Psilocybin reduces alcohol self-administration via selective left nucleus accumbens activation in rats.

The use of psilocybin to treat alcohol use disorder is very promising, but the mechanisms of action remain poorly understood. We combined behavioral, pharmacological and gene expression analyses to decipher the mechanisms of action of psilocybin, for the first time injected into the brain. Male Long Evans rats underwent chronic operant ethanol self-administration before testing the effect of intraperitoneal psilocybin or directly within the nucleus accumbens core or the ventral tegmental area. Transcripts from the dopaminergic system were quantified in the nucleus accumbens and prefrontal cortex. Psilocybin significantly reduced (50%) ethanol self-administration when injected 4 hours before the session either intraperitoneally (1mg/kg) or directly within the left nucleus accumbens (0.15µg) but not the right nucleus accumbens or the left ventral tegmental area. The effect of intraperitoneal injection of psilocybin was prevented by intra left nucleus accumbens injection of 0.3µg of the 5-HT2AR antagonist ketanserin. In rats that self-administered ethanol but not in those self-administering saccharin, dopamine D2 receptor mRNA were increased in both the nucleus accumbens and the prefrontal cortex by psilocybin, while D1R mRNA was increased only in the prefrontal cortex. As in humans, psilocybin reduced ethanol self-administration in rats through the 5-HT2AR within the left nucleus accumbens possibly through increased D2R expression. Our results open unexpected perspectives regarding the hemispheric lateralization of psychedelic effects.

A revisited version of the disputatio for pharmacological training: An educational study.

OBJECTIVE: The disputatio is a pedagogical method existing since the Middle-Ages where students had to debate about a question asked by a "master", exercising their thinking and oratory skills. To move away from traditional vertical teaching methods, the disputatio has been revived by pharmacologists. Thus, for almost three successive years, several groups of young French pharmacologists and therapists confronted their ideas concerning a medical question at a therapeutic impasse. The aim here is to describe the initial feedback received from participants. METHODS: An anonymous questionnaire was sent by email in May 2023 to the participants of the different disputationes of 2019, 2022 and 2023. Participants were asked about different aspects of their feelings before, during and after the disputatio, using the 5-point Likert scale. They were also asked to describe the event in 2 to 5 words. Finally, participants could leave their comments in a free-field and were asked to give an overall satisfaction score out of 10. RESULTS: Out of the 39 participants, 27 (69.2%) answered the questionnaire. Although 50% of respondents reported a feeling of anxiety before participating, most enjoyed the expert talks as well as working with people they did not know. Besides, over 66% reported having underestimated the skills they could share with colleagues from different backgrounds. Over 55% of respondents reported progress in methodology, and over 83% in pharmacology and/or therapeutics. Participants reported an overall satisfaction score of 8.6/10, and the main terms used to describe the event were "sharing", "enriching" and "meeting". CONCLUSION: The disputatio is an innovative training program whose pedagogical and human values were underlined by most of the participants. Beyond pharmacology and therapeutics, the principle of disputatio could be extended to other disciplines, spanning the centuries.

Spiky: An ImageJ Plugin for Data Analysis of Functional Cardiac and Cardiomyocyte Studies.

INTRODUCTION AND OBJECTIVE: Nowadays, investigations of heart physiology and pathophysiology rely more and more upon image analysis, whether for the detection and characterization of events in single cells or for the mapping of events and their characteristics across an entire tissue. These investigations require extensive skills in image analysis and/or expensive software, and their reproducibility may be a concern. Our objective was to build a robust, reliable and open-source software tool to quantify excitation-contraction related experimental data at multiple scales, from single isolated cells to the whole heart. METHODS AND RESULTS: A free and open-source ImageJ plugin, Spiky, was developed to detect and analyze peaks in experimental data streams. It allows rapid and easy analysis of action potentials, intracellular calcium transient and contraction data from cardiac research experiments. As shown in the provided examples, both classical bi-dimensional data (XT signals) and video data obtained from confocal microscopy and optical mapping experiments (XYT signals) can be analyzed. Spiky was written in ImageJ Macro Language and JAVA, and works under Windows, Mac and Linux operating systems. CONCLUSION: Spiky provides a complete working interface to process and analyze cardiac physiology research data.

Gabapentinoid-induced peripheral edema and acute heart failure: A translational study combining pharmacovigilance data and in vitro animal experiments.

INTRODUCTION: Gabapentinoids are ligands of the α2-δ subunit of voltage-gated calcium channels (Cav) that have been associated with a risk of peripheral edema and acute heart failure in connection with a potentially dual mechanism, vascular and cardiac. OBJECTIVES & METHODS: All cases of peripheral edema or heart failure involving gabapentin or pregabalin reported to the French Pharmacovigilance Centers between January 1, 1994 and April 30, 2020 were included to describe their onset patterns (e.g., time to onset). Based on these data, we investigated the impact of gabapentinoids on the myogenic tone of rat third-order mesenteric arteries and on the electrophysiological properties of rat ventricular cardiomyocytes. RESULTS: A total of 58 reports were included (gabapentin n = 5, pregabalin n = 53). The female-to-male ratio was 4:1 and the median age was 77 years (IQR 57-85, range 32-95). The median time to onset were 23 days (IQR 10-54) and 17 days (IQR 3-30) for non-cardiogenic edema and acute heart failure, respectively. Cardiogenic and non-cardiogenic peripheral edema occurred frequently after a dose escalation (27/45, 60%), and the course was rapidly favorable after discontinuation of gabapentinoid (median 7 days, IQR 5-13). On rat mesenteric arteries, gabapentinoids significantly decreased the myogenic tone to the same extent as verapamil and nifedipine. Acute application of gabapentinoids had no significant effect on Cav1.2 currents of ventricular cardiomyocytes. CONCLUSION: Gabapentinoids can cause concentration-dependent peripheral edema of early onset. The primary mechanism of non-cardiogenic peripheral edema is vasodilatory edema secondary to altered myogenic tone, independent of Cav1.2 blockade under the experimental conditions tested.

Adjuvant-induced arthritis is a relevant model to mimic coronary and myocardial impairments in rheumatoid arthritis.

OBJECTIVES: To determine if the adjuvant-induced arthritis model reproduced coronary and cardiac impairments observed in rheumatoid arthritis patients. The link between disease activity and circulating levels of angiotensin II and endothelin-1 have been studied, as well as the myocardial susceptibility to ischemia. METHODS: At the acute inflammatory phase, coronary reactivity was assessed in isolated arteries, and cardiac function was studied in isolated perfused hearts, before and after global ischemia/reperfusion. Ischemic insult was evaluated by the infarct size, lactate dehydrogenase and creatine phosphokinase levels in coronary effluents. Cardiac myeloperoxidase activity was measured, as well as angiotensin II and endothelin-1 levels. RESULTS: Compared to controls, adjuvant-induced arthritis had reduced coronary Acetylcholine-induced relaxation associated with cardiac hypertrophy, both being correlated with plasma levels of endothelin-1 and angiotensin II, and arthritis score. Although cardiac function at baseline was similar from controls, adjuvant-induced arthritis rats exhibited lower cardiac functional recovery, increased myeloperoxidase activity, higher infarct size and creatine phosphokinase levels after ischemia/reperfusion. CONCLUSIONS: The adjuvant-induced arthritis model displays coronary endothelial dysfunction associated with myocardial hypertrophy and a reduced tolerance to ischemia. This model might be useful for deciphering the pathophysiology of cardiac dysfunction in rheumatoid arthritis and paves the way for studying the role of endothelin-1 and angiotensin II.

Automatic Activity Arising in Cardiac Muscle Sleeves of the Pulmonary Vein.

Ectopic activity in the pulmonary vein cardiac muscle sleeves can both induce and maintain human atrial fibrillation. A central issue in any study of the pulmonary veins is their difference from the left atrial cardiac muscle. Here, we attempt to summarize the physiological phenomena underlying the occurrence of ectopic electrical activity in animal pulmonary veins. We emphasize that the activation of multiple signaling pathways influencing not only myocyte electrophysiology but also the means of excitation-contraction coupling may be required for the initiation of triggered or automatic activity. We also gather information regarding not only the large-scale structure of cardiac muscle sleeves but also recent studies suggesting that cellular heterogeneity may contribute to the generation of arrythmogenic phenomena and to the distinction between pulmonary vein and left atrial heart muscle.

Vascular Arginase Is a Relevant Target to Improve Cerebrovascular Endothelial Dysfunction in Rheumatoid Arthritis: Evidence from the Model of Adjuvant-Induced Arthritis.

Emerging data revealed that rheumatoid arthritis (RA) is associated with higher risk of cerebrovascular diseases. Whereas cerebral endothelial dysfunction is acknowledged as a critical aspect of cerebrovascular diseases, its presence in RA and the mechanisms involved are currently unknown. By using the model of rat adjuvant-induced arthritis (AIA), the present study investigated cerebrovascular reactivity in pressurized middle cerebral arteries (MCA) on day 33 post-immunization. The results revealed that arthritis induced a dramatic decrease in the vasodilatory response to acetylcholine (ACh), ADP, and bradykinin (n = 7-9 arteries, p < 0.0001). By using nor-NOHA, L-NAME, BH4, and Tempol, the results showed that the reduced response to ACh relied on arginase overactivation (n = 8), low NOS activity (n = 8), BH4 deficiency (n = 9), and excessive superoxide production (n = 9). Immunohistological analysis revealed an endothelial upregulation of arginase 2 (p < 0.05, n = 5-6) and NADPH oxidase (p < 0.05, n = 5-7) while eNOS expression was unchanged in AIA (n = 6). To assess whether arginase inhibition may be a relevant therapeutic, AIA rats were treated with an arginase inhibitor (nor-NOHA, 40 mg/kg/day, i.p., n = 20 rats) daily from day 10 to day 33 post-immunization. The treatment alleviated the impaired response of MCA to endothelium-dependent agonists, through an increase in NOS signaling and a suppression of BH4 deficiency and superoxide overproduction. By contrast, it did not change the course of arthritis. In conclusion, arthritis induced a cerebrovascular endothelial dysfunction involving an imbalance in the arginase/NOS pathway. Arginase inhibition appears as a promising therapy beyond anti-rheumatic drugs for reducing the risk of cerebrovascular diseases in RA.

Structural efficacy of NSAIDs, COX-2 inhibitor and glucocorticoid compared with TNFα blocker: a study in adjuvant-induced arthritis rats.

OBJECTIVE: To evaluate radiographic outcomes after an early treatment for 21 days with etanercept, naproxen, celecoxib, prednisone or methotrexate in adjuvant-induced arthritis in rats. METHODS: At the onset of arthritis, rats were daily treated with naproxen (10 mg/kg/day i.p.), celecoxib (3 mg/kg/day), prednisolone (10 mg/kg/day), etanercept (10 mg/kg/3 days), methotrexate (2 mg/kg/3 days) or saline solution (vehicle) for 21 days. The arthritis score was daily monitored. At the end of treatment, a hind paw radiographic examination was performed with a BMA high-resolution digital X-ray system (40 mV, 10 mA). A score of 0-20 was determined for each paw. Plasma levels of TNFα were measured. RESULTS: Compared with vehicle, all treatments reduced (P < 0.001) the arthritis score. All treatments, except methotrexate, slowed radiographic destruction (P < 0.001). All treatments, except etanercept, reduced the plasma level of TNFα. Naproxen, glucocorticoid and celecoxib were more effective than etanercept on the radiographic score (P < 0.01). Naproxen was the only treatment to be more effective on all different radiographic subscores than etanercept. CONCLUSION: Our study demonstrated for the first time that an early treatment with NSAIDs, excluding cyclooxygenase-2 selective inhibitor, is more beneficial than a TNFα blocker in preventing structural damage in adjuvant-induced arthritis.

Methotrexate did not improve endothelial function in rheumatoid arthritis: a study in rats with adjuvant-induced arthritis.

OBJECTIVES: Rheumatoid arthritis is associated with an increased cardiovascular risk, secondary to endothelial dysfunction. There is accumulating evidence that methotrexate reduces cardiovascular risk in rheumatoid arthritis, but the mechanisms involved are still unknown. In this study, we aimed to determine the effect of methotrexate on endothelial function and traditional cardiovascular risk factors in the adjuvant-induced arthritis (AIA) rat model. METHODS: On the first signs of arthritis, methotrexate (1 mg/kg/week, s.c.) or saline (Vehicle) was administered to AIA for 3 weeks. Endothelial function was studied in aortic rings relaxed with acetylcholine in the presence or not of inhibitors of nitric oxide synthase, cyclooxygenase-2, arginase, EDHF and superoxide anions production. Arthritis and radiological scores, blood pressure and blood levels of cytokines, triglycerides, cholesterol, homocysteine and BMP-4 were measured. RESULTS: Although methotrexate significantly reduced the arthritis score, it had no effect on Ach-induced relaxation. As regards mechanisms, methotrexate increased nitric oxide synthase activity and reduced the superoxide anions production but did not change arginase, cyclooxygenase-2 and EDHF pathways. Methotrexate did not change the radiological score or blood pressure, lipid, glucose and homocysteine levels. By contrast, methotrexate significantly reduced plasma IL-1ß and TNF-α levels and increased serum BMP-4 level. CONCLUSIONS: Despite a reduction of clinical and biological inflammation, methotrexate did not improve endothelial function in AIA rats. Overall data suggest that mechanisms other than the ED reduction are likely involved, and remain to be elucidated to better understand the cardiovascular benefits of methotrexate in rheumatoid arthritis.

Pristane-induced arthritis in dark Agouti rat is a relevant model for mimicking vascular dysfunction and lipid paradox in rheumatoid arthritis.

OBJECTIVES: To understand the pathophysiology of cardiovascular (CV) dysfunction in rheumatoid arthritis (RA) is crucial, but limited by the paucity of animal models able to mimic CV impairments. We wanted to determine if the rat model of Pristane-Induced Arthritis (PIA) reproduced cardiometabolic impairments of RA. METHODS: Dark Agouti rats received an injection of pristane or saline (controls) at day 0. Reactivity to vasoconstrictors and vasodilators was studied in aortic rings and mesenteric arteries at day 28 (acute) and day 120 post-induction (chronic phase). Circulating markers of inflammation, lipid and glucose levels, arthritis and radiographic scores were assessed. RESULTS: In aortic rings, PIA induced a reduced vasoconstriction to phenylephrine and serotonin in both phases of the model. The relaxant effect of acetylcholine was decreased in PIA in acute (P < 0.05) but not in chronic phase. In mesenteric arteries, only the acetylcholine-induced vasorelaxation was impaired in PIA rats in the chronic phase (P < 0.001). Serum interleukin-6 levels were higher, total cholesterol and triglycerides levels were lower in PIA in both phases (P < 0.001) whereas myeloperoxidase activity and blood glucose were unchanged. Adiponectine levels were lower in PIA in acute (P < 0.001) but not in chronic phase. Endothelial function correlated with interleukin-6, total cholesterol levels and arthritis score in aorta but not in mesenteric arteries. CONCLUSIONS: As new information, PIA induces endothelial dysfunction in micro-/macro-vascular beds and low lipid levels, like in RA. This model of chronic arthritis might be useful to study CV pathophysiology and to screen new therapeutic options for reducing CV risk in RA.

Microvascular endothelial dysfunction in rheumatoid arthritis.

The systemic autoimmune disease rheumatoid arthritis (RA) is characterized by increased cardiovascular mortality and morbidity and is an independent cardiovascular risk factor. Cardiovascular diseases (CVDs) result from accelerated atherogenesis, which is a consequence of endothelial dysfunction in the early stages of the disease. Endothelial dysfunction is a functional and reversible alteration of endothelial cells and leads to a shift in the properties of the endothelium towards reduced vasodilation, a pro-inflammatory state, and proliferative and prothrombotic properties. In RA, endothelial dysfunction can occur in the large vessels (such as the conduit arteries) and in the small vessels of the microvasculature, which supply oxygen and nutrients to the tissue and control inflammation, repair and fluid exchange with the surrounding tissues. Growing evidence suggests that microvascular endothelial dysfunction contributes to CVD development, as it precedes and predicts the development of conduit artery atherosclerosis and associated risk factors. As such, numerous studies have investigated microvascular endothelial dysfunction in RA, including its link with disease activity, disease duration and inflammation, the effect of treatments on endothelial function, and possible circulating biomarkers of microvascular endothelial dysfunction. Such findings could have important implications in the cardiovascular risk management of patients with RA.