TAAR1 activation modulates monoaminergic neurotransmission, preventing hyperdopaminergic and hypoglutamatergic activity.

The trace amine-associated receptor 1 (TAAR1), activated by endogenous metabolites of amino acids like the trace amines p-tyramine and ß-phenylethylamine, has proven to be an important modulator of the dopaminergic system and is considered a promising target for the treatment of neuropsychiatric disorders. To decipher the brain functions of TAAR1, a selective TAAR1 agonist, RO5166017, was engineered. RO5166017 showed high affinity and potent functional activity at mouse, rat, cynomolgus monkey, and human TAAR1 stably expressed in HEK293 cells as well as high selectivity vs. other targets. In mouse brain slices, RO5166017 inhibited the firing frequency of dopaminergic and serotonergic neurons in regions where Taar1 is expressed (i.e., the ventral tegmental area and dorsal raphe nucleus, respectively). In contrast, RO5166017 did not change the firing frequency of noradrenergic neurons in the locus coeruleus, an area devoid of Taar1 expression. Furthermore, modulation of TAAR1 activity altered the desensitization rate and agonist potency at 5-HT(1A) receptors in the dorsal raphe, suggesting that TAAR1 modulates not only dopaminergic but also serotonergic neurotransmission. In WT but not Taar1(-/-) mice, RO5166017 prevented stress-induced hyperthermia and blocked dopamine-dependent hyperlocomotion in cocaine-treated and dopamine transporter knockout mice as well as hyperactivity induced by an NMDA antagonist. These results tie TAAR1 to the control of monoamine-driven behaviors and suggest anxiolytic- and antipsychotic-like properties for agonists such as RO5166017, opening treatment opportunities for psychiatric disorders.

The use of the dynamic weight bearing test to assess the effects of acute, intramuscularly administered botulinum neurotoxin type A1 in rats.

Assessing the efficacy of botulinum neurotoxin (BoNT) in vivo is essential given the growing number of BoNT products used in the clinic. Here, we evaluated the dynamic weight bearing (DWB) test for sensitivity to paralytic effects of BoNT-A following intramuscular administration. The toxin was administered into the gastrocnemius lateralis as a single bolus or into the gastrocnemius lateralis and medialis as two boluses. The effects of BoNT-A in DWB were compared to those in the compound muscle action potential (CMAP) and the Digit Abduction Score (DAS) tests. Female Sprague-Dawley rats received an acute, intramuscular (i.m.) injection of BoNT-A1 (0.1, 1, 10 pg/rat) into the right gastrocnemius muscle, while the left received vehicle. The DWB and CMAP tests were performed one-two days after the injection in order to detect the onset of sub-maximal BoNT-A activity. Both tests were preceded by the DAS test. BoNT-A produced dose-related reductions in both the weight-bearing and surface-bearing outcomes of up to 60% while showing moderate activity in the DAS. BoNT-A effects in the DWB test were well-aligned with those in the CMAP test, which showed dose-dependent reductions in CMAP amplitude and the area under the curve (AUC; up to 100%) as well as increases in latency (up to 130%). The efficacy of BoNT-A in DWB and CMAP was more pronounced with two boluses. Thus, the DWB test can be used to assess the properties of BoNTs following i.m. administration. It can be used to assess the candidate therapies and is more ethical than the mouse lethality assay.

Comparison of TransFemoral Transcatheter Aortic Valve Replacement Performed With a Minimally Invasive Simplified Technique: "FAST" Versus a Standard Approach.

OBJECTIVES: To assess the safety and efficacy of a new simplified procedure for transfemoral (TF) transcatheter aortic valve replacement (TAVR): the FAST protocol. BACKGROUND: A minimalist approach for TF-TAVR has been reported. The goal of this simplified strategy is to reduce the rate of specific complications associated with general anesthesia, second vascular access, and use of temporary pacemaker, and to reduce the length of stay. METHODS: We retrospectively reviewed all TF-TAVR cases performed at our center between January 2015 and December 2017. The FAST strategy consisted of local anesthesia with conscious sedation, echocardiographically guided TF puncture for main vascular access, radial approach for secondary arterial access, and left ventricular guidewire rapid pacing. Patients were sorted according to the initial strategy (FAST vs standard). The primary outcome was an early safety composite outcome including all-cause mortality, all stroke, life-threatening bleeding, acute kidney injury, coronary artery obstruction, major vascular complication, and valve-related dysfunction. RESULTS: A total of 285 consecutive patients were included in the present analysis (76 FAST patients and 209 standard patients). There were no baseline differences between groups. Complete FAST procedure was feasible in 83.0% of cases and all FAST procedures were successful. The primary outcome was significantly lower in the FAST group (1.3% vs 14.3%; P<.001). The use of FAST protocol resulted in a reduction of major bleeding (1.3% vs 10.1%; P=.01), blood transfusion (2.6% vs 14.3%; P<.01), and vascular complications related to the secondary access (0.0% vs 5.3%; P=.04). The length of stay was also significantly lower in the FAST group (4.9 days vs 6.4 days; P<.01). CONCLUSIONS: FAST can be safely performed and is associated with lower rates of iatrogenic complications and a shorter length of stay.

Lu 35-138 ((+)-(S)-3-{1-[2-(1-acetyl-2,3-dihydro-1H-indol-3-yl)ethyl]-3,6-dihydro-2H-pyridin-4-yl}-6-chloro-1H-indole), a dopamine D4 receptor antagonist and serotonin reuptake inhibitor: characterisation of its in vitro profile and pre-clinical antipsychotic potential.

The present study describes the pharmacological profile of the putative antipsychotic drug Lu 35-138 ((+)-(S)-3-{1-[2-(1-acetyl-2,3-dihydro-1H-indol-3-yl)ethyl]-3,6-dihydro-2H-pyridin-4-yl}-6-chloro-1H-indole). The in vitro receptor profile of Lu 35-138 revealed high affinity (K(i)=5 nM) and competitive antagonism (K(b)=8 nM) at dopamine D(4) receptors combined with potent 5-HT uptake inhibition (IC(50)=3.2 nM) and moderate alpha(1)-adrenoceptor affinity (K(i)=45 nM). In vivo, Lu 35-138 selectively counteracted hyperlocomotion induced by d-amphetamine (0.5 mg/kg; ED(50)=4.0 mg/kg, s.c.) in rats and phencyclidine (PCP; 2.5 mg/kg; ED(50)=13 mg/kg, s.c.) in mice. Lu 35-138 was unable to affect hyperlocomotion induced by a high dose of d-amphetamine (2.0 mg/kg), which indicates a preferential action on limbic versus striatal structures. A similar limbic selectivity of Lu 35-138 was indicated in voltammetric measure of dopamine output in the core and shell subdivisions of the nucleus accumbens in rats. Furthermore, a relatively large dose of Lu 35-138 (18 mg/kg, s.c.) counteracted d-amphetamine-induced disruption of pre-pulse inhibition in rats and repeated administration of Lu 35-138 (0.31 or 1.25 mg/kg, p.o. once daily for 3 weeks) reduced the number of spontaneously active dopamine neurones in the ventral tegmental area, underlining its antipsychotic-like profile. Lu 35-138 failed to induce catalepsy in rats or dystonia in Cebus apella monkeys and did not deteriorate spatial memory in rats as assessed by water maze performance. Collectively, these results suggest that Lu 35-138 possesses antipsychotic activity combined with a low extrapyramidal and cognitive side effect liability.

Beneficial effects of galantamine on performance in the object recognition task in Swiss mice: deficits induced by scopolamine and by prolonging the retention interval.

Episodic memory has been found to be impaired in several neuropsychiatric disorders. The object recognition task (ORT), introduced by Ennaceur and Delacour [Ennaceur A., Delacour J. A new one-trial test for neurobiological studies of memory in rats: 1. Behavioral data. Behav Brain Res 1988; 31: 47-59.], is a method to measure a specific form of episodic memory in rats and mice. It is based on the spontaneous behavior of rodents and can be considered as a retention test completely free of reference memory components. Therefore, the ORT has been increasingly used as an experimental tool in assessing drug effects on memory and investigating the neural mechanisms underlying learning and memory. In the present study, the main goal was to evaluate the effects of galantamine in Swiss mice in the ORT on scopolamine-induced deficits and with different retention intervals. Mice had a good object recognition memory at the 15 min retention intertrial interval (ITI). Object discrimination was absent at the longer intervals (1 h, 4 h and 24 h). Galantamine (10 mg/kg, administered s.c., 30 min prior to acquisition) partially reversed effects of scopolamine (0.63 mg/kg, administered s.c., 30 min prior to acquisition) and normalized performance to control levels. A lower dose of galantamine (0.63 mg/kg) was also investigated when two different retention intervals (15 min and 1 h) were used. Galantamine (0.63 mg/kg) had no adverse effects. Solvent-treated mice in the 1 h ITI condition did not discriminate between the novel and the familiar object (discrimination index was equal to zero), while galantamine (0.63 mg/kg)-treated mice attained a good object recognition memory performance. In conclusion, galantamine was shown to possess memory-enhancing effects in two conditions that reduced object discrimination: scopolamine-induced deficits and when a longer retention interval was used.

Mesothelial cell transplantation in the infarct scar induces neovascularization and improves heart function.

OBJECTIVES: Cell transplantation and associated neovascularization in vivo may be beneficial in ischemic disease. We hypothesized that transplanted mesothelial cells (MCs) could improve neovascularization in the post-myocardial infarct scar in rats. METHODS: Myocardial infarction was created by left coronary artery ligation in Lewis rats. After 3 weeks, surviving rats with left ventricular (LV) ejection fraction (EF) <50% were randomized into 2 groups which received, via injection into the infarct scar, either syngeneic rat peritoneal MCs (transplanted group) or vehicle alone (control group). Rats were followed-up echocardiographically for 4 weeks. Before transplantation, cells were transfected in vitro or labeled by a fluorescent dye for subsequent tracking in vivo. Transplanted cells and neovascularization were assessed histologically in the infarct scar by immunostaining or intravenous FITC-dextran injection prior to sacrifice, from 1 to 30 days post-transplantation. RESULTS: Among other pro-angiogenic chemokines, cultured MCs released stromal cell-derived factor (SDF-1alpha) (15.9 +/- 1.8 microg/mg protein) in vitro. At 1 month, some transplanted MCs were visualized (surviving or proliferating) in the LV scar and were incorporated in new vessels. The transplanted rats presented an increased vascular density in the scar, improved LV-EF (44.0 +/- 8.6% vs. 24.0 +/- 4.5%, p < 0.01) with decreased LV end-diastolic diameter (9.6 +/- 0.6 vs. 11.1 +/- 0.6 mm, p < 0.01) and volume (0.47 +/- 0.1 vs. 0.63+/-0.1 ml, p < 0.01) vs. controls. One week post-transplantation, higher levels of SDF-1alpha were extracted from LV peri-infarct tissue (32.3 +/- 5.8 vs. 22.6 +/- 3.1 pg/mg protein in controls, p < 0.01). CONCLUSIONS: Since autologous MCs can be obtained easily and cultured in large quantities, MC transplantation may represent a new angiogenic strategy in the prevention of ischemic remodeling.

Efficacy of chordal cutting to relieve chronic persistent ischemic mitral regurgitation.

BACKGROUND: Mitral regurgitation (MR) conveys adverse prognosis in ischemic heart disease. Leaflet closure is restricted by tethering to displaced papillary muscles, and is, therefore, incompletely treated by annular reduction. In an acute ischemic model, we reduced such MR by cutting a limited number of critically positioned chordae to the leaflet base that most restrict closure but are not required to prevent prolapse. Whether this is effective without prolapse, recurrent MR, or left ventricular (LV) failure in chronic persistent ischemic MR, despite greater LV remodeling, remains to be established. Therefore, we studied 7 sheep with chronic inferobasal infarcts known to produce progressive MR over 2 months. In all of those sheep, after a mean of 4.1 months, the 2 central basal (intermediate) chordae were cut at the chronic ischemic MR stage. 3-Dimensional echo quantified MR, LV function, and valve geometry. Five other sheep were followed for a mean of 7.8+/-1.2 months after inferobasal infarction with chordal cutting. RESULTS: All 7 of the sheep with chronic ischemic MR (increased from 1.4+/-0.4 to 11.1+/-0.5 mL/beat, regurgitant fraction=39.0+/-4.2%, P<0.0001) showed anterior leaflet angulation at the basal chord insertion. Although end-systolic volume had doubled, cutting the 2 central basal chordae significantly decreased the MR to baseline (P<0.0001) without prolapse or decline in EF (41.1+/-1.5% to 42.6+/-1.6%, P=not significant [NS]). The five sheep with long-term follow-up showed no prolapse or MR, and no significant post-infarct decrease in LV ejection fraction (EF; 38.9+/-2.4% to 41.4+/-1.2%, P=NS). CONCLUSIONS: Cutting a minimum number of basal (intermediate) chordae can improve coaptation and reduce chronic persistent ischemic MR without impairing LVEF. No adverse effects were noted long-term after chordal cutting at the time of infarction.

Long-term efficacy of myoblast transplantation on regional structure and function after myocardial infarction.

BACKGROUND: Transplantation (Tx) of skeletal myoblasts (SM) within an infarcted myocardium improves global left ventricular (LV) function, although a direct systolic effect remains controversial. METHODS AND RESULTS: Global and regional LV functions were studied in a sheep model (n=16) of infarction before (baseline), and 4 (M4), and 12 (M12) months after in-scar injections of autologous SM or culture medium (CM). LV end-diastolic volume (EDV), ejection fraction (EF), wall motion score (WMS), and systolic myocardial velocity gradient (MVG) across the scar were measured by echocardiography with tissue Doppler imaging. Parameters were similar at baseline between groups. At M4, Tx of SM reduced the postinfarction increase in EDV (72+/-8 versus 105+/-13 mL in the CM group, P<0.05) and the decrease in EF (48+/-5 versus 33+/-3% in the CM group, P=0.006) although it improved WMS (5.4+/-1.2 versus 13+/-2.2 in the CM group, P<0.01) and SMVG (0.60+/-0.13 versus -0.04+/-.13 seconds(-1) in the CM group, P<0.05). Results were similar at M12. In-scar accumulation of myotubes and SM were detected in all Tx animals up to M12, with co-expression of fast and slow isoforms of the myosin heavy chain (MHC) (30% of the fibers versus 0% in the normal skeletal muscle) and decreased collagen density (30+/-2% versus 73+/-3%, P<0.0001). CONCLUSIONS: For up to 1 year, Tx of SM limits postinfarction EF deterioration and improves systolic scar function through colonization of fibrosis by skeletal muscle cells with expression of both MHC isoforms, which may confer to the graft the ability to withstand a cardiac-type workload.

Autologous skeletal myoblast transplantation for severe postinfarction left ventricular dysfunction.

OBJECTIVES: This phase I trial was designed to assess the feasibility and safety of autologous skeletal myoblast transplantation in patients with severe ischemic cardiomyopathy. BACKGROUND: Experimentally, myoblast grafting into postinfarction myocardial scars improves left ventricular function. METHODS: Ten patients were included on the basis of the following criteria: 1) severe left ventricular dysfunction (ejection fraction < or = 35%); 2) the presence of a postinfarction akinetic and nonviable scar, as assessed by dobutamine echocardiography and 18-fluorodeoxyglucose positron emission tomography; and 3) an indication of coronary bypass in remote areas. Skeletal myoblasts were grown from a biopsy taken at the thigh. RESULTS: An average of 871 x 10(6) cells (86% of myoblasts) were obtained after a mean period of 16 days and implanted uneventfully across the scar at the time of bypass. Except for one patient whose early death was unrelated to the cell transplantation, all patients had an uncomplicated postoperative course. Four patients showed delayed episodes of sustained ventricular tachycardia and were implanted with an internal defibrillator. At an average follow-up of 10.9 months, the mean New York Heart Association functional class improved from 2.7 +/- 0.2 preoperatively to 1.6 +/- 0.1 postoperatively (p < 0.0001), and the ejection fraction increased from 24 +/- 1% to 32 +/- 1% (p < 0.02). A blinded echocardiographic analysis showed that 63% of the cell-implanted scars (14 of 22) demonstrated improved systolic thickening. One noncardiac death occurred 17.5 months after transplantation. CONCLUSIONS: These preliminary data suggest the feasibility and safety of autologous skeletal myoblast transplantation in severe ischemic cardiomyopathy, with the caveat of an arrhythmogenic potential. New-onset contraction of akinetic and nonviable segments suggests a functional efficacy that requires confirmation by randomized studies.

Clinical and hemodynamic performance of the 19-mm medtronic mosaic bioprosthesis.

BACKGROUND AND AIM OF THE STUDY: The Medtronic Mosaic valve (MMV) is a latest generation supra-annular stented porcine valve, which combines a low-profile stent, leaflet fixation at zero pressure in a predilated aortic root, and amino-oleic acid anti-mineralization treatment for improved hemodynamics and durability. A study was conducted to evaluate the clinical and hemodynamic performances of the MMV in patients with a small aortic root (19 mm aortic annulus). METHODS: Between 1998 and 2004, 81 consecutive patients (69 females, 12 males; mean age 78.0 +/- 5.5 years) underwent aortic valve replacement using the 19-mm MMV. Concomitant coronary artery bypass grafting was performed in 28 patients (29.2%), and mitral valve surgery in one patient (1.2%). RESULTS: The 30-day mortality rate was 9.9% (eight deaths). Postoperative actuarial survival estimates were 90.1 +/- 3.3%, 78.5 +/- 4.6% and 69.1 +/- 5.5% at one month, one year and two years, respectively. After a mean follow up of 2.7 +/- 1.9 years, no cases of structural dysfunction, non-structural dysfunction or valve thrombosis were noted. Four ischemic cerebral complications (2.0% per patient-year (pt-yr)), five bleeding complications (2.0%/pt-yr) and two prosthetic valve infections (1.0%/pt-yr) were observed. No reoperation on a MMV was performed. Postoperatively, the mean systolic gradient was 23.4 +/- 7.0 mmHg, and the effective orifice area (EOA) 1.06 +/- 0.33 cm2. Valve prosthesis-patient mismatch (VP-PM) was moderate (indexed EOA > 0.65 cm2/m2 and < or = 0.85 cm2/m2) in 40 patients (49.4%), and severe (indexed EOA < or = 0.65 cm2/m2) in 41 (50.6%). CONCLUSION: Although providing acceptable clinical results, implantation of the 19-mm MMV resulted in a high incidence of postoperative VP-PM. Hence, this valve should be reserved for patients in whom the projected indexed EOA calculated preoperatively is deemed acceptable, given the patient's clinical condition.

Spatial memory deficits induced by perinatal treatment of rats with PCP and reversal effect of D-serine.

It has been suggested that perinatal treatment with the noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist phencyclidine (PCP) induces transient neurodegeneration in the limbic and cortical structures of rats. Since dysfunction of these structures is associated with cognitive deficits in patients with schizophrenia, we studied the effects of subchronic treatment with PCP in perinatal rats with respect to spatial reference, reversal, and spatial working memories using the Morris water maze task in adulthood. In addition, we investigated the effect of D-serine, which has clinical relevance for the treatment of cognitive deficits in patients with schizophrenia. Our goal was to develop a neurodevelopmental model with predictive validity for the cognitive dysfunction described in patients with schizophrenia. Male and female Sprague-Dawley rats were treated with either saline or PCP (8.7 mg/kg s.c.) on days 7, 9, and 11, postnatal, and the long-term behavioral effects were investigated in adulthood. Male PCP-treated rats were slightly impaired during the spatial reference memory task, but strongly impaired during the reversal and spatial working memory tasks. Female rats were not significantly affected by this treatment. This cognitive deficit was reversed by chronic treatment with D-serine. We suggest that this model mimics some of the cognitive deficits of patients with schizophrenia and might be appropriate for the screening of putative antipsychotic agents for the treatment of these cognitive deficits.

Hippocampal lesioned rats are able to learn a spatial position using non-spatial strategies.

In the last two decades, many experiments have demonstrated that the hippocampus plays a role in the learning and processing of spatial and contextual information. Despite these demonstrations, some recent publications have indicated that the hippocampus is not the only structure involved in spatial learning and that even after hippocampal lesions, rats can perform spatial tasks. However, it is not well established whether animals with hippocampal dysfunction still have some spatial learning capacities or develop non-spatial solutions; these may require lengthier acquisition training. We now report the effects of conventional, dorsal hippocampal ablation on rats' performance on the water maze. We tested rats using a short (4 days) versus a long (16 days) acquisition period. We demonstrated that animals with dorsal hippocampal lesions have some residual capacity for learning the localization of a hidden escape platform in a pool during both a reference memory task and a working memory task. The animals with dorsal hippocampal lesions learned to escape at a fixed location, but only with extended training. It is suggested that these animals used non-spatial strategies to compensate for a spatial memory impairment. The results are discussed with respect to the experimental procedure and the strategy applied by the lesioned rats.

Papillary muscle sling: a new functional approach to mitral repair in patients with ischemic left ventricular dysfunction and functional mitral regurgitation.

BACKGROUND: In patients with ischemic left ventricular dysfunction (LVD) and functional mitral regurgitation (FMR), restoring a more normal alignment between mitral annulus and laterally displaced papillary muscles (PM) may be beneficial in terms of mitral repair and regional dynamics. METHODS: Ten patients, 29 to 78 years old, with an ejection fraction of 25% to 45%, pulmonary hypertension greater than 60, and New York Heart Association Class III-IV, had their PMs drawn together by a tightly encircling loop using a 4-mm Gore-Tex tube. Associated mitral annuloplasty rings were only moderately undersized. Efficiency was essentially evaluated on reversal of mitral tenting and control of FMR. RESULTS: Postoperative echocardioraphy revealed changes in "tenting effect" from 14 +/- 2.8 mm to 4 +/- 1.41 mm. Regurgitation is none to trivial in 9 patients, and mild in 1 patient. The posterior left ventricular wall between the PMs is shortened as a result of the surgical remodeling and may be beneficial on local dynamics. CONCLUSIONS: Joining the PM side-by-side has an obvious immediate effect on mitral leaflet mobility by suppressing the tethering due to displacement of the PM. An eventual result on local ventricular dynamics needs confirmation.

Is there a place for preconditioning during cardiac operations in humans?

BACKGROUND: Activation of the kinase cascade (protein kinase C (PKC), tyrosine kinase (TK), and mitogen-activated protein kinase (MAPK) is a key feature of the transduction pathway, elicited by preconditioning signals and mediating their cardioprotective effects. We assessed whether such an activation occurred during cardiac operations and could thus represent a target for cardioprotective strategies. METHODS: A total of 20 patients undergoing coronary artery bypass grafting surgery were studied. During the first 10 minutes of cardiopulmonary bypass (CPB), 10 were treated with sevoflurane (2.5 minimum alveolar concentration), an inhalational anesthetic that mimics preconditioning through a similar activation of the kinase cascade. Ten case-matched patients undergoing 10 minutes of sevoflurane-free CPB served as controls. Right atrial biopsies were taken before and 10 minutes after CPB and were then processed for the measurement of PKC, TK, and p38 MAPK activities by enzyme assay techniques. Troponin I was also monitored over the first 2 postoperative days. RESULTS: Compared with pre-CPB values, PKC and p38 MAPK activities (in nanomoles per milligram of protein per minute and arbitrary units, respectively) increased significantly and to the same extent in both groups: PKC, from 20.7+/-0.7 to 29.9+/-3.9 in controls (p = 0.037) and from 18.4+/-1.1 to 23.9+/-1.8 in sevoflurane (p = 0.016); p38 MAPK, from 88.6+/-8.5 to 312.9+/-66.2 in controls (p = 0.005) and from 114.6+/-14.7 to 213.4+/-51.8 in sevoflurane (p = 0.045). Conversely, sevoflurane triggered a significant increase in TK activity (from 68.5+/-1.4 to 83.7+/-2.9 picomoles per milligram of protein per minute p = 0.0015) which did not occur in controls (from 67.5+/-1.9 to 76.8+/-4.2 picomoles per milligram of protein per minute, p = 0.09). Likewise, the peak postoperative value of troponin I was not different between controls and sevoflurane-treated patients (3.4+/-0.6 vs 2.4+/-0.4, p = 0.21). CONCLUSIONS: Cardiopulmonary bypass triggers an activation of the kinase cascade that is mechanistically linked to opening of potassium channels. The direct opening of these channels by the anesthetic sevoflurane does not increase kinase activation further, nor does it improve markers of cell necrosis, thus suggesting that pharmacologically targeting potassium channels may overlap the preconditioning-like effects of CPB alone.

Trace amine-associated receptor 1 partial agonism reveals novel paradigm for neuropsychiatric therapeutics.

BACKGROUND: Trace amines, compounds structurally related to classical biogenic amines, represent endogenous ligands of the trace amine-associated receptor 1 (TAAR1). Because trace amines also influence the activity of other targets, selective ligands are needed for the elucidation of TAAR1 function. Here we report on the identification and characterization of the first selective and potent TAAR1 partial agonist. METHODS: The TAAR1 partial agonist RO5203648 was evaluated for its binding affinity and functional activity at rodent and primate TAAR1 receptors stably expressed in HEK293 cells, for its physicochemical and pharmacokinetic properties, for its effects on the firing frequency of monoaminergic neurons ex vivo, and for its properties in vivo with genetic and pharmacological models of central nervous system disorders. RESULTS: RO5203648 showed high affinity and potency at TAAR1, high selectivity versus other targets, and favorable pharmacokinetic properties. In mouse brain slices, RO5203648 increased the firing frequency of dopaminergic and serotonergic neurons in the ventral tegmental area and the dorsal raphe nucleus, respectively. In various behavioral paradigms in rodents and monkeys, RO5203648 demonstrated clear antipsychotic- and antidepressant-like activities as well as potential anxiolytic-like properties. Furthermore, it attenuated drug-taking behavior and was highly effective in promoting attention, cognitive performance, and wakefulness. CONCLUSIONS: With the first potent and selective TAAR1 partial agonist, RO5203648, we show that TAAR1 is implicated in a broad range of relevant physiological, behavioral, and cognitive neuropsychiatric dimensions. Collectively, these data uncover important neuromodulatory roles for TAAR1 and suggest that agonists at this receptor might have therapeutic potential in one or more neuropsychiatric domains.

Drug targets for cognitive enhancement in neuropsychiatric disorders.

The investigation of novel drug targets for treating cognitive impairments associated with neurological and psychiatric disorders remains a primary focus of study in central nervous system (CNS) research. Many promising new therapies are progressing through preclinical and clinical development, and offer the potential of improved treatment options for neurodegenerative diseases such as Alzheimer's disease (AD) as well as other disorders that have not been particularly well treated to date like the cognitive impairments associated with schizophrenia (CIAS). Among targets under investigation, cholinergic receptors have received much attention with several nicotinic agonists (α7 and α4ß2) actively in clinical trials for the treatment of AD, CIAS and attention deficit hyperactivity disorder (ADHD). Both glutamatergic and serotonergic (5-HT) agonists and antagonists have profound effects on neurotransmission and improve cognitive function in preclinical experiments with animals; some of these compounds are now in proof-of-concept studies in humans. Several histamine H3 receptor antagonists are in clinical development not only for cognitive enhancement, but also for the treatment of narcolepsy and cognitive deficits due to sleep deprivation because of their expression in brain sleep centers. Compounds that dampen inhibitory tone (e.g., GABA(A) α5 inverse agonists) or elevate excitatory tone (e.g., glycine transporter inhibitors) offer novel approaches for treating diseases such as schizophrenia, AD and Down syndrome. In addition to cell surface receptors, intracellular drug targets such as the phosphodiesterases (PDEs) are known to impact signaling pathways that affect long-term memory formation and working memory. Overall, there is a genuine need to treat cognitive deficits associated with many neuropsychiatric conditions as well as an increasingly aging population.

The d-amphetamine-treated Göttingen miniature pig: an animal model for assessing behavioral effects of antipsychotics.

RATIONALE: Rodents are usually used to assess the ability of antipsychotic drugs to antagonize hyperlocomotion induced by dopamine agonists, such as the psychostimulant d-amphetamine. However, the substantial differences between rodents and humans may hinder extrapolation of experimental results to humans. For this reason, we speculated that Göttingen miniature pigs, which show strong physiological and genetic homology with humans, might be a better model for investigating the effects of antipsychotics. To investigate this, we determined whether d-amphetamine induced hyperlocomotion in miniature pigs and whether this effect was reversible by antipsychotics. MATERIALS AND METHODS: d-amphetamine was tested in the dose range of 0.2 to 2.0 mg kg(-1) for its ability to induce hyperactivity in the open field, and the effects of two antipsychotics, haloperidol and risperidone, on amphetamine-induced hyperactivity were examined. RESULTS: d-amphetamine increased open-field activity at 0.2, 0.4, and 0.7 mg kg(-1) s.c. but not at higher doses. The stimulation of open-field activity induced by 0.4 mg kg(-1) s.c. d-amphetamine was antagonized by haloperidol and risperidone (0.01 and 0.04 mg kg(-1) s.c.). CONCLUSION: d-amphetamine-induced hyperlocomotion in miniature pigs may be a useful model for studying the effect of putative antipsychotics.

Isoflurane, 0.5 minimum alveolar concentration administered through the precardiopulmonary bypass period, reduces postoperative dobutamine requirements of cardiac surgery patients: a randomized study.

OBJECTIVE: Cardioprotective properties have been shown with halogenated volatile agents. It was hypothesized that low-dose isoflurane administered before aortic cross-clamping may reduce the amount of dobutamine required to improve impaired postoperative cardiac function after various types of cardiac surgery. DESIGN: A prospective, randomized trial. SETTING: An anesthesia and intensive care unit, university hospital. PARTICIPANTS: Two hundred eighty cardiac surgery patients. INTERVENTIONS: All patients allocated to either isoflurane treatment (T) or no treatment (control group [C]) received total intravenous anesthesia. In the treatment group, isoflurane was administered at a 0.5 minimum alveolar concentration (MAC) from tracheal intubation to initiation of cardiopulmonary bypass (CPB). During weaning from CPB, dobutamine was introduced by using a hemodynamically driven decision tree. MEASUREMENTS AND MAIN RESULTS: The number of patients receiving dobutamine was comparable (66 v 78, p = 0.07, in T and C groups, respectively). The total amount of postoperative dobutamine indexed to patient weight, considered as the primary endpoint, was reduced in the isoflurane-treated group (4.2 +/- 8 v 7.2 +/- 15, p < 0.02, in T and C, respectively). Isoflurane was identified as an independent variable significantly (odds ratio [confidence interval]) influencing the total amount of postoperative dobutamine (0.53 [0.31-0.92], p < 0.02). Postoperative troponin I release at 20 hours was not affected by isoflurane treatment. CONCLUSIONS: This study revealed that exposure to 0.5 MAC isoflurane before CPB reduced the total amount of dobutamine required to normalize postoperative cardiac dysfunction in various types of cardiac surgical patients.

SB-258741: a 5-HT7 receptor antagonist of potential clinical interest.

Recently, a series of 5-HT7 receptor antagonists have been developed (24,29,36,68). Among them SB-258741, R-(+)-1-(toluene-3-sulfonyl)-2-[2-(4-methylpiperidin-1-yl)ethyl]-pyrrolidine, (compound "13" in 36,37) was one of the most potent and specific compounds. Due to a lack of specific ligands the pharmacology of 5-HT7 receptor antagonists is still relatively unexplored. It has been suggested, however, that 5-HT7 receptor ligands could be useful in the therapy of various disorders such as sleep disorders, schizophrenia, depression, migraine, epilepsy, pain, or memory impairment. Many of these conceivable indications are not supported by pharmacological data. It is, therefore, of particular interest to review the data generated from studies of one of these most potent and specific 5-HT7 receptor antagonists, SB-258741, with a goal of testing the validity of the proposed clinical indications. In this review, the author describes pharmacology of this compound in order to define its potential clinical use. The available safety pharmacology data are discussed in an attempt to predict potential side effects of specific 5-HT7 receptor antagonists.

Optimization of in vitro vascular cell transfection with non-viral vectors for in vivo applications.

BACKGROUND: Syngeneic vascular cells are interesting tools for indirect gene therapy in the cardiovascular system. This study aims to optimize transfection conditions of primary cultures of vascular smooth muscle cells (VSMCs) using different non-viral vectors and zinc as an adjuvant and to implant these transfected cells in vivo. METHODS: Non-liposomal cationic vectors (FuGene 6), polyethylenimines (ExGen 500), and histidylated polylysine (HPL) were used as non-viral vectors in vitro with secreted alkaline phosphatase (SEAP) as reporter gene. Transfection efficiency was compared in cultured rat, rabbit and human VSMCs and fibroblasts. Zinc chloride (ZnCl2) was added to optimize transfection of rat VSMCs in vitro which were then seeded in vivo. RESULTS: Much higher SEAP levels were obtained in rabbit cells with FuGene 6 (p <0.0001) at day 2 than in equivalent rat and human cells. Rat VSMCs transfected in vitro with FuGene 6 and ExGen 500 expressed higher SEAP levels than with HPL. In rat VSMCs, SEAP secretion was more than doubled by addition of 250 microM ZnCl2 (p <0.0001) for all vectors. Seeding of syngeneic VSMCs transfected under optimized conditions (FuGene 6/pcDNA3-SEAP +250 microM ZnCl2) into healthy Lewis rats using various routes or into post-infarct myocardial scar resulted in a peak of SEAP expression at day 2 and detectable activity in the plasma for at least 8 days. CONCLUSIONS: FuGene 6 is an efficient non-viral transfection reagent for gene transfer in somatic smooth muscle cells in vitro and ZnCl2 enhances its efficiency. This increased expression of the transgene product is maintained after seeding in vivo.