The influence of cannabinoids on generic traits of neurodegeneration.

UNLABELLED: In an increasingly ageing population, the incidence of neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease and Huntington's disease are rising. While the aetiologies of these disorders are different, a number of common mechanisms that underlie their neurodegenerative components have been elucidated; namely neuroinflammation, excitotoxicity, mitochondrial dysfunction and reduced trophic support. Current therapies focus on treatment of the symptoms and attempt to delay the progression of these diseases but there is currently no cure. Modulation of the endogenous cannabinoid system is emerging as a potentially viable option in the treatment of neurodegeneration. Endocannabinoid signalling has been found to be altered in many neurodegenerative disorders. To this end, pharmacological manipulation of the endogenous cannabinoid system, as well as application of phytocannabinoids and synthetic cannabinoids have been investigated. Signalling from the CB1 and CB2 receptors are known to be involved in the regulation of Ca(2+) homeostasis, mitochondrial function, trophic support and inflammatory status, respectively, while other receptors gated by cannabinoids such as PPARγ, are gaining interest in their anti-inflammatory properties. Through multiple lines of evidence, this evolutionarily conserved neurosignalling system has shown neuroprotective capabilities and is therefore a potential target for neurodegenerative disorders. This review details the mechanisms of neurodegeneration and highlights the beneficial effects of cannabinoid treatment. LINKED ARTICLES: This article is part of a themed section on Cannabinoids 2013. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-6.

Tensile strain as a regulator of mesenchymal stem cell osteogenesis.

A role for mechanical stimulation in the control of cell fate has been proposed and mechanical conditioning of mesenchymal stem cells (MSCs) is of interest in directing MSC behavior for tissue engineering applications. This study investigates strain-induced differentiation and proliferation of MSCs, and investigates the cellular mechanisms of mechanotransduction. MSCs were seeded onto a collagen-coated silicone substrate and exposed to cyclic tensile mechanical strain of 2.5% at 0.17 Hz for 1-14 days. To examine mechanotransduction, cells were strained in the presence of the stretch-activated cation channel (SACC) blocker, gadolinium chloride (GdCl(3)); the extracellular regulated kinase (ERK) inhibitor, U0126; the p38 inhibitor, SB203580; and the phosphatidylinosito1 3-kinase (PI3-kinase) inhibitor, LY294002. Following exposure to strain, the osteogenic markers Cbfalpha1, collagen type I, osteocalcin, and BMP2 were temporally expressed. Exposure to strain in the presence of GdCl(3) (10 microM) reduced the induction of collagen I expression, thus identifying a role for SACC, at least in part, as mechanosensors in strain-induced MSC differentiation. The strain-induced synthesis of BMP2 was found to be reduced by inhibitors of the kinases, ERK, p38, and PI3 kinase. Additionally, mechanical strain reduced the rate of MSC proliferation. The identification of the mechanical control of MSC proliferation and the molecular link between mechanical stimulation and osteogenic differentiation has consequences for regenerative medicine through the development of a functional tissue engineering approach.

Mechanisms of strain-mediated mesenchymal stem cell apoptosis.

Mechanical conditioning of mesenchymal stem cells (MSCs) has been adopted widely as a biophysical signal to aid tissue engineering applications. The replication of in vivo mechanical signaling has been used in in vitro environments to regulate cell differentiation, and extracellular matrix synthesis, so that both the chemical and mechanical properties of the tissue-engineered construct are compatible with the implant site. While research in these areas contributes to tissue engineering, the effects of mechanical strain on MSC apoptosis remain poorly defined. To evaluate the effects of uniaxial cyclic tensile strain on MSC apoptosis and to investigate mechanotransduction associated with strain-mediated cell death, MSCs seeded on a 2D silicone membrane were stimulated by a range of strain magnitudes for 3 days. Mechanotransduction was investigated using the stretch-activated cation channel blocker gadolinium chloride, the L-type voltage-activated calcium channel blocker nicardipine, the c-jun NH(2)-terminal kinase (JNK) blocker D-JNK inhibitor 1, and the calpain inhibitor MDL 28170. Apoptosis was assessed through DNA fragmentation using the terminal deoxynucleotidyl transferase mediated-UTP-end nick labeling method. Results demonstrated that tensile strains of 7.5% or greater induce apoptosis in MSCs. L-type voltage-activated calcium channels coupled mechanical stress to activation of calpain and JNK, which lead to apoptosis through DNA fragmentation. The definition of the in vitro boundary conditions for tensile strain and MSCs along with a proposed mechanism for apoptosis induced by mechanical events positively contributes to the development of MSC biology, bioreactor design for tissue engineering, and development of computational methods for mechanobiology.

Dynamic compression can inhibit chondrogenesis of mesenchymal stem cells.

The objective of this study was to investigate the influence of dynamic compressive loading on chondrogenesis of mesenchymal stem cells (MSCs) in the presence of TGF-beta3. Isolated porcine MSCs were suspended in 2% agarose and subjected to intermittent dynamic compression (10% strain) for a period of 42 days in a dynamic compression bioreactor. After 42 days in culture, the free-swelling specimens exhibited more intense alcian blue staining for proteoglycans, while immunohistochemical analysis revealed increased collagen type II immunoreactivity. Glycosaminoglycan (GAG) content increased with time for both free-swelling and dynamically loaded constructs, and by day 42 it was significantly higher in both the core (2.5+/-0.21%w/w vs. 0.94+/-0.03%w/w) and annulus (1.09+/-0.09%w/w vs. 0.59+/-0.08%w/w) of free-swelling constructs compared to dynamically loaded constructs. This result suggests that further optimization is required in controlling the biomechanical and/or the biochemical environment if such stimuli are to have beneficial effects in generating functional cartilaginous tissue.

Alzheimer's disease; taking the edge off with cannabinoids?

Alzheimer's disease is an age-related neurodegenerative condition associated with cognitive decline. The pathological hallmarks of the disease are the deposition of beta-amyloid protein and hyperphosphorylation of tau, which evoke neuronal cell death and impair inter-neuronal communication. The disease is also associated with neuroinflammation, excitotoxicity and oxidative stress. In recent years the proclivity of cannabinoids to exert a neuroprotective influence has received substantial interest as a means to mitigate the symptoms of neurodegenerative conditions. In brains obtained from Alzheimer's patients alterations in components of the cannabinoid system have been reported, suggesting that the cannabinoid system either contributes to, or is altered by, the pathophysiology of the disease. Certain cannabinoids can protect neurons from the deleterious effects of beta-amyloid and are capable of reducing tau phosphorylation. The propensity of cannabinoids to reduce beta-amyloid-evoked oxidative stress and neurodegeneration, whilst stimulating neurotrophin expression neurogenesis, are interesting properties that may be beneficial in the treatment of Alzheimer's disease. Delta 9-tetrahydrocannabinol can also inhibit acetylcholinesterase activity and limit amyloidogenesis which may improve cholinergic transmission and delay disease progression. Targeting cannabinoid receptors on microglia may reduce the neuroinflammation that is a feature of Alzheimer's disease, without causing psychoactive effects. Thus, cannabinoids offer a multi-faceted approach for the treatment of Alzheimer's disease by providing neuroprotection and reducing neuroinflammation, whilst simultaneously supporting the brain's intrinsic repair mechanisms by augmenting neurotrophin expression and enhancing neurogenesis. The evidence supporting a potential role for the cannabinoid system as a therapeutic target for the treatment of Alzheimer's disease will be reviewed herewith.

A comparison of the osteogenic potential of adult rat mesenchymal stem cells cultured in 2-D and on 3-D collagen glycosaminoglycan scaffolds.

Adult mesenchymal stem cells (MSCs) have the capability to differentiate along several lineages including those of bone, cartilage, tendon and muscle, thus offering huge potential for the field of tissue engineering. The purpose of this study was to characterise the differentiation capacity of rat MSCs cultured on standard plastic coverslips in 2 dimensions and on a novel collagen glycosaminoglycan scaffold in the presence of a standard combination of osteoinductive factors. Cells were cultured for 3, 7, 14 and 21 days and several markers of osteogenesis were analysed. While the initial response of the cells in 3-D seemed to be faster than cells cultured in 2-D, as evidenced by collagen type I expression, later markers showed that osteogenic differentiation of MSCs took longer in the 3-D environment of the collagen GAG scaffold compared to standard 2-D culture conditions. Furthermore, it was shown that complete scaffold mineralisation could be evoked within a 6 week timeframe. This study further demonstrates the potential use of MSC-seeded collagen GAG scaffolds for bone tissue engineering applications.

Direct mechanical measurement of geodesic structures in rat mesenchymal stem cells.

During numerous biological processes, cell adhesion, cell migration and cell spreading are vital. These basic biological functions are regulated by the interaction of cells with their extracellular environment. To examine the morphology and mechanical changes occurring in mesenchymal stem cells cultured on a mechanically rigid substrate, atomic force microscopy and fluorescence microscopy were employed. Investigations of the cells revealed both linear and geodesic F-actin configurations. No particular cell characteristics or intra-cellular location were implicated in the appearance of the geodesic structures. However, the length of time the cells were cultured on the substrate correlated with the percentage appearance of the geodesic structures. Calculating energy dissipation from cell images acquired by dynamic mode atomic force microscopy, it was observed that the vertices of the geodesic structures had significantly higher energy dissipation compared to the linear F-actin and the glass. This supports work by Lazarides [J. Cell Biol. 68, 202-219 (1976)], who postulated that the vertices of these geodesic structures should have a greater flexibility. Our results also support predictions based on the microfilament tensegrity model. By understanding the basic principles of cell ultrastructure and cell mechanics in relation to different extracellular environments, a better understanding of physiological and pathological process will be elicited.

Tetrahydrocannabinol-induced apoptosis of cultured cortical neurones is associated with cytochrome c release and caspase-3 activation.

Delta(9)-tetrahydrocannabinol (THC), the principal psychoactive component of marijuana, is associated with impaired cognition and altered cortical function. THC transduces its central effects via activation of the G-protein linked cannabinoid receptor CB1. In this study we report that THC induces morphological degenerative changes in cultured cortical neurones, such as membrane blebbing and formation of apoptotic bodies, that are consistent with the apoptotic pathway of cell death. The THC-induced apoptosis was blocked by the CB1 receptor antagonist AM251 and pertussis toxin (PTX), suggesting that this effect of THC involves receptor-mediated activation of the G-protein subtypes G(i) or G(o). THC also promoted translocation of mitochondrial cytochrome c to the cytosol and increased the activity of the cysteine protease caspase-3, in a PTX-sensitive manner. The results from this study suggest that coupling of THC to a PTX-sensitive G-protein promotes cytochrome c release, caspase-3 activation and subsequent degeneration of cultured cortical neurones. This apoptotic pathway may underlie the compromised neuronal function that is associated with marijuana usage.

Reduced inflammation in genetically hypertensive rat airways is associated with reduced tachykinin NK(1) receptor numbers.

The airways of the genetically hypertensive rat (GH) are hyperinnervated by substance P-containing sensory nerves and exhibit reduced inflammatory responsiveness to substance P and to capsaicin. The present study measured tracheal inflammation to resiniferatoxin (1.0 microgram/kg i.v.), a capsaicin analogue, which lacks the hypotensive action of capsaicin itself, alone or after the neuronal nitric oxide synthase inhibitor 1-(2-trifluoromethylphenyl)imidazole (TRIM) (50 mg/kg i.p.). The inflammatory response to resiniferatoxin alone was 50% lower in untreated GH than in control rats, a similar strain difference to that seen previously with capsaicin. Pre-treatment with TRIM had no effect on inflammation in either strain. Binding kinetics of the tachykinin NK(1) receptor antagonist [3H](S)-1-(2-[3-(3, 4-dichlorophenyl)-1-(3-isopropoxyphenylacetyl)piperidin-3-yl]ethyl)-4- phenyl-l-azoniabicyclo[2,2,2,]octane chloride ([3H]SR140333)(0.125-16.0 nM) showed 50% reduction of B(max) in GH versus control tracheae (74+/-13 cf.165+/-26 fmol/mg protein). Our results indicate that the reduced neurogenic inflammatory responsiveness in GH rats can be attributed entirely to reduced tachykinin NK(1) receptor numbers.

Enhancement of (45)Ca(2+) influx and voltage-dependent Ca(2+) channel activity by beta-amyloid-(1-40) in rat cortical synaptosomes and cultured cortical neurons. Modulation by the proinflammatory cytokine interleukin-1beta.

Beta-amyloid protein is thought to underlie the neurodegeneration associated with Alzheimer's disease by inducing Ca(2+)-dependent apoptosis. Elevated neuronal expression of the proinflammatory cytokine interleukin-1beta is an additional feature of neurodegeneration, and in this study we demonstrate that interleukin-1beta modulates the effects of beta-amyloid on Ca(2+) homeostasis in the rat cortex. beta-Amyloid-(1-40) (1 microM) caused a significant increase in (45)Ca(2+) influx into rat cortical synaptosomes via activation of L- and N-type voltage-dependent Ca(2+) channels and also increased the amplitude of N- and P-type Ca(2+) channel currents recorded from cultured cortical neurons. In contrast, interleukin-1beta (5 ng/ml) reduced the (45)Ca(2+) influx into cortical synaptosomes and inhibited Ca(2+) channel activity in cultured cortical neurons. Furthermore, the stimulatory effects of beta-amyloid protein on Ca(2+) influx were blocked following exposure to interleukin-1beta, suggesting that interleukin-1beta may govern neuronal responses to beta-amyloid by regulating Ca(2+) homeostasis.

Surveillance for sensory impairment, activity limitation, and health-related quality of life among older adults--United States, 1993-1997.

PROBLEM/CONDITION: Increases in life expectancy in the United States are accompanied by concerns regarding the cumulative impact of chronic disease and impairments on the prevalence of disability and the health status and quality of life of the growing number of older adults (defined as persons aged > or =65 years). Although older adults are the focus of these surveillance summaries, persons aged 55-64 years have also been included, when data were available, as a comparison. One important public health goal for an aging society is to minimize the impact of chronic disease and impairments on the health status of older adults, maintain their ability to live independently, and improve their quality of life. This report examines three dimensions of health status: sensory impairments, activity limitations, and health-related quality of life among older adults. REPORTING PERIOD: This report examines data regarding activity limitations and sensory impairments for 1994 and health-related quality of life for 1993-1997. DESCRIPTION OF SYSTEM: The 1994 National Health Interview Survey (NHIS) Core, NHIS disability supplement (NHIS-D1), and the 1994 NHIS Second Supplement on Aging (SOA II) were used to estimate vision impairments, hearing loss, and activity limitation. Data from the Behavioral Risk Factor Surveillance System (BRFSS) for 1993 through 1997 were used to estimate two general measures of health-related quality of life: a) the prevalence of self-rated fair or poor general health and b) the number of days during the preceding 30 days when respondents reported their physical or mental health was "not good." RESULTS: Sensory impairments are common among older adults. Among adults aged > or =70 years, 18.1% reported vision impairments, 33.2% reported hearing impairments, and 8.6% reported both hearing and vision impairments. Although older adults who reported vision and hearing impairments reported more comorbidities than their non-hearing-impaired and nonvisually impaired peers, impaired adults with sensory loss were able to sustain valued social participation roles. Advancing age was associated with increased likelihood of difficulty in performing functional activities and instrumental and basic activities of daily living, regardless of race/ethnicity, sex, and region of residence in the United States. Unhealthy days (a continuous measure of population health-related quality of life) was consistent with self-rated health (a commonly used categorical measure) and useful in identifying subtle differences among sociodemographic groups of older adults. An important finding was that adults aged 55-64 years with low socioeconomic status (i.e., less than a high school education or an annual household income of <$15,000) reported substantially greater numbers of unhealthy days than their peers aged 65-74 years. INTERPRETATION: Sensory impairments are common in adults aged > or =70 years, and prevalence of activity limitations among older adults is high and associated with advancing age. Health-related quality of life is less closely related to age, particularly when health-related quality of life includes aspects of mental health.

Confirmed abuse cases in public residential facilities for persons with mental retardation: a multi-state study.

Data regarding cases of confirmed abuse or neglect in large state-operated facilities in 6 states were collected and analyzed. Neglect and physical abuse were the most common abuse types. Incidents occurred more frequently on the afternoon-early evening shift, particularly between 3 and 6 p.m., and more frequently in residential than in nonresidential areas. In-transit activities were found to be relatively risky. The major risk factors for victims were maladaptive behavior and previous abuse victimization. Staff perpetrators were more likely to be males, assigned to the afternoon shift, newer employees, and previous perpetrators. Abuse reporters tended to be newer employees, and the likelihood of reporting abuse was increased by recent related inservice. The findings should assist administrators in focusing abuse prevention efforts.

Regulation of intracellular Ca2+ concentration by interleukin-1beta in rat cortical synaptosomes: an age-related study.

The pro-inflammatory cytokine interleukin-1beta (IL-1beta) is released by cells during injury and stress, and increased neuronal expression of IL-1beta is a feature of age-related neurodegeneration. We have recently reported that IL-1beta has a biphasic effect on the K+-induced rise in intracellular Ca2+ concentration ([Ca2+]i) in cortical synaptosomes, exerting an inhibitory effect on the K+-induced rise in [Ca2+]i at lower (3.5 ng/mL) concentrations and a stimulatory effect on the K+-induced rise in [Ca2+]i at higher (100 ng/mL) concentrations. In the present study, we observed that the K+-induced rise in [Ca2+]i was inhibited to a similar extent by the lower concentration of IL-1beta in cortical synaptosomes prepared from young (3-month-old), middle-aged (12-month-old) and aged (24-month-old) rats. In contrast, cortical synaptosomes prepared from the aged rats exhibited an increased susceptibility to the higher concentration of IL-1beta, resulting in a marked elevation in [Ca2+]i. We propose that the age-related increase in neuronal concentration of IL-1beta promotes a dramatic elevation in [Ca2+]i following membrane depolarization, thereby altering Ca2+ homeostasis and exacerbating neuronal vulnerability to excitotoxicity.

Permanency planning by older parents who care for adult children with mental retardation.

In a study of 57 older parent caregivers of adult children with mental retardation, more than half had not planned for their child's future care. Income, race, child's gender and level of adaptive behavior, and degree of parental interaction with relatives and friends were significantly related to future care-planning activity.

Oral hygiene levels and periodontal disease prevalence among residents with mental retardation at various residential settings.

This pilot study compared oral hygiene levels and periodontal disease prevalence among residents with mental retardation in a large traditional state institution, a small regional facility, and community group homes. Plaque scores and periodontal disease levels were high in all groups. However, there was a significant difference (P less than 0.05) among the group home residents, who had lower scores, than the other groups. These results indicate that preventive dental programs are necessary in new residential settings for individuals with mental retardation.

Comparison of methods for classifying community residential settings for mentally retarded individuals.

Research on differential effects of residential environments has been hampered by the lack of a formal classification scheme for placement types. Two systematic approaches (dimensional and typological) were used to develop classification systems. Each approach was evaluated on criteria applicable to general classification schemes and residential environments for retarded persons. A third, nested system was derived that satisfied rules for development and evaluative criteria.