Norepinephrine Uptake Inhibitor Research Articles

Abstract SS02-02: Hormone Replacement and Alternatives for Relief of Vasomotor Symptoms in Women at Increased Risk for Breast Cancer

Abstract 70% of women will experience vasomotor symptoms sufficient to impact their quality of life during menopause transition and the early menopause. These symptoms are thought result from neurotransmitter imbalances resulting from ovarian hormone reductions and hypersecretion of gonadotropins. Increases in gonadotropins result in neurotransmitter triggered stimulation of the neurokinin 3 (NK3) receptor and thermoregulatory imbalance. Estrogen deficiency also reduces serotonin which can also trigger increases in hot flashes, and sleep disturbances. Vasomotor symptoms last on the average for 7 years until acclimation to persistent low estrogen levels occurs. Estrogen +/- progestin replacement therapy is associated with the greatest likelihood of vasomotor symptom relief as it reduces gonadotropin and NK3 receptor signaling and increases serotonin. Progestins also increase the neuroinhibitory transmitter gamma-aminobutyric acid (GABA) which improves sleep quality. There continues to be confusion on the part of providers and patients regarding the excess risk of breast cancer and thromboembolic events as these risks are affected by type of agent, route of delivery, age, duration of treatment, and presence of obesity. The majority of placebo controlled randomized clinical trial data on hormone replacement with estrogen or estrogen + a progestin comes from the Women’s Health Initiative (WHI) for women 50-79 in which oral conjugated estrogen (CE) 0.625 mg was used as the estrogen for women without a uterus and medroxyprogesterone acetate (MPA) was added to CE for women with a uterus to protect against endometrial hyperplasia and cancer. The median age at entry to WHI that trial was 63 and a substantial proportion had previously taken hormones. Large longitudinal cohort studies have been helpful in assessing risks in women starting hormones at a more clinically relevant age (45-55) and with hormonal preparations other than oral CE and MPA. Five to seven years of estrogen alone results in minimal if any increased risk for breast cancer. However, combined estrogen+ progestin replacement for women over 50, necessary for women with a uterus, results in an ~ 30 % relative increased risk for breast cancer if taken for up to 5 years and a doubling of risk with 10 years of treatment. So called bioidentical hormones often compounded as oral troches of estradiol, progesterone, and testosterone, are also associated with increased breast cancer risk. Vaginal hormones have not been found to increase risk for breast cancer. Increased risk of thromboembolism is predominately observed in women over 50 using oral as opposed to transdermal preparations. Increased risk for stroke and dementia was observed in the WHI again with oral hormones in women over 65. In the WHI there was no increase in cancer related, cardiovascular or overall mortality with estrogen or estrogen and progestin. For high-risk peri and post-menopausal women with who would like to reduce/alleviate their vasomotor symptoms with no increase in risk for breast cancer there are several options: 1) the tissue selective estrogen complex bazedoxifene (BZA) combined with conjugated estrogen (CE) 2) the non-hormonal option of NK3 receptor antagonists such as fezolinetant ( 3) non-hormonal options of gabapentin, selective serotonin reuptake inhibitors (SSRI) and serotonin and norepinephrine uptake inhibitors (SNRI). BZA and CE and fezolinetant are reported to reduce hot flashes in 70% or more of individuals with paroxetine effectiveness reported as 50%. All three are FDA approved for reduction of vasomotor symptoms. The combination of BZA and CE is also being investigated for breast cancer risk reduction. These agents differ with respect to side effects with increased risk of blood clots for bazedoxifene and conjugated estrogen, increased risk of nausea, diarrhea, and liver dysfunction for fezolinetant and drowsiness and dry mouth for SSRIs. Drug costs may also dramatically affect insurance coverage and patient uptake of a particular strategy. A recent online perusal of a popular site for finding the lowest drug price suggested substantial differences in the cost of drugs for relief of vasomotor symptoms. The approximate cost for a 30- day supply of oral estradiol was $30, estradiol transdermal patches $35, oral progesterone $15, combined estradiol and levonorgestrel transdermal patches $240, oral CE $200, oral CE + medoxyprogesterone acetate $240, and for BZA+ CE $200. For non-hormonal therapies the cost of 30 days of gabapentin was $11, paroxetine $30 and fezolinetant $550. Crandall, Mehta, and Manson JAMA 2023 329:405-420 Collaborative Group on Hormonal Factors in Breast Cancer Lancet 2019 394: 1159-1168 Fabian et al Ca Prev Res 2019 10:711-720 Modi and Dhillo Neuroendocrinology 2019 109:242–248 Citation Format: C. Fabian. Hormone Replacement and Alternatives for Relief of Vasomotor Symptoms in Women at Increased Risk for Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr SS02-02.

Optogenetic and pharmacological interventions link hypocretin neurons to impulsivity in mice

Neurons in the lateral hypothalamus expressing the neuropeptide Hypocretin, also known as orexin, are known critical modulators of arousal stability. However, their role in the different components of the arousal construct such as attention and decision making is poorly understood. Here we study Hypocretin neuronal circuit dynamics during stop action impulsivity in a Go/NoGo task in mice. We show that Hypocretin neuronal activity correlates with anticipation of reward. We then assessed the causal role of Hypocretin neuronal activity using optogenetics in a Go/NoGo task. We show that stimulation of Hypocretin neurons during the cue period dramatically increases the number of premature responses. These effects are mimicked by amphetamine, reduced by atomoxetine, a norepinephrine uptake inhibitor, and blocked by a Hypocretin receptor 1 selective antagonist. We conclude that Hypocretin neurons have a key role in the integration of salient stimuli during wakefulness to produce appropriate and timely responses to rewarding and aversive cues.

Neurodevelopmental Problems Not Linked to Antidepressant Exposure In Utero

Neurodevelopmental Problems Not Linked to Antidepressant Exposure In Utero

Oncoguía del manejo del dolor en cáncer 2020

In Oncoguía del manejo del dolor en cáncer 2020 we present the epidemiology and the pathology scope caused by cancer pain, the World Health Organization’s analgesic ladder —and its subsequent adaptations—, the evaluation of the cancer-origin pain (that may be the result of the disease or be associated with the oncology treatment and that should include the complete clinical record and physical examination), and the use of the extension studies. Likewise, we addressed the pharmacological management based on the detailed multidimensional assessment of the pain severity, which starts at the appropriate level of the ladder for the pain degree and corresponds to the pharmacokinetics of the chosen drug. The use of opioids, coadjuvants, serotonin and noradrenaline uptake inhibitors, anticonvulsants, and N-Methyl D-Aspartate antagonists are also included. In the same way, we present the general guidelines and objectives for acute pain management and the medicare phases, as well as the primary interventionists management.

Remote Digital Measurement of Facial and Vocal Markers of Major Depressive Disorder Severity and Treatment Response: A Pilot Study.

Objectives: Multiple machine learning-based visual and auditory digital markers have demonstrated associations between major depressive disorder (MDD) status and severity. The current study examines if such measurements can quantify response to antidepressant treatment (ADT) with selective serotonin reuptake inhibitors (SSRIs) and serotonin–norepinephrine uptake inhibitors (SNRIs).Methods: Visual and auditory markers were acquired through an automated smartphone task that measures facial, vocal, and head movement characteristics across 4 weeks of treatment (with time points at baseline, 2 weeks, and 4 weeks) on ADT (n = 18). MDD diagnosis was confirmed using the Mini-International Neuropsychiatric Interview (MINI), and the Montgomery–Åsberg Depression Rating Scale (MADRS) was collected concordantly to assess changes in MDD severity.Results: Patient responses to ADT demonstrated clinically and statistically significant changes in the MADRS [F(2, 34) = 51.62, p < 0.0001]. Additionally, patients demonstrated significant increases in multiple digital markers including facial expressivity, head movement, and amount of speech. Finally, patients demonstrated significantly decreased frequency of fear and anger facial expressions.Conclusion: Digital markers associated with MDD demonstrate validity as measures of treatment response.

Astrocytes as Perspective Targets of Exercise- and Caloric Restriction\u2010Mimetics

Enhanced mental and physical activity can have positive effects on the function of aging brain, both in the experimental animals and human patients, although cellular mechanisms underlying these effects are currently unclear. There is a growing evidence that pre-clinical stage of many neurodegenerative diseases involves changes in interactions between astrocytes and neurons. Conversely, astrocytes are strategically positioned to mediate the positive influence of physical activity and diet on neuronal function. Thus, development of therapeutic agents which could improve the astroglia-neuron communications in ageing brain is of crucial importance. Recent advances in studies of cellular mechanisms of brain longevity suggest that astrocyte-neuron communications have a vital role in the beneficial effects of caloric restriction, physical exercise and their pharmacological mimetics on synaptic homeostasis and cognitive function. In particular, our recent data indicate that noradrenaline uptake inhibitor atomoxetine can enhance astrocytic Ca2+-signaling and astroglia-driven modulation of synaptic plasticity. Similar effects were exhibited by caloric restriction-mimetics metformin and resveratrol. The emerged data also suggest that astrocytes could be involved in the modulatory action of caloric restriction and its mimetics on neuronal autophagy. Still, the efficiency of astrocyte-targeting compounds in preventing age-related cognitive decline is yet to be fully explored, in particular in the animal models of neurodegenerative diseases and autophagy impairment.

Angiotensin II mediates the axonal trafficking of tyrosine hydroxylase and dopamine β-hydroxylase mRNAs and enhances norepinephrine synthesis in primary sympathetic neurons.

In the sympatho-adrenal system, angiotensin II (Ang II) acts as a key neuromodulatory component. At sympathetic nerve terminals, Ang II influences sympathetic transmission by enhancing norepinephrine (NE) synthesis, facilitating NE release and inhibiting NE uptake. Previously, it was demonstrated that tyrosine hydroxylase (TH) mRNA is trafficked to the distal axons of primary superior cervical ganglia (SCG) neurons, directed by a cis-acting regulatory element (i.e. zipcode) located in the 3'UTR of the transcript. Results of metabolic labeling studies established that the mRNA is locally translated. It was further shown that the axonal trafficking of the mRNA encoding the enzyme plays an important role in mediating dopamine (DA) and NE synthesis and may facilitate the maintenance of axonal catecholamine levels. In the present study, the hypothesis was tested that Ang II induces NE synthesis in rat primary SCG neurons via the modulation of the trafficking of the mRNAs encoding the catecholamine synthesizing enzymes TH and dopamine β-hydroxylase (DBH). Treatment of SCG neurons with the Ang II receptor type 1 (AT1R) agonist, L-162,313, increases the axonal levels of TH and DBH mRNA and protein and results in elevated NE levels. Conversely, treatment of rat SCG neurons with the AT1R antagonist, Eprosartan, abolished the L-162,313-mediated increase in axonal levels of TH and DBH mRNA and protein. In a first attempt to identify the proteins involved in the Ang II-mediated axonal transport of TH mRNA, we used a biotinylated 50-nucleotide TH RNA zipcode as bait in the affinity purification of TH zipcode-associated proteins. Mass spectrometric analysis of the TH zipcode ribonucleoprotein (RNP) complex immune-purified from SCG neurons led to the identification of 163 somal and 127 axonal proteins functionally involved in binding nucleic acids, the translational machinery or acting as subunits of cytoskeletal and motor proteins. Surprisingly, immune-purification of the TH axonal trafficking complex, results in the acquisition of DBH mRNA, suggesting that these mRNAs maybe transported to the axon together, possibly in the same RNP complex. Taken together, our results point to a novel mechanism by which Ang II participates in the regulation of axonal synthesis of NE by modulating the local trafficking and expression of TH and DBH, two key enzymes involved in the catecholamine biosynthetic pathway.

A characterization of behavior and monoamine interactions during conditioned avoidance maintained in a within‐session behavioral economic avoidance task

The mesolimbic dopamine (DA) system is generally considered to be a reward pathway, however, It is becoming increasingly evident that dopamine release events also process aversion and influence aversively motivated behavior. To investigate the role that dopamine plays in the motivation to avoid, we first developed an economics‐based shock avoidance task in which rats are given the opportunity to avoid electrical foot‐shock. Within each session, we provide rats with the opportunity to avoid footshock across a range of prices (response requirement/mA shock). A stimulus light, or warning signal, placed above the lever signals the opportunity to avoid impending footshock. Using fast‐scan cyclic voltammetry, we determined that dopamine concentration at both the warning signal and successful avoidance decreases with price. However, an attenuation of avoidance and dopamine release at session onset developed over the course of training. It is possible that session onset begins to predict an aversive session terminus because sessions terminate after a minimum of 15 footshocks occur. To further characterize this initial suppression we are currently measuring ultrasonic vocalizations (USVs) during the acquisition of avoidance in the behavioral economics task. We predict that 22khz USVs will develop at session onset in a manner that conincides with both the attenuation of dopamine release and avoidance. While characterizing a novel approach to measure conditioned fear is worthwhile in its own right, we primarily developed our task to measure changes in the price rats will pay to avoid. We measure the price rats will pay to avoid by using demand curves. Demand curves are a common tool used by economists to measure price sensitivity that depict the relationship between consumption (mA footshock avoided) and price (responses/mA). The rate at which demand curves decay can be used to make inferences regarding the value individuals place on the commodity being consumed. If the slope decays at a faster rate we would infer that the value to avoid is decreased because the rats are paying less to avoid. Using optogenetics, we found that increasing dopamine release at successful avoidance increases the price rats will pay for cocaine. Follow‐up optogenetic studies are investigating the role of the habenula‐RMTg‐mesolimbic dopamine circuitry. We predict that exciting glutamate neurons in the habenula will produce opposite behavioral effects to those occurring from direct dopamine stimulation. We are also beginning to compare the effects of discrete monoamine systems. To begin, we are simply pre‐treating rats with dopamine, serotonin and norepinephrine uptake inhibitors. Based on our preliminary optogenetics data, we predict that the dopamine uptake inhibitor will increase the price rats will pay to avoid whereas, serotonin and norephinephreine manipulations will produce distinct effects.Support or Funding InformationThis work was supported by the National Science Foundation Grant IOS‐1557755, the National Institutes of Health Grant R03DA038734, the Boettcher Young Investigator Award and the National Alliance for Research on Schizophrenia and Depression Young Investigator Award (E.B.O.)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Chronic heart failure: a disease of the brain.

The underlying mechanism for clinical and biochemical manifestations of chronic heart failure (HF) may be due in part to neurohumoral adaptations, such as activation of the renin-angiotensin-aldosterone and sympathetic nervous systems in the periphery and the brain. Internet search and discussion with colleagues are the methods for this study. Since chronic HF is associated with autonomic imbalance with increased sympathetic nerve activity and a withdrawal of parasympathetic activity, it may be considered a brain disease. This phenomenon may be the result of an increased systemic and cerebral angiotensin II signaling because plasma angiotensin II is increased in humans and animals with chronic HF. The increase in angiotensin II signaling enhances sympathetic nerve activity through actions on both central and peripheral sites during chronic HF. Activation of angiotensin II signaling in different brain sites such as the paraventricular nucleus (PVN), rostral ventrolateral medulla (RVLM), and area postrema (AP) may increase the release of norepinephrine, oxidative stress, and inflammation leading to increased cardiac contractility. It is possible that blocking angiotensin II type 1 receptors decreases sympathetic nerve activity and cardiac sympathetic afferent reflex when therapy is administered to the PVN. The administration of an angiotensin receptor blocker by injection into the AP activates the sympatho-inhibitory baroreflex indicating that receptor blockers act by increasing parasympathetic activity. In chronic HF, in peripheral regions, angiotensin II elevates both norepinephrine release and synthesis and inhibits norepinephrine uptake at nerve endings, which may contribute to the increase in sympathetic nerve activity. Increased circulating angiotensin II during chronic HF may enhance the sympatho-excitatory chemoreflex and inhibit the sympatho-inhibitory baroreflex resulting in worsening of HF. Increased circulating angiotensin II signaling can directly act on the central nervous system via the subfornical organ and the AP to increase sympathetic outflow resulting in to neurohumoral dysfunction, resulting in to heart failure.

Serotonin and Norepinephrine Reuptake Inhibitors.

This chapter covers antidepressants that fall into the class of serotonin (5-HT) and norepinephrine (NE) reuptake inhibitors. That is, they bind to the 5-HT and NE transporters with varying levels of potency and binding affinity ratios. Unlike the selective serotonin (5-HT) reuptake inhibitors (SSRIs), most of these antidepressants have an ascending rather than a flat dose-response curve. The chapter provides a brief review of the chemistry, pharmacology, metabolism, safety and adverse effects, clinical use, and therapeutic indications of each antidepressant. Venlafaxine, a phenylethylamine, is a relatively weak 5-HT and weaker NE uptake inhibitor with a 30-fold difference in binding of the two transporters. Therefore, the drug has a clear dose progression, with low doses predominantly binding to the 5-HT transporter and more binding of the NE transporter as the dose ascends. Venlafaxine is metabolized to the active metabolite O-desmethylvenlafaxine (ODV; desvenlafaxine) by CYP2D6, and it therefore is subject to significant inter-individual variation in blood levels and response dependent on variations in CYP2D6 metabolism. The half-life of venlafaxine is short at about 5h, with the ODV metabolite being 12h. Both parent compound and metabolite have low protein binding and neither inhibit CYP enzymes. Therefore, both venlafaxine and desvenlafaxine are potential options if drug-drug interactions are a concern, although venlafaxine may be subject to drug-drug interactions with CYP2D6 inhibitors. At low doses, the adverse effect profile is similar to an SSRI with nausea, diarrhea, fatigue or somnolence, and sexual side effects, while venlafaxine at higher doses can produce mild increases in blood pressure, diaphoresis, tachycardia, tremors, and anxiety. A disadvantage of venlafaxine relative to the SSRIs is the potential for dose-dependent blood pressure elevation, most likely due to the NE reuptake inhibition caused by higher doses; however, this adverse effect is infrequently observed at doses below 225mg per day. Venlafaxine also has a number of potential advantages over the SSRIs, including an ascending dose-antidepressant response curve, with possibly greater overall efficacy at higher doses. Venlafaxine is approved for MDD as well as generalized anxiety disorder, social anxiety disorder, and panic disorder. Desvenlafaxine is the primary metabolite of venlafaxine, and it is also a relatively low-potency 5-HT and NE uptake inhibitor. Like venlafaxine it has a favorable drug-drug interaction profile. It is subject to CYP3A4 metabolism, and it is therefore vulnerable to enzyme inhibition or induction. However, the primary metabolic pathway is direct conjugation. It is approved in the narrow dose range of 50-100mg per day. Duloxetine is a more potent 5-HT and NE reuptake inhibitor with a more balanced profile of binding at about 10:1 for 5HT and NE transporter binding. It is also a moderate inhibitor of CYP2D6, so that modest dose reductions and careful monitoring will be needed when prescribing duloxetine in combination with drugs that are preferentially metabolized by CYP2D6. The most common side effects identified in clinical trials are nausea, dry mouth, dizziness, constipation, insomnia, asthenia, and hypertension, consistent with its mechanisms of action. Clinical trials to date have demonstrated rates of response and remission in patients with major depression that are comparable to other marketed antidepressants reviewed in this book. In addition to approval for MDD, duloxetine is approved for diabetic peripheral neuropathic pain, fibromyalgia, and musculoskeletal pain. Milnacipran is marketed as an antidepressant in some countries, but not in the USA. It is approved in the USA and some other countries as a treatment for fibromyalgia. It has few pharmacokinetic and pharmacodynamic interactions with other drugs. Milnacipran has a half-life of about 10h and therefore needs to be administered twice per day. It is metabolized by CYP3A4, but the major pathway for clearance is direct conjugation and renal elimination. As with other drugs in this class, dysuria is a common, troublesome, and dose-dependent adverse effect (occurring in up to 7% of patients). High-dose milnacipran has been reported to cause blood pressure and pulse elevations. Levomilnacipran is the levorotary enantiomer of milnacipran, and it is pharmacologically very similar to the racemic compound, although the side effects may be milder within the approved dosing range. As with other NE uptake inhibitors, it may increase blood pressure and pulse, although it appears to do so less than some other medications. All medications in the class can cause serotonin syndrome when combined with MAOIs.

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.

Cocaine-Induced Endocannabinoid Mobilization in the Ventral Tegmental Area.

SUMMARYCocaine is a highly addictive drug that acts upon the brain’s reward circuitry via the inhibition of mono-amine uptake. Endogenous cannabinoids (eCB) are lipid molecules released from midbrain dopamine (DA) neurons that modulate cocaine’s effects through poorly understood mechanisms. We find that cocaine stimulates release of the eCB, 2-arach-idonoylglycerol (2-AG), in the rat ventral midbrain to suppress GABAergic inhibition of DA neurons, through activation of presynaptic cannabinoid CB1 receptors. Cocaine mobilizes 2-AG via inhibition of norepinephrine uptake and promotion of a cooperative interaction between Gq/11-coupled type-1 metabotropic glutamate and α1-adrenergic receptors to stimulate internal calcium stores and activate phospholipase C. The disinhibition of DA neurons by cocaine-mobilized 2-AG is also functionally relevant because it augments DA release in the nucleus accumbens in vivo. Our results identify a mechanism through which the eCB system can regulate the rewarding and addictive properties of cocaine.

The profile of mephedrone on human monoamine transporters differs from 3,4-methylenedioxymethamphetamine primarily by lower potency at the vesicular monoamine transporter

Mephedrone (4-methylmethcathinone, MMC) and 3,4-methylenedioxymethamphetamine (MDMA) are constituents of popular party drugs with psychoactive effects. Structurally they are amphetamine-like substances with monoamine neurotransmitter enhancing actions. We therefore compared their effects on the human monoamine transporters using human cell lines stably expressing the human noradrenaline, dopamine and serotonin transporter (NET, DAT and SERT); preparations of synaptic vesicles from human striatum in uptake experiments; and a superfusion system where releasing effects can be reliably measured. MMC and MDMA were equally potent in inhibiting noradrenaline uptake at NET, with IC50 values of 1.9 and 2.1µM, respectively. Compared to their NET inhibition potency, both drugs were weaker uptake inhibitors at DAT and SERT, with MMC being more potent than MDMA at DAT (IC50: 5.9 vs 12.6µM) and less potent than MDMA at SERT (IC50: 19.3 vs 7.6µM). MMC and MDMA both induced concentration-dependently [3H]1-methyl-4-phenylpyridinium-release from NET-, DAT or SERT-expressing cells which was clearly transporter-mediated release as demonstrated by the selective inhibitory effects of nmolar to low µmolar concentrations of desipramine, GBR 12909 and fluoxetine, respectively. MMC and MDMA differed most in their inhibition of [3H]dopamine uptake by synaptic vesicles from human striatum with MDMA being 10-fold more potent than MMC (IC50: 20 vs 223µM) and their ability to release [3H]dopamine from human vesicular monoamine transporter expressing SH-SY5Y neuroblastoma cells in which MDMA seems to have a stronger effect. Our findings give a molecular explanation to the lower long-term neurotoxicity of MMC compared to MDMA.

Psychostimulants and atomoxetine alter the electrophysiological activity of prefrontal cortex neurons, interaction with catecholamine and glutamate NMDA receptors.

Attention-deficit hyperactivity disorder (ADHD) is the most frequently diagnosed neuropsychiatric disorder in childhood. Currently available ADHD drugs include the psychostimulants methylphenidate (MPH) and D-amphetamine (D-AMP), acting on norepinephrine and dopamine transporters/release, and atomoxetine (ATX), a selective norepinephrine uptake inhibitor. Recent evidence suggests an involvement of glutamate neurotransmission in the pathology and treatment of ADHD, via mechanisms to be clarified. We have investigated how ADHD drugs could modulate, through interaction with catecholamine receptors, basal and glutamate-induced excitability of pyramidal neurons in the prefrontal cortex (PFC), a region which plays a major role in control of attention and impulsivity. We have used the technique of extracellular single-unit recording in anaesthetised rats coupled with microiontophoresis. Both MPH (1-3mg/kg) and D-AMP (1-9mg/kg) increased the firing activity of PFC neurons in a dopamine D1 receptor-dependent manner. ATX administration (1-6mg/kg) also increased the firing of neurons, but this effect is not significantly reversed by D1 (SCH 23390) or alpha1 (prazosin) receptor antagonists but potentiated by alpha2 antagonist (yohimbine). All drugs induced a clear potentiation of the excitatory response of PFC neurons to the microiontophoretic application of the glutamate agonist N-methyl-D-aspartate (NMDA), but not to the glutamate agonist α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA). The potentiating effect of D-AMP on NMDA-induced activation of PFC neurons was partially reversed or prevented by dopamine D1 receptor blockade. Our data shows that increase in excitability of PFC neurons in basal conditions and via NMDA receptor activation may be involved in the therapeutic response to ADHD drugs.

Abstract 333: Existence of Functional Norepinephrine Transport in Perivascular Adipose Tissue

Perivascular Tissue (PVAT) is a recent focus of studies for its regulation of blood vessel tone. Contraction to norepinephrine (NE) is reduced by PVAT through mechanisms not entirely clear. Loss of this anti-contractile function of PVAT occurs in obesity-related hypertension. We hypothesized that PVAT can remove NE from the blood vessel environment through transporters and reduce NE induced contraction in health. RT-PCR of mesenteric PVAT was positive for norepinephrine transporter (NET; Ct=33.2±1.4) and serotonin transporter (SERT; Ct=31.9±0.9) relative to beta-2-microglobulin. To study NE uptake in the healthy state, mesenteric and aortic PVAT from the male Sprague Dawley rat was incubated with 10 μM NE after pre-incubation with an inhibitor of transport (10 μM desipramine to inhibit NET and SERT, 100 μM corticosterone to inhibit organic cation transporter 3) or vehicle and quantified by HPLC for NE. Desipramine plus corticosterone inhibited NE uptake in mesenteric PVAT (figure) but desipramine (410.5±80.8 ng/g vs. 414.4±67.0 ng/g NE only; n=8) or corticosterone (225.0±26.1 ng/g vs. 319.2±35.9 ng/g NE only; n=5) alone did not, indicating a robust uptake capacity. In aortic PVAT, NE uptake was not inhibited by desipramine plus corticosterone (figure), desipramine (1763.5±460.8 ng/g vs. 1702.7±298.4 ng/g NE only; n=6), or corticosterone (1085.8±205.3 ng/g vs. 2245.8±506.8 ng/g NE only; n=4). Protein staining revealed bands positive for NET in mesenteric PVAT by Western blot. Taken together, we found that PVAT is a reservoir of NE that can remove NE from the blood vessel environment, an important finding to understand vasculature-PVAT interactions in health and disease.

DSP4, a selective neurotoxin for the locus coeruleus noradrenergic system. A review of its mode of action.

DSP4 (N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine hydrochloride) is a selective neurotoxin for the locus coeruleus noradrenergic system in the rodent and bird brain. It readily passes the blood-brain barrier and cyclizes to a reactive aziridinium derivative that is accumulated into the noradrenergic nerve terminals via the noradrenaline transporter. DSP4 is also an irreversible inhibitor of this transporter. Within the nerve terminals the aziridinium derivative reacts with unknown vital cellular components, destroying the terminals. At the dose 50 mg/kg i.p. this is characterized by a rapid and long-lasting loss of noradrenaline and a slower decrease in the dopamine-β-hydroxylase enzyme activity and immunoreactivity in the regions innervated from locus coeruleus. The tissue level of noradrenaline is reduced to 10-30% of the normal value. The extraneuronal concentration is, on the other hand, increased due to inflow from non-lesioned regions. Like the peripheral sympathetic nerves the non-locus coeruleus noradrenergic systems in the rodent brain is resistant to the neurotoxic action of DSP4. Serotoninergic and dopaminergic nerves are only slightly or not at all affected by DSP4. The neurotoxic effect is counteracted by pretreatment with noradrenaline uptake inhibitors (e.g., desipramine). MAO-B inhibitors of the N-propargylamine type (e.g., selegiline) also counteract the DSP4-induced neurotoxicity with another, yet unknown mechanism. Because of its selectivity for the locus coeruleus system DSP4 is a useful tool in studies of the functional role of this noradrenergic system in the brain.

Influence of acute treatment with sibutramine on the sympathetic neurotransmission of the young rat vas deferens

The effects of acute treatment with sibutramine on the peripheral sympathetic neurotransmission in vas deferens of young rats were still not evaluated. Therefore, we carried out this study in order to verify the effects of acute sibutramine treatment on the neuronal- and exogenous agonist-induced contractions of the young rat vas deferens. Young 45-day-old male Wistar rats were pretreated with sibutramine 6mg/kg and after 4h the vas deferens was used for experiment. The acute treatment with sibutramine was able to increase the potency (pD2) of noradrenaline and phenylephrine. Moreover, the efficacy (Emax) of noradrenaline was increased while the efficacy of serotonin and nicotine were decreased. The maximum effect induced by a single concentration of tyramine was diminished in the vas deferens from treated group. Moreover, the leftward shift of the noradrenaline curves promoted by uptake blockers (cocaine and corticosterone) and β-adrenoceptor antagonist (propranolol) was reduced in the vas deferens of treated group. The initial phasic and secondary tonic components of the neuronal-evoked contractions of vas deferens from treated group at the frequencies of 2Hz were decreased. Moreover, only the initial phasic component at 5Hz was diminished by the acute treatment with sibutramine. In conclusion, we showed that the acute treatment with sibutramine in young rats was able to affect the peripheral sympathetic nervous system by inhibition of noradrenaline uptake and reduction of the neuronal content of this neurotransmitter, leading to an enhancement of vas deferens sensitivity to noradrenaline.

Monoamine transporter and receptor interaction profiles of a new series of designer cathinones

Psychoactive β-keto amphetamines (cathinones) are sold as “bath salts” or “legal highs” and recreationally abused. We characterized the pharmacology of a new series of cathinones, including methedrone, 4-methylethcathinone (4-MEC), 3-fluoromethcathinone (3-FMC), pentylone, ethcathinone, buphedrone, pentedrone, and N,N-dimethylcathinone. We investigated norepinephrine (NE), dopamine (DA), and serotonin (5-HT) uptake inhibition using human embryonic kidney 293 (HEK 293) cells that express the respective human monoamine transporter, the drug-induced efflux of NE, DA, and 5-HT from monoamine-preloaded cells, and binding affinity to monoamine transporters and receptors. All of the cathinones were potent NE uptake inhibitors but differed in their DA vs. 5-HT transporter inhibition profiles and monoamine release effects. Methedrone was a more potent 5-HT than DA transporter inhibitor and released NE and 5-HT similar to para-methoxymethamphetamine (PMMA), para-methoxyamphetamine (PMA), 4-methylthioamphetamine (4-MTA), and 3,4-methylenedioxymethamphetamine (MDMA). 4-MEC and pentylone equipotently inhibited all of the monoamine transporters and released 5-HT. Ethcathinone and 3-FMC inhibited NE and DA uptake and released NE, and 3-FMC also released DA similar to N-ethylamphetamine and methamphetamine. Pentedrone and N,N-dimethylcathinone were non-releasing NE and DA uptake inhibitors as previously shown for pyrovalerone cathinones. Buphedrone preferentially inhibited NE and DA uptake and also released NE. None of the cathinones bound to rodent trace amine-associated receptor 1, in contrast to the non-β-keto-amphetamines. None of the cathinones exhibited relevant binding to other monoamine receptors. In summary, we found considerable differences in the monoamine transporter interaction profiles among different cathinones and compared with related amphetamines.

Antidepressants for bipolar disorder: A meta-analysis of randomized, double-blind, controlled trials.

OBJECTIVE:To examine the efficacy and safety of short-term and long-term use of antidepressants in the treatment of bipolar disorder.DATA SOURCES:A literature search of randomized, double-blind, controlled trials published until December 2012 was performed using the PubMed, ISI Web of Science, Medline and Cochrane Central Register of Controlled Trials databases. The keywords “bipolar disorder, bipolar I disorder, bipolar II disorder, bipolar mania, bipolar depression, cyclothymia, mixed mania and depression, rapid cycling and bipolar disorder”, AND “antidepressant agent, antidepressive agents second- generation, antidepressive agents tricyclic, monoamine oxidase inhibitor, noradrenaline uptake inhibitor, serotonin uptake inhibitor, and tricyclic antidepressant agent” were used. The studies that were listed in the reference list of the published papers but were not retrieved in the above-mentioned databases were supplemented.STUDY SELECTION:Studies selected were double-blind randomized controlled trials assessing the efficacy and safety of antidepressants in patients with bipolar disorder. All participants were aged 18 years or older, and were diagnosed as having primary bipolar disorder. Antidepressants or antidepressants combined with mood stabilizers were used in experimental interventions. Placebos, mood stabilizers, antipsychotics and other antide pressants were used in the control interventions. Studies that were quasi-randomized studies, or used antidepressants in combination with antipsychotics in the experimental group were excluded. All analyses were conducted using Review Manager 5.1 provided by the Cochrane Collaboration.MAIN OUTCOME MEASURES:The primary outcome was the response and switching to mania. The secondary outcomes included remission, discontinuation rate, and suicidality.RESULTS:Among 5 001 treatment studies published, 14 double-blind randomized controlled trials involving 1 244 patients were included in the meta-analysis. Eleven short-term studies and three maintenance studies were included. Studies suggested that patients treated with antidepressants were not significantly more likely to achieve higher response and remission rates in the short-term or long-term treatment than patients treated with placebo and other medications. Antidepressants were not associated with an increased risk of discontinuation, relapse or suicidality. When one antidepressant was compared with another, no significant difference in efficacy and tolerability was found.CONCLUSION:Existing evidence of efficacy does not support the short-term or long-term application of antidepressant therapy in patients with bipolar disorder, although the tolerability and safety of antidepressants have been generally acknowledged. There is a need for large-sample, double-blind, randomized controlled trials to elucidate the role of antidepressants in patients with different subcategories of bipolar disorder.

Wither codeine?

Wither codeine?