CB1 receptor selective activation inhibits beta-amyloid-induced iNOS protein expression in C6 cells and subsequently blunts tau protein hyperphosphorylation in co-cultured neurons

Cannabidiol: a promising drug for neurodegenerative disorders?

Neurodegenerative diseases represent, nowadays, one of the main causes of death in the industrialized country. They are characterized by a loss of neurons in particular regions of the nervous system. It is believed that this nerve cell loss underlies the subsequent decline in cognitive and motor function that patients experience in these diseases. A range of mutant genes and environmental toxins have been implicated in the cause of neurodegenerative disorders but the mechanism remains largely unknown. At present, inflammation, a common denominator among the diverse list of neurodegenerative diseases, has been implicated as a critical mechanism that is responsible for the progressive nature of neurodegeneration. Since, at present, there are few therapies for the wide range of neurodegenerative diseases, scientists are still in search of new therapeutic approaches to the problem. An early contribution of neuroprotective and antiinflammatory strategies for these disorders seems particularly desirable because isolated treatments cannot be effective. In this contest, marijuana derivatives have attracted special interest, although these compounds have always raised several practical and ethical problems for their potential abuse. Nevertheless, among Cannabis compounds, cannabidiol (CBD), which lacks any unwanted psychotropic effect, may represent a very promising agent with the highest prospect for therapeutic use.

Amyloid precursor protein 96-110 and beta-amyloid 1-42 elicit developmental anomalies in sea urchin embryos and larvae that are alleviated by neurotransmitter analogs for acetylcholine, serotonin and cannabinoids

Amyloid precursor protein (APP) is overexpressed in the developing brain and portions of its extracellular domain, especially amino acid residues 96-110, play an important role in neurite outgrowth and neural cell differentiation. In the current study, we evaluated the developmental abnormalities caused by administration of exogenous APP(96-110) in sea urchin embryos and larvae, which, like the developing mammalian brain, utilize acetylcholine and other neurotransmitters as morphogens; effects were compared to those of beta-amyloid 1-42 (Abeta42), the neurotoxic APP fragment contained within neurodegenerative plaques in Alzheimer's Disease. Although both peptides elicited dysmorphogenesis, Abeta42 was far more potent; in addition, whereas Abeta42 produced abnormalities at developmental stages ranging from early cleavage divisions to the late pluteus, APP(96-110) effects were restricted to the intermediate, mid-blastula stage. For both agents, anomalies were prevented or reduced by addition of lipid-permeable analogs of acetylcholine, serotonin or cannabinoids; physostigmine, a carbamate-derived cholinesterase inhibitor, was also effective. In contrast, agents that act on NMDA receptors (memantine) or alpha-adrenergic receptors (nicergoline), and that are therapeutic in Alzheimer's Disease, were themselves embryotoxic, as was tacrine, a cholinesterase inhibitor from a different chemical class than physostigmine. Protection was also provided by agents acting downstream from receptor-mediated events: increasing cyclic AMP with caffeine or isobutylmethylxanthine, or administering the antioxidant, a-tocopherol, were all partially effective. Our findings reinforce a role for APP in development and point to specific interactions with neurotransmitter systems that act as morphogens in developing sea urchins as well as in the mammalian brain.

Selective CB2 up-regulation in women affected by endometrial inflammation

Endometritis is defined as an inflammation of the endometrial mucosa of the uterus. In endometritis large amounts of toxic mediators, including nitric oxide (NO) are released by inflammatory cells. As a consequence of nitric oxide-dependent injury, the cells respond by triggering protective mechanisms, by changing the endocannabinoid system (ECS) which comprises both CB(1) and CB(2) cannabinoid receptors and their endogenous ligands. The aim of our study was to seek out evidence for the presence of cannabinoid receptors in inflammatory endometrial tissue as well as for their potential role in endometrial inflammation. Our results showed a selective up-regulation of both transcription and expression of CB(2) receptors in biopsies from women affected by endometrial inflammation compared to healthy women. The experiments with the nitric oxide-donor S-Nitroso-L-Glutathione (GSNO) suggest that such a selective up-regulation may be related to the nitric oxide release occurring during endometrial inflammation. In addition, we demonstrated an increase in chymase expression, a marker of mast cells, in biopsies of women affected by endometritis. Therefore our results support the hypothesis that the up-regulation of CB(2) occurs mainly on mast cells and that it might tend to sensitize these cells to the anti-inflammatory effect exerted by endogenous cannabinoids by binding their receptor and thus preventing the mast cell degranulation and the release of pro-inflammatory mediators. In conclusion, we believe that the selective CB(2) up-regulation might play a role as a novel prognostic factor in endometrial inflammation.

Expression of a noncoding RNA is elevated in Alzheimer's disease and drives rapid feed-forward regulation of beta-secretase

Recent efforts have revealed that numerous protein-coding messenger RNAs have natural antisense transcript partners, most of which seem to be noncoding RNAs. Here we identify a conserved noncoding antisense transcript for beta-secretase-1 (BACE1), a crucial enzyme in Alzheimer's disease pathophysiology. The BACE1-antisense transcript (BACE1-AS) regulates BACE1 mRNA and subsequently BACE1 protein expression in vitro and in vivo. Upon exposure to various cell stressors including amyloid-beta 1-42 (Abeta 1-42), expression of BACE1-AS becomes elevated, increasing BACE1 mRNA stability and generating additional Abeta 1-42 through a post-transcriptional feed-forward mechanism. BACE1-AS concentrations were elevated in subjects with Alzheimer's disease and in amyloid precursor protein transgenic mice. These data show that BACE1 mRNA expression is under the control of a regulatory noncoding RNA that may drive Alzheimer's disease-associated pathophysiology. In summary, we report that a long noncoding RNA is directly implicated in the increased abundance of Abeta 1-42 in Alzheimer's disease.

Adelmidrol, a palmitoylethanolamide analogue, reduces chronic inflammation in a carrageenin-granuloma model in rats

Palmitoylethanolamide (PEA) and some of its analogues have shown great efficacy in the treatment of pain and inflammation. Adelmidrol – the International Nonproprietary Name (INN) of the di-amide derivative of azelaic acid – is one of these analogues. The anti-inflammatory and analgesic effects of PEA and adelmidrol are hypothesized to be mediated, at least in part, by mast cell down-modulation. Mast cell mediators released at early stage of the inflammatory process drive the inflammatory reaction to chronicity as it happens in X-carrageenin-induced granulomatous tissue formation. In the present study, the choice of testing adelmidrol depends upon the physicochemical properties of the compound, i.e. the amphipatic feature, that make it more easily soluble than PEA. In this study, we investigated the effect of adelmidrol on granuloma formation induced by λ-carrageenin-soaked sponge implant in rats. Our results show that the local administration of the compound under study significantly decreases weight and neo-angiogenesis in granulomatous tissue. The anti-inflammatory effect was due to the modulation of mast cells degranulation, as shown by histological analysis and by the inhibition of the release of several pro-inflammatory and pro-angiogenic enzymes (e.g. iNOS, chymase and metalloproteinase MMP-9), and mediators (e.g. nitric oxide and TNF-α). The results indicate that adelmidrol, given locally, may represent a potential therapeutic tool in controlling chronic inflammation.

The endocannabinoid system and Alzheimer's disease

The importance of the role of the endocannabinoid system (ECS) in neurodegenerative diseases has grown during the past few years. Mostly because of the high density and wide distribution of cannabinoid receptors of the CB(1) type in the central nervous system (CNS), much research focused on the function(s) that these receptors might play in pathophysiological conditions. Our current understanding, however, points to much diverse roles for this system. In particular, other elements of the ECS, such as the fatty acid amide hydrolase (FAAH) or the CB(2) cannabinoid receptor are now considered as promising pharmacological targets for some diseases and new cannabinoids have been incorporated as therapeutic tools. Although still preliminary, recent reports suggest that the modulation of the ECS may constitute a novel approach for the treatment of Alzheimer's disease (AD). Data obtained in vitro, as well as in animal models for this disease and in human samples seem to corroborate the notion that the activation of the ECS, through the use of agonists or by enhancing the endogenous cannabinoid tone, may induce beneficial effects on the evolution of this disease.

Sea urchin embryonic development provides a model for evaluating therapies against beta-amyloid toxicity

Accumulation of beta-amyloid protein is an Alzheimer's disease hallmark but also may be mechanistically involved in neurodegeneration. One of its cleavage peptides, Abeta42, has been used to evaluate the mechanisms underlying amyloid-induced cytotoxicity and targeting of acetylcholine systems. We studied Sphaerechinus granularis sea urchin embryos which utilize acetylcholine and other neurotransmitters as morphogens. At a threshold concentration of 0.1 microM Abeta42, there was damage to the larval skeleton, accumulation of ectodermal cells in the blastocoele and underdevelopment of larval arms. Raising the Abeta42 concentration to 0.2-0.4 microM produced anomalies depending on the stage at which Abeta42 was introduced: at the first cleavage divisions, abnormalities appeared within 1-2 cell cycles; at the mid-blastula stage, the peak period of sensitivity to Abeta42, gastrulation was blocked; at later stages, there was progressive damage to the larval skeleton, digestive tract and larval spicules, as well as regression of larval arms. Each of these anomalies could be offset by the addition of lipid-permeable analogs of acetylcholine (arachidonoyl dimethylaminoethanol), serotonin (arachidonoyl serotonin) and cannabinoids (arachidonoyl vanillylamine), with the greatest activity exhibited by the acetylcholine analog. These results indicate that sea urchin embryos provide a model suitable to characterize the mechanisms underlying the cytotoxicity of Abeta42, as well as providing a system that enables the rapid screening of potential therapeutic interventions. The protection provided by neurotransmitter analogs, especially that for acetylcholine, points to unsuspected advantages of existing therapies that enhance cholinergic function, as well as indicating novel approaches that may prove protective in Alzheimer's disease.

Opposing control of cannabinoid receptor stimulation on amyloid-beta-induced reactive gliosis: in vitro and in vivo evidence

Beside cytotoxic mechanisms impacting on neurons, amyloid beta (A beta)-induced astroglial activation is operative in Alzheimer's disease brain, suggesting that persistent inflammatory response may have a role in the illness and that positive results may be achieved by curbing the astroglial reaction. Because the role of the endocannabinoid system could represent a promising field of research, the present study conducted in vitro and in vivo experiments to assess this system. C6 rat astroglioma cells were challenged with 1 microg/ml A beta 1-42 in the presence or absence of selective agonists and antagonists of cannabinoid (CB)1 and CB2 receptors. Furthermore, rats were inoculated into the frontal cortex with 30 ng of A beta 1-42 and were i.p. administered with 5 mg/kg of the same substances. Immunohistochemical and biochemical findings revealed that selective agonism at CB1 and antagonism at CB2 receptors was able to blunt A beta-induced reactive astrogliosis with subsequent overexpression of glial fibrillary acidic protein and S100B protein. Moreover, A beta provoked down-regulation of CB1 receptors together with a reduction of anandamide concentration, whereas CB2 receptors were up-regulated and 2-arachidonoyl glycerol concentration was increased. Finally, to our knowledge, the current study is the first showing that interactions at cannabinoid receptors result in a dual regulation of A beta-induced reactive astrogliosis. The data support the assumption that compounds able to selectively block CB2 receptors may have therapeutic potential in controlling A beta-related pathology, due to their beneficial effects devoid of psychotropic consequences.