Alpha-2a adrenergic receptor activation in genetic absence epilepsy: An absence status model?

OBJECTIVE

The objective of the study was to propose a candidate animal model of absence status epilepticus induced by specific alpha-2a adrenergic receptor (α2AR) activation. We also aim to investigate the responsiveness of this model to classical anti-status or anti-absence medications.

METHODS

An α2AR agonist, dexmedetomidine (DEX), was injected intracerebroventricularly into adult rats with genetic absence epilepsy, and their electroencephalography (EEG) was recorded. The total duration, number, and mean duration of each spike-and-wave discharges (SWDs) were evaluated. The blocks of absence status events were classified as the initial and second sets of absence statuses. Ethosuximide (ETX) was administered as a pretreatment to another group of rats and later injected with 2.5 μg DEX. In addition, ETX, valproic acid (VPA), diazepam (DIAZ), and atipamezole (ATI) were administered after induced status-like events following DEX administration. Power spectral characteristics and coherence analysis were performed on the EEG to assess the absence status events and sleep.

RESULTS

The 2.5 μg dose of DEX increased the total SWD duration and induced continuous SWDs up to 26 min. Following the initial absence status event, sleep was induced; then, the second period of absence status-like activities were initiated. ETX pretreatment blocked the occurrence of absence status-like activities. Power spectral density analyses revealed that DEX-induced post-sleep activities had higher power in delta frequency band (1-4 Hz) and attenuated power of 7 Hz harmonics (14 and 21 Hz) than the pre-injection seizure. The mean duration of SWDs were decreased in all the groups, but occasional prolonged activities were seen in ETX or VPA-injected rats but not with DIAZ or ATI.

SIGNIFICANCE

This study presents an absence status epilepticus animal model that is activated by α2AR activation to investigate the pathophysiological role of absence status. Unlike other agents ATI switched off the second set of absence statuses to normal SWDs, without sedation or lethargy, can show it may preferentially block absence status-like activity.

THE PLAIN LANGUAGE SUMMARY

This study proposes a rat model for prolonged seizures, resembling absence status epilepticus. Activating the brain's alpha-2a adrenergic receptor with dexmedetomidine induced seizures lasting up to 26 minutes. Ethosuximide pretreatment and post-treatment with valproic acid, diazepam, and atipamezole decreased induced seizures. The findings suggest this model is valuable for studying absence status epilepticus. In addition, atipamezole normalized abnormal seizures without sedation, hinting at its potential for targeted treatment and further research.

Sympathetic activity regulates epithelial proliferation and wound healing via adrenergic receptor α2A

Innervation of the intestinal mucosa by the sympathetic nervous system is well described but the effects of adrenergic receptor stimulation on the intestinal epithelium remain equivocal. We therefore investigated the effect of sympathetic neuronal activation on intestinal cells in mouse models and organoid cultures, to identify the molecular routes involved. Using publicly available single-cell RNA sequencing datasets we show that the α2A isoform is the most abundant adrenergic receptor in small intestinal epithelial cells. Stimulation of this receptor with norepinephrine or a synthetic specific α2A receptor agonist promotes epithelial proliferation and stem cell function, while reducing differentiation in vivo and in intestinal organoids. In an anastomotic healing mouse model, adrenergic receptor α2A stimulation resulted in improved anastomotic healing, while surgical sympathectomy augmented anastomotic leak. Furthermore, stimulation of this receptor led to profound changes in the microbial composition, likely because of altered epithelial antimicrobial peptide secretion. Thus, we established that adrenergic receptor α2A is the molecular delegate of intestinal epithelial sympathetic activity controlling epithelial proliferation, differentiation, and host defense. Therefore, this receptor could serve as a newly identified molecular target to improve mucosal healing in intestinal inflammation and wounding.

ADRA2A and IRX1 are putative risk genes for Raynaud's phenomenon

Raynaud's phenomenon (RP) is a common vasospastic disorder that causes severe pain and ulcers, but despite its high reported heritability, no causal genes have been robustly identified. We conducted a genome-wide association study including 5,147 RP cases and 439,294 controls, based on diagnoses from electronic health records, and identified three unreported genomic regions associated with the risk of RP (p < 5 × 10-8). We prioritized ADRA2A (rs7090046, odds ratio (OR) per allele: 1.26; 95%-CI: 1.20-1.31; p < 9.6 × 10-27) and IRX1 (rs12653958, OR: 1.17; 95%-CI: 1.12-1.22, p < 4.8 × 10-13) as candidate causal genes through integration of gene expression in disease relevant tissues. We further identified a likely causal detrimental effect of low fasting glucose levels on RP risk (rG = -0.21; p-value = 2.3 × 10-3), and systematically highlighted drug repurposing opportunities, like the antidepressant mirtazapine. Our results provide the first robust evidence for a strong genetic contribution to RP and highlight a so far underrated role of α2A-adrenoreceptor signalling, encoded at ADRA2A, as a possible mechanism for hypersensitivity to catecholamine-induced vasospasms.

A pilot study of ADRA2A genotype association with doses of dexmedetomidine for sedation in pediatric patients

STUDY OBJECTIVE

Dexmedetomidine is titrated to achieve sedation in the pediatric and cardiovascular intensive care units (PICU and CVICU). In adults, dexmedetomidine response has been associated with an ADRA2A polymorphism (rs1800544); CC genotype is associated with an increased sedative response compared with GC and GG. To date, this has not been studied in children.

DESIGN

We conducted a pilot study to determine whether ADRA2A genotype is associated with dexmedetomidine dose in children.

MEASUREMENTS AND MAIN RESULTS

Forty intubated PICU or CVICU patients who received dexmedetomidine as a continuous infusion for at least 2 days were genotyped for ADRA2A with a custom-designed TaqMan® Assay. Ten (25%) subjects were wildtype (GG), 15 (37.5%) were heterozygous (GC), and 15 (37.5%) were homozygous (CC) variant. The maximum dexmedetomidine doses (mCg/kg/h) were not different between genotype groups CC (1, 0.3-1.2), GC (1, 0.3-1.3), and GG (0.8, 0.3-1.2), (p = 0.37); neither were mean dexmedetomidine doses for these respective genotype groups 0.68 (0.24-1.07), 0.72 (0.22-0.98), 0.58 (0.3-0.94), (p = 0.67).

CONCLUSIONS

These findings did not confirm the results from adult studies where ADRA2A polymorphisms correlate with dexmedetomidine response, therefore highlighting the need for pediatric studies to validate PGx findings in adults prior to implementation in pediatrics.

Genetic biomarkers of life-threatening pheochromocytoma-induced cardiomyopathy

The release of excessive amounts of catecholamine by pheochromocytoma-paragangliomas (PPGL) can lead to life-threatening catecholamine-induced cardiomyopathy (CIC). Single-nucleotide polymorphisms of the beta1 and alpha-2c adrenergic receptors alter myocyte receptor function and enhanced norepinephrine release. We tested the hypothesis that such genetic variations may impact the risk of developing CIC in the context of PPGL. Thirty-one patients with PPGL, including nine with a history of CIC, were analyzed for alpha-2-adrenergic receptors: ADRA2C, beta-1 and beta-2 adrenergic receptors: ADRB1 and ADRB2 genotyping. CIC was defined either by a history of heart failure or cardiogenic shock associated with dilated or Takotsubo cardiomyopathy. Subjects were genotyped for ADRA2C (rs61767072 for del322_325), ADRB1 (rs1801252 for Ser49Gly and rs1801253 for Arg389Gly) and ADRB2 (rs1042713 for Arg16Gly and rs1042714 for Gln27Glu). Single-locus analysis revealed that variant in ADRA2C (alpha 2CDel322-325) was more common among patients with CIC than among controls (allele frequency, 0.44 vs 0.05; P< 0.001). The lack of alpha 2CDel322-325 polymorphism has a negative predictive value of 95% for the onset of CIC. In a replication cohort including 26 patients with PPGL whom eight have developed a CIC, the association between Alpha 2CDel322-325 and CIC was confirmed (allele frequency, 0.33 vs 0.; P= 0.0001). In conclusion, Alpha 2CDel322-325 through the identification of patients at low risk of developing CIC can help physicians to better determine the most appropriate therapeutic approach, notably in patients at high risk of surgical complications.

Sympathetic Denervation Ameliorates Renal Fibrosis via Inhibition of Cellular Senescence

Objective

Continuous overactivation of the renal sympathetic nerve is considered to be an important cause of renal fibrosis. Accumulated senescent cells in the damaged kidney have metabolic activities and secrete amounts of proinflammatory factors as part of the SASP (the senescence-associated secretory phenotype), which induce chronic inflammation and fibrosis. It is still unclear whether renal sympathetic nerves affect renal inflammation and fibrosis by regulating cellular senescence. Therefore, we hypothesize that sympathetic activation in the injured kidney induces cellular senescence, which contributes to progressive renal inflammation and fibrosis.

Methods

Renal denervation was performed 2 days before the UUO (unilateral ureteral obstruction) and UIRI (unilateral ischemia-reperfusion injury) models. The effects of renal denervation on renal fibrosis and cellular senescence were observed. In vitro, cellular senescence was induced in renal proximal tubular epithelial cell lines (TKPTS cells) by treatment with norepinephrine (NE). The selective α_2A-adrenergic receptor (α_2A-AR) antagonists BRL44408 and β-arrestin2 siRNA, were administered to inhibit NE-induced cellular senescence. A significantly altered pathway was identified through immunoblotting, immunofluorescence, immunocytochemistry, and functional assays involved in mitochondrial function.

Results

Renal fibrosis and cellular senescence were significantly increased in UUO and UIRI models, which were partially reversed by renal denervation. In vitro, NE induced epithelial cells secreting proinflammatory cytokines and promoted cell senescence by activating α_2A-AR. Importantly, the effects of NE during cellular senescence were blocked by α_2A-AR selective antagonist and β-arrestin2 (downstream of α_2A-AR) siRNA.

Conclusion

Renal sympathetic activation and cellular senescence are important neurometabolic and neuroimmune mechanisms in the development of renal fibrosis. Renal sympathetic neurotransmitter NE acting on the α_2A-AR of epithelial cells promotes cellular senescence through the downstream β-arrestin2 signaling, which is a potential preventive target for renal fibrosis.

Role of α2-Adrenoceptor Subtypes in Suppression of L-Type Ca2+ Current in Mouse Cardiac Myocytes

Sarcolemmal α2 adrenoceptors (α2-AR), represented by α2A, α2B and α2C isoforms, can safeguard cardiac muscle under sympathoadrenergic surge by governing Ca²⁺ handling and contractility of cardiomyocytes. Cardiomyocyte-specific targeting of α2-AR would provide cardiac muscle-delimited stress control and enhance the efficacy of cardiac malfunction treatments. However, little is known about the specific contribution of the α2-AR subtypes in modulating cardiomyocyte functions. Herein, we analyzed the expression profile of α2A, α2B and α2C subtypes in mouse ventricle and conducted electrophysiological antagonist assay evaluating the contribution of these isoforms to the suppression of L-type Ca²⁺ current (I_CaL). Patch-clamp electro-pharmacological studies revealed that the α2-agonist-induced suppression of I_CaL involves mainly the α2C, to a lesser extent the α2B, and not the α2A isoforms. RT-qPCR evaluation revealed the presence of adra2b and adra2c (α2B and α2C isoform genes, respectively), but was unable to identify the expression of adra2a (α2A isoform gene) in the mouse left ventricle. Immunoblotting confirmed the presence only of the α2B and the α2C proteins in this tissue. The identified α2-AR isoform-linked regulation of I_CaL in the mouse ventricle provides an important molecular substrate for the cardioprotective targeting.

Alpha-2 beta-adrenergic receptor (301-303 I/D) gene polymorphism in hypertension and type 2 diabetes mellitus diseases among Saudi cases in the Qassim region

The hypertension (HTN) and type 2 diabetes mellitus (T2DM) are a common multifactorial disease due to genetics and environmental factors. The alpha 2B adrenergic receptor (α2B-AR) has relationship with secretion of insulin and mediates the vasoconstriction that elevate blood pressure. This study aimed to determine the association between α2B-AR gene polymorphism with HTN and T2DM in Saudi cases. 200 cases and 100 healthy controls from Saudi population were recruited from the Internal Medicine clinic, Qassim University. The patients were grouped into: 72 HTN without T2DM; 62 HTN with T2DM and 66 T2DM only. Full medical history, examination and biochemical assays were performed for all participants. Genomic DNA was isolated from blood lymphocytes of all subjects for detection of α2B-AR gene polymorphism by using polymerase chain reaction (PCR). The results found a significant association between D carriers genotype and HTN with T2DM cases (p < 0.05) as well as with T2DM-only cases, (p < 0.05) compared to control. Regardless of HTN status, only cases with HTN and T2DM as well as those with T2DM were significantly associated with the recessive model DD versus II+ID (p < 0.05). So, D carriers genotype was significantly associated with total cases of HTN and T2DM (p < 0.05) compared to controls. Our results suggested that there is a relationship between the α2B-AR I/D gene polymorphism and the risk for T2DM with or without HTN, but no such comparable relationship is evident with HTN-only cases among Saudi population in Qassim region.

α2-Adrenergic Receptor in Liver Fibrosis: Implications for the Adrenoblocker Mesedin

The noradrenergic system is proposed to play a prominent role in the pathogenesis of liver fibrosis. While α1- and β-adrenergic receptors (ARs) are suggested to be involved in a multitude of profibrogenic actions, little is known about α2-AR-mediated effects and their expression pattern during liver fibrosis and cirrhosis. We explored the expression of α2-AR in two models of experimental liver fibrosis. We further evaluated the capacity of the α2-AR blocker mesedin to deactivate hepatic stellate cells (HSCs) and to increase the permeability of human liver sinusoidal endothelial cells (hLSECs). The mRNA of α2a-, α2b-, and α2c-AR subtypes was uniformly upregulated in carbon tetrachloride-treated mice vs the controls, while in bile duct-ligated mice, only α2b-AR increased in response to liver injury. In murine HSCs, mesedin led to a decrease in α-smooth muscle actin, transforming growth factor-β and α2a-AR expression, which was indicated by RT-qPCR, immunocytochemistry, and Western blot analyses. In a hLSEC line, an increased expression of endothelial nitric oxide synthase was detected along with downregulated transforming growth factor-β. In conclusion, we suggest that the α2-AR blockade alleviates the activation of HSCs and may increase the permeability of liver sinusoids during liver injury.

An ɑ2-adrenergic receptor is involved in larval metamorphosis in the mussel, Mytilus coruscus

Metamorphosis is crucial in the life-cycle transition between the larval and juvenile stages of marine invertebrates. Although a number of agonists and antagonists of the adrenergic receptor (AR) are known to regulate larval metamorphosis in Mytilus coruscus (Mc), the molecular basis of the modulation of larval metamorphosis by the AR gene in this species remains elusive. Herein, the role of the AR gene in M. coruscus larval metamorphosis using the RNA interference technique was examined. The Mcα₂AR transcript was observed to be present during the entire process of larval development and its level in the post-larvae was significantly increased compared to that in the pediveligers. Mcα₂AR-knockdown resulted in a substantial reduction in the abundance of the Mcα₂AR transcript and significantly inhibited the metamorphosis of M. coruscus larvae. These findings provide new insights into the molecular basis of modulation of larval metamorphosis in M. coruscus by the AR gene.

A Genetically Encoded Fluorescent Sensor for Rapid and Specific In Vivo Detection of Norepinephrine

Norepinephrine (NE) is a key biogenic monoamine neurotransmitter involved in a wide range of physiological processes. However, its precise dynamics and regulation remain poorly characterized, in part due to limitations of available techniques for measuring NE in vivo. Here, we developed a family of GPCR activation-based NE (GRABNE) sensors with a 230% peak ΔF/F0 response to NE, good photostability, nanomolar-to-micromolar sensitivities, sub-second kinetics, and high specificity. Viral- or transgenic-mediated expression of GRABNE sensors was able to detect electrical-stimulation-evoked NE release in the locus coeruleus (LC) of mouse brain slices, looming-evoked NE release in the midbrain of live zebrafish, as well as optogenetically and behaviorally triggered NE release in the LC and hypothalamus of freely moving mice. Thus, GRABNE sensors are robust tools for rapid and specific monitoring of in vivo NE transmission in both physiological and pathological processes.

Prenatal Tobacco Exposure Modulated the Association of Genetic variants with Diagnosed ADHD and its symptom domain in children: A Community Based Case-Control Study

The purpose of our study was to test the hypothesis that prenatal tobacco smoking exposure (PSE) could modulate the association of genetic variants with ADHD. A community based case-control study was conducted among Chinese children and 168 ADHD patients and 233 controls were recruited by using combination diagnosis of DSM-IV, SNAP-IV and semi-structured clinical interview. Logistic regression analysis was performed to estimate the effect of prenatal tobacco smoking exposure and genotype frequencies on ADHD susceptibility individually by adjustment for potential confounders. Multiplicative and additive interaction analysis were performed to evaluate the interactions between risk genes and PSE with regard to ADHD. Prenatal tobacco smoke exposure was a significant risk factor of ADHD even after adjusted for other potential confounders. ADRA2A rs553668, DRD2 rs1124491 and SLC6A4 rs6354 were identified to be associated with ADHD. A significant multiplicative and additive gene-environment interactions were observed between the PSE and the ADRA2A rs553668 in relation to ADHD and ADHD-ODD. The risk of the genetic variants in ADHD was increased significantly if the child had prenatal tobacco exposure. The genetic risk for ADHD could be influenced by the presence of environmental risks. The environmental and the genetic risks are not distinct to each other. More gene-environment interaction studies were needed to reveal the etiology of ADHD.

Strategies to Treat Chronic Pain and Strengthen Impaired Descending Noradrenergic Inhibitory System

Gabapentinoids (gabapentin and pregabalin) and antidepressants (tricyclic antidepressants and serotonin noradrenaline reuptake inhibitors) are often used to treat chronic pain. The descending noradrenergic inhibitory system from the locus coeruleus (LC) to the dorsal horn of the spinal cord plays an important role in the analgesic mechanisms of these drugs. Gabapentinoids activate the LC by inhibiting the release of γ-aminobutyric acid (GABA) and inducing the release of glutamate, thereby increasing noradrenaline levels in the spinal cord. Antidepressants increase noradrenaline levels in the spinal cord by inhibiting reuptake, and accumulating noradrenaline inhibits chronic pain through α₂-adrenergic receptors in the spinal cord. Recent animal studies, however, revealed that the function of the descending noradrenergic inhibitory system is impaired in chronic pain states. Other recent studies found that histone deacetylase inhibitors and antidepressants restore the impaired noradrenergic descending inhibitory system acting on noradrenergic neurons in the LC.

Dexmedetomidine Attenuates Orthotopic Liver Transplantation-Induced Acute Gut Injury via α 2-Adrenergic Receptor-Dependent Suppression of Oxidative Stress

Patients with orthotopic liver transplantation (OLT) frequently develop acute gut injury (AGI), and dexmedetomidine (Dex) has been reported to exert a protective effect against AGI. We investigated whether Dex protects against AGI through antioxidative stress effects by the Nrf2/HO-1 antioxidative signaling pathway. Rats were randomly allocated into a sham group and six orthotopic autologous liver transplantation (OALT) groups receiving different doses of Dex together with/without α ₂-adrenergic receptor (AR) blockers. Intestinal tissues were collected to visualize the barrier damage and to measure the indexes of oxidative stress. For in vitro studies, rat intestinal recess epithelial cells (IEC-6) underwent hypoxia/reoxygenation (H/R), and the protective role of Dex was evaluated after α _2A-AR siRNA silencing. OALT resulted in increased oxidative stress, significant intestinal injury, and barrier dysfunction. Dex attenuated OALT-induced oxidative stress and intestinal injury, which was abolished by the pretreatment with the nonspecific α _2A-AR siRNA blocker atipamezole and the specific α _2A-AR siRNA blocker BRL-44408, but not by the specific _2B/C-AR siRNA blocker ARC239. Silencing of α _2A-AR siRNA also attenuated the protective role of Dex on alleviating oxidative stress in IEC-6 cells subjected to H/R. Dex exerted its protective effects by activating Nrf2/HO-1 antioxidative signaling. Collectively, Dex attenuates OALT-induced AGI via α _2A-AR-dependent suppression of oxidative stress, which might be a novel potential therapeutic target for OALT-induced AGI.

Melatonin modulate the expression of α1- and β2-adrenoceptors in the hippocampus of rats subjected to unpredictable chronic mild stress

OBJECTIVE

This study investigated the effects of chronic melatonin treatment on gene expression of α1-, α2-, β1- and β2-adrenoceptors in the hippocampus of rats subjected to chronic unpredictable mild stress (CUMS).

BACKGROUND

Preclinical studies have also shown that melatonin prevented short- and long-term memory impairments and exhibited antidepressant-like actions.

METHODS

For this study, we used 24 animals, which were divided into four groups, and the experiment lasted 4 weeks. We quantified the changes in mRNA and protein levels of α1-, α2-, β1- and β2-adrenoceptors in the hippocampus after melatonin treatment.

RESULTS

Our results demonstrated a decreased gene expression of α1-, α2- and β2-adrenoceptors in the hippocampus of rats subjected to unpredictable chronic mild stress, while there was no change in gene expression of β1-adrenoceptors. Melatonin treatment in the CUMS rats prevented the stress-induced decrease in mRNA and protein levels of α1-and β2-adrenoceptors, whereas did not affect either on mRNA or protein level of β1-and α2-adrenoceptors.

CONCLUSION

Our data suggest that melatonin, by increasing reduced levels of α1- and β2-adrenoceptors mRNA and protein in the hippocampus of chronic stressed rats, may be beneficial in conditions such as chronic stress and provides an experimental opportunity to probe into further molecular mechanisms underlying the regulation of these receptor subtype (Fig. 2, Ref. 28).

[Left Ventricular Myocardial Hypertrophy as a Result of Arterial Hypertension Among Mountain Shoria Population. The Role of Genetic Polymorphism]

OBJECTIVE

to establish associations of candidate genes ACE, AGT, AGTR1, ADRB1, ADRA2B, MTHFR and NOS3 polymorphisms with left ventricular myocardial hypertrophy (LVH) in patients with arterial hypertension (AH) among the indigenous (the Shors) and non-indigenous population of Mountain Shoria.

MATERIALS AND METHODS

We examined 788 people in a clinical and epidemiological study of compactly living population in the remote areas of Mountain Shoria, located in the south of Western Siberia (468 members of indigenous ethnic group [the Shors], 320 members of non-indigenous ethnic group [90% Caucasian]). Diagnosis of AH was set in accordance with recommendations of Society of Cardiology of the Russian Federation/Medical Society of the Russian Federation on the Problem of Arterial Hypertension (RMOAG) (2010). Assessment of the structural and functional state of myocardium in patients with AH (n=201 among Shors and 158 among non-indigenous residents) was made by echocardiography. The polymorphisms of genes ACE (I/D, rs 4340), АGT (c.803T>C, rs699), AGTR1 (А1166С, rs5186), ADRB1 (с.145A>G, Ser49Gly, rs1801252), ADRA2B (I/D, rs 28365031), MTHFR (c.677С>Т, Ala222Val, rs1801133) and NOS3 (VNTR, 4b/4a) were tested by PCR.

RESULTS

Among patients with AH LVH occurred more often within the indigenous (Shor) than in non-indigenous (non-Shor) ethnic group (51.5 vs 42.2%, respectively, p=0.034). The frequency of homozygous genotype I/I of the ACE gene among AH patients with LVH in the Shor group was higher than in the non-Shor group (41.2 vs 19.3%, p=0.004). The prevalence of mutant genotype A/A of the ADRB1 gene was lower in the Shor compared to non-Shor group (53.6 vs 75.0%, p=0.014). The percentage of the carriers of prognostically favorable genotype 4b/4b of the NOS3 gene was higher in Shor than in non-Shor group (71.9 vs 52.7%, p=0.018), while the percentage of homozygous genotype 4a/4a carriers in the Shor group was lower (2.1% vs 18.2%, p=0.008).

CONCLUSION

The following studied genes were found to be associated of with LVH: in the Shor cohort - the MTHFR gene (log additive model of inheritance), the A/G genotype of the ADRB1 gene (among people with normal body weight), the I/D genotype of the ACE gene (among men); in the non-indigenous cohort - D/D genotype of the ACE gene (the codominant model of inheritance), the NOS3 gene (the log additive model of inheritance).

PtdIns(4,5)P2 stabilizes active states of GPCRs and enhances selectivity of G-protein coupling

G-protein-coupled receptors (GPCRs) are involved in many physiological processes and are therefore key drug targets1. Although detailed structural information is available for GPCRs, the effects of lipids on the receptors, and on downstream coupling of GPCRs to G proteins are largely unknown. Here we use native mass spectrometry to identify endogenous lipids bound to three class A GPCRs. We observed preferential binding of phosphatidylinositol-4,5-bisphosphate (PtdIns(4,5)P2) over related lipids and confirm that the intracellular surface of the receptors contain hotspots for PtdIns(4,5)P2 binding. Endogenous lipids were also observed bound directly to the trimeric Gαsβγ protein complex of the adenosine A2A receptor (A2AR) in the gas phase. Using engineered Gα subunits (mini-Gαs, mini-Gαi and mini-Gα12)2, we demonstrate that the complex of mini-Gαs with the β1 adrenergic receptor (β1AR) is stabilized by the binding of two PtdIns(4,5)P2 molecules. By contrast, PtdIns(4,5)P2 does not stabilize coupling between β1AR and other Gα subunits (mini-Gαi or mini-Gα12) or a high-affinity nanobody. Other endogenous lipids that bind to these receptors have no effect on coupling, highlighting the specificity of PtdIns(4,5)P2. Calculations of potential of mean force and increased GTP turnover by the activated neurotensin receptor when coupled to trimeric Gαiβγ complex in the presence of PtdIns(4,5)P2 provide further evidence for a specific effect of PtdIns(4,5)P2 on coupling. We identify key residues on cognate Gα subunits through which PtdIns(4,5)P2 forms bridging interactions with basic residues on class A GPCRs. These modulating effects of lipids on receptors suggest consequences for understanding function, G-protein selectivity and drug targeting of class A GPCRs.

α2A-adrenergic blockade attenuates septic cardiomyopathy by increasing cardiac norepinephrine concentration and inhibiting cardiac endothelial activation

Cardiomyopathy is a common complication associated with increased mortality in sepsis, but lacks specific therapy. Here, using genetic and pharmacological approaches, we explored the therapeutic effect of α_2A-adrenergic receptor (AR) blockade on septic cardiomyopathy. CLP-induced septic rats were treated with BRL44408 (α_2A-AR antagonist), prazosin (α₁-AR antagonist) and/or reserpine. CLP-induced cardiomyopathy, indicated by reduced dP/dt and increased cardiac troponin I phosphorylation, was attenuated by BRL44408, this was associated with reduced cardiac TNF-α and endothelial VCAM-1 expression, cardiomyocyte apoptosis and related signal molecule phosphorylation. BRL44408 increased cardiac norepinephrine (NE) concentration in CLP rats. Pretreatment with reserpine that exhausts cardiac NE without affecting the circulating NE concentration or with prazosin partially abolished the cardioprotection of BRL44408 and reversed its inhibitory effects on myocardial TNF-α, apoptosis and related signal molecule phosphorylation, but not on VCAM-1 expression in septic rats. These effects of BRL44408 were confirmed by α_2A-AR gene deletion in septic mice. Furthermore, α₂-AR agonist not only enhanced LPS-induced TNF-α and VCAM-1 expression in cardiac endothelial cells that express α_2A-AR, but also enhanced LPS-induced cardiac dysfunction in isolated rat hearts. Our data indicate that α_2A-AR blockade attenuates septic cardiomyopathy by promoting cardiac NE release that activates myocardial α₁-AR and suppressing cardiac endothelial activation.

Selection on the regulation of sympathetic nervous activity in humans and chimpanzees

Adrenergic α2C receptor (ADRA2C) is an inhibitory modulator of the sympathetic nervous system. Knockout mice for this gene show physiological and behavioural alterations that are associated with the fight-or-flight response. There is evidence of positive selection on the regulation of this gene during chicken domestication. Here, we find that the neuronal expression of ADRA2C is lower in human and chimpanzee than in other primates. On the basis of three-dimensional chromatin structure, we identified a cis-regulatory region whose DNA sequences have been significantly accelerated in human and chimpanzee. Active histone modification marks this region in rhesus macaque but not in human and chimpanzee; instead, repressive marks are enriched in various human brain samples. This region contains two neuron-restrictive silencer factor (NRSF) binding motifs, each of which harbours a polymorphism. Our genotyping and analysis of population genome data indicate that at both polymorphic sites, the derived allele has reached fixation in humans and chimpanzees but not in bonobos, whereas only the ancestral allele is present among macaques. Our CRISPR/Cas9 genome editing and reporter assays show that both derived nucleotides repress ADRA2C, most likely by increasing NRSF binding. In addition, we detected signatures of recent positive selection for lower neuronal ADRA2C expression in humans. Our findings indicate that there has been selective pressure for enhanced sympathetic nervous activity in the evolution of humans and chimpanzees.

Multiplate® evaluation of acetylsalicylic acid efficacy in carotid surgery: routine and genetic influencing factors

Essentials Acetylsalicylic acid (ASA) is prescribed to patients scheduled for carotid endarterectomy (CEA). We measured ASA efficacy during CEA by Multiplate® and searched for influencing factors. Most patients scheduled for CEA and treated by ASA are sensitive to this therapy. Influencing genomic factors are involved in ASA metabolism and in platelet function modulations.

SUMMARY

Background Acetylsalicylic acid (ASA) is recommended before, during and after carotid endarterectomy (CEA). The efficacy of ASA is influenced by numerous biological and genotypic factors. Objectives To determine the biological efficacy of ASA by using the Multiplate® method, and to explore the biological parameters and genomic factors influencing this efficacy. Methods This descriptive cross-sectional study included all patients scheduled for CEA between January 2012 and April 2013. Multiplate® tests were performed at day 0 and day 30. A set of 66 single-nucleotide polymorphisms (SNPs) from 38 genes or DNA regions were selected and studied along with phenotypic parameters by the use of hierarchical clustering (HC) for multidimensional data management. Results Fifty-five patients receiving ASA were analyzed. Of the patients, 95% were found to be sensitive to ASA, with values under the threshold of normality (400 AU min-1 ). However, there were notable differences in residual aggregation among subjects over a wide range. HC revealed four subclusters comprising three categories of parameters: (i) routine and functional parameters - in ASA-treated patients, the ASPItest was highly linked to the ADPtest, to platelet count, and, to a lesser extent, to fibrinogen and hematocrit; (ii) polymorphisms in genes involved in ASA absorption and in the arachidonic acid pathway (ABCB1 and COX-1); and (iii) polymorphisms in genes modulating basal platelet function, i.e. TBXA2R, ADRA2A, PEAR1, ITGA2 and ITGB1. Conclusion Most patients treated with ASA before CEA were sensitive to it, according to Multiplate® ASPItest results. Genomic factors influencing this efficacy are SNPs involved in ASA absorption and metabolic pathway, and in modulations in basal platelet function.

Increased Energy Expenditure, Lipolysis and Hyperinsulinemia Confer Resistance to Central Obesity and Type 2 Diabetes in Mice Lacking Alpha2α-Adrenoceptors

The alpha2A-adrenoceptors (α2A-ARs) are Gi-coupled receptors, which prejunctionally inhibit the release of norepinephrine (NE) and epinephrine (Epi), and postjunctionally inhibit insulin secretion and lipolysis. We have earlier shown that α2A-/- mice display sympathetic hyperactivity, hyperinsulinemia and improved glucose tolerance. Here we employed α2A-/- mice and placed the mice on a high-fat diet (HFD) to test the hypothesis that lack of α2A-ARs protects from diet-induced obesity and type 2 diabetes (T2D). In addition, a high-caloric diet was combined with running wheel exercise to test the interaction of diet and exercise. HFD was obesogenic in both genotypes, but α2A-/- mice accumulated less visceral fat than the wild-type controls, were protected from T2D, and their insulin secretion was unaltered by the diet. Lack of α2A-ARs is associated with an increased sympatho-adrenal tone, which resulted in increased energy expenditure and fat oxidation rate potentiated by HFD. Fittingly, α2A-/- mice displayed enhanced lipolytic responses to Epi, and increased faecal lipids suggesting altered fat mobilization and absorption. Subcutaneous white fat appeared to be thermogenically more active (measured as Ucp1 mRNA expression) in α2A-/- mice, and brown fat showed an increased response to NE. Exercise was effective in reducing total body adiposity and increasing lean mass in both genotypes, but there was a significant diet-genotype interaction, as even modestly increased physical activity combined with lack of α2A-AR signalling promoted weight loss more efficiently than exercise with normal α2A-AR function. These results suggest that blockade of α2A-ARs may be exploited to reduce visceral fat and to improve insulin secretion.

Association of α2A-Adrenergic Receptor Genetic Variants with Platelet Reactivity in Chinese Patients on Dual Antiplatelet Therapy Undergoing Percutaneous Coronary Intervention

OBJECTIVE

The alpha 2A-adrenergic receptor gene (ADRA2A) polymorphism in individuals modifies the antiplatelet response to sympathetic stimulation. The aim of this study was to investigate the effect of ADRA2A variants on platelet reactivity in Chinese patients on dual antiplatelet therapy (DAPT) after undergoing percutaneous coronary intervention (PCI).

METHODS

From March 2011 to March 2013, 1,024 patients were enrolled in this prospective, single-center, observational study in China. Four single nucleotide polymorphisms (SNPs) of ADRA2A gene (rs11195419, rs3750625, rs13306146, and rs553668) and CYP2C19*2 were detected by ligase detection reaction (LDR), and adenosine diphosphate (ADP) inhibition was detected by thromboelastography (TEG®).

RESULTS

The minor allele frequencies of ADRA2A SNPs were common. Platelet ADP inhibition was significantly different among patients carrying rs11195419 (adjusted P = 0.022) and rs3750625 (adjusted P = 0.016). The homozygous allele carriers had the lowest ADP inhibition. However, ADP inhibition was not significantly different in rs553668 and rs13306146. At the multivariate analysis, rs11195419 (P = 0.033), rs3750625 (P = 0.020) and CYP2C19*2 (P = 0.002) were independent predictors of ADP inhibition. Subgroups analysis based on sex showed rs11195419 (P = 0.003) and rs3750625 (P = 0.002) were significantly associated with ADP inhibition in males, but not in females.

CONCLUSION

ADRA2A genetic variations were associated with ADP-induced platelet aggregation during DAPT in Chinese patients undergoing PCI, and the effect was particularly more pronounced in males.

Variation in the α2A-adrenergic receptor gene and risk of gestational diabetes

AIM

Sympathetic activation suppresses insulin secretion via pancreatic ADRA2A.  Because sympathetic activity and insulin demand increase during pregnancy, we tested the hypothesis  that ADRA2A variants are associated with gestational diabetes (GDM).

PATIENTS & METHODS

Among Caucasian pregnant women without pre-existing diabetes, we genotyped 458 who had GDM and 1537 without GDM for seven ADRA2A variants.

RESULTS

rs1800038 (OR: 2.34; p = 0.020) and rs3750625 (OR: 1.56; p = 0.010) increased the risk of GDM, and rs11195418 decreased it (OR: 0.62; p = 0.025). The associations remained significant after adjustment for maternal age, maternal BMI, parity and a genetic risk score that included variants previously associated with Type 2 diabetes mellitus and GDM.

CONCLUSION

ADRA2A genetic variation contributes independently to the risk of GDM in Caucasian women.

Evolution of the α2-adrenoreceptors in vertebrates: ADRA2D is absent in mammals and crocodiles

Evolutionary studies of genes that have been functionally characterized and whose variation has been associated with pathological conditions represent an opportunity to understand the genetic basis of pathologies. α₂-Adrenoreceptors (ADRA2) are a class of G protein-coupled receptors that regulate several physiological processes including blood pressure, platelet aggregation, insulin secretion, lipolysis, and neurotransmitter release. This gene family has been extensively studied from a molecular/physiological perspective, yet much less is known about its evolutionary history. Accordingly, the goal of this study was to investigate the evolutionary history of α₂-adrenoreceptors (ADRA2) in vertebrates. Our results show that in addition to the three well-recognized α₂-adrenoreceptor genes (ADRA2A, ADRA2B and ADRA2C), we recovered a clade that corresponds to the fourth member of the α₂-adrenoreceptor gene family (ADRA2D). We also recovered a clade that possesses two ADRA2 sequences found in two lamprey species. Furthermore, our results show that mammals and crocodiles are characterized by possessing three α₂-adrenoreceptor genes, whereas all other vertebrate groups possess the full repertoire of α₂-adrenoreceptor genes. Among vertebrates ADRA2D seems to be a dispensable gene, as it was lost two independent times during the evolutionary history of the group. Additionally, we found that most examined species possess the most common alleles described for humans; however, there are cases in which non-human mammals possess the alternative variant. Finally, transcript abundance profiles revealed that during the early evolutionary history of gnathostomes, the expression of ADRA2D in different taxonomic groups became specialized to different tissues, but in the ancestor of sarcopterygians this specialization would have been lost.

Amelioration of atherosclerotic inflammation and plaques via endothelial adrenoceptor-targeted eNOS gene delivery using redox-sensitive polymer bearing l-arginine

Endothelial dysfunction combined with inflammation leads to atherosclerosis. Endothelium-specific delivery of therapeutic agents at the cellular level-specifically in vivo-is still a difficult task for proper management of atherosclerosis. We designed a redox-sensitive poly(oligo-l-arginine) (rsPOLA) playing dual roles as an endothelium α-2 adrenoceptors(α-2ARs)-targeted gene carrier and as a substrate for endothelial nitric oxide synthase (eNOS). Overexpression of α-2ARs on atherosclerotic endothelial cells was confirmed and the eNOS/rsPOLA nanoplexes following systemic injection demonstrated to 1) enhance eNOS gene delivery into endothelial cells via α-2ARs/l-arginine specific binding, 2) increase intracellular level of nitric oxide, 3) suppress inflammatory response in endothelium and finally 4) reduce atherosclerotic plaque in a Ldlr^-/- atherosclerotic mouse model. Among the tested nanoplexes [eNOS/rsPOLA, eNOS/{poly(oligo-d-arginine), rsPODA} and eNOS/(racemic mixture, rsRM)], eNOS/rsPOLA reduced atherosclerotic inflammation most effectively as we hypothesized. Current treatment strategy provides strong potential for further development of a gene therapeutic system to ameliorate inflammation and progressive atherosclerotic plaques.

Alpha2A adrenergic receptor genetic variation contributes to hyperglycemia after myocardial infarction

BACKGROUND

Acute myocardial infarction (AMI) is frequently associated with transient hyperglycemia even in patients without pre-existing diabetes. Acute stress can lead to increased blood glucose through the effect of catecholamines on alpha2A-adrenergic receptors (α2A-ARs) present in pancreatic islet β-cells. Variation in the gene (ADRA2A) that encodes the α2A-AR affects insulin release and glucose control and may play a particularly important role during times of stress.

METHODS

We performed a retrospective cohort study using de-identified electronic medical records linked to a DNA repository in 521 Caucasians and 55 African-American non-diabetic patients with AMI. We examined the association between admission blood glucose concentrations and ten selected ADRA2A SNPs in Caucasians.

RESULTS

Three ADRA2A SNPS were associated with stress-induced hyperglycemia in Caucasians. Individuals homozygous for the rs10885122 variant (n=9) had a 23% lower admission glucose (geometric mean [95% CI], 99 [83-118]mg/dl) compared with non-carriers (121 [118-125] mg/dl; n=401; P=0.001). Admission glucose was 14% higher in rs1800544 variant homozygotes (134 [119-150]mg/dl; n=36) compared to non-carriers (118 [115-121]mg/dl; n=290, P=0.046). Furthermore, homozygotes of the rs553668 variant (n=13) had a 13% higher glucose (133 [110-160]mg/dl) compared to non-carriers (118 [115-122]mg/dl; n=366; P=0.056). Haplotypes including these ADRA2A SNPs were associated with higher admission glucose levels.

CONCLUSIONS

Three ADRA2A genetic variants are associated with blood glucose and stress-induced hyperglycemia after AMI in Caucasians.

MafA-Controlled Nicotinic Receptor Expression Is Essential for Insulin Secretion and Is Impaired in Patients with Type 2 Diabetes

Monoamine and acetylcholine neurotransmitters from the autonomic nervous system (ANS) regulate insulin secretion in pancreatic islets. The molecular mechanisms controlling neurotransmitter signaling in islet β cells and their impact on diabetes development are only partially understood. Using a glucose-intolerant, MafA-deficient mouse model, we demonstrate that MAFA controls ANS-mediated insulin secretion by activating the transcription of nicotinic (ChrnB2 and ChrnB4) and adrenergic (Adra2A) receptor genes, which are integral parts of acetylcholine-and monoamine-signaling pathways. We show that acetylcholine-mediated insulin secretion requires nicotinic signaling and that nicotinic receptor expression is positively correlated with insulin secretion and glycemic control in human donor islets. Moreover, polymorphisms spanning MAFA-binding regions within the human CHRNB4 gene are associated with type 2 diabetes. Our data show that MAFA transcriptional activity is required for establishing β cell sensitivity to neurotransmitter signaling and identify nicotinic signaling as a modulator of insulin secretion impaired in type 2 diabetes.

Lack of α2C-Adrenoceptor Results in Contrasting Phenotypes of Long Bones and Vertebra and Prevents the Thyrotoxicosis-Induced Osteopenia

A series of studies have demonstrated that activation of the sympathetic nervous system (SNS) causes osteopenia via β₂-adrenoceptor (β₂-AR) signaling. However, in a recent study, we found an unexpected and generalized phenotype of high bone mass in female mice with chronic sympathetic hyperactivity, due to double gene inactivation of adrenoceptors that negatively regulate norepinephrine release, α_2A-and α_2C-AR (α_2A/2C-AR^-/-). These findings suggest that β₂-AR is not the single adrenoceptor involved in bone turnover regulation and show that α₂-AR signaling may also mediate the SNS actions in the skeleton. In addition, we found that α_2A/2C-AR^-/- animals are resistant to the thyrotoxicosis-induced osteopenia, suggesting that thyroid hormone (TH), when in supraphysiological levels, interacts with the SNS to control bone mass and structure, and that this interaction may also involve α₂-AR signaling. In the present study, to further investigate these hypotheses and to discriminate the roles of α₂-AR subtypes, we have evaluated the bone phenotype of mice with the single gene inactivation of α_2C-AR subtype, which mRNA expression was previously shown to be down regulated by triiodothyronine (T3). A cohort of 30 day-old female α_2CAR^-/- mice and their wild-type (WT) controls were treated with a supraphysiological dose of T3 for 30 or 90 days, which induced a thyrotoxic state in both mouse lineages. The micro-computed tomographic (μCT) analysis showed that α_2C-AR^-/- mice present lower trabecular bone volume (BV/TV) and number (Tb.N), and increased trabecular separation (Tb.Sp) in the femur compared with WT mice; which was accompanied by decreased bone strength (determined by the three-point bending test) in the femur and tibia. The opposite was observed in the vertebra, where α_2C-AR^-/- mice show increased BV/TV, Tb.N and trabecular thickness (Tb.Th), and decreased Tb.Sp, compared with WT animals. In spite of the contrasting bone phenotypes of the femur and L5, thyrotoxicosis negatively regulated most of the micro architectural features of the trabecular bone in both skeletal sites of WT, but not of α_2C-AR^-/- mice. T3 treatment also decreased biomechanical properties (maximum load and ultimate load) in the femur and tibia of WT, but not of knockout mice. The mRNA expression of osteocalcin, a marker of mature osteoblasts, and tartrate-resistant acid phosphatase, which is expressed by osteoclasts and is involved in collagen degradation, was increased by T3 treatment only in WT, and not in α_2C-AR^-/- mice. Altogether, these findings suggest that α_2C-AR subtype mediates the effects of the SNS in the bone in a skeletal site-dependent manner, and that thyrotoxicosis depends on α_2C-AR signaling to promote bone loss, which sustains the hypothesis of a TH-SNS interaction to modulate bone remodeling and structure.

Perception of emotion in facial stimuli: The interaction of ADRA2A and COMT genotypes, and sex

Emotional facial stimuli are important social signals that are essential to be perceived and recognized in order to make appropriate decisions and responses in everyday communication. The ability to voluntarily guide attention to perceive and recognize emotions, and react to them varies largely across individuals, and has a strong genetic component (Friedman et al., 2008). Two key genetic variants of the catecholamine system that have been related to emotion perception and attention are the catechol-O-methyl transferase genetic variant (COMT Val158Met) and the α2A-receptor gene promoter polymorphism (ADRA2A C-1291G) accordingly. So far, the interaction of the two with sex in emotion perception has not been studied. Multilevel modeling method was applied to study how COMT Val158Met, ADRA2A C-1291G and sex are associated with measures of emotion perception in a large sample of young adults. Participants (n=506) completed emotion recognition and behavioral emotion detection tasks. It was found that COMT Val158Met genotype in combination with the ADRA2A C-1291G and sex predicts emotion detection, and perception of valence and arousal. In simple visual detection, the ADRA2A C-1291G G-allele leads to slower detection of a highly arousing face (scheming), which is modulated by each additional COMT Val158Met Met-allele and male sex predicting faster responses. The combination of G-allele, Met-allele and male sex also predicts higher perceived negativity in sad faces. No effects of C-1291G, Val158Met, and sex were found on verbal emotion recognition. Applying the findings to study the interplay between catecholamine-O-methyl transferase activity and α2A-receptors in emotion perception disorders (such as ADHD, autism and schizophrenia) in men and women would be the next step towards understanding individual differences in emotion perception.

A Comparison of the Anorectic Effect and Safety of the Alpha2-Adrenoceptor Ligands Guanfacine and Yohimbine in Rats with Diet-Induced Obesity

The search for drugs with anorectic activity, acting within the adrenergic system has attracted the interest of researchers. Partial α₂-adrenoceptor agonists might offer the potential for effective and safe treatment of obesity. We compared the effectiveness and safety of α₂-adrenoceptor ligands in reducing body mass. We also analyzed if antagonist and partial agonists of α₂-adrenoceptor––yohimbine and guanfacine––act similarly, and determined which course of action is connected with anorectic activity. We tested intrinsic activity and effect on the lipolysis of these compounds in cell cultures, evaluated their effect on meal size, body weight in Wistar rats with high-fat diet-induced obesity, and determined their effect on blood pressure, heart rate, lipid profile, spontaneous locomotor activity, core temperature and glucose, as well as glycerol and cortisol levels. Both guanfacine and yohimbine showed anorectic activity. Guanfacine was much more effective than yohimbine. Both significantly reduced the amount of intraperitoneal adipose tissue and had a beneficial effect on lipid profiles. Decreased response of α_2A-adrenoceptors and partial stimulation of α_2B-receptors seem to be responsible for the anorectic action of guanfacine. The stimulation of α₁-adrenoceptors by guanfacine is responsible for cardiovascular side effects but may also be linked with improved anorexic effect. α₁-adrenoceptor blockade is connected with the side effects of yohimbine, but it is also associated with the improvement of lipid profiles. Guanfacine has been approved by the Food and Drug Administration (FDA) to treat hypertension and conduct disorder, but as it reduces body weight, it is worth examining its effectiveness and safety in models of obesity.

Association between Common Genetic Variants of α2A-, α2B-, and α2C-Adrenergic Receptors and Orthostatic Hypotension

BACKGROUND

The genetic background associated with the dysregulation of orthostatic blood pressure remains poorly understood. The sympathetic nervous system plays a pivotal role in the regulation of blood pressure, as well as in response to positional changes. The essential role of adrenergic receptors in the sympathetic nervous system prompted us to hypothesize that common genetic variants of the α2-adrenergic receptor might contribute to the dysregulation of orthostatic blood pressure in general populations. This study is to explore the association between the polymorphisms of the α2-adrenergic receptor genes and the occurrence of orthostatic hypotension in Chinese populations.

METHODS

The polymorphisms ADRA2A C-1291G (rs1800544), ADRA2B 301-303 I/D (rs28365031), and ADRA2C 322-325 I/D (rs61767072) were genotyped in 317 patients with orthostatic hypotension and 664 age- and gender-matched controls. Logistic regression analyses, adjusted for multiple comparisons, were used to determine the association between the allele/genotype of each ADRA2 gene and the risk of orthostatic hypotension.

RESULTS

No significant association was found between the ADRA2A C-1291G, ADRA2B 301-303 I/D, and ADRA2C 322-325 I/D polymorphisms and orthostatic hypotension.

CONCLUSIONS

We concluded that the common polymorphisms in the alpha2-adrenergic receptor gene is not associated with orthostatic hypotension risk in Chinese.

Spinophilin Is Indispensable for the α2B Adrenergic Receptor-Elicited Hypertensive Response

The α₂ adrenergic receptor (AR) subtypes are important for blood pressure control. When activated, the α_2A subtype elicits a hypotensive response whereas the α_2B subtype mediates a hypertensive effect that counteracts the hypotensive response by the α_2A subtype. We have previously shown that spinophilin attenuates the α_2AAR-dependent hypotensive response; in spinophilin null mice, this response is highly potentiated. In this study, we demonstrate that spinophilin impedes arrestin-dependent phosphorylation and desensitization of the α_2BAR subtype by competing against arrestin binding to this receptor subtype. The Del301-303 α_2BAR, a human variation that shows impaired phosphorylation and desensitization and is linked to hypertension in certain populations, exhibits preferential interaction with spinophilin over arrestin. Furthermore, Del301-303 α_2BAR-induced ERK signaling is quickly desensitized in cells without spinophilin expression, showing a profile similar to that induced by the wild type receptor in these cells. Together, these data suggest a critical role of spinophilin in sustaining α_2BAR signaling. Consistent with this notion, our in vivo study reveals that the α_2BAR-elicited hypertensive response is diminished in spinophilin deficient mice. In arrestin 3 deficient mice, where the receptor has a stronger binding to spinophilin, the same hypertensive response is enhanced. These data suggest that interaction with spinophilin is indispensable for the α_2BAR to elicit the hypertensive response. This is opposite of the negative role of spinophilin in regulating α_2AAR-mediated hypotensive response, suggesting that spinophilin regulation of these closely related receptor subtypes can result in distinct functional outcomes in vivo. Thus, spinophilin may represent a useful therapeutic target for treatment of hypertension.

Hippocampal transcriptional and neurogenic changes evoked by combination yohimbine and imipramine treatment

Adjunct α2-adrenoceptor antagonism is a potential strategy to accelerate the behavioral effects of antidepressants. Co-administration of the α2-adrenoceptor antagonist yohimbine hastens the behavioral and neurogenic effects of the antidepressant imipramine. We examined the transcriptional targets of short duration (7days), combination treatment of yohimbine and imipramine (Y+I) within the adult rat hippocampus. Using microarray and qPCR analysis we observed functional enrichment of genes involved in intracellular signaling cascades, plasma membrane, cellular metal ion homeostasis, multicellular stress responses and neuropeptide signaling pathways in the Y+I transcriptome. We noted reduced expression of the α2A-adrenoceptor (Adra2a), serotonin 5HT2C receptor (Htr2c) and the somatostatin receptor 1 (Sstr1), which modulate antidepressant action. Further, we noted a regulation of signaling pathway genes like inositol monophosphatase 2 (Impa2), iodothyronine deiodinase 3 (Dio3), regulator of G-protein signaling 4 (Rgs4), alkaline ceramidase 2 (Acer2), doublecortin-like kinase 2 (Dclk2), nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (Nfkbia) and serum/glucocorticoid-regulated kinase 1 (Sgk1), several of which are implicated in the pathophysiology of mood disorders. Comparative analysis revealed an overlap in the hippocampal regulation of Acer2, Nfkbia, Sgk1 and Impa2 between Y+I treatment, the fast-acting electroconvulsive seizure (ECS) paradigm, and the slow-onset chronic (21days) imipramine treatment. Further, Y+I treatment enhanced the quiescent neural progenitor pool in the hippocampal neurogenic niche similar to ECS, and distinct from chronic imipramine treatment. Taken together, our results provide insight into the molecular and cellular targets of short duration Y+I treatment, and identify potential leads for the development of rapid-action antidepressants.

[Genetic Association of ADRA2A and ADRB3 Genes with Metabolic Syndrome among the Tatars]

An association study was performed for genetic polymorphisms in ADRB3 (rs4994) and ADRA2A (rs1800544, rs553668) genes to estimate their effect on quantitative parameters, including glucose, insulin, and HOMA-IR index in women from the Tatar population of Russia. It has been shown that CT and CC are associated with metabolic syndrome and increased insulin. It was shown that ADRA2A (rs1800544) gene polymorphism was associated with high levels of insulin and an increased HOMA-IR index in GG- and GC-genotype carriers.

3-iodothyronamine differentially modulates α-2A-adrenergic receptor-mediated signaling

Most in vivo effects of 3-iodothyronamine (3-T1AM) have been thus far thought to be mediated by binding at the trace amine-associated receptor 1 (TAAR1). Inconsistently, the 3-T1AM-induced hypothermic effect still persists in Taar1 knockout mice, which suggests additional receptor targets. In support of this general assumption, it has previously been reported that 3-T1AM also binds to the α-2A-adrenergic receptor (ADRA2A), which modulates insulin secretion. However, the mechanism of this effect remains unclear. We tested two different scenarios that may explain the effect: the sole action of 3-T1AM at ADRA2A and a combined action of 3-T1AM at ADRA2A and TAAR1, which is also expressed in pancreatic islets. We first investigated a potential general signaling modification using the label-free EPIC technology and then specified changes in signaling by cAMP inhibition and MAPKs (ERK1/2) determination. We found that 3-T1AM induced Gi/o activation at ADRA2A and reduced the norepinephrine (NorEpi)-induced MAPK activation. Interestingly, in ADRA2A/TAAR1 hetero-oligomers, application of NorEpi resulted in uncoupling of the Gi/o signaling pathway, but it did not affect MAPK activation. However, 3-T1AM application in mice over a period of 6 days at a daily dose of 5 mg/kg had no significant effects on glucose homeostasis. In summary, we report an agonistic effect of 3-T1AM on the ADRA2A-mediated Gi/o pathway but an antagonistic effect on MAPK induced by NorEpi. Moreover, in ADRA2A/TAAR1 hetero-oligomers, the capacity of NorEpi to stimulate Gi/o signaling is reduced by co-stimulation with 3-T1AM. The present study therefore points to a complex spectrum of signaling modification mediated by 3-T1AM at different G protein-coupled receptors.

A Population Based Study of the Genetic Association between Catecholamine Gene Variants and Spontaneous Low-Frequency Fluctuations in Reaction Time

The catecholamines dopamine and noradrenaline have been implicated in spontaneous low-frequency fluctuations in reaction time, which are associated with attention deficit hyperactivity disorder (ADHD) and subclinical attentional problems. The molecular genetic substrates of these behavioral phenotypes, which reflect frequency ranges of intrinsic neuronal oscillations (Slow-4: 0.027-0.073 Hz; Slow-5: 0.010-0.027 Hz), have not yet been investigated. In this study, we performed regression analyses with an additive model to examine associations between low-frequency fluctuations in reaction time during a sustained attention task and genetic markers across 23 autosomal catecholamine genes in a large young adult population cohort (n = 964), which yielded greater than 80% power to detect a small effect size (f² = 0.02) and 100% power to detect a small/medium effect size (f² = 0.15). At significance levels corrected for multiple comparisons, none of the gene variants were associated with the magnitude of low-frequency fluctuations. Given the study’s strong statistical power and dense coverage of the catecholamine genes, this either indicates that associations between low-frequency fluctuation measures and catecholamine gene variants are absent or that they are of very small effect size. Nominally significant associations were observed between variations in the alpha-2A adrenergic receptor gene (ADRA2A) and the Slow-5 band. This is in line with previous reports of an association between ADRA2A gene variants and general reaction time variability during response selection tasks, but the specific association of these gene variants and low-frequency fluctuations requires further confirmation. Pharmacological challenge studies could in the future provide convergent evidence for the noradrenergic modulation of both general and time sensitive measures of intra-individual variability in reaction time.

Predicting Methylphenidate Response in ADHD Using Machine Learning Approaches

BACKGROUND

There are no objective, biological markers that can robustly predict methylphenidate response in attention deficit hyperactivity disorder. This study aimed to examine whether applying machine learning approaches to pretreatment demographic, clinical questionnaire, environmental, neuropsychological, neuroimaging, and genetic information can predict therapeutic response following methylphenidate administration.

METHODS

The present study included 83 attention deficit hyperactivity disorder youth. At baseline, parents completed the ADHD Rating Scale-IV and Disruptive Behavior Disorder rating scale, and participants undertook the continuous performance test, Stroop color word test, and resting-state functional MRI scans. The dopamine transporter gene, dopamine D4 receptor gene, alpha-2A adrenergic receptor gene (ADRA2A) and norepinephrine transporter gene polymorphisms, and blood lead and urine cotinine levels were also measured. The participants were enrolled in an 8-week, open-label trial of methylphenidate. Four different machine learning algorithms were used for data analysis.

RESULTS

Support vector machine classification accuracy was 84.6% (area under receiver operating characteristic curve 0.84) for predicting methylphenidate response. The age, weight, ADRA2A MspI and DraI polymorphisms, lead level, Stroop color word test performance, and oppositional symptoms of Disruptive Behavior Disorder rating scale were identified as the most differentiating subset of features.

CONCLUSIONS

Our results provide preliminary support to the translational development of support vector machine as an informative method that can assist in predicting treatment response in attention deficit hyperactivity disorder, though further work is required to provide enhanced levels of classification performance.

Antineoplastic Effects of siRNA against TMPRSS2-ERG Junction Oncogene in Prostate Cancer

TMPRSS2-ERG junction oncogene is present in more than 50% of patients with prostate cancer and its expression is frequently associated with poor prognosis. Our aim is to achieve gene knockdown by siRNA TMPRSS2-ERG and then to assess the biological consequences of this inhibition. First, we designed siRNAs against the two TMPRSS2-ERG fusion variants (III and IV), most frequently identified in patients’ biopsies. Two of the five siRNAs tested were found to efficiently inhibit mRNA of both TMPRSS2-ERG variants and to decrease ERG protein expression. Microarray analysis further confirmed ERG inhibition by both siRNAs TMPRSS2-ERG and revealed one common down-regulated gene, ADRA2A, involved in cell proliferation and migration. The siRNA against TMPRSS2-ERG fusion variant IV showed the highest anti-proliferative effects: Significantly decreased cell viability, increased cleaved caspase-3 and inhibited a cluster of anti-apoptotic proteins. To propose a concrete therapeutic approach, siRNA TMPRSS2-ERG IV was conjugated to squalene, which can self-organize as nanoparticles in water. The nanoparticles of siRNA TMPRSS2-ERG-squalene injected intravenously in SCID mice reduced growth of VCaP xenografted tumours, inhibited oncoprotein expression and partially restored differentiation (decrease in Ki67). In conclusion, this study offers a new prospect of treatment for prostate cancer based on siRNA-squalene nanoparticles targeting TMPRSS2-ERG junction oncogene.

Relationship between human evolution and neurally mediated syncope disclosed by the polymorphic sites of the adrenergic receptor gene α2B-AR

The objective of this study was to clarify the effects of disease on neurally mediated syncope (NMS) during an acute stress reaction. We analyzed the mechanism of the molecular interaction and the polymorphisms of the alpha-2 adrenoreceptor (α2B-AR) gene as the potential psychiatric cause of incentive stress. We focused on the following three genotypes of the repeat polymorphism site at Glu 301-303 in the α2B-AR gene: Glu12/12, Glu12/9, and Glu9/9. On the basis of our clinical research, NMS is likely to occur in people with the Glu12/9 heterotype. To verify this, we assessed this relationship with the interaction of Gi protein and adenylate cyclase by in silico analysis of the Glu12/9 heterotype. By measuring the difference in the dissociation time of the Gi-α subunit twice, we found that the Glu12/9 heterotype suppressed the action of adenylate cyclase longer than the Glu homotypes. As this difference in the Glu repeat number effect is thought to be one of the causes of NMS, we investigated the evolutionary significance of the Glu repeat number. Glu8 was originally repeated in simians, while the Glu12 repeats occurred over time during the evolution of bipedalism in humans. Taken with the Glu12 numbers, NMS would likely become a defensive measure to prevent significant blood flow to the human brain.

Cannabinoid modulation of alpha2 adrenergic receptor function in rodent medial prefrontal cortex

Endocannabinoids acting at the cannabinoid type 1 receptor (CB1R) are known to regulate attention, cognition and mood. Previous studies have shown that, in the rat medial prefrontal cortex (mPFC), CB1R agonists increase norepinephrine release, an effect that may be attributed, in part, to CB1Rs localised to noradrenergic axon terminals. The present study was aimed at further characterising functional interactions between CB1R and adrenergic receptor (AR) systems in the mPFC using in vitro intracellular electrophysiology and high-resolution neuroanatomical techniques. Whole-cell patch-clamp recordings of layer V/VI cortical pyramidal neurons in rats revealed that both acute and chronic treatment with the synthetic CB1R agonist WIN 55,212-2 blocked elevations in cortical pyramidal cell excitability and increases in input resistance evoked by the α2-adrenergic receptor (α2-AR) agonist clonidine, suggesting a desensitisation of α2-ARs. These CB1R-α2-AR interactions were further shown to be both action potential- and gamma-aminobutyric acid-independent. To better define sites of cannabinoid-AR interactions, we localised α2A-adrenergic receptors (α2A-ARs) in a genetically modified mouse that expressed a hemoagglutinin (HA) tag downstream of the α2A-AR promoter. Light and electron microscopy indicated that HA-α2A-AR was distributed in axon terminals and somatodendritic processes especially in layer V of the mPFC. Triple-labeling immunocytochemistry revealed that α2A-AR and CB1R were localised to processes that contained dopamine-β-hydroxylase, a marker of norepinephrine. Furthermore, HA-α2A-AR was localised to processes that were directly apposed to CB1R. These findings suggest multiple sites of interaction between cortical cannabinoid-adrenergic systems that may contribute to understanding the effect of cannabinoids on executive functions and mood.

Quercetin-3-O-glucronide inhibits noradrenaline binding to α2-adrenergic receptor, thus suppressing DNA damage induced by treatment with 4-hydroxyestradiol and noradrenaline in MCF-10A cells

Risk factors for breast cancer include estrogens such as 17β-estradiol (E2) and high stress levels. 4-Hydroxyestradiol (4-OHE2), a metabolite of E2 formed preferentially by cytochrome P450 1B1, is oxidized to E2-3,4-quinone, which reacts with DNA to form depurinating adducts that exert genotoxicity and carcinogenicity. Endogenous catecholamines such as adrenaline (A) and noradrenaline (NA) are released from the adrenal gland and sympathetic nervous system during exposure to stress. Here, we found that treatment with 4-OHE2 (3 μM) and NA (3 nM) significantly induced the phosphorylation of histone H2AX (γ-H2AX), one of the earliest indicators of DNA damage, and apurinic (AP) sites via the α2-adrenergic receptor (α2-AR) in human mammary epithelial MCF-10A cells. As an inverse association between a higher intake of flavonoids and breast cancer risk has previously been suggested from epidemiological studies, we investigated the effects of quercetin-3-O-glucuronide (Q3G), a circulating metabolite of quercetin in the blood, on 4-OHE2- and NA-induced γ-H2AX and AP sites. Q3G (0.1 μM) suppressed their induction and inhibited the binding of [(3)H]-NA to α2-AR. These results suggest that Q3G acts as an α2-AR antagonist and that it could be used as a chemopreventive agent for stress-promoted breast cancer.

The α2B-adrenergic receptor is mutant in cortical myoclonus and epilepsy

OBJECTIVE

Autosomal dominant cortical myoclonus and epilepsy (ADCME) is characterized by distal, fairly rhythmic myoclonus and epilepsy with variable severity. We have previously mapped the disease locus on chromosome 2p11.1-q12.2 by genome-wide linkage analysis. Additional pedigrees affected by similar forms of epilepsy have been associated with chromosomes 8q, 5p, and 3q, but none of the causing genes has been identified. We aim to identify the mutant gene responsible for this form of epilepsy.

METHODS

Genes included in the ADCME critical region were directly sequenced. Coimmunoprecipitation, immunofluorescent, and electrophysiologic approaches to transfected human cells have been utilized for testing the functional significance of the identified mutation.

RESULTS

Here we show that mutation in the α2 -adrenergic receptor subtype B (α2B -AR) is associated with ADCME by identifying a novel in-frame insertion/deletion in 2 Italian families. The mutation alters several conserved residues of the third intracellular loop, hampering neither the α2B -AR plasma membrane localization nor the arrestin-mediated internalization capacity, but altering the binding with the scaffolding protein spinophilin upon neurotransmitter activation. Spinophilin, in turn, regulates interaction of G protein coupled receptors with regulator of G protein signaling proteins. Accordingly, the mutant α2B -AR increases the epinephrine-stimulated calcium signaling.

INTERPRETATION

The identified mutation is responsible for ADCME, as the loss of α2B -AR/spinophilin interaction causes a gain of function effect. This work implicates for the first time the α-adrenergic system in human epilepsy and opens new ways of understanding the molecular pathway of epileptogenesis, widening the spectrum of possible therapeutic targets.

[The role of alfa-2-beta-adrenoreceptor in development of ventricular conduction disturbance]

BACKGROUND

The purpose of this study was to investigate association between the genetic polymorphism I/D of gene α2β-adrenoreceptor (ADRA2B) and hereditary disorders of ventricular conduction.

PATIENTS AND METHODS

In this study, 102 people with complete left bundle branch block (45.71 ± 1.852 years)--46 females and 56 males, and 86 people with complete right bundle branch block (34.59 ± 1.86 years)--41 females and 45 males. The study was approved by Ethic Committee of the KrasSMU. All participants were included in the study after written informed consent form. Cardiological examination included clinical examination, electrocardiography, echocardiography, Holter monitoring, stress-test, koronaroangiografy and radionuclide method of a myocardium and molecular and genetic researches.

RESULTS

Statistically, significant prevalence of a homozygous genotype of DD on rare allele gene ADRA2B in both groups in comparison with group of control is established. The reliable dominance of the homozygous rare genotypes (D allele) of gene ADRA2B were detected in all groups.

CONCLUSION

Polymorphism DD of a gene ADRA2B is a genetic predictor of predisposition to the blockade of the right and left bundle branch block.

Systems pharmacology identifies drug targets for Stargardt disease-associated retinal degeneration

A systems pharmacological approach that capitalizes on the characterization of intracellular signaling networks can transform our understanding of human diseases and lead to therapy development. Here, we applied this strategy to identify pharmacological targets for the treatment of Stargardt disease, a severe juvenile form of macular degeneration. Diverse GPCRs have previously been implicated in neuronal cell survival, and crosstalk between GPCR signaling pathways represents an unexplored avenue for pharmacological intervention. We focused on this receptor family for potential therapeutic interventions in macular disease. Complete transcriptomes of mouse and human samples were analyzed to assess the expression of GPCRs in the retina. Focusing on adrenergic (AR) and serotonin (5-HT) receptors, we found that adrenoceptor α 2C (Adra2c) and serotonin receptor 2a (Htr2a) were the most highly expressed. Using a mouse model of Stargardt disease, we found that pharmacological interventions that targeted both GPCR signaling pathways and adenylate cyclases (ACs) improved photoreceptor cell survival, preserved photoreceptor function, and attenuated the accumulation of pathological fluorescent deposits in the retina. These findings demonstrate a strategy for the identification of new drug candidates and FDA-approved drugs for the treatment of monogenic and complex diseases.

[The correlation research between the polymorphism of genotype of site-1296 in alpha2A-AR receptor gene and the susceptibility of vestibular function]

OBJECTIVE

To investigate the correlation between the polymorphism of genotype of site-1296 in alpha2A-AR receptor gene and the susceptibility of vestibular function.

METHOD

Ninety-four blood samples were collected from pilot cadets, consisting of susceptible and tolerance groups to vestibular function. Genomic DNA was isolated, and the coding region of alpha2A-AR receptor gene was amplified by polymerase chain reaction (PCR). The PCR products were analyzed by gene sequencing. Gene frequency was calculated, and, the coincidence between the polymorphism of alpha2A-AR receptor gene in the groups and Hardy-Weinberg balance was evaluated. The allele frequency of the two groups was compared by Chi square test.

RESULT

G/C polymorphism was existed in Site-1296 of alpha2A-AR gene regulation zone, including GG, GC, CC. The express of GG Genotype in susceptible group exceeded that of the other group. There were significance differences in both genotype constituent ratio and alleles frequency of the two groups.

CONCLUSION

The polymorphism of genotype of site-1296 in alpha2A-AR receptor gene is possibly correlated with the susceptibility to vestibular function.

REEPs are membrane shaping adapter proteins that modulate specific g protein-coupled receptor trafficking by affecting ER cargo capacity

Receptor expression enhancing proteins (REEPs) were identified by their ability to enhance cell surface expression of a subset of G protein-coupled receptors (GPCRs), specifically GPCRs that have proven difficult to express in heterologous cell systems. Further analysis revealed that they belong to the Yip (Ypt-interacting protein) family and that some REEP subtypes affect ER structure. Yip family comparisons have established other potential roles for REEPs, including regulation of ER-Golgi transport and processing/neuronal localization of cargo proteins. However, these other potential REEP functions and the mechanism by which they selectively enhance GPCR cell surface expression have not been clarified. By utilizing several REEP family members (REEP1, REEP2, and REEP6) and model GPCRs (α2A and α2C adrenergic receptors), we examined REEP regulation of GPCR plasma membrane expression, intracellular processing, and trafficking. Using a combination of immunolocalization and biochemical methods, we demonstrated that this REEP subset is localized primarily to ER, but not plasma membranes. Single cell analysis demonstrated that these REEPs do not specifically enhance surface expression of all GPCRs, but affect ER cargo capacity of specific GPCRs and thus their surface expression. REEP co-expression with α2 adrenergic receptors (ARs) revealed that this REEP subset interacts with and alter glycosidic processing of α2C, but not α2A ARs, demonstrating selective interaction with cargo proteins. Specifically, these REEPs enhanced expression of and interacted with minimally/non-glycosylated forms of α2C ARs. Most importantly, expression of a mutant REEP1 allele (hereditary spastic paraplegia SPG31) lacking the carboxyl terminus led to loss of this interaction. Thus specific REEP isoforms have additional intracellular functions besides altering ER structure, such as enhancing ER cargo capacity, regulating ER-Golgi processing, and interacting with select cargo proteins. Therefore, some REEPs can be further described as ER membrane shaping adapter proteins.

Genetic association of adrenergic receptor alpha 2A with obesity and type 2 diabetes

OBJECTIVE

The sympathetic nervous system (SNS) is linked to glucose, lipid, and protein metabolism. The α2A -adrenergic receptor (ADRA2A) is involved in the SNS and mediates inhibition of insulin secretion and lipolysis. The association of ADRA2A single-nucleotide polymorphisms (SNPs) with obesity and/or type 2 diabetes (T2D) was investigated.

DESIGN AND METHODS

Genotyping was performed in a case-control study of 1,177 Swedish individuals, including lean and obese subjects with normal glucose tolerance (NGT) and T2D patients. ADRA2A mRNA expression was measured in pancreatic islets isolated from T2D patients and nondiabetic subjects.

RESULTS

SNP rs553668 was associated with T2D in men (odds ratio [OR] = 1.47; 95% confidence interval [CI] = 1.08-2.01; P = 0.015) but this association was lost after adjusting for age and for body mass index (BMI). Associations were also detected when comparing obese NGT and lean NGT subjects (OR = 1.49; 95% CI = 1.07-2.07; P = 0.017), and in obese (OR = 1.62; 95% CI = 1.06-2.49; P = 0.026), but not in lean T2D. In women, multiple logistic regression regarding SNP rs521674 demonstrated an increased OR of 7.61 (95% CI = 1.70-34.17; P = 0.008) for T2D when including age as a covariant. Correcting for BMI removed the significant association. When age was included in the model, association also found when obese T2D patients were compared with lean NGT subjects (P = 0.041). ADRA2A mRNA expression in human pancreatic islets was detectable, but with no statistically significant difference between the diabetic and the control groups.

CONCLUSIONS

ADRA2A genetic polymorphisms are mainly associated with obesity and possibly with T2D in a Swedish population.

[α-2β-adrenoreceptor gene polymorphism in patients with disorders of cardiac conduction]

The article is devoted to the role of insertion-deletion polymorphism of -2-adrenoreceptor gene in development of hereditary disorders of cardiac conduction. We examined 71 patients with atrioventricular blocks and 92 patients with sick sinus node syndrome. Statistically significant preponderance of homozygous genotype DD of ADRA2B gene was found in both groups. Associations of alleles with male or female gender were also revealed.

Preventing risky driving: A novel and efficient brief intervention focusing on acknowledgement of personal risk factors

Impulsive personality is an important predictor of risky driving. Acknowledging their impulsive tendencies may help novice drivers to drive more safely. The aim of this study was to evaluate the efficacy of a novel brief intervention targeting novice drivers' risky behavior in traffic, taking into account potential moderator effects. Driving school students (n=1866) were divided into an intervention group and a control group. The intervention consisted of a lecture and group work (1.5h). Subjects' traffic offenses and crashes were monitored during the following year using police and traffic insurance fund databases. The groups were similar in their baseline characteristics. The intervention group had half as many speeding violations in the year following the intervention compared with the controls. The proportion of speeders was significantly lower in the intervention group compared with the control group in subgroups of subjects with medium cognitive abilities and low or medium BIS-11 impulsiveness levels. In alpha(2A)-adrenoceptor gene (ADRA2A) G allele carriers, general traffic risk and speeding decreased in response to the intervention, unlike in subjects with the CC genotype. It is concluded that brief interventions that are integrated into the driving education program and focus on personal psychological risk factors may be effective for improving traffic safety.