Forced limb-use and recovery following brain injury

Repetitive xenon treatment improves post-stroke sensorimotor and neuropsychiatric dysfunction

Stroke is a life-changing event as stroke survivors experience changes in personality, emotions and mood. We investigated the effect of xenon gas encapsulated in liposomes on stroke-generated sensorimotor impairments, and anxiety- and depression-like phenotypes. Ischemic stroke was created by the intraluminal middle cerebral artery occlusion (MCAO) for 6 h followed by reperfusion in rats. Xenon-liposome (6 mg/kg, intravenous) treatment was given multiple times starting at 2 h post-ischemia through 6 h (5X), and once-daily for next 3 days. Rats underwent ischemic injury displayed sensorimotor deficits in the adhesive removal, vibrissae-evoked forelimb placement and rotarod tests. These animals also made lesser entries and spent less time on open arms of the elevated-plus maze and swam more in passive mode in the forced swimming test, indicating anxiety- and depression-like behaviors at 28- and 35-days post-injury, respectively. Repeated intravenous treatment with xenon-liposomes ameliorated these behavioral aberrations (p < 0.05). Gut microbiome analysis (16S ribosomal-RNA gene sequencing) showed a decrease in the Clostridium clusters XI, XIVa, XVIII and Lactobacillus bacterium, and increase of the Prevotella in the xenon-liposome group. No microbiota communities were majorly affected across the treatments. Moreover, xenon treatment group showed augmented plasma levels of IL-6 cytokines (∼5 fold) on day-35 post-ischemia, while no change was noticed in the IL-1β, IL-4, IL-10, IL-13 and MCP-1 levels. Our data highlights the safety, behavioral recovery and reversal of post-stroke brain injury following xenon-liposome treatment in an extended ischemic model. These results show the potential for this treatment strategy to be translated to patients with stroke.

An adverse outcome pathway for parkinsonian motor deficits associated with mitochondrial complex I inhibition

Epidemiological studies have observed an association between pesticide exposure and the development of Parkinson's disease, but have not established causality. The concept of an adverse outcome pathway (AOP) has been developed as a framework for the organization of available information linking the modulation of a molecular target [molecular initiating event (MIE)], via a sequence of essential biological key events (KEs), with an adverse outcome (AO). Here, we present an AOP covering the toxicological pathways that link the binding of an inhibitor to mitochondrial complex I (i.e., the MIE) with the onset of parkinsonian motor deficits (i.e., the AO). This AOP was developed according to the Organisation for Economic Co-operation and Development guidelines and uploaded to the AOP database. The KEs linking complex I inhibition to parkinsonian motor deficits are mitochondrial dysfunction, impaired proteostasis, neuroinflammation, and the degeneration of dopaminergic neurons of the substantia nigra. These KEs, by convention, were linearly organized. However, there was also evidence of additional feed-forward connections and shortcuts between the KEs, possibly depending on the intensity of the insult and the model system applied. The present AOP demonstrates mechanistic plausibility for epidemiological observations on a relationship between pesticide exposure and an elevated risk for Parkinson's disease development.

MPTP mouse models of Parkinson's disease: an update

Among the most widely used models of Parkinson's disease (PD) are those that employ toxins, especially 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Depending on the protocol used, MPTP yields large variations in nigral cell loss, striatal dopamine loss and behavioral deficits. Motor deficits do not fully replicate those seen in PD. Nonetheless, MPTP mouse models mimic many aspects of the disease and are therefore important tools for understanding PD. In this review, we will discuss the ability of MPTP mouse models to replicate the pathophysiology of PD, the mechanisms of MPTP-induced neurotoxicity, strain differences in susceptibility to MPTP, and the models' roles in testing therapeutic approaches.

LSVT LOUD and LSVT BIG: Behavioral Treatment Programs for Speech and Body Movement in Parkinson Disease

Recent advances in neuroscience have suggested that exercise-based behavioral treatments may improve function and possibly slow progression of motor symptoms in individuals with Parkinson disease (PD). The LSVT (Lee Silverman Voice Treatment) Programs for individuals with PD have been developed and researched over the past 20 years beginning with a focus on the speech motor system (LSVT LOUD) and more recently have been extended to address limb motor systems (LSVT BIG). The unique aspects of the LSVT Programs include the combination of (a) an exclusive target on increasing amplitude (loudness in the speech motor system; bigger movements in the limb motor system), (b) a focus on sensory recalibration to help patients recognize that movements with increased amplitude are within normal limits, even if they feel "too loud" or "too big," and (c) training self-cueing and attention to action to facilitate long-term maintenance of treatment outcomes. In addition, the intensive mode of delivery is consistent with principles that drive activity-dependent neuroplasticity and motor learning. The purpose of this paper is to provide an integrative discussion of the LSVT Programs including the rationale for their fundamentals, a summary of efficacy data, and a discussion of limitations and future directions for research.

May exercise prevent addiction?

Amphetamines exert their persistent addictive effects by activating brain's reward pathways, perhaps through the release of dopamine in the nucleus accumbens (and/or in other places). On the other hand, there is a relationship between dopamine and all behavioural aspects that involve motor activity and it has been demonstrated that exercise leads to an increase in the synthesis and release of dopamine, stimulates neuroplasticity and promotes feelings of well-being. Moreover, exercise and drugs of abuse activate overlapping neural systems. Thus, our aim was to study the influence of chronic exercise in the mechanism of addiction using an amphetamine-induced conditioned-place-preference in rats.

Adult male Sprague-Dawley rats were randomly separated in groups with and without chronic exercise. Chronic exercise consisted in a 8 week treadmill running program, with increasing intensity. The conditioned place preference test was performed in both groups using a procedure and apparatus previously established. A 2 mg.kg^-1 amphetamine or saline solution was administered intraperitonially according to the schedule of the conditioned place preference.

Before conditioning none of the animals showed preference for a specific compartment of the apparatus. The used amphetamine dose in the conditioning phase was able to produce a marked preference towards the drug-associated compartment in the group without exercise. In the animals with exercise a significant preference by the compartment associated with saline was observed.

These results lead us to conclude that a previous practice of regular physical activity may help preventing amphetamine addiction in the conditions used in this test.

Telepractice Supported Delivery of LSVT®LOUD

This article outlines the essential features and underlying principles of Lee Silverman Voice Treatment (LSVT®LOUD) and explores the delivery of this treatment via telepractice. A detailed summary of the core features of LSVT®LOUD and the principles underpinning this treatment are presented. Current evidence to support the feasibility and validity of synchronous and asynchronous delivery of LSVT®LOUD to people with Parkinson disease (PD) is reviewed. Technology specifications, cost-benefit analyses, and patient satisfaction are discussed. The challenges involved in delivery of LSVT®LOUD via telepractice, such as inconsistent audio and video quality during videoconferencing, accurate measurement of vocal parameters, technical skill level of the clinician, and patient candidacy, are highlighted. LSVT®LOUD can be effectively and reliably delivered via telepractice. Improvements in telecommunications are required to overcome some of the technology challenges encountered in this mode of delivery. Positive benefits of online treatment in relation to savings in time and money and reduced carer burden are emerging. Patient satisfaction with telepractice in the management of the speech disorder associated with PD is high. The uptake of LSVT®LOUD into telepractice is likely to steadily increase with advances in mobile technologies and web-based applications designed to deliver this treatment.

Benefits of activity and virtual reality based balance exercise programmes for adults with traumatic brain injury: Perceptions of participants and their caregivers

OBJECTIVE

To explore multi-dimensional benefits of exercise participation perceived by adults with traumatic brain injury (TBI) and their caregivers.

METHODS

Adults (n=27, aged 18-66) with moderate or severe TBI 6 months or more earlier participated in focus groups following 6 weeks of an activity-based (ABE) or a virtual reality (VR) delivered balance exercise programme. Family members and care providers participated in separate focus groups. Perceptions related to programme participation as well as balance confidence and lower extremity function were extracted from focus group verbatim and quantitative scales, respectively.

OUTCOMES

Benefits in three domains, psychosocial, physical and programme, were identified from transcription and analyses of focus group verbatim. Improvements were noted in balance confidence and function in both groups. Substantially greater enthusiasm and knowledge was expressed by participants in the VR group and their caregivers.

CONCLUSIONS

Both exercise programmes offered benefits in addition to improved balance. The VR participants had greater improvements on quantitative measures and provided more comments expressing enjoyment and improved confidence. Applications in terms of community reintegration and quality of life are discussed.

Influence of chronic exercise on the amphetamine-induced dopamine release and neurodegeneration in the striatum of the rat

The aim of this study was to verify the effect of chronic exercise on the striatal dopamine (DA) outflow induced by low and high single doses of amphetamine (AMPH), and verify the existence of an exercise protective role on neurodegeneration. Adult male Sprague-Dawley rats were randomly separated into six groups: chronic exercise, saline; chronic exercise, 5 mg kg(-1) AMPH; chronic exercise, 30 mg kg(-1) AMPH; without exercise, saline; without exercise, 5 mg kg(-1) AMPH; without exercise, 30 mg kg(-1) AMPH. Chronic exercise consisted of an 8-week running program on a treadmill, with increasing intensity. Animals were anesthetized, placed into a stereotaxic frame and an intracerebral guide cannula implanted into the caudate-putamen. When indicated, microdialysis was performed. Dialysate samples were collected during 30-min intervals for 6 h, before and after the intraperitonial administration of AMPH or saline solution. HPLC with electrochemical detection was used to quantify DA. Chronic exercise did not significantly change the extracellular DA basal values. Regarding the maximal DA levels in the dialysates, in the rats treated with 5 mg kg(-1) AMPH, there was no significant difference between groups with and without chronic exercise; on the contrary, in animals treated with 30 mg kg(-1) AMPH, the DA release was lower in the group with chronic exercise. Moreover, the maintenance of higher levels of DA along time in the training group suggests a diminished reuptake of DA. By using the Fluoro-Jade C staining technique, we did not find neuronal death in any of the groups. In conclusion, these results suggest that chronic exercise leads to a diminished release and reuptake of DA after administration of a high dose of AMPH, whereas neither chronic exercise nor AMPH seems to induce neurodegeneration.

Behavioral models of Parkinson's disease in rodents: a new look at an old problem

The circuitry important for voluntary movement is influenced by dopamine from the substantia nigra and regulated by the nigrostriatal system. The basal ganglia influence the pyramidal tract and other motor systems, such as the mesopontine nuclei and the rubrospinal tract. Although the neuroanatomical substrates underlying motor control are similar for humans and rodents, the behavioral repertoire mediated by those circuits is not. The principal aim of this review is to evaluate how injury to dopamine-mediated pathways in rodents gives rise to motor dysfunction that mimics human Parkinsonism. We will examine the behavioral tests in common use with rodent models of Parkinson's disease and critically evaluate the appropriateness of each test for detecting motor impairment. We will show how tests of motor performance must be guided by a thorough understanding of the clinical symptoms accompanying the disease, the circuitry mediating dopamine deficits in rodents, and familiarity with the rodent behavioral repertoire. We will explain how investigations in rodents of skilled forepaw actions, including placing, grooming, or foot faults, have clear correlates in Parkinson's disease, and are, therefore, the most sensitive ways of detecting motor impairment following dopamine loss from the basal ganglia of rodents.

The Lee Silverman Voice Treatment® for voice, speech and other orofacial disorders in patients with Parkinson’s disease

Parkinson’s disease (PD) impairs voice, speech, swallowing and facial expressions, thus affecting communication, food intake, work, socialization and overall health and quality of life. This article reviews current research on the characteristics and features of these disorders in individuals with PD, and the types of treatment techniques available (medical, surgical or behavioral), with emphasis on the Lee Silverman Voice Treatment (LSVT®) as the treatment of choice to improve voice, speech and other orofacial functions. LSVT addresses major deficits underlying voice and speech in PD, namely, impaired scaling of movement amplitude and poor perception and self-regulation of vocal output. Based upon this, LSVT emphasizes increased amplitude of vocal output through intensive training in increased vocal loudness (with good voice quality), recalibration of vocal loudness perception and self-regulation of vocal effort. The potential contribution of LSVT and analogous behavioral treatment approaches to neural plasticity is also addressed, as are directions for future research.

Reduced Functional Recovery by Delaying Motor Training After Spinal Cord Injury

The purpose of this study was to examine if a delay in rehabilitative motor training after spinal cord injury affects functional motor recovery. We studied a skilled motor task in which rats traversed a raised horizontal ladder and we quantified errors in accurate stepping, i.e., foot slips between rungs. After lesions to the dorsal quadrant of the thoracic (T8) spinal cord that aimed to unilaterally sever the corticospinal and rubrospinal tracts, rats were re-trained to walk across the ladder, either immediately after injury or after a 3-mo delay. Before training, the error rate in accurate stepping of the affected hindlimb was similar in the immediately (69.4 ± 5.3%) and delay (62.7 ± 4.1%; means ± SE)-trained animals (not significantly different), suggesting that accurate stepping did not improve spontaneously if rats were not exposed to the ladder. After a 3-wk course of training (30 runs across the ladder per day, 5 day/wk), improvements in accurate stepping performance were greater if training was implemented immediately after injury. On average, immediately trained animals improved stepping performance by 61.5 ± 28.2%, whereas the delay trained group improved by only 34.9 ± 28.8% (significantly different). The degree of damage to the corticospinal and rubrospinal tracts was very similar in the two groups of animals, indicating that differences in lesion size did not contribute to the differences in performance improvement. Animals with large lesions to the corticospinal and rubrospinal tracts (>70%) displayed poor recovery from training (especially for delay-trained animals), suggesting that these two pathways were important in mediating improvements in accurate stepping. In addition, recovery of stepping-like reflexes appeared not to contribute to the recovery of accurate stepping given that the time course of reflex recovery was not related to the time course of recovery of accurate stepping. We conclude that training of a skilled motor task that relies on descending control is more beneficial when initiated immediately after a partial spinal cord injury.

Exercise-induced behavioral recovery and neuroplasticity in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-lesioned mouse basal ganglia

Physical activity has been shown to be neuroprotective in lesions affecting the basal ganglia. Using a treadmill exercise paradigm, we investigated the effect of exercise on neurorestoration. The 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned mouse model provides a means to investigate the effect of exercise on neurorestoration because 30-40% of nigrostriatal dopaminergic neurons survive MPTP lesioning and may provide a template for neurorestoration to occur. MPTP-lesioned C57 BL/6J mice were administered MPTP (four injections of 20 mg/kg free-base, 2 hr apart) or saline and divided into the following groups: (1). saline; (2). saline + exercise; (3). MPTP; and (4) MPTP + exercise. Mice in exercise groups were run on a motorized treadmill for 30 days starting 4 days after MPTP lesioning (a period after which MPTP-induced cell death is complete). Initially, MPTP-lesioned + exercise mice ran at slower speeds for a shorter amount of time compared to saline + exercise mice. Both velocity and endurance improved in the MPTP + exercise group to near normal levels over the 30-day exercise period. The expression of proteins and genes involved in basal ganglia function including the dopamine transporter (DAT), tyrosine hydroxylase (TH), and the dopamine D1 and D2 receptors, as well as alterations on glutamate immunolabeling were determined. Exercise resulted in a significant downregulation of striatal DAT in the MPTP + exercise compared to MPTP nonexercised mice and to a lesser extent in the saline + exercised mice compared to their no-exercise counterparts. There was no significant difference in TH protein levels between MPTP and MPTP + exercise groups at the end of the study. The expression of striatal dopamine D1 and D2 receptor mRNA transcript was suppressed in the saline + exercise group; however, dopamine D2 transcript expression was increased in the MPTP + exercise mice. Immunoelectron microscopy indicated that treadmill exercise reversed the lesioned-induced increase in nerve terminal glutamate immunolabeling seen after MPTP administration. Our data demonstrates that exercise promotes behavioral recovery in the injured brain by modulating genes and proteins important to basal ganglia function.