The complexity of leadership in coproduction practices: a guiding framework based on a systematic literature review.

BACKGROUND: As coproduction in public services increases, understanding the role of leadership in this context is essential to the tasks of establishing relational partnerships and addressing power differentials among groups. The aims of this review are to explore models of coproduction leadership and the processes involved in leading coproduction as well as, based on that exploration, to develop a guiding framework for coproduction practices. METHODS: A systematic review that synthesizes the evidence reported by 73 papers related to coproduction of health and welfare. RESULTS: Despite the fact that models of coleadership and collective leadership exhibit a better fit with the relational character of coproduction, the majority of the articles included in this review employed a leader-centric underlying theory. The practice of coproduction leadership is a complex activity pertaining to interactions among people, encompassing nine essential practices: initiating, power-sharing, training, supporting, establishing trust, communicating, networking, orchestration, and implementation. CONCLUSIONS: This paper proposes a novel framework for coproduction leadership practices based on a systematic review of the literature and a set of reflective questions. This framework aims to help coproduction leaders and participants understand the complexity, diversity, and flexibility of coproduction leadership and to challenge and enhance their capacity to collaborate effectively.

A co-design study to develop supportive interventions to improve psychological and social adaptation among adults with new-onset type 1 diabetes in Denmark and the UK.

OBJECTIVE: To develop supportive interventions for adults with new-onset type 1 diabetes (T1D) to facilitate positive adaptive strategies during their transition into a life with diabetes. DESIGN: The study used a co-design approach informed by Design Thinking to stimulate participants' reflections on their experiences of current care and generate ideas for new supportive interventions. Visual illustrations were used to depict support needs and challenges. Initial discussions of these needs and challenges were facilitated by researchers and people with diabetes in workshops. Data comprising transcribed audio recordings of the workshop discussions and materials generated during the workshops were analysed thematically. SETTINGS: Specialised diabetes centres in Denmark and the United Kingdom. PARTICIPANTS: Adults with new-onset T1D (n=24) and healthcare professionals (HCPs) (n=56) participated in six parallel workshops followed by four joint workshops with adults (n=29) and HCPs (n=24) together. RESULTS: The common solution prioritised by both adults with new-onset T1D and HCP participants was the development of an integrated model of care addressing the psychological and social elements of the diagnosis, alongside information on diabetes self-management. Participants also indicated a need to develop the organisation, provision and content of care, along with the skills HCPs need to optimally deliver that care. The co-designed interventions included three visual conversation tools that could be used flexibly in the care of adults with new-onset T1D to support physical, psychological and social adaptation to T1D. CONCLUSION: This co-design study has identified the care priorities for adults who develop T1D, along with some practical conversational tools that may help guide HCPs in attending to the disruptive experience of the diagnosis and support adults in adjusting into a life with diabetes.

In-PREP: a new learning design framework and methodology applied to a relational care training intervention for healthcare assistants.

BACKGROUND: 'Older People's Shoes' is a training intervention designed for healthcare assistants (HCAs) to improve the relational care of older people in hospital. The intervention formed part of a broader evaluation, in this paper we describe its development from a learning design and methodological perspective. METHODS: Learning theory and an instructional design model were key components of the In-PREP (Input, Process, Review and Evaluation, Product) development methodology used in the design of the 'Older People's Shoes' training intervention to improve the delivery of relational care by front-line hospital staff. An expert panel, current evidence, and pedagogical theory were used to co-design a training programme tailored to a challenging work environment and taking account of trainees' diverse educational experience. Peer review and process evaluation were built into the development model. RESULTS: In-PREP provided a methodological scaffold for producing evidence-based, peer-reviewed, co-designed training. The product, 'Older People's Shoes', involved a one-day Train the Trainers event, followed by delivery of a two-day, face-to-face training programme by the trainers, with accompanying handbooks underpinned by a range of digital resources. Evaluation found the approach met learner needs, was applicable in practice and won approval from trainers. DISCUSSION: In-PREP enables high quality learning content, alignment with learner needs and a product that is relevant, practical and straightforward to implement.

Lost in the shadows: reflections on the dark side of co-production.

This article is a response to Oliver et al.'s Commentary 'The dark side of coproduction: do the costs outweigh the benefits for health research?' recently published in Health Research Policy and Systems (2019, 17:33). The original commentary raises some important questions about how and when to co-produce health research, including highlighting various professional costs to those involved. However, we identify four related limitations in their inquiry, as follows: (1) the adoption of a problematically expansive definition of co-production that fails to acknowledge key features that distinguish co-production from broader collaboration; (2) a strong focus on technocratic rationales for co-producing research and a relative neglect of democratic rationales; (3) the transposition of legitimate concerns relating to collaboration between researchers and practitioners onto work with patients, service users and marginalised citizens; and (4) the presentation of bad practice as an inherent flaw, or indeed 'dark side', of co-production without attending to the corrupting influence of contextual factors within academic research that facilitate and even promote such malpractice. The Commentary's limitations can be seen to reflect the contemporary use of the term 'co-production' more broadly. We describe this phenomenon as 'cobiquity' - an apparent appetite for participatory research practice and increased emphasis on partnership working, in combination with the related emergence of a plethora of 'co' words, promoting a conflation of meanings and practices from different collaborative traditions. This phenomenon commonly leads to a misappropriation of the term 'co-production'. Our main motivation is to address this imprecision and the detrimental impact it has on efforts to enable co-production with marginalised and disadvantaged groups. We conclude that Oliver et al. stray too close to 'the problem' of 'co-production' seeing only the dark side rather than what is casting the shadows. We warn against such a restricted view and argue for greater scrutiny of the structural factors that largely explain academia's failure to accommodate and promote the egalitarian and utilitarian potential of co-produced research.

Exploring the sustainability of quality improvement interventions in healthcare organisations: a multiple methods study of the 10-year impact of the 'Productive Ward: Releasing Time to Care' programme in English acute hospitals.

BACKGROUND: The 'Productive Ward: Releasing Time to Care' programme is a quality improvement (QI) intervention introduced in English acute hospitals a decade ago to: (1) Increase time nurses spend in direct patient care. (2) Improve safety and reliability of care. (3) Improve experience for staff and patients. (4) Make changes to physical environments to improve efficiency. OBJECTIVE: To explore how timing of adoption, local implementation strategies and processes of assimilation into day-to-day practice relate to one another and shape any sustained impact and wider legacies of a large-scale QI intervention. DESIGN: Multiple methods within six hospitals including 88 interviews (with Productive Ward leads, ward staff, Patient and Public Involvement representatives and senior managers), 10 ward manager questionnaires and structured observations on 12 randomly selected wards. RESULTS: Resource constraints and a managerial desire for standardisation meant that, over time, there was a shift away from the original vision of empowering ward staff to take ownership of Productive Ward towards a range of implementation 'short cuts'. Nonetheless, material legacies (eg, displaying metrics data; storage systems) have remained in place for up to a decade after initial implementation as have some specific practices (eg, protected mealtimes). Variations in timing of adoption, local implementation strategies and contextual changes influenced assimilation into routine practice and subsequent legacies. Productive Ward has informed wider organisational QI strategies that remain in place today and developed lasting QI capabilities among those meaningfully involved in its implementation. CONCLUSIONS: As an ongoing QI approach Productive Ward has not been sustained but has informed contemporary organisational QI practices and strategies. Judgements about the long-term sustainability of QI interventions should consider the evolutionary and adaptive nature of change processes.

The challenges of training, support and assessment of healthcare support workers: A qualitative study of experiences in three English acute hospitals.

BACKGROUND: Ever-growing demands on care systems have increased reliance on healthcare support workers. In the UK, their training has been variable, but organisation-wide failures in care have prompted questions about how this crucial section of the workforce should be developed. Their training, support and assessment has become a policy priority. OBJECTIVES: This paper examines: healthcare support workers' access to training, support and assessment; perceived gaps in training provision; and barriers and facilitators to implementation of relevant policies in acute care. DESIGN AND SETTINGS: We undertook a qualitative study of staff caring for older inpatients at ward, divisional or organisational-level in three acute National Health Service hospitals in England in 2014. PARTICIPANTS: 58 staff working with older people (30 healthcare support workers and 24 staff managing or working alongside them) and 4 healthcare support worker training leads. METHODS: One-to-one semi-structured interviews included: views and experiences of training and support; translation of training into practice; training, support and assessment policies and difficulties of implementing them. Transcripts were analysed to identify themes. RESULTS: Induction training was valued, but did not fully prepare healthcare support workers for the realities of the ward. Implementation of hospital policies concerning supervision and formal assessment of competencies varied between and within hospitals, and was subject to availability of appropriate staff and competing demands on staff time. Gaps identified in training provision included: caring for people with cognitive impairment; managing the emotions of patients, families and themselves; and having difficult conversations. Access to ongoing training was affected by: lack of time; infrequent provision; attitudes of ward managers to additional support workforce training, and their need to balance this against patients' and other staff members' needs; and the use of e-learning as a default mode of training delivery. CONCLUSIONS: With the current and unprecedented policy focus on training, support and assessment of healthcare support workers, our study suggests improved training would be welcomed by them and their managers. Provision of training, support and assessment could be improved by organisational policy that promotes and protects healthcare support worker training; formalising the provision and availability of on-ward support; and training and IT support provided on a drop-in basis. Challenges in implementation are likely to be faced in all international settings where there is increased reliance on a support workforce. While recent policies in the UK offers scope to overcome some of these challenges there is a risk that some will be exacerbated.

Developing a novel peer support intervention to promote resilience after stroke.

Stroke can lead to physical, mental and social long-term consequences, with the incidence of stroke increasing with age. However, there is a lack of evidence of how to improve long-term outcomes for people with stroke. Resilience, the ability to 'bounce back', flourish or thrive in the face of adversity improves mental health and quality of life in older adults. However, the role of resilience in adjustment after stroke has been little investigated. The purpose of this study is to report on the development and preliminary evaluation of a novel intervention to promote resilience after stroke. We applied the first two phases of the revised UK Medical Research Council (UKMRC) framework for the development and evaluation of complex interventions: intervention development (phase 1) and feasibility testing (phase 2). Methods involved reviewing existing evidence and theory, interviews with 22 older stroke survivors and 5 carers, and focus groups and interviews with 38 professionals to investigate their understandings of resilience and its role in adjustment after stroke. We used stakeholder consultation to co-design the intervention and returned to the literature to develop its theoretical foundations. We developed a 6-week group-based peer support intervention to promote resilience after stroke. Theoretical mechanisms of peer support targeted were social learning, meaning-making, helping others and social comparison. Preliminary evaluation with 11 older stroke survivors in a local community setting found that it was feasible to deliver the intervention, and acceptable to stroke survivors, peer facilitators, and professionals in stroke care and research. This study demonstrates the application of the revised UKMRC framework to systematically develop an empirically and theoretically robust intervention to promote resilience after stroke. A future randomised feasibility study is needed to determine whether a full trial is feasible with a larger sample and wider age range of people with stroke.

Can Healthcare Assistant Training (CHAT) improve the relational care of older people? Study protocol for a pilot cluster randomised controlled trial.

BACKGROUND: People aged 75 years and over account for 1 in 4 of all hospital admissions. There has been increasing recognition of problems in the care of older people, particularly in hospitals. Evidence suggests that older people judge the care they receive in terms of kindness, empathy, compassion, respectful communication and being seen as a person not just a patient. These are aspects of care to which we refer when we use the term 'relational care'. Healthcare assistants deliver an increasing proportion of direct care to older people, yet their training needs are often overlooked. METHODS/DESIGN: This study will determine the acceptability and feasibility of a cluster randomised controlled trial of 'Older People's Shoes' a 2-day training intervention for healthcare assistants caring for older people in hospital. Within this pilot, 2-arm, parallel, cluster randomised controlled trial, healthcare assistants within acute hospital wards are randomised to either the 2-day training intervention or training as usual. Registered nurses deliver 'Older People's Shoes' over 2 days, approximately 1 week apart. It contains three components: experiential learning about ageing, exploration of older people's stories, and customer care. Outcomes will be measured at the level of patient (experience of emotional care and quality of life during their hospital stay), healthcare assistant (empathy and attitudes towards older people), and ward (quality of staff/patient interaction). Semi-structured interviews of a purposive sample of healthcare assistants receiving the intervention, and all trainers delivering the intervention, will be undertaken to gain insights into the experiences of both the intervention and the trial, and its perceived impact on practice. DISCUSSION: Few training interventions for care staff have been rigorously tested using randomised designs. This study will establish the viability of a definitive cluster randomised controlled trial of a new training intervention to improve the relational care proided by healthcare assistants working with older people in hospital. TRIAL REGISTRATION: The study was registered as an International Standard Randomised Controlled Trial ( ISRCTN10385799 ) on 29 December 2014.

Longitudinal follow-up and characterization of a robust rat model for Parkinson's disease based on overexpression of alpha-synuclein with adeno-associated viral vectors.

Testing of new therapeutic strategies for Parkinson's disease (PD) is currently hampered by the lack of relevant and reproducible animal models. Here, we developed a robust rat model for PD by injection of adeno-associated viral vectors (rAAV2/7) encoding α-synuclein into the substantia nigra, resulting in reproducible nigrostriatal pathology and behavioral deficits in a 4-week time period. Progressive dopaminergic dysfunction was corroborated by histopathologic and biochemical analysis, motor behavior testing and in vivo microdialysis. L-DOPA treatment was found to reverse the behavioral phenotype. Non-invasive positron emission tomography imaging and magnetic resonance spectroscopy allowed longitudinal monitoring of neurodegeneration. In addition, insoluble α-synuclein aggregates were formed in this model. This α-synuclein rat model shows improved face and predictive validity, and therefore offers the possibility to reliably test novel therapeutics. Furthermore, it will be of great value for further research into the molecular pathogenesis of PD and the importance of α-synuclein aggregation in the disease process.

NMDA receptor antagonism potentiates the L-DOPA-induced extracellular dopamine release in the subthalamic nucleus of hemi-parkinson rats.

Long term treatment with L-3,4-dihydroxyphenylalanine (L-DOPA) is associated with several motor complications. Clinical improvement of this treatment is therefore needed. Lesions or high frequency stimulation of the hyperactive subthalamic nucleus (STN) in Parkinson's disease (PD), alleviate the motor symptoms and reduce dyskinesia, either directly and/or by allowing the reduction of the L-DOPA dose. N-methyl-D-aspartate (NMDA) receptor antagonists might have similar actions. However it remains elusive how the neurochemistry changes in the STN after a separate or combined administration of L-DOPA and a NMDA receptor antagonist. By means of in vivo microdialysis, the effect of L-DOPA and/or MK 801, on the extracellular dopamine (DA) and glutamate (GLU) levels was investigated for the first time in the STN of sham and 6-hydroxydopamine-lesioned rats. The L-DOPA-induced DA increase in the STN was significantly higher in DA-depleted rats compared to shams. MK 801 did not influence the L-DOPA-induced DA release in shams. However, MK 801 enhanced the L-DOPA-induced DA release in hemi-parkinson rats. Interestingly, the extracellular STN GLU levels remained unchanged after nigral degeneration. Furthermore, administration of MK 801 alone or combined with L-DOPA did not alter the STN GLU levels in both sham and DA-depleted rats. The present study does not support the hypothesis that DA-ergic degeneration influences the STN GLU levels neither that MK 801 alters the GLU levels in lesioned and non-lesioned rats. However, NMDA receptor antagonists could be used as a beneficial adjuvant treatment for PD by enhancing the therapeutic efficacy of l-DOPA at least in part in the STN.

A systematic review of qualitative studies on adjusting after stroke: lessons for the study of resilience.

PURPOSE: To synthesize qualitative studies on adjusting after stroke, from stroke survivors' and carers' perspectives, and to outline their potential contribution to an understanding of resilience. METHODS: A systematic review of qualitative studies in peer reviewed journals from 1990 to 2011 was undertaken. Findings from selected studies were summarized and synthesized and then considered alongside studies of resilience. RESULTS: Forty studies were identified as suitable. These suggested that the impact of stroke was felt on many dimensions of experience, and that the boundaries between these were permeable. Nor was stroke as an adverse "event" temporally bounded. Adjustment was often marked by setbacks and new challenges over time. Participants identified personal characteristics as key, but also employed practical and mental strategies in their efforts to adjust. Relationships and structural factors also influenced adjustment after stroke. CONCLUSIONS: The impacts of stroke and the processes of adjusting to it unfold over time. This presents a new challenge for resilience research. Processes of adjustment, like resilience, draw on personal, inter-personal and structural resources. But the reviewed studies point to the importance of an emic perspective on adversity, social support, and what constitutes a "good" outcome when researching resilience, and to a greater focus on embodiment. Implications for Rehabilitation Stroke is a sudden onset condition which for around a third of people has long-term consequences. Stroke can cause a variety of physical and cognitive impairments, some of which may not be obvious to an outsider. As well as physical functioning, stroke can have a profound effect on survivors' sense of self and on their relationships. Stroke survivors' accounts suggest that relationships (including relationships with health care professionals) and structural factors (such as access to health services, employment possibilities and welfare systems) mediate efforts to adjust after stroke. While there is considerable overlap between notions of adjustment and resilience, the experiences of stroke survivors suggest further issues that need to be addressed in order to gain a more comprehensive understanding of resilience.

Proteomic analysis of global protein expression changes in the endothelin-1 rat model for cerebral ischemia: rescue effect of mild hypothermia.

Mild hypothermia is a promising neuroprotective therapy in stroke management. However, little is known about its effects on the global protein expression patterns in brain regions affected by ischemic stroke. We investigated protein expression changes associated with the neuroprotective effects of hypothermia via a functional proteomics approach through the analysis of the core (striatum) and the penumbra (cortex) after an ischemic insult in rats induced by endothelin-1 (Et-1). Functional outcome, infarct volume and related global protein expression changes were assessed 24h after the insult using two-dimensional difference gel electrophoresis. Mild hypothermia, induced 20 min after endothelin-1 infusion, improved the neurological outcome, reflected by a 36% reduction in infarct volume and a significantly better neurological deficit score. Hypothermia was typically associated with opposite protein expression changes inthe cortex to those induced by stroke under normothermic conditions, but not in the striatum. The main cellular processes rescued by hypothermia and potentially involved in the protection of the cortex are cellular assembly and organization, followed by cell signaling, thereby confirming that hypothermia is neuroprotective through multiple molecular and cellular pathways.

Mild hypothermia reduces activated caspase-3 up to 1 week after a focal cerebral ischemia induced by endothelin-1 in rats.

Hypothermia is a promising neuroprotective therapy that has been shown to reduce apoptosis after an ischemic insult. This study evaluated the effect of mild hypothermia on activated caspase-3 up to 1 week after the induction of a stroke. Endothelin-1 (Et-1) was used to elicit transient focal cerebral ischemia in rats. Twenty minutes after the ischemic insult, a state of mild hypothermia (33°C) was imposed for a duration of 2h. The functional outcome, infarct volume and activated caspase-3 immunoreactivity (IR) were assessed at 8, 24 and 72h, and one week after the insult. During the experiment the cerebral blood flow (CBF) was measured via Laser Doppler Flowmetry. Hypothermia improved the neurological outcome at all of the time points studied compared to the normothermic group, and was associated with a reduction in infarct volume. In both groups, activated caspase-3 IR peaked 24h after the Et-1 induced insult and hypothermia significantly reduced the number of apoptotic cells at 8h, 24h and 1 week after ischemia. Furthermore, the hypothermic treatment did not affect the CBF in the Et-1 model. These findings indicate that in the Et-1 model, hypothermia exerts a long lasting effect on stroke-induced apoptosis.

The neuroprotective effect of post ischemic brief mild hypothermic treatment correlates with apoptosis, but not with gliosis in endothelin-1 treated rats.

BACKGROUND: Stroke remains one of the most common diseases with a serious impact on quality of life but few effective treatments exist. Mild hypothermia (33°C) is a promising neuroprotective therapy in stroke management. This study investigated whether a delayed short mild hypothermic treatment is still beneficial as neuroprotective strategy in the endothelin-1 (Et-1) rat model for a transient focal cerebral ischemia. Two hours of mild hypothermia (33°C) was induced 20, 60 or 120 minutes after Et-1 infusion. During the experiment the cerebral blood flow (CBF) was measured via Laser Doppler Flowmetry in the striatum, which represents the core of the infarct. Functional outcome and infarct volume were assessed 24 hours after the insult. In this sub-acute phase following stroke induction, the effects of the hypothermic treatment on apoptosis, phagocytosis and astrogliosis were assessed as well. Apoptosis was determined using caspase-3 immunohistochemistry, phagocytic cells were visualized by CD-68 expression and astrogliosis was studied by glial fibrillary acidic protein (GFAP) staining. RESULTS: Cooling could be postponed up to 1 hour after the onset of the insult without losing its positive effects on neurological deficit and infarct volume. These results correlated with the caspase-3 staining. In contrast, the increased CD-68 expression post-stroke was reduced in the core of the insult with all treatment protocols. Hypothermia also reduced the increased levels of GFAP staining, even when it was delayed up to 2 hours after the insult. The study confirmed that the induction of the hypothermia treatment in the Et-1 model does not affect the CBF. CONCLUSIONS: These data indicate that in the Et-1 rat model, a short mild hypothermic treatment delayed for 1 hour is still neuroprotective and correlates with apoptosis. At the same time, hypothermia also establishes a lasting inhibitory effect on the activation of astrogliosis.

Oxidative stress in genetic mouse models of Parkinson's disease.

There is extensive evidence in Parkinson's disease of a link between oxidative stress and some of the monogenically inherited Parkinson's disease-associated genes. This paper focuses on the importance of this link and potential impact on neuronal function. Basic mechanisms of oxidative stress, the cellular antioxidant machinery, and the main sources of cellular oxidative stress are reviewed. Moreover, attention is given to the complex interaction between oxidative stress and other prominent pathogenic pathways in Parkinson's disease, such as mitochondrial dysfunction and neuroinflammation. Furthermore, an overview of the existing genetic mouse models of Parkinson's disease is given and the evidence of oxidative stress in these models highlighted. Taken into consideration the importance of ageing and environmental factors as a risk for developing Parkinson's disease, gene-environment interactions in genetically engineered mouse models of Parkinson's disease are also discussed, highlighting the role of oxidative damage in the interplay between genetic makeup, environmental stress, and ageing in Parkinson's disease.

Spontaneously hypertensive rats display reduced microglial activation in response to ischemic stroke and lipopolysaccharide.

BACKGROUND: For successful translation to clinical stroke studies, the Stroke Therapy Academic Industry Round Table criteria have been proposed. Two important criteria are testing of therapeutic interventions in conscious animals and the presence of a co-morbidity factor. We chose to work with hypertensive rats since hypertension is an important modifiable risk factor for stroke and influences the clinical outcome. We aimed to compare the susceptibility to ischemia in hypertensive rats with those in normotensive controls in a rat model for induction of ischemic stroke in conscious animals. METHODS: The vasoconstrictor endothelin-1 was stereotactically applied in the vicinity of the middle cerebral artery of control Wistar Kyoto rats (WKYRs) and spontaneously hypertensive rats (SHRs) to induce a transient decrease in striatal blood flow, which was measured by the laser Doppler technique. Infarct size was assessed histologically by cresyl violet staining. Sensory-motor functions were measured at several time points using the neurological deficit score. Activation of microglia and astrocytes in the striatum and cortex was investigated by immunohistochemistry using antibodies against CD68/Iba-1 and glial fibrillary acidic protein. RESULTS AND CONCLUSIONS: The SHRs showed significantly larger infarct volumes and more pronounced sensory-motor deficits, compared to the WKYRs at 24 h after the insult. However, both differences disappeared between 24 and 72 h. In SHRs, microglia were less susceptible to activation by lipopolysaccharide and there was a reduced microglial activation after induction of ischemic stroke. These quantitative and qualitative differences may be relevant for studying the efficacy of new treatments for stroke in accordance to the Stroke Therapy Academic Industry Round Table criteria.

Determination of reboxetine in rat brain microdialysates and plasma samples using liquid chromatography coupled to fluorescence detection.

A liquid chromatographic method with fluorescence detection was developed and validated for the quantification of the antidepressant reboxetine (RBX), a selective noradrenalin reuptake inhibitor, in rat brain microdialysates. After modification of the method in terms of sample preparation and sensitivity, it was also validated for the quantification of RBX in rat plasma samples. To enable fluorescence detection, a pre-column derivatization step with 9-fluorenylmethyl chloroformate was included. Separations were performed on a reversed phase C18 column using gradient elution. The retention time for RBX was found to be 8.8 min. The assay of RBX in brain microdialysis samples showed a linear relationship in the calibration curve from 2 to 200 ng/mL, with a correlation coefficient ≥0.999. The limit of detection (LOD) and the lower limit of quantification (LLOQ) were 0.6 and 2.0 ng/mL respectively. The intra-day and the inter-day precision (RSD %) ranged between 1.5% and 11.7% with an average recovery of 101.2±8.2% (mean±SD, n=40). For the analysis of plasma samples, the calibration curve was linear between 20 and 700 ng/mL with a correlation coefficient ≥0.999. LOD and LLOQ were 6 and 20 ng/mL respectively. The intra-day and the inter-day precision (RSD %) ranged between 1.7% and 11.5% with an average recovery of 98.5±7.3% (mean±SD, n=40). We demonstrated the applicability of the method to determine the concentration-time profiles of RBX in brain and plasma following systemic administration.

Differential modulations of striatal tyrosine hydroxylase and dopamine metabolism by cannabinoid agonists as evidence for functional selectivity in vivo.

It is generally assumed that cannabinoids induce transient modulations of dopamine transmission through indirect regulation of its release. However, we previously described a direct cannabinoid-mediated control of tyrosine hydroxylase (TH) expression, in vitro. We herein report on the influence of cannabinoid agonists on the expression of this key enzyme in catecholamine synthesis as well as on the modification of dopamine content in adult rats. As expected for cannabinoid agonists, the exposure to either Δ(9)-THC, HU 210 or CP 55,940 induced both catalepsy and hypolocomotion. Supporting a possible long-lasting control on dopaminergic activity, we noticed a significant HU 210-mediated increase in TH expression in the striatum that was concomitant with an increase in striatal dopamine content. Surprisingly, while a similar trend was reported with Δ(9)-THC, CP 55,940 completely failed to modulate TH expression or dopamine content. Nevertheless, the access of CP 55,940 to brain structures was validated by determinations of drug concentrations in the tissue and by ex vivo binding experiments. Furthermore, confirming the central activity of CP 55,940, the analysis of dopamine metabolites revealed a reduction in striatal DOPAC concentrations. Consistent with the involvement of the CB(1) cannabinoid receptor in these different responses, both HU 210- and CP 55,940-mediated effects were prevented by SR 141716A. Therefore, the present data suggest that both HU 210 and CP 55,940 cause a delayed/persistent regulation of the dopamine neurotransmission system. Nevertheless, these commonly used cannabinoid agonists endowed with similar pharmacodynamic properties clearly triggered distinct biochemical responses highlighting the existence of functional selectivity in vivo.

Acute running stimulates hippocampal dopaminergic neurotransmission in rats, but has no influence on brain-derived neurotrophic factor.

Hippocampal brain-derived neurotrophic factor (BDNF) protein is increased with exercise in rats. Monoamines seem to play a role in the regulation of BDNF, and monoamine neurotransmission is known to increase with exercise. The purpose of this study was to examine the influence of acute exercise on monoaminergic neurotransmission and BDNF protein concentrations. Hippocampal microdialysis was performed in rats that were subjected to 60 min of treadmill running at 20 m/min or rest. Two hours postexercise, the rats were killed, and the hippocampus was dissected. In experiments without microdialysis, hippocampus and serum samples were collected immediately after exercise. Exercise induced a twofold increase in hippocampal dopamine release. Noradrenaline and serotonin release were not affected. Hippocampal BDNF levels were not influenced, whether they were measured immediately or 2 h after the exercise protocol. Serum BDNF levels did not change either, but serum BDNF was negatively correlated to peripheral corticosterone concentrations, indicating a possible inhibitory reaction to the stress of running. Sixty minutes of exercise enhances dopamine release in the hippocampus of the rat in vivo. However, this increase is not associated with changes in BDNF protein levels immediately nor 2 h after the acute exercise bout. An increased corticosterone level might be the contributing factor for the absence of changes in BDNF.