Chalcone T4 Inhibits RANKL-Induced Osteoclastogenesis and Stimulates Osteogenesis In Vitro.

Chalcones are phenolic compounds produced during the biosynthesis of flavonoids that have numerous biological activities, including anti-inflammatory, antioxidant and anticancer. In this in vitro study, we investigate a newly synthesized chalcone (Chalcone T4) in the context of bone turnover, specifically on the modulation of osteoclast differentiation and activity and osteoblast differentiation. Murine macrophages (RAW 264.7) and pre-osteoblasts (MC3T3-E1) were used as models of osteoclasts and osteoblasts, respectively. Differentiation and activity osteoclasts were induced by RANKL in the presence and absence of non-cytotoxic concentrations of Chalcone T4, added in different periods during osteoclastogenesis. Osteoclast differentiation and activity were assessed by actin ring formation and resorption pit assay, respectively. Expression of osteoclast-specific markers (Nfatc1, Oscar, Acp5, Mmp-9 and Ctsk) was determined by RT-qPCR, and the activation status of relevant intracellular signaling pathways (MAPK, AKT and NF-kB) by Western blot. Osteoblast differentiation and activity was induced by osteogenic culture medium in the presence and absence of the same concentrations of Chalcone T4. Outcomes assessed were the formation of mineralization nodules via alizarin red staining and the expression of osteoblast-related genes (Alp e Runx2) by RT-qPCR. Chalcone T4 reduced RANKL-induced osteoclast differentiation and activity, suppressed Oscar, Acp5 and Mmp-9 expression, and decreased ERK and AKT activation in a dose-dependent manner. Nfact1 expression and NF-kB phosphorylation were not modulated by the compound. Mineralized matrix formation and the expression of Alp and Runx2 by MC3T3-E1 cells were markedly stimulated by Chalcone T4. Collectively, these results demonstrate that Chalcone T4 inhibits in osteoclast differentiation and activity and stimulates osteogenesis, which indicates a promising therapeutic potential in osteolytic diseases.

COVID-19, liver dysfunction and pathophysiology: A conceptual discussion.

The intra and extracellular pathways of hepatic injury by coronavirus disease 2019 (COVID-19) are still being studied. Understanding them is important to treat this viral disease and other liver and biliary tract disorders. Thus, this paper aims to present three hypotheses about liver injury caused by COVID-19: (1) The interactions between severe acute respiratory syndrome coronavirus 2 spike protein and membrane receptors in the hepatocyte; (2) The dysbiosis and "gut-liver axis" disruption in patients with serious clinical presentations of COVID-19; and (3) The inflammatory response exacerbated through the production of interleukins such as interleukin-6. However, despite these new perspectives, the pathophysiological process of liver injury caused by COVID-19 is still complex and multifactorial. Thus, understanding all these variables is a challenge to science but also the key to propose individualized and effective patient therapies.

Bioimaging approaches for quantification of individual cell behavior during cell fate decisions.

Tracking individual cells has allowed a new understanding of cellular behavior in human health and disease by adding a dynamic component to the already complex heterogeneity of single cells. Technically, despite countless advances, numerous experimental variables can affect data collection and interpretation and need to be considered. In this review, we discuss the main technical aspects and biological findings in the analysis of the behavior of individual cells. We discuss the most relevant contributions provided by these approaches in clinically relevant human conditions like embryo development, stem cells biology, inflammation, cancer and microbiology, along with the cellular mechanisms and molecular pathways underlying these conditions. We also discuss the key technical aspects to be considered when planning and performing experiments involving the analysis of individual cells over long periods. Despite the challenges in automatic detection, features extraction and long-term tracking that need to be tackled, the potential impact of single-cell bioimaging is enormous in understanding the pathogenesis and development of new therapies in human pathophysiology.

Photobiomodulation Improves the Inflammatory Response and Intracellular Signaling Proteins Linked to Vascular Function and Cell Survival in the Brain of Aged Rats.

Photobiomodulation is a non-pharmacological tool widely used to reduce inflammation in many tissues. However, little is known about its effects on the inflammatory response in the aged brain. We conducted the study to examine anti-inflammatory effects of photobiomodulation in aging brains. We used aged rats (20 months old) with control (handled, laser off) or transcranial laser (660 nm wavelength, 100 mW power) treatments for 10 consecutive days and evaluated the level of inflammatory cytokines and chemokines, and the expression and activation of intracellular signaling proteins in the cerebral cortex and the hippocampus. Inflammatory analysis showed that aged rats submitted to transcranial laser treatment had increased levels of IL-1alpha and decreased levels of IL-5 in the cerebral cortex. In the hippocampus, the laser treatment increased the levels of IL-1alpha and decreased levels of IL-5, IL-18, and fractalkine. Regarding the intracellular signaling proteins, a reduction in the ERK and p38 expression and an increase in the STAT3 and ERK activation were observed in the cerebral cortex of aged rats from the laser group. In addition, the laser treatment increased the hippocampal expression of p70S6K, STAT3, and p38 of aged rats. Taken together, our data indicate that transcranial photobiomodulation can improve the inflammatory response and the activation of intracellular signaling proteins linked to vascular function and cell survival in the aged brain.

INitial Steps of Insulin Action in Parotid Glands of Male Wistar Rats.

The parotid gland is the largest salivary gland. It produces watery saliva, rich in proteins (amylase, lysozymes, and antibodies). Due to the gland's morphological cytoarchitecture composed of only serous acini, it contributes almost 50% of total salivary volume upon stimulation. It has been reported that the prevalence of saliva secretion impairments, periodontitis, delayed wound healing, and xerostomia increase in diabetic patients. Herein we evaluated the acute effects of insulin on insulin receptor phosphorylation status and its substrates IRS-1 and IRS-2 in the parotid glands of adult male Wistar rats, using Western blot analyses. We confirmed an acute effect of insulin on IR/IRS/PI3K/Akt and MAPK intracellular pathway activation in the parotid glands of male Wistar rats similar to the classical metabolic targets of the hormone, like the liver.

Transcranial Laser Photobiomodulation Improves Intracellular Signaling Linked to Cell Survival, Memory and Glucose Metabolism in the Aged Brain: A Preliminary Study.

Aging is often accompanied by exacerbated activation of cell death-related signaling pathways and decreased energy metabolism. We hypothesized that transcranial near-infrared laser may increase intracellular signaling pathways beneficial to aging brains, such as those that regulate brain cell proliferation, apoptosis, and energy metabolism. To test this hypothesis, we investigated the expression and activation of intracellular signaling proteins in the cerebral cortex and hippocampus of aged rats (20 months old) treated with the transcranial near-infrared laser for 58 consecutive days. As compared to sham controls, transcranial laser treatment increased intracellular signaling proteins related to cell proliferation and cell survival, such as signal transducer and activator of transcription 3 (STAT3), extracellular signal-regulated protein kinase (ERK), c-Jun N-terminal kinase (JNK), p70 ribosomal protein S6 kinase (p70S6K) and protein kinase B (PKB), also known as Akt that is linked to glucose metabolism. In addition, ERK is linked to memory, while ERK and JNK signaling pathways regulate glucose metabolism. Specifically, the laser treatment caused the activation of STAT3, ERK, and JNK signaling proteins in the cerebral cortex. In the hippocampus, the laser treatment increased the expression of p70S6K and STAT3 and the activation of Akt. Taken together, the data support the hypothesis that transcranial laser photobiomodulation improves intracellular signaling pathways linked to cell survival, memory, and glucose metabolism in the brain of aged rats.

Panorama of the Intracellular Molecular Concert Orchestrated by Actinoporins, Pore-Forming Toxins from Sea Anemones.

Actinoporins (APs) are soluble pore-forming proteins secreted by sea anemones that experience conformational changes originating in pores in the membranes that can lead to cell death. The processes involved in the binding and pore-formation of members of this protein family have been deeply examined in recent years; however, the intracellular responses to APs are only beginning to be understood. Unlike pore formers of bacterial origin, whose intracellular impact has been studied in more detail, currently, we only have knowledge of a few poorly integrated elements of the APs' intracellular action. In this review, we present and discuss an updated landscape of the studies aimed at understanding the intracellular pathways triggered in response to APs attack with particular reference to sticholysin II, the most active isoform produced by the Caribbean Sea anemone Stichodactyla helianthus. To achieve this, we first describe the major alterations these cytolysins elicit on simpler cells, such as non-nucleated mammalian erythrocytes, and then onto more complex eukaryotic cells, including tumor cells. This understanding has provided the basis for the development of novel applications of sticholysins such as the construction of immunotoxins directed against undesirable cells, such as tumor cells, and the design of a cancer vaccine platform. These are among the most interesting potential uses for the members of this toxin family that have been carried out in our laboratory.

Th17/Treg-Related Intracellular Signaling in Patients with Chronic Obstructive Pulmonary Disease: Comparison between Local and Systemic Responses.

Th17/Treg imbalance plays a pivotal role in COPD development and progression. We aimed to assess Th17/Treg-related intracellular signaling at different COPD stages in local and systemic responses. Lung tissue and/or peripheral blood samples were collected and divided into non-obstructed (NOS), COPD stages I and II, and COPD stages III and IV groups. Gene expression of STAT3 and -5, RORγt, Foxp3, interleukin (IL)-6, -17, -10, and TGF-ß was assessed by RT-qPCR. IL-6, -17, -10, and TGF-ß levels were determined by ELISA. We observed increased STAT3, RORγt, Foxp3, IL-6, and TGF-ß gene expression and IL-6 levels in the lungs of COPD I and II patients compared to those of NOS patients. Regarding the systemic response, we observed increased STAT3, RORγt, IL-6, and TGF-ß gene expression in the COPD III and IV group and increased IL-6 levels in the COPD I and II group. STAT5 was increased in COPD III and IV patients, although there was a decrease in Foxp3 expression and IL-10 levels in the COPD I and II and COPD III and IV groups, respectively. We demonstrated that an increase in Th17 intracellular signaling in the lungs precedes this increase in the systemic response, whereas Treg intracellular signaling varies between the compartments analyzed in different COPD stages.

Involvement of Phosphorylated Akt and FOXO3a in the Effects of Growth and Differentiation Factor-9 (GDF-9) on Inhibition of Follicular Apoptosis and Induction of Granulosa Cell Proliferation After In Vitro Culture of Sheep Ovarian Tissue.

This study aimed to evaluate the effects of growth and differentiation factor-9 (GDF-9) on the morphology, activation, apoptosis, and granulosa cell proliferation of ovine preantral follicles cultured within ovarian tissue slices and to verify whether GDF-9 could influence follicular activation through the phosphatidylinositol 3-kinase/protein kinase B/forkhead box O3a (PI3K/Akt/FOXO3a) pathway. Ovine ovarian fragments were cultured in α-MEM+ or α-MEM+ with GDF-9 (1, 50, 100, 200, or 400 ng/ml) for 7 days. Apoptosis and cell proliferation were analyzed. Next, the activation of the PI3K was inhibited with LY294002, and immunostaining for p-Akt and p-FOXO3a proteins was assessed. The concentration of 50 ng/ml GDF-9 had (P < 0.05) more morphologically normal follicles compared to all treatments, except 1 ng/ml GDF-9. Moreover, 50 ng/ml GDF-9 increased primordial follicle activation compared to all treatments, except α-MEM+ and 1 ng/ml GDF-9. However, the concentration of 50 ng/ml GDF-9 showed higher cell proliferation and lower apoptosis than α-MEM+ and 1 ng/ml GDF-9 treatments. Culture of the ovarian tissue with LY294002 inhibited the activation of primordial follicles and reduced p-Akt immunostaining in both α-MEM+ and 50 ng/ml GDF-9 treatments. In addition, after culture with LY294002, the percentage of oocytes with nuclear p-FOXO3 was higher in 50 ng/ml GDF-9 than in the control medium (α-MEM+). In conclusion, after culture of ovine ovarian cortical slices, the addition of 50 ng/ml GDF-9 reduces follicular apoptosis and promotes granulosa cell proliferation likely through the involvement of phosphorylated Akt and FOXO3a.

Avaliação molecular e imuno-histoquímica de malformações linfáticas orais / Molecular and immunohistochemistry evaluation of oral lymphatic malformations

As malformações linfáticas são distúrbios do desenvolvimento caracterizados pelo crescimento excessivo de vasos linfáticos. Essa condição acontece principalmente em região de cabeça e pescoço devido à presença fisiológica de grande concentração de vasos linfáticos na região. As malformações linfáticas podem ocorrer de maneira isolada ou associadas a síndromes como de CLOVES e Klippel-Trènaunay. A presença de mutações no gene PIK3CA e a ativação das vias PI3K/AKT e MAPK/ERK pode ocorrer tanto nas malformações linfáticas esporádicas, como naquelas associadas a síndromes. As mutações em PIK3CA ocorrem nos éxons 10 e 20, sendo as mutações no códon 1047 (éxon 20) as mais frequente nas malformações linfáticas esporádicas. No entanto, em malformações linfáticas orais não se sabe se estes fenômenos ocorrem. O objetivo deste estudo foi avaliar a presença de mutações no códon 1047 do gene PIK3CA e avaliar a ativação das vias PI3K/AKT e MAPK/ERK em amostras de malformações linfáticas orais. Uma amostra de conveniência de 14 tecidos de malformações linfáticas orais fixados em formol e embebidos em parafina foram submetidas a reações de imuno-histoquímica para as formas fosforiladas de AKT1 (pAKT-Ser473) e ERK1/2 (pERK1/2-Thr202/Tyr204), marcadores de ativação das vias PI3K/AKT e MAPK/ERK, respectivamente. Quatro destas amostras foram submetidas a Sequenciamento de Sanger para o códon 1047 do gene PIK3CA. Foram observados padrões de marcação positivas para pAKT1 e pERK1/2 nas células endoteliais de todas as amostras de malformações linfáticas orais avaliadas. Todas as amostras submetidas ao Sequenciamento de Sanger apresentaram sequência selvagem para a região de interesse. Com os resultados obtidos sugere-se que as vias PI3K/AKT e MAPK/ERK estão envolvidas na patogênese das malformações linfáticas orais.

Lymphatic malformations are developmental disorders characterized by excessive growth of lymphatic vessels. This condition occurs mainly in the head and neck region due to the physiological presence of high concentration of lymphatic vessels in the region. Lymphatic malformations may occur in isolation or associated with syndromes such as CLOVES and Klippel-Trènaunay. Mutations in the PIK3CA gene and activation of the PI3K/AKT and MAPK/ERK pathways may occur both in sporadic lymphatic malformations and in those associated with syndromes. Mutations in hotspot 1047 are the most frequently found in isolated lymphatic malformation. However, in oral lymphatic malformations it is not known whether these mutations occur. The aim of this study was to evaluate the presence of mutations in codon 1047 of the PIK3CA gene and to evaluate the activation of PI3K/AKT and MAPK/ERK pathways in samples of oral lymphatic malformations. A convenience sample of 14 tissues of oral lymphatic malformations formalin fixed paraffin embedded were submitted to immunohistochemistry reactions to the phosphorylated forms of AKT1 (pAKT-Ser473) and ERK1/2 (pERK1/2-Thr202/Tyr204), activation markers of PI3K/AKT and MAPK/ERK pathways, respectively. Four of these samples were submitted to Sanger Sequencing for codon 1047 of the PIK3CA gene. Positive marking patterns for pAKT1 and pERK1/2 were observed in the endothelial cells of all samples of oral lymphatic malformations evaluated. All samples submitted to Sanger Sequencing were wild type for the region of interest. With the results obtained it is suggested that the PI3K/AKT and MAPK/ERK pathways are involved in the pathogenesis of oral lymphatic malformations.

The Controversial Role of Autophagy in Tumor Development: A Systematic Review.

Autophagy is a natural regulatory mechanism of the cell that eliminates unnecessary and dysfunctional cellular components to maintain homeostasis. Several authors have demonstrated that this mechanism can be induced by pathological conditions as cancer. However, their role in tumor development is still a controversial issue in cancer research. Here, we discussed the most relevant findings concerning autophagy in tumor development. In this critical review performed with studies published between 2002 and 2018, we found that the main pathway involved in the autophagy process is the PI3K/AKT/mTOR intracellular signaling pathway. Regarding their role in cancer development, breast cancer is the main study target, followed by lung, prostate and colon cancer. In these issues, 46% of the works consulted suggesting that autophagy inhibits tumor progression by favor a better antitumor response, 4% suggest that favors growth and tumor progression and, 50% of the authors failed to establish whether autophagy inhibits or favors tumor development. Herein, we concluded that depending on the study model, autophagy may favor or inhibits growth and cancer progression.

The controversial role of autophagy in tumor development: a systematic review

Autophagy is a natural regulatory mechanism of the cell that eliminates unnecessary and dysfunctional cellular components to maintain homeostasis. Several authors have demonstrated that this mechanism can be induced by pathological conditions as cancer. However, their role in tumor development is still a controversial issue in cancer research. Here, we discussed the most relevant findings concerning autophagy in tumor development. In this critical review performed with studies published between 2002 and 2018, we found that the main pathway involved in the autophagy process is the PI3K/AKT/mTOR intracellular signaling pathway. Regarding their role in cancer development, breast cancer is the main study target, followed by lung, prostate and colon cancer. In these issues, 46% of the works consulted suggesting that autophagy inhibits tumor progression by favor a better antitumor response, 4% suggest that favors growth and tumor progression and, 50% of the authors failed to establish whether autophagy inhibits or favors tumor development. Herein, we concluded that depending on the study model, autophagy may favor or inhibits growth and cancer progression.

Inhibition of RAGE Axis Signaling: A Pharmacological Challenge.

The Receptor for Advanced Glycation End Products (RAGE) is an important cell surface receptor, which belongs to the IgG super family and is now considered as a pattern recognition receptor. Because of its relevance in many human clinical settings, it is now pursued as a very attractive therapeutic target. However, particular features of this receptor such as a wide repertoire of ligands with different binding domains, the existence of many RAGE variants as well as the presence of cytoplasmatic adaptors leading a diverse signaling, are important limitations in the search for successful pharmacological approaches to inhibit RAGE signaling. Therefore, the present review aimed to display the most promising approaches to inhibit RAGE signaling, and provide an up to date review of progress in this area.

Exploring major signaling cascades in melanomagenesis: a rationale route for targetted skin cancer therapy.

Although most melanoma cases may be treated by surgical intervention upon early diagnosis, a significant portion of patients can still be refractory, presenting low survival rates within 5 years after the discovery of the illness. As a hallmark, melanomas are highly prone to evolve into metastatic sites. Moreover, melanoma tumors are highly resistant to most available drug therapies and their incidence have increased over the years, therefore leading to public health concerns about the development of novel therapies. Therefore, researches are getting deeper in unveiling the mechanisms by which melanoma initiation can be triggered and sustained. In this context, important progress has been achieved regarding the roles and the impact of cellular signaling pathways in melanoma. This knowledge has provided tools for the development of therapies based on the intervention of signal(s) promoted by these cascades. In this review, we summarize the importance of major signaling pathways (mitogen-activated protein kinase (MAPK), phosphoinositide 3-kinase (PI3K)-Akt, Wnt, nuclear factor κ-light-chain-enhancer of activated B cell (NF-κB), Janus kinase (JAK)-signal transducer and activator of transcription (STAT), transforming growth factor ß (TGF-ß) and Notch) in skin homeostasis and melanoma progression. Available and developing melanoma therapies interfering with these signaling cascades are further discussed.

Insulin-induced exocytosis regulates the cell surface level of low-density lipoprotein-related protein-1 in Müller Glial cells.

Low-density lipoprotein (LDL) receptor-related protein-1 (LRP1) is expressed in retinal Müller glial cells (MGCs) and regulates intracellular translocation to the plasma membrane (PM) of the membrane proteins involved in cellular motility and activity. Different functions of MGCs may be influenced by insulin, including the removal of extracellular glutamate in the retina. In the present work, we investigated whether insulin promotes LRP1 translocation to the PM in the Müller glial-derived cell line MIO-M1 (human retinal Müller glial cell-derived cell line). We demonstrated that LRP1 is stored in small vesicles containing an approximate size of 100 nm (mean diameter range of 100-120 nm), which were positive for sortilin and VAMP2, and also incorporated GLUT4 when it was transiently transfected. Next, we observed that LRP1 translocation to the PM was promoted by insulin-regulated exocytosis through intracellular activation of the IR/PI3K/Akt axis and Rab-GTPase proteins such as Rab8A and Rab10. In addition, these Rab-GTPases regulated both the constitutive and insulin-induced LRP1 translocation to the PM. Finally, we found that dominant-negative Rab8A and Rab10 mutants impaired insulin-induced intracellular signaling of the IR/PI3K/Akt axis, suggesting that these GTPase proteins as well as the LRP1 level at the cell surface are involved in insulin-induced IR activation.

Role of Collecting Duct Renin in the Pathogenesis of Hypertension.

The presence of renin production by the principal cells of the collecting duct has opened new perspectives for the regulation of intrarenal angiotensin II (Ang II). Angiotensinogen (AGT) and angiotensin-converting enzyme (ACE) are present in the tubular fluid coming from the proximal tubule and collecting duct. All the components needed for Ang II formation are present along the nephron, and much is known about the mechanisms regulating renin in juxtaglomerular cells (JG); however, those in the collecting duct remain unclear. Ang II suppresses renin via protein kinase C (PKC) and calcium (Ca2+) in JG cells, but in the principal cells, Ang II increases renin synthesis and release through a pathophysiological mechanism that increases further intratubular Ang II de novo formation to enhance distal Na + reabsorption. Transgenic mice overexpressing renin in the collecting duct demonstrate the role of collecting duct renin in the development of hypertension. The story became even more interesting after the discovery of a specific receptor for renin and prorenin: the prorenin receptor ((P)RR), which enhances renin activity and fully activates prorenin. The interactions between (P)RR and prorenin/renin may further increase intratubular Ang II levels. In addition to Ang II, other mechanisms have been described in the regulation of renin in the collecting duct, including vasopressin (AVP), bradykinin (BK), and prostaglandins. Current active investigations are aimed at elucidating the mechanisms regulating renin in the distal nephron segments and understand its role in the pathogenesis of hypertension.

P2X7 receptor large pore signaling in avian Müller glial cells.

ATP is a pleiotropic molecule that promotes extra- and intracellular signaling to regulate numerous functions. This nucleotide activates purine and pyrimidine receptors at the plasma membrane, categorized as ionotropic P2X or G-protein-coupled receptor (GPCR) P2Y receptors. P2X are ligand-gated ion channel receptors, expressed in both retinal neurons and Müller cells leading to neuron-glia communication, calcium waves and neurovascular coupling. However, how P2X pore is formed upon ATP activation and how signaling pathways regulates the complex is still a matter of controversy. Here we studied the properties of the P2X7 receptor (P2X7R) using electrophysiology, single cell Ca2+ imaging, and dye uptake assay in purified avian Müller glia in culture. Our data show that ATP (or benzoyl-benzoyl ATP, BzATP) evoked large inward currents in patch-clamp studies while addition of P2X7R antagonist such as brilliant Blue G (BBG), abolished these currents. Ruthenium red (RU-2), a general transient receptor potential (TRP) inhibitor, reduced currents induced by ATP. Our data also point to the involvement of mitogen activated protein kinase (MAPK), phosphoinositide 3-kinase (PI3K), Ca2+-calmodulin kinase II (CAMKII), microtubules or protein kinase C (PKC) modulating ATP-induced ionic current in Müller cells. We show that ATP induced Ca2+ influx, partially inhibited by P2X7R antagonists (oxidized ATP or BBG), and totally inhibited by blockers of other pores such as transient receptor potential (TRPs) or connexin hemichannel. Additionally, MAPK, PKC, PI3K or CAMKII inhibitors also are involved in the modulation of intracellular calcium signaling. Finally, ATP induced 80-90% of dye uptake in Muller glia cells, while oxidized ATP (oATP), BBG or A740003 inhibited this effect. We conclude that large conductance channel and other P2XRs are not involved in the ATP-induced dye uptake, but signaling pathways such as MAPK, PI3-K, microtubules or PKC are involved in pore formation.

[Cell signaling pathways interaction in cellular proliferation: Potential target for therapeutic interventionism]. / Interacción de las vías de señalización intracelulares participantes en la proliferación celular: potencial blanco de intervencionismo terapéutico.

Nowadays, cellular physiology is best understood by analysing their interacting molecular components. Proteins are the major components of the cells. Different proteins are organised in the form of functional clusters, pathways or networks. These molecules are ordered in clusters of receptor molecules of extracellular signals, transducers, sensors and biological response effectors. The identification of these intracellular signaling pathways in different cellular types has required a long journey of experimental work. More than 300 intracellular signaling pathways have been identified in human cells. They participate in cell homeostasis processes for structural and functional maintenance. Some of them participate simultaneously or in a nearly-consecutive progression to generate a cellular phenotypic change. In this review, an analysis is performed on the main intracellular signaling pathways that take part in the cellular proliferation process, and the potential use of some components of these pathways as target for therapeutic interventionism are also underlined.

Involvement of PKA, PKC, CAMK-II and MEK1/2 in the acute antidepressant-like effect of creatine in mice.

BACKGROUND: The aim of this study was to investigate the involvement of signaling pathways on the creatine antidepressant-like effect in the tail suspension test (TST) in mice. METHODS: The TST was used to assess the antidepressant-like properties of creatine. RESULTS: The anti-immobility effect of creatine (1mg/kg, p.o.) in the TST was blocked by i.c.v. pretreatment with H-89 (1µg/site, PKA inhibitor), KN-62 (1µg/site, CAMK-II inhibitor), chelerythrine (1µg/site, PKC inhibitor), U0126 (5µg/site, MEK1/2 inhibitor) or PD09058 (5µg/site, MEK1/2 inhibitor). CONCLUSION: These results suggest that the antidepressant-like effect of creatine is dependent on PKA, CaMK-II, PKC and MEK 1/2 activation.