Specific Agonist Research Articles

Pharmacological Utility of PPAR Modulation for Angiogenesis in Cardiovascular Disease.

Peroxisome proliferator activated receptors, including PPARα, PPARβ/δ, and PPARγ, are ligand-activated transcription factors belonging to the nuclear receptor superfamily. They play important roles in glucose and lipid metabolism and are also supposed to reduce inflammation and atherosclerosis. All PPARs are involved in angiogenesis, a process critically involved in cardiovascular pathology. Synthetic specific agonists exist for all PPARs. PPARα agonists (fibrates) are used to treat dyslipidemia by decreasing triglyceride and increasing high-density lipoprotein (HDL) levels. PPARγ agonists (thiazolidinediones) are used to treat Type 2 diabetes mellitus by improving insulin sensitivity. PPARα/γ (dual) agonists are supposed to treat both pathological conditions at once. In contrast, PPARβ/δ agonists are not in clinical use. Although activators of PPARs were initially considered to have favorable effects on the risk factors for cardiovascular disease, their cardiovascular safety is controversial. Here, we discuss the implications of PPARs in vascular biology regarding cardiac pathology and focus on the outcomes of clinical studies evaluating their benefits in cardiovascular diseases.

Vitamin D ameliorates insulin resistance-induced osteopenia by inactivating the nucleotide-binding oligomerization domain-like receptor protein 3 inflammasome

ObjectiveOsteoporosis (OP) can be considered a chronic complication of type 2 diabetes mellitus (T2DM). Aberrant activation of the nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome is associated with the pathogenesis of various inflammation-related diseases, e.g., T2DM and OP. Vitamin D affects the inflammatory pathway and inhibits an excessive inflammatory response. The current study investigated the inter-relationship between vitamin D and inflammasome activation in T2DM. MethodHepatocellular carcinoma (HepG2) cells and bone marrow stromal cells (BMSCs) were treated with Conditioned Medium of bone marrow mesenchymal stem cells after VitD treatment (CM-VitD), as well as phosphoinositide 3-kinase (PI3K) specific agonist, 740Y-P, or the PI3K specific inhibitor, LY294002, respectively, or both. 40 Eight-week-old female Sprague Dawley rats were selected and established as a DM model. The rats were injected with CM-VitD, as well as the 740Y-P specific agonist, or the LY294002 inhibitor, respectively, or both. A quantitative reverse transcription polymerase chain reaction and western blotting were conducted to evaluate the expression of messenger ribonucleic acid and protein in the RUX2 gene, alkaline phosphatase (ALP), OsteoPontiN (OPN), peroxisome proliferator-activated receptor gamma (PPARγ), fatty acid-binding protein 4 (FABP4), protein kinase B (AKT), PI3K, NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), caspase-1, interleukin (IL)-1 beta (β), IL-18, and tumor necrosis factor alpha (TNF-α) in the BMSCs and liver tissue of rats. Enzyme-linked immunosorbent assay was used to detect the concentration of inflammatory factors in the cell supernatant and serum of rats. ResultsAn isolated co-culture of HepG2/insulin-resistance cells and BMSCs promoted the adipogenic transformation of the latter and inhibited the transformation of BMSCs into osteogenesis. The PI3K specific agonist, 740Y-P, significantly increased the expression of PI3K, AKT, NLRP3, ASC and Caspase-1 while the PI3K specific inhibitor, LY294002, does the opposite. Additionally, CM-VitD reduced the expression of NLRP3, ASC, caspase-1, IL-1β, and IL-18 in BMSCs and rat liver via the PI3K/AKT pathway. ConclusionVitamin D can inhibit the inflammatory response induced by T2DM and promote the osteogenesis of BMSCs, which may play a key role in the treatment of type 2 diabetes patients with OP.

MiR-135 protects against atrial fibrillation by suppressing intracellular calcium-mediated NLRP3 inflammasome activation.

Atrial fibrillation (AF), one of the most common types of arrhythmias, is associated with high morbidity and mortality, seriously endangering human health. Inflammation is closely associated with AF development. Activation of the nucleotide-binding domain-like receptor protein 3 (NLRP3) inflammasome in cardiomyocytes has been shown to promote AF progression. Here, we demonstrate the effect of miR-135 on NLRP3 inflammasome and study the cardioprotective role of miR-135 in AF. We observed that overexpression of miR-135 in mice reduced the AFincidence and duration, and inhibited both excessive activation of NLRP3 inflammasome and the increased intracellular calcium release during AF. However, the inhibitory effect of miR-135 on AFwas partly abolished in the presence of a specific agonist of the calcium-sensing receptor (CaSR). We showed in the present study that miR-135 has a protective effect against AF by suppressing intracellular calcium-mediated NLRP3 inflammasome activation, suggesting the potential of miR-135as a therapeutic agent in thetreatment of AF.

FM1-43 Dye Memorizes Piezo1 Activation in the Trigeminal Nociceptive System Implicated in Migraine Pain.

It has been proposed that mechanosensitive Piezo1 channels trigger migraine pain in trigeminal nociceptive neurons, but the mechanosensitivity of satellite glial cells (SGCs) supporting neuronal sensitization has not been tested before. Moreover, tools to monitor previous Piezo1 activation are not available. Therefore, by using live calcium imaging with Fluo-4 AM and labeling with FM1-43 dye, we explored a new strategy to identify Piezo channels' activity in mouse trigeminal neurons, SGCs, and isolated meninges. The specific Piezo1 agonist Yoda1 induced calcium transients in both neurons and SGCs, suggesting the functional expression of Piezo1 channels in both types of cells. In Piezo1-transfected HEK cells, FM1-43 produced only a transient fluorescent response, whereas co-application with Yoda1 provided higher transient signals and a remarkable long-lasting FM1-43 'tail response'. A similar Piezo1-related FM1-43 trapping was observed in neurons and SGCs. The non-specific Piezo channel blocker, Gadolinium, inhibited the transient peak, confirming the involvement of Piezo1 receptors. Finally, FM1-43 labeling demonstrated previous activity in meningeal tissues 3.5 h after Yoda1 washout. Our data indicated that trigeminal neurons and SGCs express functional Piezo channels, and their activation provides sustained labeling with FM1-43. This long-lasting labelling can be used to monitor the ongoing and previous activation of Piezo1 channels in the trigeminal nociceptive system, which is implicated in migraine pain.

Ligand-dependent protein interactions of the juvenile hormone receptor captured in real time.

Juvenile hormone (JH) signalling provides vital regulatory functions during insect development via transcriptional regulation of genes critical for the progression of metamorphosis and oogenesis. Despite the importance of JH signalling, the underlying molecular mechanisms remain largely unknown. Our current understanding of the pathway depends on static end-point information and suffers from the lack of time-resolved data. Here, we have addressed the dynamic aspect of JH signalling by monitoring in real time the interactions of insect JH receptor proteins. Use of two tags that reconstitute a functional luciferase when in proximity enabled us to follow the rapid assembly of a JH receptor heterodimer from basic helix-loop-helix/Per-Arnt-SIM (bHLH-PAS) proteins, methoprene-tolerant (Met) and taiman (Tai), upon specific JH binding to Met. On a similar timescale (minutes), the dissociation of Met-Met complexes occurred, again strictly dependent on Met interaction with specific agonist ligands. To resolve questions regarding the regulatory role of the chaperone Hsp90/83 in the JHR complex formation, we used the same technique to demonstrate that the Met-Hsp83 complex persisted in the agonist absence but readily dissociated upon specific binding of JH to Met. Preincubation with the Hsp90 inhibitor geldanamycin showed that the chaperone interaction protected Met from degradation and was critical for Met to produce the active signalling dimer with Tai. Thus, the JH receptor functions appear to be governed by principles similar to those regulating the aryl hydrocarbon receptor, the closest vertebrate homologue of the arthropod JH receptor.

Agonist-controlled competition of RAR and VDR nuclear receptors for heterodimerization with RXR is manifested in their DNA binding

We found previously that nuclear receptors (NRs) compete for heterodimerization with their common partner, retinoid X receptor (RXR), in a ligand-dependent manner. To investigate potential competition in their DNA binding, we monitored the mobility of retinoic acid receptor (RAR) and vitamin D receptor (VDR) in live cells by fluorescence correlation spectroscopy. First, specific agonist treatment and RXR coexpression additively increased RAR DNA binding, while both agonist and RXR were required for increased VDR DNA binding, indicating weaker DNA binding of the VDR/RXR dimer. Second, coexpression of RAR, VDR, and RXR resulted in competition for DNA binding. Without ligand, VDR reduced the DNA-bound fraction of RAR and vice versa, i.e., a fraction of RXR molecules was occupied by the competing partner. The DNA-bound fraction of either RAR or VDR was enhanced by its own and diminished by the competing NR's agonist. When treated with both ligands, the DNA-bound fraction of RAR increased as much as due to its own agonist, whereas that of VDR increased less. RXR agonist also increased DNA binding of RAR at the expense of VDR. In summary, competition between RAR and VDR for RXR is also manifested in their DNA binding in an agonist-dependent manner: RAR dominates over VDR in the absence of agonist or with both agonists present. Thus, side effects of NR-ligand-based (retinoids, thiazolidinediones) therapies may be ameliorated by other NR ligands and be at least partly explained by reduced DNA binding due to competition. Our results also complement the model of NR action by involving competition both for RXR and for DNA sites.

PACAP-PAC1 receptor inhibition is effective in opioid induced hyperalgesia and medication overuse headache models

Opioids prescribed for pain and migraine can produce opioid-induced hyperalgesia (OIH) or medication overuse headache (MOH). We previously demonstrated that pituitary adenylate cyclase activating polypeptide (PACAP) is upregulated in OIH and chronic migraine models. Here we determined if PACAP acts as a bridge between opioids and pain chronification. We tested PACAP-PAC1 receptor inhibition in novel models of opioid-exacerbated trigeminovascular pain. The PAC1 antagonist, M65, reversed chronic allodynia in a model which combines morphine with the migraine trigger, nitroglycerin. Chronic opioids also exacerbated cortical spreading depression, a correlate of migraine aura; and M65 inhibited this augmentation. In situ hybridization showed MOR and PACAP co-expression in trigeminal ganglia, and near complete overlap between MOR and PAC1 in the trigeminal nucleus caudalis and periaqueductal gray. PACAPergic mechanisms appear to facilitate the transition to chronic headache following opioid use, and strategies targeting this system may be particularly beneficial for OIH and MOH.

GPR30 Alleviates Pressure Overload-Induced Myocardial Hypertrophy in Ovariectomized Mice by Regulating Autophagy.

The incidence of heart failure mainly resulting from cardiac hypertrophy and fibrosis increases sharply in post-menopausal women compared with men at the same age, which indicates a cardioprotective role of estrogen. Previous studies in our group have shown that the novel estrogen receptor G Protein Coupled Receptor 30 (GPR30) could attenuate myocardial fibrosis caused by ischemic heart disease. However, the role of GPR30 in myocardial hypertrophy in ovariectomized mice has not been investigated yet. In this study, female mice with bilateral ovariectomy or sham surgery underwent transverse aortic constriction (TAC) surgery. After 8 weeks, mice in the OVX + TAC group exhibited more severe myocardial hypertrophy and fibrosis than mice in the TAC group. G1, the specific agonist of GPR30, could attenuate myocardial hypertrophy and fibrosis of mice in the OVX + TAC group. Furthermore, the expression of LC3II was significantly higher in the OVX + TAC group than in the OVX + TAC + G1 group, which indicates that autophagy might play an important role in this process. An in vitro study showed that G1 alleviated AngiotensionII (AngII)-induced hypertrophy and reduced the autophagy level of H9c2 cells, as revealed by LC3II expression and tandem mRFP-GFP-LC3 fluorescence analysis. Additionally, Western blot results showed that the AKT/mTOR pathway was inhibited in the AngII group, whereas it was restored in the AngII + G1 group. To further verify the mechanism, PI3K inhibitor LY294002 or autophagy activator rapamycin was added in the AngII + G1 group, and the antihypertrophy effect of G1 on H9c2 cells was blocked by LY294002 or rapamycin. In summary, our results demonstrate that G1 can attenuate cardiac hypertrophy and fibrosis and improve the cardiac function of mice in the OVX + TAC group through AKT/mTOR mediated inhibition of autophagy. Thus, this study demonstrates a potential option for the drug treatment of pressure overload-induced cardiac hypertrophy in postmenopausal women.

Desmosterol: A natural product derived from macroalgae modulates inflammatory response and oxidative stress pathways in intestinal epithelial cells.

The serum level of cholesterol and its biosynthetic intermediates are critical indicators to access metabolism-related disorders in humans and animals. However, the molecular actions of these intermediates on gene functions and regulation remained elusive. Here, we show that desmosterol (DES) is the most abundant intermediate involved in cholesterol biosynthesis and is highly enriched in red/brown algae. It exerts a pivotal role in modulating core genes involved in oxidative stress and inflammatory response processes in the ileum epithelial cells (IPI-2I). We observed that the DES extracted from red algae did not affect IPI-2I cell growth or survival. A transcriptomic measurement revealed that the genes enrolled in the oxidative process and cholesterol homeostasis pathway were significantly down-regulated by DES treatment. Consistent with this notion, cellular reactive oxygen species (ROS) levels were markedly decreased in response to DES treatment. In contrast, key inflammatory genes including IL-6, TNF-α, and IFN-γ were remarkably upregulated in the RNA-seq analysis, as further confirmed by qRT-PCR. Given that DES is a specific agonist of nuclear receptor RORγ, we also found that DES caused the elevated expression of RORγ at mRNA and protein levels, suggesting it is a potential mediator under DES administration. Together, these results underscore the vital physiological actions of DES in inflammatory and oxidative processes possibly via RORγ, and may be helpful in anti-oxidation treatment and immunotherapy in the future.

LDL-Dependent Regulation of TNFα/PGE2 Induced COX-2/mPGES-1 Expression in Human Macrophage Cell Lines

Inflammation is a hallmark in severe diseases such as atherosclerosis and non-alcohol-induced steatohepatitis (NASH). In the development of inflammation, prostaglandins, especially prostaglandin E2 (PGE2), are major players alongside with chemo- and cytokines, like tumor-necrosis-factor alpha (TNFα) and interleukin-1 beta (IL-1β). During inflammation, PGE2 synthesis can be increased by the transcriptional induction of the two key enzymes: cyclooxygenase 2 (COX-2), which converts arachidonic acid to PGH2, and microsomal prostaglandin E2 synthase 1 (mPGES-1), which synthesizes PGE2 from PGH2. Both COX-2 and mPGES-2 were induced by a dietary intervention where mice were fed a fatty acid-rich and, more importantly, cholesterol-rich diet, leading to the development of NASH. Since macrophages are the main source of PGE2 synthesis and cholesterol is predominantly transported as LDL, the regulation of COX-2 and mPGES-1 expression by native LDL was analyzed in human macrophage cell lines. THP-1 and U937 monocytes were differentiated into macrophages, through which TNFα and PGE-2 induced COX-2 and mPGES-1 expression by LDL could be analyzed on both mRNA and protein levels. In addition, the interaction of LDL- and EP receptor signal chains in COX-2/mPGES-1 expression and PGE2-synthesis were analyzed in more detail using EP receptor specific agonists. Furthermore, the LDL-mediated signal transduction in THP-1 macrophages was analyzed by measuring ERK and Akt phosphorylation as well as transcriptional regulation of transcription factor Egr-1. COX-2 and mPGES-1 were induced in both THP-1 and U937 macrophages by the combination of TNFα and PGE2. Surprisingly, LDL dose-dependently increased the expression of mPGES-1 but repressed the expression of COX-2 on mRNA and protein levels in both cell lines. The interaction of LDL and PGE2 signal chains in mPGES-1 induction as well as PGE2-synthesis could be mimicked by through simultaneous stimulation with EP2 and EP4 agonists. In THP-1 macrophages, LDL induced Akt-phosphorylation, which could be blocked by a PI3 kinase inhibitor. Alongside blocking Akt-phosphorylation, the PI3K inhibitor inhibited LDL-mediated mPGES-1 induction; however, it did not attenuate the repression of COX-2 expression. LDL repressed basal ERK phosphorylation and expression of downstream transcription factor Egr-1, which might lead to inhibition of COX-2 expression. These findings suggest that simultaneous stimulation with a combination of TNFα, PGE2, and native LDL-activated signal chains in macrophage cell lines leads to maximal mPGES-1 activity, as well repression of COX-2 expression, by activating PI3K as well as repression of ERK/Egr-1 signal chains.

The TGR5 Agonist INT-777 Promotes Peripheral Nerve Regeneration by Activating cAMP-dependent Protein Kinase A in Schwann Cells.

Schwann cell (SC) myelination is a pivotal event in the normal physiological functioning of the peripheral nervous system (PNS), where myelination is finely controlled by a series of factors within SCs to ensure timely onset and correct myelin thickness for saltatory conduction. Among these, cyclic AMP (cAMP) is a promising factor for driving myelin gene expression in SCs. It has been shown that TGR5 activation is often associated with increased production of cAMP. Therefore, we speculated that the G-protein-coupled receptor (TGR5) might be involved in the PNS myelination. To test this hypothesis, sciatic nerve crush-injured mice were treated with INT-777, a specific agonist of TGR5, which significantly improved remyelination and functional recovery. Furthermore, rats that underwent sciatic nerve transection were treated with INT-777, which also promoted nerve regeneration and functional recovery. In primary SCs, the stimulatory effect of INT-777 on myelin gene expression was largely counteracted by H89, a potent inhibitor of cAMP-dependent protein kinase A (PKA). Additionally, INT-777 stimulated cell migration was blunted in the presence of H89. Overall, these data indicate that INT-777 is capable of promoting peripheral nerve regeneration and functional recovery after injury, and these benefits are likely due to the activation of the TGR5/cAMP/PKA axis. As such, INT-777, together with other TGR5 agonists, may hold great therapeutic potential for treating peripheral nerve injury.

Determining Endosomal Toll-Like Receptors Gene Expression in NK Cells After Stimulation with Specific Agonists.

Poor knowledge is currently available about the biology of Toll-like receptors (TLRs) in natural killer (NK) cells. This is particularly due to the old belief that NK cells are unable to specifically eliminate microbes without presensitization. On the contrary, it has been clearly demonstrated that not only they can be activated through the engagement of Toll-like receptors (TLRs) by microbial molecules, but also that this interaction induces NK cells to release cytokines that, in turn, activate other cells of both innate and adaptive immunity. For this reason, immunotherapy based on local infusion of TLRs ligands is currently considered as a novel potential strategy to treat solid tumors. Here, we provide a protocol to efficiently stimulate NK cells via endosomal TLRs agonists and to determine endosomal TLRs gene expression level. This protocol can be used for in vitro investigation into endosomal TLRs function in NK cells under different conditions.

Chapter 1 - History of migraine

Migraine symptoms were described in ancient Babylonia, and supernatural forces were felt to play a role in etiology and treatment. This changed in the Greco-Roman period, when the (dis)balance of humors was considered in (patho)physiology and treatment based on this. Aretaeus distinguished between cephalalgia, cephalea, and heterocrania. The latter term was changed to hemicrania by Galen. Physicians in the 17th century attributed headache to the meninges, extracranial periost, and cranial blood vessels. As for the pathophysiology, Willis suggested intracranial vasoconstriction with subsequent dilatation. Tissot and Fothergill gave comprehensive descriptions of migraine, including visual symptoms. Symptomatic and idiopathic hemicrania were distinguished in the early 19th century. Vasomotor pathophysiology was scientifically studied in the 1860s, leading to sympathicotonic and angioparalytic theories. Latham combined them, stating the latter follows the first. Ergot was introduced in 1868; ergotamine was isolated in 1918. This led to the vasodilatation theory of migraine (Wolff), the discovery of 5-HT, and later the specific agonists. Aura and cortical spreading depression were studied in the early 1940s and related to spreading oligemia in the 1980s. Subsequently, hyperemia followed by oligemia after CSD was found. After the discovery of CGRP, a new a class of drugs became the subject of clinical studies.

Chemical Activation of Piezo1 Alters Biomechanical Behaviors toward Relaxation of Cultured Airway Smooth Muscle Cells

Inspired by the well-known phenomenon of stretch-induced airway dilation in normal lungs and the emerging stretch-responsive Piezo1 channels that can be chemically activated by specific agonists such as Yoda1, we attempted to investigate whether chemical activation of Piezo1 by Yoda1 can modulate the biomechanical behaviors of airway smooth muscle cells (ASMCs) so that it may be exploited as a novel approach for bronchodilation. Thus, we treated in vitro cultured rat ASMCs with Yoda1, and examined the cells for calcium signaling, cell stiffness, traction force, cell migration, and the mRNA expression and distribution of molecules relevant to cell biomechanics. The data show that ASMCs expressed abundant mRNA of Piezo1. ASMCs exposed to 1 µM Yoda1 exhibited a potent but transient Ca2+ signaling, and treatment with 1 µM Yoda1 for 24 h led to decreased cell stiffness and traction force, all of which were partially reversed by Piezo1 inhibitor GsMTx4 and Piezo1 knockdown, respectively. In addition, ASMCs treated with 1 µM Yoda1 for 24 h exhibited impaired horizontal but enhanced vertical cell migration, as well as significant changes in key components of cells' contractile machinery including the structure and distribution of stress fibers and alpha-smooth muscle actin (α-SMA) fibrils, the mRNA expression of molecules associated with cell biomechanics. These results provide the first evidence that chemical activation of Piezo1 by Yoda1 resulted in marked pro-relaxation alterations of biomechanical behaviors and contractile machinery of the ASMCs. These findings suggest that Piezo1-specific agonists may indeed have great potential as alternative drug agents for relaxing ASMCs.

Pericyte Dysfunction Contributes to Vascular Cognitive Impairment Induced by Chronic Cerebral Hypoperfusion in Rats.

Vascular cognitive impairment (VCI) encompasses cognitive disorders associated with cerebrovascular disease, often manifesting as white matter lesions (WMLs), irrespective of precise triggers. The integrity of white matter is essential for neural communication and cognitive function maintenance. Persistent cerebral hypoperfusion-induced WMLs are now acknowledged as a key driver of VCI and dementia, though their exact formation mechanism remains unclear. Recent studies link pericyte dysfunction to diverse brain disorders like Alzheimer disease. However, the exact pathological connection between pericyte dysfunction and cognitive impairment in VCI remains unexplored. In this study, we aimed to examine whether pericyte dysfunction could impact WMLs and cognitive impairment in a rat VCI model. Using a rat model of chronic cerebral hypoperfusion-induced VCI through two-vessel occlusion (2VO), we verified that 2VO induced both WMLs and cognitive impairment. Notably, the number of pericytes in the brain was significantly altered after 2VO. Furthermore, we observed significantly increased capillary constrictions at pericyte bodies in the brains of 2VO-induced rats compared to sham-operated rats, accompanied by reduced cerebral blood flow (CBF). To tackle this issue, we administered CGS21680, a specific adenosine A2A subtype receptor agonist, intranasally twice a day for 7 days. We found that rats treated with CGS21680 exhibited a significant increase in CBF at 7 and 14 days after 2VO, compared to the vehicle group. Moreover, capillary lumens beneath pericytes also increased after the CGS21680 treatment. Importantly, the treatment led to substantial improvements in WMLs and cognitive impairment compared to the vehicle group. Our findings suggest a critical role of pericyte dysfunction in WMLs and cognitive impairment within the rat VCI model. This insight contributes to our understanding of pathogenesis and offers prospects for targeted intervention in VCI.

A review of neuroprotective mechanisms of dexmedetomidine

Dexmedetomidine (DEX) is a highly specific and effective α2-adrenergic receptor agonist. Due to its high protein binding rate, intravenous pumping can play a good role in sedation and hypnosis, analgesia, anti-anxiety, reducing inflammation, and so on, so it has been widely used in clinical anesthesia and basic research. In recent years, with the further study of dexmedetomidine, it has been found that it has a certain protective effect on nerve injury caused by various causes.

Avaliação do efeito antinociceptivo gerado por isômeros do monoterpeno citronelal

Due to the complex nature of pain and the participation of physical, cognitive, psychological and behavioral aspects, pain management has several approaches. The use of medicinal plants in developing countries is quite expressive. Seeking new options for the treatment of emerging or debilitating diseases. Therefore, the present study seeks to elucidate the effects of the monoterpene, citronellal, differentiating its activity by isomers (R)-(+) and (S)-(-) citronellal. The study used several methods to evaluate the effects of citronellal isomers on motor coordination, nociceptive response, and the involvement of opioid, glutamatergic, and transient receptor pathways. The methods included rota-rod, hot-plate, and formalin tests, as well as the use of specific inhibitors and agonists. Data were analyzed using inferential statistics with a 95% confidence level. Both isomers did not significantly affect the motor coordination of the studied animals. The isomer (S)-(-) citronellal showed better results in relation to its structural counterpart, managing to have an antinociceptive effect in the formalin and hot plate tests with a lower concentration (100 mg/kg) and presenting fewer side effects, however, the this study was not able to elucidate the mechanism of action of this isomer despite having activity in studies with substances that act on specific targets such as glutamate and capsaicin, its activity was not reversed with the use of antagonists for pathways related to nociception. While the (R)-(+) citronellal isomer, despite showing total activity only at a concentration of 150 mg/kg, was able to determine its mechanism of action related to the opioid pathway by reversing its activity by the antagonist naloxone, being this is a pathway already correlated with nociception control treatments, however, it is also related to some unwanted side effects. In this way, new studies are sought to elucidate the mechanism related to the isomer (S)-(-) citronellal and a possibility of use in other areas related to the treatment of pain or inflammation.

Reverse Engineering Drugs: Lorcaserin as an Example.

Novel central nervous system (CNS)-based therapies have been difficult to produce due to the complexity of the brain, limited knowledge of CNS-based disease development and associated pathways, difficulty in penetrating the blood brain barrier, and a lack of reliable biomarkers of disease. Reverse engineering in drug development allows the utilization of new knowledge of disease pathways and the use of innovative technology to develop medications with enhanced efficacy and reduced toxicities. Lorcaserin was developed as a specific 5HT2C serotonin receptor agonist for the treatment of obesity with limited off-target effects at the 5HT2A and 5HT2B receptors. This receptor specificity limited the hallucinogenic and cardiovascular side effects noted with other serotonin receptor agonists. Reverse engineering approaches to drug development reduce the cost of producing new medications, identify specific populations of patients that will derive the most benefit from therapy, and produce novel therapies with greater efficacy and limited toxicity.

MPRα and PR co-operate in progesterone inhibition of endothelial cell focal adhesion.

Progesterone causes vascular smooth muscle cell relaxation through membrane progesterone receptors (mPRs), which are members of the progestin and adipoQ receptor (PAQR) family, and nuclear PRs (nPRs). However, beneficial vascular effects of progesterone in preventing pre-atherosclerosis and the involvement of mPRs and nPRs remain unclear. The results show short- to long-term treatments with 100 nM progesterone (P4) and specific agonists for mPRs, OD 02-0, and nPRs, R5020, inhibited pre-atherosclerotic events in human umbilical vein endothelial cells (HUVECs), decreasing focal adhesion (FA) by monocytes, FA signaling, HUVEC migration and invasion, and vinculin expression. Progesterone and OD 02-0, but not R5020, inhibited phosphorylation of Src and focal adhesion kinase, critical kinases of FA signaling, within 20 min and migration and invasion of HUVECs and monocyte adhesion after 3 h. These inhibitory P4 and 02-0 effects were attenuated with MAP kinase and Pi3k inhibitors, indicating involvement of these kinases in this mPR-mediated action. However, after 16 h, OD 02-0 was no longer effective in inhibiting FA signaling, while both progesterone and R5020 decreased the activity of the two kinases. Knockdown of receptor expression with siRNA confirmed that mPRα mediates short-term and nPR long-term inhibitory effects of progesterone on FA signaling. Thus, progesterone inhibition of FA signaling and pre-atherosclerosis is coordinated through mPRα and nPRs.

Metabotropic glutamate receptors and cognition: From underlying plasticity and neuroprotection to cognitive disorders and therapeutic targets.

Metabotropic glutamate (mGlu) receptors are G protein-coupled receptors that play pivotal roles in mediating the activity of neurons and other cell types within the brain, communication between cell types, synaptic plasticity, and gene expression. As such, these receptors play an important role in a number of cognitive processes. In this chapter, we discuss the role of mGlu receptors in various forms of cognition and their underlying physiology, with an emphasis on cognitive dysfunction. Specifically, we highlight evidence that links mGlu physiology to cognitive dysfunction across brain disorders including Parkinson's disease, Alzheimer's disease, Fragile X syndrome, post-traumatic stress disorder, and schizophrenia. We also provide recent evidence demonstrating that mGlu receptors may elicit neuroprotective effects in particular disease states. Lastly, we discuss how mGlu receptors can be targeted utilizing positive and negative allosteric modulators as well as subtype specific agonists and antagonist to restore cognitive function across these disorders.