanning from January 2004 to June 2015. These patients were asked to fill in a questionnaire that included the Quick version of the Disability of Arm, Shoulder, and Hand (DASH) (primary outcome) and the Pediatric Quality of Life Inventory (Peds-QL). Until July 2017, we were able to get a response from 56 of these patients, resulting in a follow-up of 81%. RESULTS: Treatment was conservative in all cases but one. In these cases, after a mean follow-up of 6.5 years (range, 1 to 13.2 y), the mean Quick-DASH was 1.2 (SD, 4.4) at a scale of 0 to 100, with lower values representing better quality of life. The mean physical function score of the Peds-QL was 97.8 (SD, 4.4), and the mean psychosocial function score was 91.8 (SD, 10.8), both at a scale of 0 to 100, with higher values representing better quality of life.There was no statistically significant association of age at the time of injury on the primary outcome Quick-DASH.There were no statistically significant associations between fracture or displacement patterns with regard to health-related quality of life. CONCLUSIONS: Conservative treatment of lateral clavicular fractures in children and adolescents is associated with excellent health-related quality of life, as measured with the disease-specific Quick-DASH and the non-disease-specific Peds-QL at a mean follow-up of 6.5 years (range, 1 to 13.2 y). There was no effect of age at the time of injury, and we were unable to identify associations to commonly analyzed risk factors, such as displacement patterns.As the conservative treatment of this type of fracture in children and adolescents is associated with such a good health-related quality of life, it is unlikely that these results could be further improved by surgical interventions. LEVEL OF EVIDENCE: Level IV-case series.

Small-Molecule Inhibition of the UNC-Src Interaction Impairs Dynamic Src Localization in Cells.

Interference with the signaling activity of the N-myristoylated nonreceptor protein tyrosine kinase Src is considered a viable approach in anti-cancer drug discovery. However, ATP-competitive Src inhibitors have not reached the clinic yet and alternative approaches are in high demand. The UNC119A/B proteins bind the myristoylated N terminus of Src and thereby mediate energy-driven spatial cycles that maintain Src enrichment at the plasma membrane, which is critical for Src signaling activity. We describe the discovery of a potent and specific inhibitor of the UNC119-Src interaction with unprecedented chemotype. The inhibitor binds to UNC119 in cells, and induces redistribution of Src to endomembranes and reduction of activating Src autophosphorylation on Y419. UNC119 inhibition in Src-dependent colorectal cancer cells results in the specific reduction of cell growth and clonogenic potential. Our results demonstrate that small-molecule interference with the dynamics of the Src spatial cycle may provide an opportunity to impair oncogenic Src signaling.

Modulation of autophagy by the novel mitochondrial complex I inhibitor Authipyrin.

Autophagy ensures cellular homeostasis by the degradation of long-lived proteins, damaged organelles and pathogens. This catabolic process provides essential cellular building blocks upon nutrient deprivation. Cellular metabolism, especially mitochondrial respiration, has a significant influence on autophagic flux, and complex I function is required for maximal autophagy. In Parkinson's disease mitochondrial function is frequently impaired and autophagic flux is altered. Thus, dysfunctional organelles and protein aggregates accumulate and cause cellular damage. In order to investigate the interdependency between mitochondrial function and autophagy, novel tool compounds are required. Herein, we report the discovery of a structurally novel autophagy inhibitor (Authipyrin) using a high content screening approach. Target identification and validation led to the discovery that Authipyrin targets mitochondrial complex I directly, leading to the potent inhibition of mitochondrial respiration as well as autophagy.

Photoactivatable Myristic Acid Probes for UNC119-Cargo Interactions.

Protein myristoylation plays key roles in biological processes, for instance, in membrane attachment and activation of proteins and in mediating protein-protein and protein-lipid interactions. Furthermore, myristoylated proteins are involved in disorders, including cancer and viral infections. Therefore, new tools to study protein myristoylation are in high demand. Herein, we report the development of photoactivatable probes, based on a diazirine-substituted analogue of myristic acid. The probes bind to and, upon irradiation, covalently label the lipid-binding chaperone protein uncoordinated 119 (UNC119). UNC119 increases overall solubility and regulates specifically the transport of myristoylated proteins between intercellular membranes. The binding mode of the probes is similar to that of the myristate moiety, and the residues inside the hydrophobic pocket of UNC119 proteins that are critical for covalent binding have been identified. The interaction with UNC119 was also demonstrated in cell lysate by means of affinity enrichment. Moreover, it is shown that the myristate analogue can be incorporated into peptide substrates by N-myristoyl transferases of Leishmania and Trypanosoma protozoan parasites.

Blunt nasal trauma in children: a frequent diagnostic challenge.

OBJECTIVE: The clinical challenge in blunt nasal trauma in children, is to identify cases requiring specialized care among frequently encountered banalities, whilst trying to minimize the exposure to diagnostic procedures. We aim to evaluate the related diagnostic and therapeutic pathways and its outcome during follow-up. METHODS: This retrospective cohort study includes children up to 16 years presenting at the emergency department with blunt nasal trauma of our tertiary reference center. RESULTS: The incidence of blunt nasal injuries was estimated 1750 cases in 7 years. A total of 459 consecutive cases with suspected complications were enrolled. Univariate comparison between age groups revealed a statistically significant diminution of downfall related injuries with growing up, whereas blows (including violence) significantly increased with age (p < 0.001 each). The logistic regression model identified male sex as an independent risk factor for soft tissue lesions (OR 1.699, p = 0.017) and for frontobasal fractures (OR 2.415, p = 0.050). Age was not identified to play a significant role regarding localization of injuries. Delayed septorhinoplasties became necessary in 2 cases only (0.4%). The logistic regression model identified nasal bone fracture (OR 17.038, p < 0.001) and mandibular fracture (OR 4.753, p = 0.004) as independent risk factor for a surgical intervention. CONCLUSIONS: Blunt trauma to the nose is frequent in children. Trauma mechanisms differ significantly between age groups, whereas localization and concomitant injuries do not. Male sex was identified as an independent risk factor for soft tissue lesions and frontobasal fractures. In our experience, initial triage by the pediatric department with consecutive involvement of the ENT specialists in case of suspected complications is safe and effective and may help to reduce unnecessary diagnostic procedures/irradiation to the young patients.

Using Clicker Training and Social Observation to Teach Rats to Voluntarily Change Cages.

Cage cleaning is a routinely performed husbandry procedure and is known to induce stress in laboratory rats. As stress can have a negative impact on well-being and can affect the comparability and reproducibility of research results, the amount of stress experienced by laboratory animals should be minimized and avoided when possible. Further, the direct contact between the rat and animal caretaker during the cage change bears hygiene risks and therefore possibly negatively impacts the well-being of the rats and the quality of the research. Our protocol aims to improve the routinely performed cage changing procedure. For this reason, we present a feasible protocol that enables rats to learn via clicker training and observation to voluntarily change to a clean cage. This training helps to reduce stress caused by the physical disturbance and handling associated with the cage changes and concurrently enables a reduction in direct contact between animal and animal caretaker after the training phase is completed. The implementation of clicker training to rats is fast and easy. Rats are generally interested in the training and efficiently learn the desired behavior, which entails changing cages through a pipe. Even without training, the rats learn to perform the desired behavior by observation, as 80% of the observational learning group successfully changed cages when tested. The training further helps to establish a relationship of trust between trainer and animal. As hygiene and well-being are both very important in animal experiments, this protocol might also help to improve high-quality research.

Small-Molecule Inhibition of the UNC119-Cargo Interaction.

N-Terminal myristoylation facilitates membrane binding and activity of proteins, in particular of Src family kinases, but the underlying mechanisms are only beginning to be understood. The chaperones UNC119A/B regulate the cellular distribution and signaling of N-myristoylated proteins. Selective small-molecule modulators of the UNC119-cargo interaction would be invaluable tools, but have not been reported yet. We herein report the development of the first UNC119-cargo interaction inhibitor, squarunkin A. Squarunkin A selectively inhibits the binding of a myristoylated peptide representing the N-terminus of Src kinase to UNC119A with an IC50 value of 10 nm. It binds to UNC119 proteins in cell lysate and interferes with the activation of Src kinase. Our results demonstrate that small-molecule inhibition of the UNC119-cargo interaction might provide new opportunities for modulating the activity of Src kinases that are independent of direct inhibition of the enzymatic kinase activity.

Cannabinoid receptor-interacting protein Crip1a modulates CB1 receptor signaling in mouse hippocampus.

The cannabinoid type 1 receptor (Cnr1, CB1R) mediates a plethora of physiological functions in the central nervous system as a presynaptic modulator of neurotransmitter release. The recently identified cannabinoid receptor-interacting protein 1a (Cnrip1a, CRIP1a) binds to the C-terminal domain of CB1R, a region known to be important for receptor desensitization and internalization. Evidence that CRIP1a and CB1R interact in vivo has been reported, but the neuroanatomical distribution of CRIP1a is unknown. Moreover, while alterations of hippocampal CRIP1a levels following limbic seizures indicate a role in controlling excessive neuronal activity, the physiological function of CRIP1a in vivo has not been investigated. In this study, we analyzed the spatial distribution of CRIP1a in the hippocampus and examined CRIP1a as a potential modulator of CB1R signaling. We found that Cnrip1a mRNA is co-expressed with Cnr1 mRNA in pyramidal neurons and interneurons of the hippocampal formation. CRIP1a protein profiles were largely segregated from CB1R profiles in mossy cell terminals but not in hippocampal CA1 region. CB1R activation induced relocalization to close proximity with CRIP1a. Adeno-associated virus-mediated overexpression of CRIP1a specifically in the hippocampus revealed that CRIP1a modulates CB1R activity by enhancing cannabinoid-induced G protein activation. CRIP1a overexpression extended the depression of excitatory currents by cannabinoids in pyramidal neurons of the hippocampus and diminished the severity of chemically induced acute epileptiform seizures. Collectively, our data indicate that CRIP1a enhances hippocampal CB1R signaling in vivo.

Cannabinoid CB1 receptor in dorsal telencephalic glutamatergic neurons: distinctive sufficiency for hippocampus-dependent and amygdala-dependent synaptic and behavioral functions.

A major goal in current neuroscience is to understand the causal links connecting protein functions, neural activity, and behavior. The cannabinoid CB1 receptor is expressed in different neuronal subpopulations, and is engaged in fine-tuning excitatory and inhibitory neurotransmission. Studies using conditional knock-out mice revealed necessary roles of CB1 receptor expressed in dorsal telencephalic glutamatergic neurons in synaptic plasticity and behavior, but whether this expression is also sufficient for brain functions is still to be determined. We applied a genetic strategy to reconstitute full wild-type CB1 receptor functions exclusively in dorsal telencephalic glutamatergic neurons and investigated endocannabinoid-dependent synaptic processes and behavior. Using this approach, we partly restored the phenotype of global CB1 receptor deletion in anxiety-like behaviors and fully restored hippocampus-dependent neuroprotection from chemically induced epileptiform seizures. These features coincided with a rescued hippocampal depolarization-induced suppression of excitation (DSE), a CB1 receptor-dependent form of synaptic plasticity at glutamatergic neurons. By comparison, the rescue of the CB1 receptor on dorsal telencephalic glutamatergic neurons prolonged the time course of DSE in the amygdala, and impaired fear extinction in auditory fear conditioning. These data reveal that CB1 receptor in dorsal telencephalic glutamatergic neurons plays a sufficient role to control neuronal functions that are in large part hippocampus-dependent, while it is insufficient for proper amygdala functions, suggesting an unexpectedly complex circuit regulation by endocannabinoid signaling in the amygdala. Our data pave the way to a better understanding of neuronal networks in the context of behavior, by fine-tuned interference with synaptic transmission processes.

Circuit specific functions of cannabinoid CB1 receptor in the balance of investigatory drive and exploration.

Well balanced novelty seeking and exploration are fundamental behaviours for survival and are found to be dysfunctional in several psychiatric disorders. Recent studies suggest that the endocannabinoid (eCB) system is an important control system for investigatory drive. Pharmacological treatment of rodents with cannabinergic drugs results in altered social and object investigation. Interestingly, contradictory results have been obtained, depending on the treatment, drug concentration and experimental conditions. The cannabinoid type 1 (CB1) receptor, a central component of the eCB system, is predominantly found at the synapses of two opposing neuronal populations, i.e. on inhibitory GABAergic and excitatory glutamatergic neurons. In the present study, using different transgenic mouse lines, we aimed at investigating the impact of CB1 receptor inactivation in glutamatergic or GABAergic neurons on investigatory behaviour. We evaluated animate (interaction partner) and inanimate (object) exploratory behaviour in three different paradigms. We show that exploration was increased when CB1 receptor was deleted from cortical and striatal GABAergic neurons. No effect was observed when CB1 receptor was deleted specifically from dopamine receptor D1-expressing striatal GABAergic medium spiny neurons. In contrast, deletion of CB1 receptor from cortical glutamatergic neurons resulted in a decreased exploration. Thus, our results indicate that exploratory behaviour is accurately balanced in both, the social and non-social context, by the eCB system via CB1 receptor activation on cortical glutamatergic and GABAergic neurons. In addition, the results could explain the contradictory findings of previous pharmacological studies and could further suggest a possibility to readjust an imbalance in exploratory behaviour observed in psychiatric disorders.

Reduced anxiety-like behaviour induced by genetic and pharmacological inhibition of the endocannabinoid-degrading enzyme fatty acid amide hydrolase (FAAH) is mediated by CB1 receptors.

Anandamide and 2-arachidonoyl glycerol, referred to as endocannabinoids (eCBs), are the endogenous agonists for the cannabinoid receptor type 1 (CB1). Several pieces of evidence support a role for eCBs in the attenuation of anxiety-related behaviours, although the precise mechanism has remained uncertain. The fatty acid amid hydrolase (FAAH), an enzyme responsible for the degradation of eCBs, has emerged as a promising target for anxiety-related disorders, since FAAH inhibitors are able to increase the levels of anandamide and thereby induce anxiolytic-like effects in rodents. The present study adopted both genetic and pharmacological approaches and tested the hypothesis that FAAH-deficient (FAAH(-/-)) mice as well as C57BL/6N mice treated with an FAAH inhibitor (URB597) would express reduced anxiety-like responses. Furthermore, as it is known that anandamide can bind several other targets than CB1 receptors, we investigated whether FAAH inhibition reduces anxiety via CB1 receptors. FAAH(-/-) mice showed reduced anxiety both in the elevated plus maze and in the light-dark test. These genotype-related differences were prevented by the CB1 receptor antagonist rimonabant (3mg/kg). Moreover, URB597 (1mg/kg) induced an anxiolytic-like effect in C57BL/6N mice exposed to the elevated plus maze, which was prevented by rimonabant (3mg/kg). The present work provides genetic and pharmacological evidence supporting the inhibition of FAAH as an important mechanism for the alleviation of anxiety. In addition, it indicates an increased activation of CB1 receptors as a mechanism underlying the effects of FAAH inhibition in two models of anxiety.