Structure-Activity relationship of novel second-generation synthetic cathinones: Mechanism of action, locomotion, reward, and immediate-early genes

Several new synthetic cathinones, which mimic the effect of classical psychostimulants such as cocaine or MDMA, have appeared in the global illicit drug market in the last decades. In fact, the illicit drug market is continually evolving by constantly adding small modifications to the common chemical structure of synthetic cathinones. Thus, the aim of this study was to investigate the in vitro and in vivo structure-activity relationship of six novel synthetic cathinones currently popular as recreational drugs, Pentedrone, Pentylone, N-ethyl-pentedrone (NEPD), N-ethyl-pentylone (NEP), 4-methyl-pentedrone (4-MPD) and 4-methyl-ethylaminopentedrone (4-MeAP), which structurally differ in the absence or presence of different aromatic substituents and in their amino terminal group. Human embryonic kidney cells (HEK293) expressing the human isoforms of SERT and DAT were used for the uptake inhibition and release assays. Moreover, Swiss-CD-1 mice were used to investigate their psychostimulant effect, rewarding properties (3, 10 and 30 mg/kg, i.p.) and the induction of immediate-early genes (IEGs) such as arc and c-fos in dorsal (DS) and ventral striatum (VS) as well as bdnf in medial prefrontal cortex (mPFC). Our results demonstrated that all tested synthetic cathinones are potent dopamine (DA) uptake inhibitors, especially the N-ethyl analogues, while the ring-substituted cathinones tested showed higher potency as SERT inhibitors than their no ring-substituted analogues. Moreover, unlike NEP, all tested compounds showed 'hybrid' properties, acting as DAT blockers but SERT substrates. Regarding the locomotion, NEP and NEPD were more efficacious (10 mg/kg) than their N-methyl analogues, which correlates with their higher potency inhibiting DAT and an overexpression of arc levels in DS and VS. Furthermore, all compounds tested induced an increase in c-fos expression in DS, except for 4-MPD, the least effective compound at inducing hyperlocomotion. Moreover, NEP induced an up-regulation of bdnf in mPFC that correlates whit its 5-HTergic properties. Finally, the present study demonstrated for the first time that pentylone, NEP, 4-MPD and 4-MeAP induce reward in mice. Altogether, this study provides valuable information about the mechanism of action, psychostimulant and rewarding properties as well as changes in the expression of IEGs related to addiction induced by novel second-generation synthetic cathinones

ERK1 Regulates the Hematopoietic Stem Cell Niches

The mitogen-activated protein kinases (MAPK) ERK1 and ERK2 are among the major signal transduction molecules but little is known about their specific functions in vivo. ERK activity is provided by two isoforms, ERK1 and ERK2, which are ubiquitously expressed and share activators and substrates. However, there are not in vivo studies which have reported a role for ERK1 or ERK2 in HSCs and the bone marrow microenvironment. The present study shows that the ERK1-deficient mice present a mild osteopetrosis phenotype. The lodging and the homing abilities of the ERK1−/− HSC are impaired, suggesting that the ERK1−/−-defective environment may affect the engrafment of HSCs. Serial transplantations demonstrate that ERK1 is involved in the maintenance of an appropriate medullar microenvironment, but that the intrinsic properties of HSCs are not altered by the ERK1−/− defective microenvironment. Deletion of ERK1 impaired in vitro and in vivo osteoclastogenesis while osteoblasts were unaffected. As osteoclasts derive from precursors of the monocyte/macrophage lineage, investigation of the monocytic compartment was performed. In vivo analysis of the myeloid lineage progenitors revealed that the frequency of CMPs increased by approximately 1.3-fold, while the frequency of GMPs significantly decreased by almost 2-fold, compared with the respective WT compartments. The overall mononuclear-phagocyte lineage development was compromised in these mice due to a reduced expression of the M-CSF receptor on myeloid progenitors. These results show that the cellular targets of ERK1 are M-CSFR-responsive cells, upstream to osteoclasts. While ERK1 is well known to be activated by M-CSF, the present results are the first to point out an ERK1-dependent M-CSFR regulation on hematopoietic progenitors. This study reinforces the hypothesis of an active cross-talk between HSCs, their progeny and bone cells in the maintenance of the homeostasis of these compartments

Les proprietes contractiles de muscles de rats soumis a un vol spatial

SIGLEINIST T 76323 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Grossesse et auto-immunité (expérience monocentrique de 2002 à 2012, intérêt d'une prise en charge multidisciplianire)

LIMOGES-BU Médecine pharmacie (870852108) / SudocSudocFranceF

Effects of high-phosphorus and/or low-calcium diets on bone tissue in trained male rats

International audiencePURPOSE: The aim of the present study was to investigate if wheel running exercise could offset the detrimental influences of independent or combined high-phosphorus and low-calcium diets on bone tissue in rats. METHODS: Forty male dark Agouti rats were randomly assigned to eight groups of five animals. Four sedentary groups (SED) and four voluntary trained groups (TR) were fed over 6 wk of either a standard food or a modified diet, namely, high phosphorus (HP), low calcium (LCa), or high phosphorus combined with low calcium (HP/LCa). After sacrifice, blood samples were collected to determine parathyroid hormone, Ca(2+), and Pi levels. Both tibiae were removed for bone mass determination and extended histomorphometric analyses. RESULTS: In SED rats, all unbalanced diets induced a sizeable bone volume decrease, up to 56%. Interestingly, steady training partially compensates for this bone volume loss, regardless of the considered modified diets. At the cellular level, only independent LCa diet induced a 38% decrease in osteoblastic surface in both SED and TR rat groups, generating thereby a reduction in bone neosynthesis. In terms of osteoclastic surface, an increase in this parameter was evidenced only in HP diets (both HP and HP-LCa), implying heightened bone resorption. The major effects of unbalanced diets are mainly observed on bone tissue because serum parameters (parathyroid hormone, Ca(2+), and Pi levels) remained only slightly modified. CONCLUSIONS: Training induced a positive effect on unbalanced diet-altered bone tissue formation but remained inadequate to reach standard bone mass measured in SED rats fed with balanced food. Further, we suggest that the nature of the diet influences the balance between bone formation and resorption: LCa diet decreases bone formation, whereas HP and HP-LCa increase bone resorption

In vivo molecular evidence of delayed titanium implant osseointegration in compromised bone

Optimization of implant osseointegration in patients with reduced bone healing potential is a challenge remaining in implant dentistry. Identification of the genes that are modulated during implant osseointegration in normal versus osteopenic bone is needed to successfully address these pertinent clinical needs. The present study aimed to assess the initial and early molecular events following titanium implant installation in normal and compromised bone in a rat tibia model. Peri-implant tissue from a well-defined tissue regeneration compartment was analyzed at 2 and 7 days post-surgery for the expression of select markers of inflammation, angiogenesis, bone resorption and bone formation. Impaired bone was induced by hindlimb unloading and validated using μCT. The essential step of angiogenesis preceding bone regeneration was evidenced for the peri-implant setting in healthy bone. Compromised bone significantly affected the angiogenesis-osteogenesis coupling in the initial phase (2 days post-surgery), with altered expressions of Vegfa and Epas1 coinciding with downregulated expressions of Col1a1, Bmp2, Bmp4, Alpl and Bglap. At 7 days post-implantation, differences between normal and compromised peri-implant bone were no longer observed. This in vivo molecular evidence of delayed implant osseointegration in compromised bone reassert modern strategies in implant development, such as surface modifications and bioengineered approaches, to improve implant osseointegration in compromised conditions.status: publishe

Establishment of an in vivo model for molecular assessment of titanium implant osseointegration in compromised bone

Shortening of the healing time before loading risks impeding successful titanium implant anchorage into compromised bone. A thorough understanding at the genetic scale of the early phases of bone regeneration at the implant interface is required before the development of strategies to enhance implant osseointegration. In this study a new in vivo implant model to explore the mechanism by which titanium implant osseointegration is affected by the host bone properties is presented. An implant was conceptualized enabling standardized harvesting of peri-implant tissue for quantitative molecular analysis while preserving the mimicking of the clinical setting. The implant is partly indented to provide a well-defined healing compartment from where tissue differentiation and de novo bone formation can be investigated and partly screw-threaded to provide a good implant anchorage into the bone. The feasibility of the implant design was assessed in osteopenic bone conditions, evoked by simulated weightlessness. Wistar rats were either hindlimb unloaded by tail suspension (HU) for 9 days or acted as controls (CTL). The status of compromised bone tissue through 9-days HU was confirmed by micro-X-ray computed tomography. The implant was installed in the proximal tibial bone 7 days after the onset of HU or CTL. Two days postimplantation, the peri-implant regenerating tissue responses were recorded by measuring expression of inflammatory, angiogenic, and bone resorption parameters (hypoxia-inducible factor 1, alpha subunit; vascular endothelial growth factor A; angiopoietin 1; endothelial PAS domain protein 1; fibroblast growth factor 2; tumor necrosis factor; interleukin 11; acid phosphatase 5, tartrate resistant; tumor necrosis factor (ligand) superfamily, member 11/RANKL). We successfully demonstrated that HU-associated bone conditions evoked a significant alteration of expression of the angiogenic markers in the peri-implant regenerative tissue during initial implant osseointegration, whereas the expression levels of the inflammatory and bone resorption parameters remained unchanged. We concluded that this in vivo implant model provides a well-designed and controlled method to examine molecular responses in implant osseointegration to impaired bone conditions. This model may serve to explore the application of anabolic strategies in peri-implant osteogenesis.status: publishe

In Situ Gene Expression in Native Cryofixed Bone Tissue

Bone is a very complex tissue that is constantly changing throughout the lifespan. The precise mechanism of bone regeneration remains poorly understood. Large bone defects can be caused by gunshot injury, trauma, accidents, congenital anomalies and tissue resection due to cancer. Therefore, understanding bone homeostasis and regeneration has considerable clinical and scientific importance in the development of bone therapy. Macrophages are well known innate immune cells secreting different combinations of cytokines and their role in bone regeneration during bone healing is essential. Here, we present a method to identify mRNA transcripts in cryosections of non-decalcified rat bone using in situ hybridization and hybridization chain reaction to explore gene expression in situ for better understanding the gene expression of the bone tissues