A protocol for developing a core outcome set for ectopic pregnancy

BACKGROUND: Randomised controlled trials (RCTs) evaluating ectopic pregnancy have reported many different outcomes, which are themselves often defined and measured in distinct ways. This level of variation results in an inability to compare results of individual RCTs. The development of a core outcome set to ensure outcomes important to key stakeholders are collected consistently will guide future research in ectopic pregnancy. STUDY AIM: To develop and implement a core outcome set to guide future research in ectopic pregnancy. METHODS AND ANALYSIS: We have established an international steering group of key stakeholders, including healthcare professionals, researchers, and individuals with lived experience of ectopic pregnancy. We will identify potential outcomes from ectopic pregnancy from a comprehensive literature review of published randomised controlled trials. We will then utilise a modified Delphi method to prioritise outcomes. Subsequently, key stakeholders will be invited to score potential core outcomes on a nine-point Likert scale, ranging from 1 (not important) to 9 (critical). Repeated reflection and rescoring should promote whole and individual stakeholder group convergence towards consensus ‘core’ outcomes. We will also establish standardised definitions and recommend high-quality measurements for individual core outcomes. TRIAL REGISTRATION: COMET 1492. Registered in November 2019

Distinct endocrine effects of chronic haloperidol or risperidone administration in male rats

Antipsychotic drugs have been used effectively for the treatment of schizophrenia symptoms, but they are often associated with metabolic side effects such as weight gain and endocrine disruptions. To investigate the possible mechanisms of antipsychotic-induced metabolic effects, we studied the impact of chronic administration of a typical antipsychotic drug (haloperidol) and an atypical antipsychotic (risperidone) to male rats on food intake, body weight, adiposity, and the circulating concentrations of hormones and metabolites that can influence energy homeostasis. Chronic (28 days) haloperidol administration had no effect on food intake, weight gain or adiposity in male rats, whereas risperidone treatment resulted in a transient reduction in food intake and significantly reduced body weight gain compared to vehicle-treated control rats. Whereas neither antipsychotic had any effect on serum lipid profiles, glucose tolerance or the circulating concentrations of hormones controlled by the hypothalamo-pituitary-thyroid (free T4), -adrenal (corticosterone), -somatotropic (IGF-1), or -gonadotropic axes (testosterone), haloperidol increased circulating insulin levels and risperidone increased serum glucagon levels. This finding suggests that haloperidol or risperidone induce distinct metabolic effects. Since metabolic disorders such as obesity and type 2 diabetes mellitus represent serious health issues, understanding antipsychotic-induced endocrine and metabolic effects may ultimately allow better control of these side effects

Behavioural profile of a new mouse model for NPY deficiency

The abundantly expressed neuropeptide Y (NPY) plays an important role in anxiety and stress reactivity, as exogenous NPY administration reduces anxiety-like behaviour in rodents. However, unlike the potent effects of NPY seen in pharmacological studies, two independent examinations of a genetic mouse model for NPY deficiency have shown only subtle, inconsistent and task dependent anxiety-related phenotypes for male mutants. Here we present results of a newly developed germline NPY-knockout model, which has been characterized behaviourally using a comprehensive multi-tiered phenotyping strategy. Mice of both sexes were investigated in locomotion and exploration tasks, anxiety-related paradigms, a hippocampus-dependent memory test and a battery of basic tasks screening for sensory and motor functions. Male and female NPY-deficient mice consistently demonstrated suppressed levels of locomotion and exploration. Furthermore, mutant mice exhibited a pronounced anxiogenic-like phenotype when tested in spatiotemporal anxiety-relevant paradigms (i.e. elevated-plus maze, open field and light–dark task). Importantly, this phenotype was more pronounced in male NPY mutants, revealing a moderate sexually dimorphic impact of NPY deficiency on behaviour. Interestingly, lack of NPY did not result in impaired learning and memory in either sex. Our carefully selected comprehensive behavioural phenotyping strategy revealed a consistent hypolocomotive and sex-dependent anxious-like phenotype. This new NPY-knockout mouse model reveals the importance of sex-specific testing. It also offers a potent new model for research into anxiety-related disorders and suggests potential treatment options for these conditions via the NPY system

Schizophrenia-relevant behaviours in a genetic mouse model for Y2 deficiency

Expression levels of neuropeptide Y (NPY) are changed in schizophrenia patients. However, the direction of changes to NPY expression and the mechanisms behind NPY's impact on the development of the illness is not understood in detail. Here we investigated whether alterations in Y2 activity may be involved in the development of schizophrenia-related behaviours. We examined NPY Y2 receptor deficient male mice in behavioural domains relevant for the illness: locomotion, learning and memory, social interaction and sensorimotor gating (baseline and after acute challenge with psychotropic drugs) and the most relevant tasks were also completed in female Y2 mutants. Our investigations confirmed a hyper-locomotive phenotype for Y2 deficient male mice and no alterations in working and reference memory performance. Mutant males exhibited an increase in social interaction and moderately improved sensorimotor gating. The psychotropic drugs dexamphetamine and MK-801 affected prepulse inhibition similarly, whereas MK-801 appeared to be a slightly more potent stimulant for the acoustic startle response (ASR). Female Y2 deficient mice showed wild type-like performances in social interaction, working memory and prepulse inhibition. However, Y2 mutant females exhibited a moderately increased ASR compared to control mice. Taken together, lack of Y2 signalling in mice not only leads to altered locomotion but also changes social behaviours and affects sensorimotor gating. Thus, Y2 depletion influences a range of behaviours, which are potentially relevant for schizophrenia-related research

Acoustic startle response and sensorimotor gating in a genetic mouse model for the Y1 receptor

Recent research has highlighted a potential role for neuropeptide Y (NPY) and its Y1 receptor in the development of schizophrenia. Genetic as well as molecular biological studies have demonstrated reduced levels of NPY in schizophrenia patients. Importantly, Y1 receptors may mediate some of the potential effects of NPY on schizophrenia, as decreased Y1 receptor expression has been found in the lymphocytes of schizophrenia patients. To clarify NPY's role in schizophrenia, we investigated a genetic animal model for Y1 deficiency in regard to (i) acoustic startle response (ASR), (ii) habituation to ASR and (iii) sensorimotor gating [i.e. prepulse inhibition (PPI)] using two different PPI protocols. Mutant and wild type-like mice were screened for baseline behaviours and after pharmacological challenge with the psychotropic drugs dexamphetamine (DEX) and MK-801. Y1 knockout mice (Y1 -/-) showed a moderate reduction of the ASR and an impaired ASR habituation at baseline and after DEX treatment. The baseline PPI performance of Y1 mutant mice was unaltered their response to DEX and MK-801 challenge was moderately different compared to control mice, which was dependent on the PPI protocol used. MK-801 challenge had a protocol-dependent differential effect in Y1 -/- mice and DEX a more pronounced impact at the highest prepulse intensities. In conclusion, it appears that the Y1 receptor influences the acoustic startle response and its habituation but does not play a major role in sensorimotor gating. Further explorations into the effects of Y1 deficiency seem valid

Behavioural effects of chronic haloperidol and risperidone treatment in rats

The therapeutic properties of typical antipsychotic drugs (APDs) such as haloperidol in schizophrenia treatment are mainly associated with their ability to block dopamine D2 receptors. This blockade is accompanied by side effects such as extrapyramidal symptoms (EPS). Atypical APDs such as risperidone have superior therapeutic efficacy possibly due to their activity at multiple receptors (in particular 5-HT2A receptors). Although the risk of EPS is significantly lower in atypical than in typical APDs, it is not negligible. To investigate and compare the behavioural profile and EPS-asssociated side effects of haloperidol and risperidone APD treatment we applied a multi-tiered, comprehensive behavioural phenotyping approach. Sprague-Dawley rats were treated chronically (28 days) with supratherapeutic EPS-inducing doses of haloperidol and risperidone using osmotic minipumps. Domains such as motor activity, exploration, memory, and anxiety were analysed together with EPS assessment (“early onset” vacuous chewing movements and catalepsy). Both APDs produced diminished motor activity and exploration, impaired working memory performances, and increased anxiety levels. These effects were more pronounced in haloperidol-treated animals. Chronic APD treatment also caused a time-course dependent elevation of EPS-like symptoms. Risperidone-treated animals showed a catalepsy-like phenotype, which differed to that of haloperidol-treated rats, indicating that processes other than the anticipated dopaminergic mechanisms are underlying this phenomenon. These EPS-related phenotypes are consistent with reported EPS-inducing D2 receptor occupancies of around 80%. Differences in the behavioural profile of haloperidol and risperidone, which were revealed by a comprehensive phenotyping strategy, are likely due to the unique receptor activation profiles of these APDs

Behavioural profile of a heterozygous mutant mouse model for EGF-like domain neuregulin 1

Human genetic studies have demonstrated that the neuregulin 1 gene (NRG1) is involved in the development of schizophrenia. Alternative splicing of NRG1 results in at least 15 distinct isoforms and all contain an extracellular epidermal growth factor (EGF)-like domain, which is sufficient for Nrg1's biological activity. Here, we characterize a heterozygous mutant model for mouse EGF-like domain neuregulin 1 (Nrg1) regarding schizophrenia-related behavioral domains. A comprehensive, multitiered phenotyping strategy was used to investigate locomotion, exploration, anxiety-related behaviors, and sensorimotor gating. Nrg1 mutant mice exhibited a hyper-locomotive phenotype and an improved ability to habituate to a new environment. Extensive analysis of anxiety-related behaviors revealed a wild type-like phenotype in this domain. However, a moderate impairment in sensorimotor gating was found after pharmacological challenge using psychoactive substances. Our study adds to the increasing behavioral data available from a variety of animal models for Nrg1 isoforms. We suggest a standardized and comprehensive behavioral phenotyping approach to distinguish between the different models and to clarify their relevance for schizophrenia research. Future behavioral investigations will focus on the negative and cognitive symptoms of schizophrenia

Cognition in transmembrane domain neuregulin 1 mutant mice

Neuregulin 1 (NRG1), which has been implicated in the development of schizophrenia, is expressed widely throughout the brain and influences key neurodevelopmental processes such as myelination and neuronal migration. The heterozygous transmembrane domain Nrg1 mutant mouse (Nrg1 TM HET) exhibits a neurobehavioural phenotype relevant for schizophrenia research, characterized by the development of locomotor hyperactivity, social withdrawal, increased sensitivity to environmental manipulation, and changes to the serotonergic system. As only limited data are available on the learning and memory performance of Nrg1 TM HET mice, we conducted a comprehensive examination of these mice and their wild type-like littermates in a variety of paradigms, including fear conditioning (FC), radial arm maze (RAM), Y maze, object exploration and passive avoidance (PA). Male neuregulin 1 hypomorphic mice displayed impairments in the novel object recognition and FC tasks, including reduced interest in the novel object and reduced FC to a context, but not a discrete cue. These cognitive deficits were task-specific, as no differences were seen between mutant and control mice in spatial learning (i.e. RAM and Y maze) for both working and reference memory measures, or in the PA paradigm. These findings indicate that neuregulin 1 plays a moderate role in cognition and present further behavioural validation of this genetic mouse model for the schizophrenia candidate gene neuregulin 1

Altered motor activity, exploration, and anxiety in heterozygous neuregulin 1 mutant mice : implications for understanding schizophrenia

Human genetic studies have shown that neuregulin 1 (NRG1) is a potential susceptibility gene for schizophrenia. Nrg1 influences various neurodevelopmental processes, which are potentially related to schizophrenia. The neurodevelopmental theory of schizophrenia suggests that interactions between genetic and environmental factors are responsible for biochemical alterations leading to schizophrenia. To investigate these interactions and to match experimental design with the pathophysiology of schizophrenia, we applied a comprehensive behavioural phenotyping strategy for motor activity, exploration and anxiety in a heterozygous Nrg1 transmembrane domain mutant mouse model (Nrg1 HET) using different housing conditions and age groups. We observed a locomotion- and exploration-related hyperactive phenotype in Nrg1 HETs. Increased age had a locomotion- and exploration-inhibiting effect, which was significantly attenuated in mutant mice. Environmental enrichment (EE) had a stimulating influence on locomotion and exploration. The impact of EE was more pronounced in Nrg1 hypomorphs. Our study also showed a moderate task-specific anxiolytic-like phenotype for Nrg1 HETs, which was influenced by external factors. The behavioural phenotype detected in heterozygous Nrg1 mutant mice is not specific to schizophrenia per se, but the increased sensitivity of mutant mice to exogenous factors is consistent with the pathophysiology of schizophrenia and the neurodevelopmental theory. Our findings reinforce the importance of carefully controlling experimental designs for external factors and of comprehensive, integrative phenotyping strategies. Thus, Nrg1 HETs may, in combination with other genetic and drug models, help to clarify pathophysiological mechanisms behind schizophrenia