A proof-of-concept study with SOM3355 (bevantolol hydrochloride) for reducing chorea in Huntington's disease.

AIMS: The study's aim is to investigate the efficacy and safety of SOM3355 (bevantolol hydrochloride), a ß1 -adrenoreceptor antagonist with recently identified vesicular monoamine transporter type 2 inhibitory properties, as a repositioned treatment to reduce chorea in Huntington's disease (HD). METHODS: A randomized, placebo-controlled proof-of-concept study was performed in 32 HD patients allocated to 2 arms of 4 sequential 6-week periods each. Patients received placebo and SOM3355 at 100 and 200 mg twice daily in a crossover design. The primary endpoint was improvement by at least 2 points in the total maximal chorea score in any active drug period compared with the placebo period. RESULTS: The primary endpoint was met in 57.1% of the patients. Improvements ≥3, ≥4, ≥5 and ≥6 points vs. placebo treatment were observed in 28.6, 25.0, 17.9 and 10.7% of the patients, respectively. A mixed-model analysis found a significant improvement in the total maximal chorea score of -1.14 (95% confidence interval, -2.11 to -0.16; P = .0224) with 200 mg twice daily SOM3355 treatment compared with placebo treatment. These results were paralleled by Clinical and Patient Global Impression of Change ratings (secondary endpoints). An elevation in plasma prolactin levels by 1.7-1.9-fold was recorded (P < .005), probably reflecting the effect on the dopamine pathway, consistent with vesicular monoamine transporter type 2 inhibition. The most frequent adverse events during SOM3355 administration were mild to moderate. CONCLUSION: Within the limits of this study, the results suggest that SOM3355 reduces chorea in patients with HD and is well-tolerated. Larger studies are necessary to confirm its therapeutic utility as an antichoreic drug. EudraCT number: 2018-000203-16 and ClinicalTrials.gov Identifier: NCT03575676.

The relationship between performance on the medical genetics and genomics in-training and certifying examinations.

PURPOSE: The American Board of Medical Genetics and Genomics (ABMGG) certifying examinations (CEs) are designed to assess relevant basic knowledge, clinical knowledge, and diagnostic skills of board-eligible candidates in primary specialty areas. The ABMGG in-training examinations (ITEs) provide formative feedback regarding knowledge and learning over time and assess readiness to attempt board certification. This study addresses the validity of the ABMGG ITE by evaluating its relationship with performance on CE utilizing established psychometric approaches. METHODS: Statistical analysis included bivariate Pearson correlation coefficients and linear regression to evaluate the strength of associations between ITE scores and CE scores. Logistic regression was used to assess the association between ITE scores and the probability of passing each CE. RESULTS: Logistic regression results indicated that ITE scores accounted for 22% to 44% of the variability in CE outcomes. Across 3 certification cycles, for every 1-point increase in ITE scores, the odds ratio for earning a passing score increased by a factor of 1.12 to 1.20 for the general CE, 1.14 to 1.25 for the clinical CE, and 1.12 to 1.20 for the laboratory CEs. CONCLUSION: The findings show a positive correlation between performance on the ITE examination and performance on and passing the ABMGG CE.

Development and validation of an LC-MS/MS quantitative method for endogenous deoxynucleoside triphosphates in cellular lysate.

The endogenous deoxynucleoside triphosphate (dNTP) pool includes deoxyadenosine triphosphate (dATP), deoxycytidine triphosphate (dCTP), deoxyguanosine triphosphate (dGTP) and thymidine triphosphate (TTP). The endogenous dNTP pool is regulated by complex enzymatic pathways that can be targeted by drugs, such as antimetabolites. In addition, these components compete with antiviral nucleos(t)ide analog triphosphates, contributing to the mechanism of pharmacologic action. This communication describes the development and validation of a sensitive method to quantify the intracellular dNTP pool in cellular lysates. The extraction process was optimized for dNTPs using an indirect strategy - the separation of mono-, di- and triphosphate moieties by strong anion exchange, dephosphorylation of target fractions to molar equivalent nucleosides - followed by sensitive quantitation using liquid chromatography-tandem mass spectrometry. The validated analytical range was 50-2500 fmol/sample for each dNTP. The assay was used to quantify dNTPs in peripheral blood mononuclear cells from 40 clinical research participants (n = 279 samples). Median (interquartile range) concentrations were 143 (116, 169) for dATP, 737 (605, 887) for dCTP, 237 (200, 290) for dGTP and 315 (220, 456) for TTP, in femtomoles per million cells. This method allows for future studies of endogenous dNTP disposition in subjects receiving antimetabolites or nucleos(t)ide analogs, or for other clinical scenarios.

Analysis of the Endogenous Deoxynucleoside Triphosphate Pool in HIV-Positive and -Negative Individuals Receiving Tenofovir-Emtricitabine.

Tenofovir (TFV) disoproxil fumarate (TDF) and emtricitabine (FTC), two nucleos(t)ide analogs (NA), are coformulated as an anti-HIV combination tablet for treatment and preexposure prophylaxis (PrEP). TDF/FTC may have effects on the deoxynucleoside triphosphate (dNTP) pool due to their similar structures and similar metabolic pathways. We carried out a comprehensive clinical study to characterize the effects of TDF/FTC on the endogenous dNTP pool, from baseline to 30 days of TDF/FTC therapy, in both treatment-naive HIV-positive and HIV-negative individuals. dATP, dCTP, dGTP, and TTP were quantified in peripheral blood mononuclear cells (PBMC) with a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) methodology. Forty individuals (19 HIV-positive) were enrolled and underwent a baseline visit and then received TDF/FTC for at least 30 days. Longitudinal measurements were analyzed using mixed-model segmented linear regression analysis. The dNTPs were reduced by 14% to 37% relative to the baseline level within 3 days in both HIV-negative and HIV-positive individuals (P ≤ 0.003). These reductions persisted to various degrees at day 30. These findings indicate that dNTP pools are influenced by TDF/FTC therapy. This may alter cellular homeostasis and could increase the antiviral effect through a more favorable analog/dNTP ratio. Further work is needed to elucidate mechanisms, to evaluate the clinical significance of these findings, and to further probe differences between HIV-negative and HIV-positive individuals. (This study has been registered at ClinicalTrials.gov under identifier NCT01040091.).

Emtricitabine-Triphosphate in Dried Blood Spots as a Marker of Recent Dosing.

New objective measures of antiretroviral adherence are needed. We determined if emtricitabine triphosphate (FTC-TP) in dried blood spots (DBS) can be used as a marker of recent dosing with tenofovir disoproxil fumarate-emtricitabine (TDF-FTC). The half-life of FTC-TP was estimated in DBS samples obtained from an intensive pharmacokinetic (PK) study of coformulated TDF-FTC in HIV-negative and HIV-infected participants. The concordance of quantifiable FTC-TP in DBS with tenofovir (TFV)/FTC in plasma was evaluated by utilizing paired plasma-DBS samples from participants enrolled in 2 large preexposure prophylaxis (PrEP) open-label trials. The time to FTC-TP nondetectability after TDF-FTC dosing was evaluated utilizing DBS from HIV-negative participants enrolled in a directly observed therapy study of variable adherence to TDF-FTC. The mean (95% confidence interval [CI]) terminal half-life of FTC-TP in the PK study was 35 (23 to 47) h. A total of 143/163 (88%) samples obtained 0 to 48 h post-TDF-FTC dose had quantifiable FTC-TP in DBS, compared with 2/93 (2%) and 0/87 (0%) obtained >48 and >96 h postdose. In 746 paired plasma-DBS samples from 445 participants enrolled in PrEP trials, when both TFV/FTC in plasma were below the limit of quantification, FTC-TP was as well in 98.9% of the samples, and when either TFV or FTC in plasma was quantifiable, FTC-TP was as well in 90.5% of the samples. The half-life of FTC-TP in DBS is short relative to that of TFV-diphosphate (TFV-DP), making it a surrogate for TFV-FTC detection in plasma. FTC-TP can be quantified in DBS simultaneously with TFV-DP, which quantifies cumulative adherence to TDF-FTC. (The clinical trials discussed in this article have been registered at ClinicalTrials.gov under identifiers NCT01040091, NCT02022657, NCT00458393, NCT01772823, and NCT02012621.).

AFQ056/mavoglurant, a novel clinically effective mGluR5 antagonist: identification, SAR and pharmacological characterization.

Here we describe the identification, structure-activity relationship and the initial pharmacological characterization of AFQ056/mavoglurant, a structurally novel, non-competitive mGlu5 receptor antagonist. AFQ056/mavoglurant was identified by chemical derivatization of a lead compound discovered in a HTS campaign. In vitro, AFQ056/mavoglurant had an IC50 of 30 nM in a functional assay with human mGluR5 and was selective over the other mGluR subtypes, iGluRs and a panel of 238 CNS relevant receptors, transporter or enzymes. In vivo, AFQ056/mavoglurant showed an improved pharmacokinetic profile in rat and efficacy in the stress-induced hyperthermia test in mice as compared to the prototypic mGluR5 antagonist MPEP. The efficacy of AFQ056/mavoglurant in humans has been assessed in L-dopa induced dyskinesia in Parkinson's disease and Fragile X syndrome in proof of principle clinical studies.

Validation of a sensitive LC/MS/MS method for the determination of telaprevir and its R-isomer in human plasma.

The purpose of this study was to validate a reversed-phase high-performance liquid chromatographic (HPLC), tandem mass spectrometry (MS/MS) assay for the determination of telaprevir and its R-diastereomer (VRT-127394) in acidified and nonacidified human plasma. The chromatographic baseline separation of telaprevir and telaprevir-R was performed on a Waters XBridge(TM) BEH Shield C18 , 2.1 × 75 mm column with a 2.5 µm particle size, under isocratic conditions consisting of a mobile phase of 50:45:5 water-acetonitrile-isopropanol with 1% ammonia at 0.2 mL/min. This method utilized a stable isotope internal standard with 11 deuterium atoms on the structure of the telaprevir molecule (telaprevir-d11). An internal standard for the telaprevir-R (telaprevir-R-d11) was also prepared by incubating telaprevir-d11 in basic solution, which facilitated isomer inter-conversion. The detection and quantitation of telaprevir, telaprevir-R, telaprevir-IS and telaprevir-R-IS was achieved by positive ion electrospray (ESI+) MS/MS detection. The assay quantifiable limit was 5.0 ng/mL when 0.100 mL of acidified human plasma was extracted. Accuracy and precision were validated over the calibration range of 5.0-5000 ng/mL. It was demonstrated using patient samples that, contrary to previous recommendations, quantitation of telaprevir does not require acidified plasma.

Gender Differences in Milestone Ratings and Medical Knowledge Examination Scores Among Internal Medicine Residents.

PURPOSE: To examine whether there are group differences in milestone ratings submitted by program directors working with clinical competency committees (CCCs) based on gender for internal medicine (IM) residents and whether women and men rated similarly on milestones perform comparably on subsequent in-training and certification examinations. METHOD: This national retrospective study examined end-of-year medical knowledge (MK) and patient care (PC) milestone ratings and IM In-Training Examination (IM-ITE) and IM Certification Examination (IM-CE) scores for 2 cohorts (2014-2017, 2015-2018) of U.S. IM residents at ACGME-accredited programs. It included 20,098/21,440 (94%) residents, with 9,424 women (47%) and 10,674 men (53%). Descriptive statistics and differential prediction techniques using hierarchical linear models were performed. RESULTS: For MK milestone ratings in PGY-1, men and women showed no statistical difference at a significance level of .01 (P = .02). In PGY-2 and PGY-3, men received statistically higher average MK ratings than women (P = .002 and P < .001, respectively). In contrast, men and women received equivalent average PC ratings in each PGY (P = .47, P = .72, and P = .80, for PGY-1, PGY-2, and PGY-3, respectively). Men slightly outperformed women with similar MK or PC ratings in PGY-1 and PGY-2 on the IM-ITE by about 1.7 and 1.5 percentage points, respectively, after adjusting for covariates. For PGY-3 ratings, women and men with similar milestone ratings performed equivalently on the IM-CE. CONCLUSIONS: Milestone ratings were largely similar for women and men. Generally, women and men with similar MK or PC milestone ratings performed similarly on future examinations. Although there were small differences favoring men on earlier examinations, these differences disappeared by the final training year. It is questionable whether these small differences are educationally or clinically meaningful. The findings suggest fair, unbiased milestone ratings generated by program directors and CCCs assessing residents.

The selective nicotinic acetylcholine receptor alpha7 agonist JN403 is active in animal models of cognition, sensory gating, epilepsy and pain.

Several lines of evidence suggest that the nicotinic acetylcholine receptor alpha7 (nAChR alpha7) is involved in central nervous system disorders like schizophrenia and Alzheimer's disease as well as in inflammatory disorders like sepsis and pancreatitis. The present article describes the in vivo effects of JN403, a compound recently characterized to be a potent and selective partial nAChR alpha7 agonist. JN403 rapidly penetrates into the brain after i.v. and after p.o. administration in mice and rats. In the social recognition test in mice JN403 facilitates learning/memory performance over a broad dose range. JN403 shows anxiolytic-like properties in the social exploration model in rats and the effects are retained after a 6h pre-treatment period and after subchronic administration. The effect on sensory inhibition was investigated in DBA/2 mice, a strain with reduced sensory inhibition under standard experimental conditions. Systemic administration of JN403 restores sensory gating in DBA/2 mice, both in anaesthetized and awake animals. Furthermore, JN403 shows anticonvulsant potential in the audiogenic seizure paradigm in DBA/2 mice. In the two models of permanent pain tested, JN403 produces a significant reversal of mechanical hyperalgesia. The onset was fast and the duration lasted for about 6h. Altogether, the present set of data suggests that nAChR alpha7 agonists, like JN403 may be beneficial for improving learning/memory performance, restoring sensory gating deficits, and alleviating pain, epileptic seizures and conditions of anxiety.

JN403, in vitro characterization of a novel nicotinic acetylcholine receptor alpha7 selective agonist.

This report describes the in vitro features of a novel selective nicotinic acetylcholine receptor (nAChR) alpha7 agonist, JN403, (S)-(1-Aza-bicyclo[2.2.2]oct-3-yl)-carbamic acid (S)-1-(2-fluoro-phenyl)-ethyl ester. JN403 was evaluated in a number of in vitro systems of different species, at recombinant receptors using radioligand binding, signal transduction and electrophysiological studies. When using [(125)I] alpha-bungarotoxin (alpha-BTX) as a radioligand, JN403 has high affinity for human recombinant nAChR alpha7 (pK(D)=6.7). Functionally, JN403 is a partial and potent agonist at human nAChR alpha7. The compound stimulates calcium influx in GH3 cells recombinantly expressing the human nAChR with an pEC(50) of 7.0 and an E(max) of 85% (compared to the full agonist epibatidine). In Xenopus oocytes expressing human nAChR alpha7 JN403 induces inward currents with an pEC(50) of 5.7 and an E(max) of 55%. In both recombinant systems JN403 is a partial agonist and the agonistic effects are blocked after pre-administration of methyllycaconitine (MLA, 100nM), a nAChR alpha7 antagonist. In functional calcium influx assays, JN403 displays a significantly lower potency for other subtypes of human nAChRs like alpha4beta2, alpha3beta4, alpha1beta1gammadelta as well as 5HT(3) receptors when tested functionally as an antagonist (pIC(50)<4.8) and is devoid of agonistic activity (pEC(50)<4). Similarly, JN403 shows low binding activity at a wide panel of neurotransmitter receptors. Thus, JN403 is a potent and selective nAChR alpha7 agonist and will be a useful tool for the characterization of nAChR alpha7 mediated effects both in vitro and in vivo.

Role of Physical Therapy Intervention in Patients With Life-Threatening Illnesses.

BACKGROUND: Physical therapy encompasses the skilled treatment and care for patients across the life span through a multitude of different practice settings. This includes caring for individuals within end-of-life or palliative care settings. The goal of treatment in this stage of care is to relieve physical, social, psychological, and spiritual suffering in order to improve overall quality of life in patients with terminal illnesses. There has been limited research conducted to investigate the utilization of physical therapy interventions in palliative care settings. PURPOSE: The purpose of this study was to contribute to the current research involving physical therapy and end-of-life care in terms of its efficacy, value, and how this value is perceived by patients and their caregivers. METHODS: This was completed by independently screening and reviewing the studies that were published between the years 1994 and 2014 and related to this topic. The databases and journals searched included CINAHL, PUBMED, MEDLINE, Cochrane, PEDro, the Journal of Palliative Care, the American Journal of Hospice and Palliative Medicine, and Google Scholar. RESULTS: Thirteen qualitative articles were selected which met all inclusion criteria and discussed the role of physical therapy intervention in the palliative care setting. Methodological quality of articles were assessed using the QASP, scale and their findings were summarized and presented in table format. CONCLUSION: These articles support the utilization of physical therapy in palliative care settings and emphasizes the impact of physical therapy on improving patients' physical, social, and emotional well-being.

The rostral anterior cingulate cortex modulates depression but not anxiety-related behaviour in the rat.

A growing body of functional imaging studies suggests that human depression and anxiety symptoms are associated with functional abnormalities in the circuitry formed by the rostral anterior cingulate cortex (rACC) and its direct limbic and paralimbic connections. In rodents however, the role of the rACC (rCG1/rCG2) remains unknown in depression-related behaviours and elusive in acute anxiety. In order to address this, we specifically lesioned the rat rCG1/rCG2, and assessed the behavioural outcome using a modified forced swim test (FST) and the elevated plus maze (EPM), tests for depression and anxiety related behaviours respectively. Lesions of the rostral anterior cingulate cortex significantly increased the time spent immobile in the FST without affecting climbing or swimming performances, suggesting a pro-depressant effect. On the contrary, none of the parameters measured in the EPM was affected by the lesion. These data point to an involvement of the rCG1/rCG2 in depression-related coping behaviours.

Application of an intracellular assay for determination of tenofovir-diphosphate and emtricitabine-triphosphate from erythrocytes using dried blood spots.

This communication describes the application of an existing intracellular methodology to the quantitation of tenofovir-diphosphate (TFV-DP) and emtricitabine-triphosphate (FTC-TP) from erythrocytes using dried blood spots (DBS). Concentrations were determined from a 3mm DBS punch extracted into a 70:30 methanol:water solution (lysed cellular matrix). This extraction solution was then subjected to a previously validated analytical procedure for lysed cellular matrix. Experiments for DBS validation used replicate samples from study participants to demonstrate acceptable reproducibility with spot volumes ranging from 10-50 µL and punch location either from the edge or center of the spot. Analysis of paired DBS with purified red blood cells showed that a 3mm DBS punch contained an average of 11.9 million cells for the observed hematocrit range of the participants (35-50%). Numerous stability tests were completed showing that whole blood in an EDTA vacutainer could sit for 24h at room temperature prior to spotting, and DBS could remain at room temperature for up to five days including shipment at ambient using 2-days delivery. DBS stability in storage was acceptable up to 18 months at -20°C or -80°C and DBS could undergo 4 Freeze/Thaw cycles. The described method was applied to HIV prophylaxis studies, demonstrating powerful associations with HIV acquisition through its ability to discriminate gradients of adherence.

AQW051, a novel, potent and selective α7 nicotinic ACh receptor partial agonist: pharmacological characterization and phase I evaluation.

BACKGROUND AND PURPOSE: Activation of the α7 nicotinic ACh receptor (nACh receptor) is considered an attractive target for the treatment of cognitive impairment associated with neurological disorders. Here we describe the novel α7-nACh receptor agonist AQW051 as a promising drug candidate for this indication. EXPERIMENTAL APPROACH: AQW051 was functionally characterized in vitro and cognitive effects evaluated in rodent behavioural models. Pharmacokinetics and tolerability were evaluated in three phase I placebo-controlled studies in 180 healthy subjects. KEY RESULTS: In vitro, AQW051 bound with high affinity to α7-nACh receptors and stimulated calcium influx in cells recombinantly expressing the human α7-nACh receptor. In vivo, AQW051 demonstrated good oral bioavailability and rapid penetration into the rodent brain. AQW051 administered over a broad dose range facilitated learning/memory performance in the object recognition and social recognition test in mice and the water maze model in aged rats. Clinically, AQW051 was well tolerated in healthy young and elderly subjects, with an adverse event (AE) profile comparable with placebo. No serious AEs were reported and all AEs were either mild or moderate in severity at single oral doses up to 200 mg and multiple daily doses up to 75 mg. Once-daily oral administration of AQW051 resulted in continuous exposure and a two- to threefold accumulation compared with steady state was achieved by 1 week. CONCLUSIONS AND IMPLICATIONS: These data support further development of AQW051 as a cognitive-enhancing agent, as a therapeutic, for example, in Alzheimer's disease or schizophrenia.

Differential effects of iloperidone, clozapine, and haloperidol on working memory of rats in the delayed non-matching-to-position paradigm.

RATIONALE: Because cognitive function, particularly working memory (WM), is severely impaired in schizophrenia, evaluation of neuroleptic medication should include investigation of possible effects on cognition. Iloperidone is a promising, novel atypical neuroleptic drug (NL), for which no cognitive data is presently available. OBJECTIVE: To investigate whether the novel atypical NL iloperidone would affect performance of rats on a WM test, using a delayed non-matching-to-position (DNMTP) paradigm, and compare its effects with those of the atypical NL clozapine and the typical NL haloperidol. METHODS: Male Lister Hooded rats trained to criterion in an operant DNMTP task (0-64 s delay intervals) were administered vehicle, iloperidone (0.03, 0.1 mg/kg, i.p.), clozapine (0.1, 0.3 mg/kg, s.c.), haloperidol (0.003, 0.01, 0.03 mg/kg, s.c.), or scopolamine (0.05 mg/kg, s.c.). Together with choice accuracy, the motor performance of the task was measured. RESULTS: It was found that: (1) iloperidone significantly improved choice accuracy delay-dependently while impairing task performance; (2) the atypical NL clozapine had no effect on choice accuracy and parameters related to motor function, but significantly increased the number of uncompleted trials; (3) haloperidol did not affect choice accuracy except at the longest delay with the highest dose, but in contrast to clozapine it significantly impaired task performance. CONCLUSION: In accordance with their different pharmacological profiles, the three NLs iloperidone, clozapine, and haloperidol have different effects in this preclinical cognitive task. These results might provide important information for the development of NLs with beneficial effects on cognition.

Differential roles of mGlu(7) and mGlu(8) in amygdala-dependent behavior and physiology.

Glutamate transmission and synaptic plasticity in the amygdala are essential for the learning and expression of conditioned fear. Glutamate activates both ionotropic glutamate receptors and eight subtypes of metabotropic glutamate receptors (mGlu1-8). In the present study, we investigated the roles of mGlu7 and mGlu8 in amygdala-dependent behavior and synaptic plasticity. We show that ablation of mGlu7 but not mGlu8 attenuates long-term potentiation (LTP) at thalamo-lateral amygdala (LA) synapses where a strong association between LTP and learning has been demonstrated. mGlu7-deficient mice express a general deficit in conditioned fear whereas mGlu8-deficient mice show a dramatic reduction in contextual fear. The mGlu7 agonist AMN082 reduced thalamo-LA LTP and intra-amygdala administration blocked conditioned fear learning. In contrast, the mGlu8 agonist DCPG decreased synaptic transmission but not LTP at thalamo-LA synapses. Intra-amygdala DCPG selectively reduced the expression of contextual fear but did not affect the acquisition and expression of cued fear. Taken together, these data revealed very different roles for mGlu7 and mGlu8 in amygdala synaptic transmission, fear learning and its expression. These receptors seem promising targets for treating anxiety disorders with different underlying pathologies with exaggerated fear learning (mGlu7) or contextual fear (mGlu8).

Gastrin-releasing peptide signaling plays a limited and subtle role in amygdala physiology and aversive memory.

Links between synaptic plasticity in the lateral amygdala (LA) and Pavlovian fear learning are well established. Neuropeptides including gastrin-releasing peptide (GRP) can modulate LA function. GRP increases inhibition in the LA and mice lacking the GRP receptor (GRPR KO) show more pronounced and persistent fear after single-trial associative learning. Here, we confirmed these initial findings and examined whether they extrapolate to more aspects of amygdala physiology and to other forms of aversive associative learning. GRP application in brain slices from wildtype but not GRPR KO mice increased spontaneous inhibitory activity in LA pyramidal neurons. In amygdala slices from GRPR KO mice, GRP did not increase inhibitory activity. In comparison to wildtype, short- but not long-term plasticity was increased in the cortico-lateral amygdala (LA) pathway of GRPR KO amygdala slices, whereas no changes were detected in the thalamo-LA pathway. In addition, GRPR KO mice showed enhanced fear evoked by single-trial conditioning and reduced spontaneous firing of neurons in the central nucleus of the amygdala (CeA). Altogether, these results are consistent with a potentially important modulatory role of GRP/GRPR signaling in the amygdala. However, administration of GRP or the GRPR antagonist (D-Phe(6), Leu-NHEt(13), des-Met(14))-Bombesin (6-14) did not affect amygdala LTP in brain slices, nor did they affect the expression of conditioned fear following intra-amygdala administration. GRPR KO mice also failed to show differences in fear expression and extinction after multiple-trial fear conditioning, and there were no differences in conditioned taste aversion or gustatory neophobia. Collectively, our data indicate that GRP/GRPR signaling modulates amygdala physiology in a paradigm-specific fashion that likely is insufficient to generate therapeutic effects across amygdala-dependent disorders.

Endocrine and behavioural responses to acute central CRF challenge are antagonized in the periphery and CNS, respectively, in C57BL/6 mice.

Corticotropin releasing factor (CRF) is a major mediator of central and peripheral responses to environmental stressors, and antagonism of its receptors (CRF-R1, -R2) is an active area of pharmacotherapeutic research for stress-related disorders. Stress responses include CRF activation of the hypothalamus-pituitary-adrenal axis and behavioural inhibition. Valid in vivo models for the study of these neuro-endocrine and -behavioural CRF pathways and their central-peripheral antagonism are important. The aims of this study in C57BL/6 mice were to describe the acute effects of intracerebroventricular (ICV) CRF using plasma ACTH-CORT titres and locomotor activity as readouts, and to study the impact on these readouts of central versus peripheral pre-treatment with the CRF-R1/2 antagonist, astressin. The following experiments were performed: Effects of (i) serial blood sampling (SBS) per se, (ii) physical confinement+SBS, (iii) ICV saline infusion+SBS, on plasma titres of ACTH-CORT. (iv) Effects of ICV or IP CRF infusion on plasma ACTH-CORT. (v) Effects of ICV CRF on plasma CRF. (vi) Effects of ICV or IP astressin on ICV or IP CRF-stimulated plasma CORT. (vii) Effects of ICV or IP astressin on ICV CRF-induced locomotor inactivity. Main findings were: (i)-(ii) Serial blood sampling per se and physical confinement+SBS led to similar, mild increases in plasma ACTH-CORT. (iii) ICV saline infusion led to a marked increase in plasma ACTH, possibly due to assay crossreactivity with "washed out" pituitary peptides, and a mild increase in plasma CORT. (iv) ICV CRF (0.001-1µg) induced no further increase in plasma ACTH versus vehicle, and induced dose-dependent increased plasma CORT. 1µg ICV CRF also reduced locomotor activity. (v) ICV CRF-induced dose-dependent increased plasma CRF. (vi) ICV astressin failed to block ICV CRF-induced increased plasma CORT, whereas IP astressin did do so. (vii) ICV CRF-induced locomotor inactivity was blocked by ICV astressin, but not by IP astressin. Therefore, ICV CRF-induced a dose-dependent increase in plasma CORT via a peripheral pathway and a reduction in locomotion via a central pathway, indicated by the double dissociation in the ability of astressin to antagonize these effects relative to its route of administration, IP or ICV, respectively. The preparation described here could be readily used to provide initial indications on the central and peripheral activity of CRF-R antagonists, including pharmacokinetics following peripheral administration.

Intra-amygdala injections of neuropeptide S block fear-potentiated startle.

Injections of neuropeptide S (NPS) into the lateral ventricle induce a strong hyperactivity. Since most behavioral paradigms are dependent of spontaneous locomotor activity, this makes it difficult to interpret the role of NPS in such paradigms. The aim of the present experiment was to investigate the effects of NPS in fear-potentiated startle, a behavioral fear paradigm which we believe is less sensitive to general changes in locomotor activity. Furthermore, NPS was directly injected into the amygdala, the central site of the neural fear circuitry. Our data shows that intra-amygdala NPS injections dose-dependently block the expression of conditioned fear and that this effect is independent of NPS effects on locomotor activity. This strongly supports a crucial role of amygdaloid NPS in conditioned fear.

Fear-reducing effects of intra-amygdala neuropeptide Y infusion in animal models of conditioned fear: an NPY Y1 receptor independent effect.

RATIONALE: Neuropeptide Y (NPY) and its receptors are densely localized in brain regions involved in the mediation and modulation of fear, including the amygdala. Several studies showed that central NPY is involved in the modulation of fear and anxiety. OBJECTIVES: In the present study, we investigated (1) whether intra-amygdala injections of NPY affect the expression of conditioned fear and (2) whether NPY Y1 receptors (Y1R) mediates the effects of these intra-amygdaloid NPY injections. RESULTS: Intra-amygdala NPY injections robustly decreased the expression of conditioned fear measured by conditioned freezing and fear-potentiated startle. These NPY effects were not mimicked by intra-amygdala injections of the Y1R agonists Y-28 or Y-36, and co-infusion of the Y1R antagonist BIBO 3304 did not block the NPY effects. Furthermore, we tested Y1R-deficient mice in conditioned freezing and found no differences between wild type and mutant littermates. Finally, we injected NPY into the amygdala of Y1R-deficient mice. Y1R deficiency had no effect on the fear-reducing effects of intra-amygdala NPY. CONCLUSIONS: These data show an important role of the transmitter NPY within the amygdala for the expression of conditioned fear. Y1R do not appear to be involved in the mediation of the observed intra-amygdala NPY effects suggesting that these effects are mediated via other NPY receptors.