Norepinephrine Uptake Research Articles

Desipramine increases cardiac parasympathetic activity via α2-adrenergic mechanism in rats.

Desipramine (DMI) is a blocker of neuronal norepinephrine (NE) uptake transporter. Although intravenous DMI has been shown to cause centrally-mediated sympathoinhibition and peripheral NE accumulation, its parasympathetic effect remains to be elucidated. We hypothesized that intravenous DMI activates the cardiac vagal nerve via an α2-adrenergic mechanism. Using a cardiac microdialysis technique, changes in myocardial interstitial acetylcholine (ACh) levels in the left ventricular free wall in response to intravenous DMI (1mg·kg-1) were examined in anesthetized rats. In rats with intact vagi (n=7), intravenous DMI increased ACh from 1.67±0.43 to 2.48±0.66nM (P<0.01). In rats with vagotomy (n=5), DMI did not significantly change ACh (from 0.92±0.16 to 0.85±0.23nM). In rats with intact vagi pretreated with intravenous yohimbine (2mg·kg-1), DMI did not significantly change ACh (from 1.25±0.23 to 1.13±0.15nM). In conclusion, while DMI is generally considered to be an agent that predominantly affects sympathetic neurotransmission, it can activate the cardiac vagal nerve via α2-adrenergic stimulation in experimental settings in vivo.

Impact of concomitant medication use on myocardial 123I-mIBG imaging results in patients with heart failure.

Medications that interfere with sympathetic neuronal norepinephrine uptake and storage, such as neuropsychiatrics (NP) and sympathomimetic amines, are most likely to affect cardiac uptake of iodine-123 metaiodobenzylguanidine (I-mIBG). The present study examined these and other medications reported to affect I-mIBG uptake using measurements of cardiac I-mIBG uptake on the heart failure (HF) patients in the ADMIRE-HF extension (X) study. Baseline concomitant medications taken by the 961 HF patients were categorized into five groups: calcium channel blockers, NP medications, β agonists and sympathomimetics, α antagonists, and other antihypertensives. NP medications were further subcategorized into those expected to have high and low impact on norepinephrine transporter (NET) function. Myocardial I-mIBG heart/mediastinum (H/M) uptake ratios on 4 h planar images were compared among the groups. Impact of medication group on the prognostic value of the H/M ratio for all-cause (AC) and cardiac death during a median 2-year follow-up was also examined. A total of 283 (29%) patients were using at least one calcium channel blocker, NP medication, or β agonist or sympathomimetic. These patients had a lower mean H/M ratio than the other study patients (1.42±0.20 vs. 1.45±0.20; P=0.022). However, the 2-year AC mortality rates in the two groups were the same [11.3% (95% confidence interval: 7.5-15.2%) vs. 11.8% (95% confidence interval: 9.2-14.4%)]. In terms of medication categories, there were no significant differences in the mean H/M ratios between patients who did and did not use NP medications, β agonists, calcium channel blockers, and α antagonists. Across all categories, patients with H/M ratio greater than or equal to 1.60 had lower AC and cardiac mortality. Patients using higher potency (for NET inhibition) NP medications had significantly lower H/M ratio values, but the prognostic significance of H/M ratio greater than or equal to 1.60 was unchanged. Only a small number of higher potency NET-inhibiting NP medications have a measurable effect on the results of I-mIBG myocardial imaging. There appears to be no basis for restricting the use of calcium channel blockers and β agonist respiratory medications in HF patients referred for cardiac I-mIBG imaging.

Pharmacokinetics and pharmacodynamics of intrathecally administered Xen2174, a synthetic conopeptide with norepinephrine reuptake inhibitor and analgesic properties.

Xen2174 is a synthetic 13-amino acid peptide that binds specifically to the norepinephrine transporter, which results in inhibition of norepinephrine uptake. It is being developed as a possible treatment for moderate to severe pain and is delivered intrathecally. The current study was performed to assess the pharmacodynamics (PD) and the cerebrospinal fluid (CSF) pharmacokinetics (PK) of Xen2174 in healthy subjects. This was a randomized, blinded, placebo-controlled study in healthy subjects. The study was divided into three treatment arms. Each group consisted of eight subjects on active treatment and two or three subjects on placebo. The CSF was sampled for 32h using an intrathecal catheter. PD assessments were performed using a battery of nociceptive tasks (electrical pain, pressure pain and cold pressor tasks). Twenty-five subjects were administered Xen2174. CSF PK analysis showed a higher area under the CSF concentration-time curve of Xen2174 in the highest dose group than allowed by the predefined safety margin based on nonclinical data. The most common adverse event was post-lumbar puncture syndrome, with no difference in incidence between treatment groups. Although no statistically significant differences were observed in the PD assessments between the different dosages of Xen2174 and placebo, pain tolerability in the highest dose group was higher than in the placebo group [contrast least squares mean pressure pain tolerance threshold of Xen2174 2.5mg-placebo (95% confidence interval), 22.2% (-5.0%, 57.1%); P = 0.1131]. At the Xen2174 dose level of 2.5mg, CSF concentrations exceeded the prespecified exposure limit based on the nonclinical safety margin. No statistically significant effects on evoked pain tests were observed.

Pharmacokinetic profiles contribute to the differences in behavioral pharmacology of 071031B enantiomers as novel serotonin and norepinephrine reuptake inhibitors.

Our previous study indicated that a chiral compound 071031B was a novel serotonin and noradrenaline reuptake inhibitor with superior antidepressant activity compared to duloxetine. The present study aimed to investigate chiral pharmacology differences of 071031B enantiomers, S-071031B and R-071031B, and disclose mechanisms underlying the behavioral differences based on target profiles and pharmacokinetic profiles. In vivo behavioral tests indicated that S-071031B was more potent than R-071031B in two depression models (the forced swimming test in mice and rats) and two pain models (the acetic acid-induced writhing and formalin tests in mice). In vitro assays revealed that both S-071031B and R-071031B showed high affinity for human serotonin transporters and norepinephrine transporters with equal potency, and showed consistently equipotent inhibitory effects on serotonin and norepinephrine uptake. Pharmacokinetic studies demonstrated that oral availability and hepatic metabolism, rather than pH stability, intestinal transport, and plasma binding, contributed to enantiomers' behavioral differences. Based on these findings, it is suggested that S-071031B is a more active enantiomer, and the differential pharmacokinetic profiles, but not target affinity, contribute to differences of S-071031B and R-071031B in behavioral pharmacology. Moreover, current PK-PD study may provide positive exploration for chiral antidepressants development.

Drug Induced Liver Injury Secondary to ‘ Monkey Dust’

Introduction: Monkey dust - a type of bath salts, is a recreational drug. Bath salts are synthetic cathinones derived from the shrub grown in East Africa, Southern Arabia and people chew its leaves leading to mild stimulant effects. Bath salts are increasingly becoming more popular among recreational drugs. Their use is detrimental and sometimes lethal. There is very limited data on systemic adverse effects of bath salts and liver injury pattern is not well described in the literature. We present a challenging case of bath salts induced liver injury concomitantly presenting with acute hepatitis C infection. Case presentation: A 40 year old male presented with right upper quadrant and epigastric abdominal pain, nausea, vomiting, fever and jaundice for 4 days. He reported injecting bath salts with shared needles in last 4 weeks and smoked marihuana regularly. He reported no alcohol use, herbal supplements or use of any hepatotoxic medications, however he gave history of unprotected sex. His vital signs and physical exam were unremarkable were except for mild epigastric tenderness. His laboratory data showed AST >717 U/L, ALT 2435 U/L, alkaline phosphatase 185 U/L and total bilirubin 4.1 with direct bilirubin of 3.3 mg/dL. His hepatitis profile came back positive for hepatitis C genotype 2b with viral load of 6900 IU/mL. He also had positive ANA and anti smooth muscle antibody. His abdominal sonogram showed no evidence of biliary obstruction or vascular thrombosis. His liver biopsy showed pattern consistent with drug induced liver injury. He was treated supportively and 4 weeks later his hepatitis C viral load became undetectable with normalization of his liver enzymes. Discussion: Bath salts induced liver injury is rare and requires high degree of clinical suspicion as most patients have polysubtance abuse and high risk for simultaneous viral infections. Patients often present with agitation, panic attack, violent behavior and other stimulant effects. It is thought that the stimulant effect is due to decreased uptake of dopamine and norepinephrine in the brain cells. Patients should be monitored in the intensive care unit for severity of symptoms which can often be lethal. Routine drug screen essays do not detect bath salts. Patient safety should be entertained and benzodiazepines should be used for sedation. Treatment is mainly supportive with intravenous hydration. It is important to recognize this entity as it may potentially lead to liver failure.

MicroRNAs 29b and 181a down-regulate the expression of the norepinephrine transporter and glucocorticoid receptors in PC12 cells.

MicroRNAs are short non-coding RNAs that provide global regulation of gene expression at the post-transcriptional level. Such regulation has been found to play a role in stress-induced epigenetic responses in the brain. The norepinephrine transporter (NET) and glucocorticoid receptors are closely related to the homeostatic integration and regulation after stress. Our previous studies demonstrated that NET mRNA and protein levels in rats are regulated by chronic stress and by administration of corticosterone, which is mediated through glucocorticoid receptors. Whether miRNAs are intermediaries in the regulation of these proteins remains to be elucidated. This study was undertaken to determine possible regulatory effects of miRNAs on the expression of NET and glucocorticoid receptors in the noradrenergic neuronal cell line. Using computational target prediction, we identified several candidate miRNAs potentially targeting NET and glucocorticoid receptors. Western blot results showed that over-expression of miR-181a and miR-29b significantly repressed protein levels of NET, which is accompanied by a reduced [3 H] norepinephrine uptake, and glucocorticoid receptors in PC12 cells. Luciferase reporter assays verified that both miR-181a and miR-29b bind the 3'UTR of mRNA of NET and glucocorticoid receptors. Furthermore, exposure of PC12 cells to corticosterone markedly reduced the endogenous levels of miR-29b, which was not reversed by the application of glucocorticoid receptor antagonist mifepristone. These observations indicate that miR-181a and miR-29b can function as the negative regulators of NET and glucocorticoid receptor translation invitro. This regulatory effect may be related to stress-induced up-regulation of the noradrenergic phenotype, a phenomenon observed in stress models and depressive patients. This study demonstrated that miR-29b and miR-181a, two short non-coding RNAs that provide global regulation of gene expression, markedly repressed protein levels of norepinephrine (NE) transporter and glucocorticoid receptor (GR), as well as NE uptake by binding the 3'UTR of their mRNAs in PC12 cells. Also, exposure of cells to corticosterone significantly reduced miR-29b levels through a GR-independent way.

Abstract P619: A Comparison of the Adrenergic System within the Perivascular Adipose Tissue in Two-High Fat Fed Models of Obesity-induced Hypertension: Dahl S and Sprague-Dawley Rats

Increased sympathetic activity is one cause of obesity-induced hypertension. Over-activity of an adrenergic system in mesenteric perivascular adipose tissue (MPVAT) could contribute to high BP given its close proximity to splanchnic arteries and veins. We tested the hypothesis that high fat (HF) fed models of obesity-induced hypertension have elevated norepinephrine (NE) in MPVAT, increasing exposure of arteries to NE. Male Dahl S and Sprague-Dawley (SD) rats were fed a HF (60% fat, 0.3% NaCl; kcal) or a normal fat diet (NF; 10% fat, 0.25% NaCl; kcal) from weaning age (n=5). At 20-29 weeks of age, rats were sacrificed and tissues collected (all results shown in the table). HF increased the body weight of Dahl but not SD. Total fat mass was increased in the HF vs NF rats of both models. Mean arterial BP measured by radiotelemetry was elevated in the Dahl S HF vs NF and slightly elevated in the SD HF vs NF rats. Plasma NE was not elevated in either model. Surprisingly, MPVAT had significantly less NE in the Dahl S HF vs NF but was not altered in the SD. Expression of genes involved in NE synthesis, uptake and metabolism was measured by PCR to determine whether the MPVAT’s adrenergic system was altered in HF rats. Tyrosine hydroxylase ( Th ) mRNA was not detected in the Dahl S (SD not measured). Expression for the NE metabolizing enzymes monoamine oxidase-A (MAO-A) and catechol-o-methyl transferase ( Comt ) was not different. However, S lc22a3 mRNA (organic cation transporter 3) was reduced in the SD HF vs NF rat. These data reveal that the elevation in BP in Dahl S and SD rats fed a HF diet may be due to a mechanism that is independent of elevated NE in PVAT.Funding: NIHP01HL70687, F31 HL12803501

Melatonin mediated antidepressant-like effect in the hippocampus of chronic stress-induced depression rats: Regulating vesicular monoamine transporter 2 and monoamine oxidase A levels

The hippocampus is sensitive to stress which activates norepinephrine terminals deriving from the locus coeruleus. Melatonin exerts positive effects on the hippocampal neurogenic process and on depressive-like behaviour. Thus, in the present study, an examination was made of the effect of chronic melatonin treatment on norepinephrine content, synthesis, uptake, vesicular transport and degradation in the hippocampus of rats exposed to CUMS. This entailed quantifying the norephinephrine, mRNA and protein levels of DBH, NET, VMAT 2, MAO-A and COMT. The results show that CUMS evoked prolonged immobility. Melatonin treatment decreased immobility in comparison with the placebo group, reflecting an antidepressant-like effect. Compared with the placebo group, a dramatic decrease in norepinephrine content, decreased VMAT2 mRNA and protein and increased MAO-A protein levels in the hippocampus of the CUMS rats were observed. However, no significant differences in the levels of DBH, NET, COMT mRNA and protein and MAO-A mRNA levels between the placebo and the stressed groups were found. The results showed the restorative effects of melatonin on the stress-induced decline in the norepinephrine content of the hippocampus. It was observed that melatonin treatment in the CUMS rats prevented the stress-induced decrease in VMAT2 mRNA and protein levels, whereas it reduced the increase of the mRNA of COMT and protein levels of MAO-A. Chronic treatment with melatonin failed to alter the gene expression of DBH or NET in the hippocampus of the CUMS rats. Additionally, the results show that melatonin enhances VMAT2 expression and norepinephrine storage, whilst it reduces norepinephrine degrading enzymes.

Acute arterial baroreflex-mediated changes in plasma catecholamine concentrations in a chronic rat model of myocardial infarction.

While it may be predictable that plasma norepinephrine (NE) concentration changes with efferent sympathetic nerve activity (SNA) in response to baroreceptor pressure inputs, an exact relationship between SNA and plasma NE concentration remains to be quantified in heart failure. We examined acute baroreflex‐mediated changes in plasma NE and epinephrine (Epi) concentrations in normal control (NC) rats and rats with myocardial infarction (MI) (n = 6 each). Plasma NE concentration correlated linearly with SNA in the NC group (slope: 2.17 ± 0.26 pg mL−1 %−1, intercept: 20.0 ± 18.2 pg mL−1) and also in the MI group (slope: 19.20 ± 6.45 pg mL−1 %−1, intercept: −239.6 ± 200.0 pg mL−1). The slope was approximately nine times higher in the MI than in the NC group (P < 0.01). Plasma Epi concentration positively correlated with SNA in the NC group (slope: 1.65 ± 0.79 pg mL−1 %−1, intercept: 115.0 ± 69.5 pg mL−1) and also in the MI group (slope: 7.74 ± 2.20 pg mL−1 %−1, intercept: 24.7 ± 120.1 pg mL−1). The slope was approximately 4.5 times higher in the MI than in the NC group (P < 0.05). Intravenous administration of desipramine (1 mg kg−1) significantly increased plasma NE concentration but decreased plasma Epi concentration in both groups, suggesting that neuronal NE uptake had contributed to the reduction in plasma NE concentration. These results indicate that high levels of plasma catecholamine in MI rats were still under the influence of baroreflex‐mediated changes in SNA, and may provide additional rationale for applying baroreflex activation therapy in patients with chronic heart failure.

Methamphetamine compromises gap junctional communication in astrocytes and neurons.

Methamphetamine (meth) is a central nervous system (CNS) stimulant that results in psychological and physical dependency. The long-term effects of meth within the CNS include neuronal plasticity changes, blood-brain barrier compromise, inflammation, electrical dysfunction, neuronal/glial toxicity, and an increased risk to infectious diseases including HIV. Most of the reported meth effects in the CNS are related to dysregulation of chemical synapses by altering the release and uptake of neurotransmitters, especially dopamine, norepinephrine, and epinephrine. However, little is known about the effects of meth on connexin (Cx) containing channels, such as gap junctions (GJ) and hemichannels (HC). We examined the effects of meth on Cx expression, function, and its role in NeuroAIDS. We found that meth altered Cx expression and localization, decreased GJ communication between neurons and astrocytes, and induced the opening of Cx43/Cx36 HC. Furthermore, we found that these changes in GJ and HC induced by meth treatment were mediated by activation of dopamine receptors, suggesting that dysregulation of dopamine signaling induced by meth is essential for GJ and HC compromise. Meth-induced changes in GJ and HC contributed to amplified CNS toxicity by dysregulating glutamate metabolism and increasing the susceptibility of neurons and astrocytes to bystander apoptosis induced by HIV. Together, our results indicate that connexin containing channels, GJ and HC, are essential in the pathogenesis of meth and increase the sensitivity of the CNS to HIV CNS disease. Methamphetamine (meth) is an extremely addictive central nervous system stimulant. Meth reduced gap junctional (GJ) communication by inducing internalization of connexin-43 (Cx43) in astrocytes and reducing expression of Cx36 in neurons by a mechanism involving activation of dopamine receptors (see cartoon). Meth-induced changes in Cx containing channels increased extracellular levels of glutamate and resulted in higher sensitivity of neurons and astrocytes to apoptosis in response to HIV infection.

3T3‐L1 Adipocytes Take Up Norepinephrine: No Canonical Norepinephrine Transporters Found

Rat perivascular adipose tissue (PVAT) and rat adipocytes contain the organic cation transporter 3 (OCT3), a transporter of norepinephrine (NE). This is physiologically relevant because PVAT reduces vasoconstriction through the uptake of NE. We hypothesized that an accepted model of adipocytes, 3T3‐L1 cells, take up NE through OCT3 or a similar catecholamine transporter. Mouse 3T3‐L1 fibroblasts were induced into adipocytes by adding 0.5 mM IBMX and 0.25 mM dexamethasone for 48 hours. AdipoRedTM assay and Oil Red O staining confirm that induction was successful (15 times more fluorescent than preadipocytes and 95% of cells exhibit lipid droplet staining, respectively) on the 10th day after the induction. NE was added to 3T3‐L1 adipocytes at 0, 1, 10, and 100 mM concentrations in physiological saline solution (PSS) with NE metabolism inhibitors [monoamine oxidase, pargyline (10−5 M), catecholamine‐O‐methyltransferase, Ro 41‐0960 (10−6 M), semicarbazide‐sensitive amine oxidase, semicarbazide hydrochloride (10−3 M)] for 30 minutes at 37 °C. Cells were washed with PSS, collected in tissue buffer, and analyzed for NE content using HPLC. There was an increase in NE, normalized for protein content, from vehicle to 10 mM and 100 mM (0.09 ± 0.01 pg/mg, 5.97 ± 1.48 pg/mg, 18.89 ± 3.37 pg/mg, respectively, p &lt; 0.05, N=6). PCR was performed on cDNA isolated from 3T3‐L1 adipocytes to test for known NE transporters: norepinephrine transporter (NET), OCT3, serotonin transporter (SERT), dopamine transporter (DAT), vesicular monoamine transporter 2 (VMAT2), and plasma membrane monoamine transporter (PMAT), using beta‐actin as the reference gene. OCT3, SERT, DAT, and VMAT2 did not reach the detectable threshold after 40 amplification cycles (CT value &gt; 40, N=4). NET and PMAT had 1 sample out of 4 with a detected CT value (37.45 ± 0.15 and 37.41 ± 0.05, respectively). The positive controls had detectable amplification (heart: 26.94 ± 0.02 for OCT3, brain: 27.53 ± 0.10 for SERT, 27.90 ± 0.03 for DAT, and 26.97 ± 0.03 for PMAT, adrenal: 25.80 ± 0.15 for VMAT2, pons: 24.59 for NET). These data suggest that NE is entering 3T3‐L1 adipocytes via mechanisms other than the canonical transporters of NE. Learning how NE interacts with adipocytes, and therefore PVAT, is essential for studying the relation between vasoconstriction and obesity.Support or Funding InformationNIH NHLBI P01HL70687IPSTP 5 T32 GM 92715‐4NIH NRSA F31 HL128035‐01

Antidepressant-like Effects of LPM580153, A Novel Potent Triple Reuptake Inhibitor.

The purpose of this study was to characterize a novel compound, 4-[2-(dimethylamino)-1-(1-hydroxycyclohexyl) ethyl] phenyl 3-nitrophenyl ether, designated LPM580153. We used several well-validated animal models of depression to assess the antidepressant-like activity of LPM580153, followed by a neurotransmitter uptake assay and a corticosterone-induced cell injury model to explore its mechanism of action. In mice, LPM580153 reduced immobility time in the tail suspension test, and in rats subjected to chronic unpredictable mild stress it reversed reductions in body weight gain and ameliorated anhedonia. The neurotransmitter uptake assay results demonstrated that LPM580153 inhibited the uptake of serotonin, norepinephrine and dopamine. Furthermore, LPM580153 protected the SH-SY5Y cells against the cytotoxic activity of corticosterone, an action that might be related to the role of LPM580153 in increasing the protein levels of BDNF, p-ERK1/2, p-AKT, p-CREB and p-mTOR. Together, these findings indicate that LPM580153 is a novel triple reuptake inhibitor with robust antidepressant-like effects.

A Novel Heterocyclic Compound CE-104 Enhances Spatial Working Memory in the Radial Arm Maze in Rats and Modulates the Dopaminergic System

Various psychostimulants targeting monoamine neurotransmitter transporters (MATs) have been shown to rescue cognition in patients with neurological disorders and improve cognitive abilities in healthy subjects at low doses. Here, we examined the effects upon cognition of a chemically synthesized novel MAT inhibiting compound 2-(benzhydrylsulfinylmethyl)-4-methylthiazole (named as CE-104). The efficacy of CE-104 in blocking MAT [dopamine transporter (DAT), serotonin transporter (SERT), and norepinephrine transporter] was determined using in vitro neurotransmitter uptake assay. The effect of the drug at low doses (1 and 10 mg/kg) on spatial memory was studied in male rats in the radial arm maze (RAM). Furthermore, the dopamine receptor and transporter complex levels of frontal cortex (FC) tissue of trained and untrained animals treated either with the drug or vehicle were quantified on blue native PAGE (BN-PAGE). The drug inhibited dopamine (IC50: 27.88 μM) and norepinephrine uptake (IC50: 160.40 μM), but had a negligible effect on SERT. In the RAM, both drug-dose groups improved spatial working memory during the performance phase of RAM as compared to vehicle. BN-PAGE Western blot quantification of dopamine receptor and transporter complexes revealed that D1, D2, D3, and DAT complexes were modulated due to training and by drug effects. The drug’s ability to block DAT and its influence on DAT and receptor complex levels in the FC is proposed as a possible mechanism for the observed learning and memory enhancement in the RAM.

Cardiac Innervation Imaging: Implications for Risk Stratification and Therapeutic Decision-Making

Heart failure (HF) is associated with reduced cardiac sympathetic neuronal uptake of norepinephrine (NE), which can be assessed noninvasively using different radiotracers and planar or single-photon emission computed tomography (SPECT)/positron emission tomography (PET) imaging. Such sympathetic derangement in HF patients has shown to be an indicator of unfavorable prognosis. Therefore, cardiac sympathetic imaging might be useful as an indicator of the effectiveness of the medical therapy and consequently for risk stratification of patients with HF to more effectively guide specific therapies. This article reviews the current status on the subject and evaluates the literature published over recent years.

The Effects of Ivabradine on Cardiac Function after Myocardial Infarction are Weaker in Diabetic Rats

Background/Aims: Plasma norepinephrine (NE) and brain natriuretic peptide (BNP, termed BNP-45 in rats) are considered as essential neurohormones indicating heart failure progression. The purposes of this study were to examine the effects of ivabradine (IBD) on cardiac function and plasma NE and BNP-45 after chronic ischemic heart failure (CHF) in non-diabetic rats and diabetic rats. We further determined if sympathetic NE uptake-1 (a major pathway to metabolize NE) mechanism is responsible for the role played by IBD. Methods: We ligated rat's coronary artery to induce CHF; and injected streptozotocin (STZ) to induce diabetic hyperglycemia. Echocardiography was employed to determine cardiac function. We used ELISA to examine plasma NE and BNP-45; and Western Blot analysis to examine the protein levels of NE uptake-1 in sympathetic nerves. Results: CHF increased the levels of NE and BNP-45 in non-STZ rats and STZ rats. Systemic injection of IBD significantly attenuated the augmented NE and BNP-45 and impaired left ventricular function induced by CHF in those rats. This effect appeared to be less in STZ rats. A liner relation was observed between the NE/BNP-45 levels and left ventricular function after administration of IBD. Also, IBD was observed to have a recovery effect on the downregulated NE uptake-1 evoked by CHF, but to a smaller degree in STZ rats. Conclusion: Our data revealed specific signaling mechanisms by which IBD improves the cardiac function as IBD alleviates impaired NE uptake-1and thereby decreases heightened NE and BNP-45 induced by CHF. Our data also demonstrated that the effects of IBD are weakened after diabetic hyperglycemia likely due to worsen NE uptake-1 pathway. Thus, targeting sympathetic NE uptake-1 signaling molecules has clinical implications for treatment and management of CHF in diabetes. Our data were also to shed light on strategies for application of this drug because NE and BNP play an important role in regulation of progression and prognosis of CHF, and in particular, because IBD affects NE uptake-1 pathway in hyperglycemic animals to a less degree.

Drugs Inducing Xerostomia

The aim of this review is to evaluate the synergistic effect of multiple xerostomia drugs. From the review It is been found that there are number of xerogenic drugs, especially antimuscarinic agents, some sympathomimetic agents, and agents affecting serotonin and noradrenaline uptake, as well as a miscellany of other drugs such as appetite suppressants, protease inhibitors and cytokines. Even non pharmacological affects causes xerostomia. It is even found that there is very highly significant reduction in the salivary flow rates of patients under multiple xerostomia-inducing drugs. Dry mouth is especially through the drugs which affecting anticholinergic activity against the M3 muscarinic receptor. Dry mouth can be treated with the administration of pilocarpine, it can even be treated by giving salivary stimulant. Even physical treatment is available for dry mouth as acupuncture.

Receptor binding profiles and quantitative structure-affinity relationships of some 5-substituted-N,N-diallyltryptamines.

N,N-Diallyltryptamine (DALT) and 5-methoxy-N,N-diallyltryptamine (5-MeO-DALT) are two tryptamines synthesized and tested by Alexander Shulgin. In self-experiments, 5-MeO-DALT was reported to be psychoactive in the 12-20mg range, while the unsubstituted compound DALT had few discernible effects in the 42-80 mg range. Recently, 5-MeO-DALT has been used in nonmedical settings for its psychoactive effects, but these effects have been poorly characterized and little is known of its pharmacological properties. We extended the work of Shulgin by synthesizing additional 5-substituted-DALTs. We then compared them to DALT and 5-MeO-DALT for their binding affinities at 45 cloned receptors and transporter proteins. Based on in vitro binding affinity, we identified 27 potential receptor targets for the 5-substituted-DALT compounds. Five of the DALT compounds had affinity in the 10-80 nM range for serotonin 5-HT1A and 5-HT2B receptors, while the affinity of DALT itself at 5-HT1A receptors was slightly lower at 100 nM. Among the 5-HT2 subtypes, the weakest affinity was at 5-HT2A receptors, spanning 250-730 nM. Five of the DALT compounds had affinity in the 50-400 nM range for serotonin 5-HT1D, 5-HT6, and 5-HT7 receptors; again, it was the unsubstituted DALT that had the weakest affinity at all three subtypes. The test drugs had even weaker affinity for 5-HT1B, 5-HT1E, and 5-HT5A subtypes and little or no affinity for the 5-HT3 subtype. These compounds also had generally nanomolar affinities for adrenergic α2A, α2B, and α2C receptors, sigma receptors σ1 and σ2, histamine H1 receptors, and norepinephrine and serotonin uptake transporters. They also bound to other targets in the nanomolar-to-low micromolar range. Based on these binding results, it is likely that multiple serotonin receptors, as well as several nonserotonergic sites are important for the psychoactive effects of DALT drugs. To learn whether any quantitative structure-affinity relationships existed, we evaluated correlations among physicochemical properties of the congeneric 5-substituted-DALT compounds. The descriptors included electronic (σp), hydrophobic (π), and steric (CMR) parameters. The binding affinity at 5-HT1A, 5-HT1D, 5-HT7, and κ opioid receptors was positively correlated with the steric volume parameter CMR. At α2A, α2B, and α2C receptors, and at the histamine H1 receptor, binding affinity was correlated with the Hammett substituent parameter σp; higher affinity was associated with larger σp values. At the σ2 receptor, higher affinity was correlated with increasing π. These correlations should aid in the development of more potent and selective drugs within this family of compounds.

Inhibition of Protein Kinase C Signalling On Cardiac Noradrenaline Uptake in the Spontaneously Hypertensive Rat

Inhibition of Protein Kinase C Signalling On Cardiac Noradrenaline Uptake in the Spontaneously Hypertensive Rat

11C]NS9531, [11C]NS9762 and [11C]NS6417, specific SERT tracers: pre-clinical evaluation in pigs and optimization of synthesis conditions using [11C]methyl triflate

IntroductionNS9531, NS9762 and NS6417 are nitroquinolinyl-diazabicyclo-alkane derivatives that have been developed as inhibitors of serotonin reuptake transporters (SERT) by NeuroSearch A/S. MethodsIC50 was measured on the up-take of serotonin, dopamine and noradrenaline in synaptosomes prepared from selected rat brain regions. For the pre-clinical evaluation in pigs, [11C]NS9531, [11C]NS9762 and [11C]NS6417 were prepared by N-methylation using [11C]methyl iodide. These syntheses were later on optimized regarding: 1) choice of labelled precursor; 2) HPLC purification conditions; and 3) formulation using SPE columns. The synthesis protocols were then fully automated on a GE FXc Pro. Preclinical evaluation was performed by PET studies in landrace pigs before and after treatment with citalopram. ResultsIC50 measurements showed that all three compounds have low nanomolar affinity for SERT, and micromolar affinity for DAT and NET. The radiochemical yield (r.y.) of all three ligands from [11C]methyl iodide was higher than 30%. From [11C]methyl triflate, the r.y. of [11C]NS9531 and [11C]NS9762 were higher than 80% whereas the r.y. of [11C]NS6417 was 65%. Residual precursor amounts in final products could be significantly reduced by the use of [11C]methyl triflate, <0.2μg compared with <10μg, calculated for a 300MBq injection at 20minutes EOS. The optimized conditions gave 2.5–4.5GBq of products with a specific radioactivity of 20–70MBq/nmol, residual acetonitrile 15–30ppm, and pH6.5–7.1. All three compounds showed a rapid and comparable high pig brain uptake of about 3%, producing PET images of good contrast, and uptake was reduced after pre-administration with citalopram. ConclusionThe three 11C labelled PET tracers could be prepared in medium to high yield and high purity. IC50 measurements showed that the three NS compounds were highly selective, high affinity SERT inhibitors. PET studies in pig showed high brain uptake that could be blocked by citalopram pre-treatment.

Organic cation transporter 3 contributes to norepinephrine uptake into perivascular adipose tissue.

Perivascular adipose tissue (PVAT) reduces vasoconstriction to norepinephrine (NE). A mechanism by which PVAT could function to reduce vascular contraction is by decreasing the amount of NE to which the vessel is exposed. PVATs from male Sprague-Dawley rats were used to test the hypothesis that PVAT has a NE uptake mechanism. NE was detected by HPLC in mesenteric PVAT and isolated adipocytes. Uptake of NE (10 μM) in mesenteric PVAT was reduced by the NE transporter (NET) inhibitor nisoxetine (1 μM, 73.68 ± 7.62%, all values reported as percentages of vehicle), the 5-hydroxytryptamine transporter (SERT) inhibitor citalopram (100 nM) with the organic cation transporter 3 (OCT3) inhibitor corticosterone (100 μM, 56.18 ± 5.21%), and the NET inhibitor desipramine (10 μM) with corticosterone (100 μM, 61.18 ± 6.82%). Aortic PVAT NE uptake was reduced by corticosterone (100 μM, 53.01 ± 10.96%). Confocal imaging of mesenteric PVAT stained with 4-[4-(dimethylamino)-styrl]-N-methylpyridinium iodide (ASP(+)), a fluorescent substrate of cationic transporters, detected ASP(+) uptake into adipocytes. ASP(+) (2 μM) uptake was reduced by citalopram (100 nM, 66.68 ± 6.43%), corticosterone (100 μM, 43.49 ± 10.17%), nisoxetine (100 nM, 84.12 ± 4.24%), citalopram with corticosterone (100 nM and 100 μM, respectively, 35.75 ± 4.21%), and desipramine with corticosterone (10 and 100 μM, respectively, 50.47 ± 5.78%). NET protein was not detected in mesenteric PVAT adipocytes. Expression of Slc22a3 (OCT3 gene) mRNA and protein in PVAT adipocytes was detected by RT-PCR and immunocytochemistry, respectively. These end points support the presence of a transporter-mediated NE uptake system within PVAT with a potential mediator being OCT3.