Functional characterization of a novel opioid, PZM21, and its influence on behavioural responses to morphine

The concept of opioid ligands biased toward the G protein pathway with minimal recruitment of β-arrestin-2 has become a promising approach for the development of novel, efficient and potentially nonaddictive opioid therapeutics. A recently discovered biased μ-opioid receptor agonist, PZM21, was reported to be analgesic and possess reduced side effects. Here, we aimed to further investigate the behavioural and biochemical properties of PZM21.We evaluated antinociceptive effects of systemic and intrathecal PZM21 administration. Its addiction-like properties were determined using several behavioural approaches: conditioned place preference, locomotor sensitization, precipitated withdrawal and self-administration. Further, we assessed the influence of PZM21 on morphine-induced antinociception, tolerance and reward. Effects of PZM21 on striatal release of monoamines were evaluated using brain microdialysis.PZM21 caused long-lasting dose-dependent antinociception. It did not induce reward- and reinforcement-related behaviour, however, its repeated administration led to antinociceptive tolerance and naloxone-precipitated withdrawal symptoms. Pretreatment with PZM21 enhanced morphine-induced antinociception and attenuated the expression of morphine reward. In comparison to morphine, PZM21 administration led to moderate release of dopamine and robust release of serotonin in the striatum.PZM21 presents antinociceptive efficacy and does not possess rewarding or reinforcing properties. However, its clinical application may be restricted, as it induces tolerance and withdrawal symptoms. Notably, its ability to diminish morphine reward implicates that PZM21 may be useful in opioid use disorder therapy

Glucocorticoid-regulated kinase CAMKIγ\gamma in the central amygdala controls anxiety-like behavior in mice

The expression of the Calcium/Calmodulin-Dependent Protein Kinase I gamma (encoded by the Camk1g gene) depends on the activation of glucocorticoid receptors (GR) and is strongly regulated by stress. Since Camk1g is primarily expressed in neuronal cells of the limbic system in the brain, we hypothesized that it could be involved in signaling mechanisms that underlie the adaptive or maladaptive responses to stress. Here, we find that restraint-induced stress and the GR agonist dexamethasone robustly increase the expression of Camk1g in neurons of the amygdalar nuclei in the mouse brain. To assess the functional role of Camk1g expression, we performed a virally induced knock-down of the transcript. Mice with bilateral amygdala-specific Camk1g knock-down showed increased anxiety-like behaviors in the light-dark box, and an increase in freezing behavior after fear-conditioning, but normal spatial working memory during exploration of a Y-maze. Thus, we confirm that Camk1g is a neuron-specific GR-regulated transcript, and show that it is specifically involved in behaviors related to anxiety, as well as responses conditioned by aversive stimuli

Glucocorticoid induced depression-like behavior in mice.

Depresja jednobiegunowa jest powszechnie występującym zaburzeniem psychiatrycznym o złożonej i wieloczynnikowej etiologii. Spośród wielu teorii, coraz bardziej popularna staje się hipoteza rozważająca rolę osi przysadkowo-przysadkowo-nadnerczowej (ang. hypothalamic–pituitary–adrenal axis; HPA) w patogenezie tej choroby. Liczne badania wskazują, że chroniczne podawanie hormonu stresu, kortykosteronu (ang. corticosterone, CORT) u gryzoni wywołuje neurobiologiczne i behawioralne zmiany podobne do wielu objawów i zmian na poziomie neuronalnym obserwowanych w depresji u ludzi. CORT oddziałuje na dwa typy receptorów kortykosteroidowych: mineralokortykoidowy (MR) i glukokortykoidowy (GR), jednak znaczenie poszczególnych receptorów w rozwoju objawów depresyjnych nie jest poznana.Celem niniejszego badania było określenie roli GR w patoetiologii depresji jednobiegunowej. Oceniane były skutki chronicznego podawania agonisty receptora glukokortykoidowego- deksametazonu (DEX), na zachowania przypominające depresję u myszy C57BL/6N. Deksametazon (w dawkach: 0,4 mg/kg lub 4 mg/kg) lub roztwór soli fizjologicznej podawane były raz dziennie przez 21 kolejnych dni. Zachowanie zwierząt oceniano w: teście wymuszonego pływania, teście preferencji sacharyny, teście instrumentalnego poszukiwania wrażeń, teście podniesionego labiryntu krzyżowego, teście wolnego pola oraz labiryncie o kształcie litery Y. Wyniki badań wskazują na rozwój wielu właściwości kojarzonych z modelem depresji u myszy którym podawano deksametazon. Są to: spadek masy ciała, zmniejszenie preferencji do konsumpcji sacharyny, wydłużenie czasu bezruchu i spadek energicznej aktywności (zachowania typu depresyjnego), wzrost zachowań lękowych oraz zaburzenie procesów uczenia się. Przewlekłe podania DEX nie miały jednak wpływu na aktywność lokomotoryczną myszy oraz na pamięć roboczą. Co więcej, ostre, jednorazowe podanie nie wpłynęło na uprzednio wyuczone zachowanie związane z poszukiwaniem wrażeń, co sugeruje, że badany lek nie posiada ani nagradzających ani awersyjnych właściwości.Wyniki przedstawionego badania sugerują, że GR może odgrywać rolę w patogenezie depresji, a także mogą przyczynić się do lepszego zrozumienia mechanizmów leżących u podstaw tej choroby.Major depression (MD) is a common psychiatric disorder with a multifactor and complex etiology. Among several hypotheses proposed to explain its pathogenesis, the hypothalamic–pituitary–adrenal (HPA) axis disruption theory is becoming increasingly popular. Numerous studies indicate that repeated exogenous administration of the stress hormone corticosterone (CORT) in rodents produces neurobiological and behavioral alterations that parallel many of the symptoms and neurobiological changes associated with human depression. CORT affects two types of corticosteroid receptors- mineralocorticoid (MR) and glucocorticoid (GR), however the role of specific receptor in development of depressive symptoms is unknown.The aim of the present study was to assess the role of GR in the pathoetiology of MD. Specifically, the effects of chronic systemic GR agonist- dexamethasone (DEX) administrations on depression-associated behavior in C57BL/6N mice were investigated. Mice were daily injected with dexamethasone (0,4 mg/kg or 4 mg/kg) or saline solution. Animals behavior was assessed in: forced swimming test, saccharin preference test, operant sensation seeking procedure, elevated plus maze test, open field and Y maze test. Tests results indicate that a variety of depression-like behaviors characterized dexamethasone-treated mice: severe loss of body mass, reduced preference for saccharin consumption, increased immobility time, decreased climbing time (depressive-like behavior), increased anxiety-like behavior and impaired learning. However, chronic DEX treatment did not influence general mice locomotor activity or working memory. What is more, acute DEX administration did not affect pre-learned mice sensation seeking behavior, indicating that tested drug does not have any rewarding or aversive properties.The data suggest that GR may play a role in the neurobiology of depression, may contribute to better understanding of the mechanisms that underlie the disorder

Calibration of the results of Rotliegend sandstones chemical analyses performed with a handheld XRF spectrometer

Handheld X-ray fluorescence spectrometers with energy dispersion (EDXRF) are increasingly used to determine the chemical composition of rocks for the oil and gas industry. The results of our research allow to create or support the lithological interpretation based on mineralogical models. In the case of quantitative interpretation based on the results of measurements using a handheld XRF device, high accuracy of measurements is required. This paper presents the problems to which attention should be paid when applying the assumed methodology, mainly related to the underestimated percentages for light (main) elements. The tests were carried out on powdered samples of drill cores taken from borehole directed to Rotliegend rocks. The measurements were carried out using Bruker’s XRF S1 TITAN spectrometer. The calibration and correction tests led to the elimination of two factors affecting the inaccuracy of the analyses. The first is the progressive aging of the X-ray tube, which should be checked by conducting systematic measurements of the standard reference material. The second concerns the effect of a change in the density of the sample after grinding, which has a significant impact on light elements (mainly silicon and aluminium), causing a decrease in absolute values in the results of measurements using a handheld XRF device. Due to the type of rock material analysed, the focus was on the calibration of the results of the main elements building the Rotliegend sandstone rock matrix. The paper presents the possibility of calibrating the results directly in the device, which results in obtaining calibrated results after each measurement, as well as calibration of results in an external file. By using external calibration, errors caused by changing the rock matrix can be avoided while ensuring that possibility the results can be recalculated. The resulting calibration coefficients are applicable to the Rotliegend rocks and the XRF spectrometer with current software and GeoChem calibrations provided by Bruker. A change in any of the factors requires re-testing and recalibration of the results. Mineralogical models prepared based on XRF analyses can be used in the future, if those appropriate calibration coefficients are used

Endocannabinoid signaling in astrocytes

International audienc

Nat Neurosci

Cannabinoids reduce tremor associated with motor disorders induced by injuries and neurodegenerative disease. Here we show that this effect is mediated by cannabinoid receptors on astrocytes in the ventral horn of the spinal cord, where alternating limb movements are initiated. We first demonstrate that tremor is reduced in a mouse model of essential tremor after intrathecal injection of the cannabinoid analog WIN55,212-2. We investigate the underlying mechanism using electrophysiological recordings in spinal cord slices and show that endocannabinoids released from depolarized interneurons activate astrocytic cannabinoid receptors, causing an increase in intracellular Ca(2+), subsequent release of purines, and inhibition of excitatory neurotransmission. Finally, we show that the anti-tremor action of WIN55,212-2 in the spinal cords of mice is suppressed after knocking out CB(1) receptors in astrocytes. Our data suggest that cannabinoids reduce tremor via their action on spinal astrocytes

Glucocorticoid-Regulated Kinase CAMKIγ in the Central Amygdala Controls Anxiety-like Behavior in Mice

The expression of the Calcium/Calmodulin-Dependent Protein Kinase I gamma (encoded by the Camk1g gene) depends on the activation of glucocorticoid receptors (GR) and is strongly regulated by stress. Since Camk1g is primarily expressed in neuronal cells of the limbic system in the brain, we hypothesized that it could be involved in signaling mechanisms that underlie the adaptive or maladaptive responses to stress. Here, we find that restraint-induced stress and the GR agonist dexamethasone robustly increase the expression of Camk1g in neurons of the amygdalar nuclei in the mouse brain. To assess the functional role of Camk1g expression, we performed a virally induced knock-down of the transcript. Mice with bilateral amygdala-specific Camk1g knock-down showed increased anxiety-like behaviors in the light-dark box, and an increase in freezing behavior after fear-conditioning, but normal spatial working memory during exploration of a Y-maze. Thus, we confirm that Camk1g is a neuron-specific GR-regulated transcript, and show that it is specifically involved in behaviors related to anxiety, as well as responses conditioned by aversive stimuli

Glucocorticoid receptor signaling in astrocytes is required for aversive memory formation

Abstract Stress elicits the release of glucocorticoids (GCs) that regulate energy metabolism and play a role in emotional memory. Astrocytes express glucocorticoid receptors (GR), but their contribution to cognitive effects of GC’s action in the brain is unknown. To address this question, we studied how astrocyte-specific elimination of GR affects animal behavior known to be regulated by stress. Mice with astrocyte-specific ablation of GR presented impaired aversive memory expression in two different paradigms of Pavlovian learning: contextual fear conditioning and conditioned place aversion. These mice also displayed compromised regulation of genes encoding key elements of the glucose metabolism pathway upon GR stimulation. In particular, we identified that the glial, but not the neuronal isoform of a crucial stress-response molecule, Sgk1, undergoes GR-dependent regulation in vivo and demonstrated the involvement of SGK1 in regulation of glucose uptake in astrocytes. Together, our results reveal astrocytes as a central element in GC-dependent formation of aversive memory and suggest their relevance for stress-induced alteration of brain glucose metabolism. Consequently, astrocytes should be considered as a cellular target of therapies of stress-induced brain diseases

Mitochondrial cannabinoid receptors gate corticosterone impact on novel object recognition

: Corticosteroid-mediated stress responses require the activation of complex brain circuits involving mitochondrial activity, but the underlying cellular and molecular mechanisms are scantly known. The endocannabinoid system is implicated in stress coping, and it can directly regulate brain mitochondrial functions via type 1 cannabinoid (CB1) receptors associated with mitochondrial membranes (mtCB1). In this study, we show that the impairing effect of corticosterone in the novel object recognition (NOR) task in mice requires mtCB1 receptors and the regulation of mitochondrial calcium levels in neurons. Different brain circuits are modulated by this mechanism to mediate the impact of corticosterone during specific phases of the task. Thus, whereas corticosterone recruits mtCB1 receptors in noradrenergic neurons to impair NOR consolidation, mtCB1 receptors in local hippocampal GABAergic interneurons are required to inhibit NOR retrieval. These data reveal unforeseen mechanisms mediating the effects of corticosteroids during different phases of NOR, involving mitochondrial calcium alterations in different brain circuits