Stable Adult Hippocampal Neurogenesis in Cannabinoid Receptor CB2 Deficient Mice.

ijms-logo “The G-protein coupled cannabinoid receptor 2 (CB2) has been implicated in the regulation of adult neurogenesis in the hippocampus. The contribution of CB2 towards basal levels of proliferation and the number of neural progenitors in the subgranular zone (SGZ) of the dentate gyrus, however, remain unclear. We stained hippocampal brain sections of 16- to 17-week-old wildtype and CB2-deficient mice, for neural progenitor and immature neuron markers doublecortin (DCX) and calretinin (CR) and for the proliferation marker Ki67 and quantified the number of positive cells in the SGZ. The quantification revealed that CB2 deficiency neither altered overall cell proliferation nor the size of the DCX+ or DCX and CR double-positive populations in the SGZ compared to control animals. The results indicate that CB2 might not contribute to basal levels of adult neurogenesis in four-month-old healthy mice. CB2 signaling might be more relevant in conditions where adult neurogenesis is dynamically regulated, such as neuroinflammation.”

https://www.ncbi.nlm.nih.gov/pubmed/31374821

“Cannabinoids have been linked to the regulation of adult neurogenesis (AN), a process in the mammalian brain that takes place in stem cell niches in the adult brain and is responsible for the continued generation of new neurons.”

https://www.mdpi.com/1422-0067/20/15/3759/htm

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The pharmacological reduction of hippocampal neurogenesis attenuates the protective effects of cannabidiol on cocaine voluntary intake.

Addiction Biology banner“The administration of cannabidiol has shown promising evidence in the treatment of some neuropsychiatric disorders, including cocaine addiction. However, little information is available as to the mechanisms by which cannabidiol reduces drug use and compulsive seeking.

We investigated the role of adult hippocampal neurogenesis in reducing cocaine voluntary intake produced by repeated cannabidiol treatment in mice.

Cannabidiol (20 mg/kg) reduced cocaine self-administration behaviour acquisition and total cocaine intake and enhanced adult hippocampal neurogenesis.

The present study confirms that adult hippocampal neurogenesis is one of the mechanisms by which cannabidiol lowers cocaine reinforcement and demonstrates the functional implication of adult hippocampal neurogenesis in cocaine voluntary consumption in mice.

Such findings highlight the possible use of cannabidiol for developing new pharmacotherapies to manage cocaine use disorders.”

https://www.ncbi.nlm.nih.gov/pubmed/31162770

https://onlinelibrary.wiley.com/doi/abs/10.1111/adb.12778

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Oral administration of the cannabigerol derivative VCE-003.2 promotes subventricular zone neurogenesis and protects against mutant huntingtin-induced neurodegeneration.

 “The administration of certain cannabinoids provides neuroprotection in models of neurodegenerative diseases by acting through various cellular and molecular mechanisms. Many cannabinoid actions in the nervous system are mediated by CB1receptors, which can elicit psychotropic effects, but other targets devoid of psychotropic activity, including CB2 and nuclear PPARγ receptors, can also be the target of specific cannabinoids.

METHODS:

We investigated the pro-neurogenic potential of the synthetic cannabigerol derivative, VCE-003.2, in striatal neurodegeneration by using adeno-associated viral expression of mutant huntingtin in vivo and mouse embryonic stem cell differentiation in vitro.

RESULTS:

Oral administration of VCE-003.2 protected striatal medium spiny neurons from mutant huntingtin-induced damage, attenuated neuroinflammation and improved motor performance. VCE-003.2 bioavailability was characterized and the potential undesired side effects were evaluated by analyzing hepatotoxicity after chronic treatment. VCE-003.2 promoted subventricular zone progenitor mobilization, increased doublecortin-positive migrating neuroblasts towards the injured area, and enhanced effective neurogenesis. Moreover, we demonstrated the proneurogenic activity of VCE-003.2 in embryonic stem cells. VCE-003.2 was able to increase neuroblast formation and striatal-like CTIP2-mediated neurogenesis.

CONCLUSIONS:

The cannabigerol derivative VCE-003.2 improves subventricular zone-derived neurogenesis in response to mutant huntingtin-induced neurodegeneration, and is neuroprotective by oral administration.”

https://www.ncbi.nlm.nih.gov/pubmed/30899454

https://translationalneurodegeneration.biomedcentral.com/articles/10.1186/s40035-019-0148-x

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[Neonatal hypoxia-ischemia: cellular and molecular brain damage and therapeutic modulation of neurogenesis].

 

 

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“Perinatal asphyxia remains a major cause of both mortality and neurological morbidity. Neonatal encephalopathy affects to 1-3/1,000 newborns, leading to significant brain damage and childhood disability.

The only standard therapy is moderate hypothermia, whose efficacy, despite proved, is limited, being partially effective.

The use of therapeutic agents such as erythropoietin and cannabinoids and mesenchymal stem cells have shown promising results in experimental models of perinatal asphyxia, being able of modulate neurogenesis, neuronal plasticity and neuroreparation processes after hypoxic-ischemic brain injury.”

https://www.ncbi.nlm.nih.gov/pubmed/30560986

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Cannabinoids as Regulators of Neural Development and Adult Neurogenesis

“Neurogenesis plays an indispensable role in the formation of the nervous system during development. The discovery that the adult brain still maintains neurogenic niches that allow the continued production of new cells after birth has changed the field of neuroscience. It has also opened a new venue of opportunities for the treatment of central nervous system disorders related to neuronal loss. This chapter has reviewed the studies showing that genetic or pharmacological manipulation of cannabinoid receptors (CB1 and CB2) or the enzymes responsible for endocannabinoid metabolism modify/regulate cell proliferation and neurogenesis during development and in the adult brain. A better characterization of the mechanisms involved in these effects could contribute to the development of new therapeutic alternatives to neurodegenerative and psychiatric disorders.”

https://link.springer.com/chapter/10.1007/978-3-319-49343-5_6?fbclid=IwAR1yxGqvrq_9Zva3HLEqjh2WrNRTxPN6Hy_IO8l2IN8v9BCNBG2jDks9N1w

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Activation of GPR55 induces neuroprotection of hippocampal neurogenesis and immune responses of neural stem cells following chronic, systemic inflammation.

Brain, Behavior, and Immunity

“New neurons are continuously produced by neural stem cells (NSCs) within the adult hippocampus. Numerous diseases, including major depressive disorder and HIV-1 associated neurocognitive disorder, are associated with decreased rates of adult neurogenesis. A hallmark of these conditions is a chronic release of neuroinflammatory mediators by activated resident glia.

Recent studies have shown a neuroprotective role on NSCs of cannabinoid receptor activation. Yet, little is known about the effects of GPR55, a candidate cannabinoid receptor, activation on reductions of neurogenesis in response to inflammatory insult.

In the present study, we examined NSCs exposed to IL-1β in vitro to assess inflammation-caused effects on NSC differentiation and the ability of GPR55 agonists to attenuate NSC injury.

Taken together, these results suggest a neuroprotective role of GPR55 activation on NSCs in vitro and in vivo and that GPR55 provides a novel therapeutic target against negative regulation of hippocampal neurogenesis by inflammatory insult.”

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Neural stem cell lineage-specific cannabinoid type-1 receptor regulates neurogenesis and plasticity in the adult mouse hippocampus.

Cerebral Cortex

“Neural stem cells (NSCs) in the adult mouse hippocampus occur in a specific neurogenic niche, where a multitude of extracellular signaling molecules converges to regulate NSC proliferation as well as fate and functional integration. However, the underlying mechanisms how NSCs react to extrinsic signals and convert them to intracellular responses still remains elusive.

NSCs contain a functional endocannabinoid system, including the cannabinoid type-1 receptor (CB1).

To decipher whether CB1 regulates adult neurogenesis directly or indirectly in vivo, we performed NSC-specific conditional inactivation of CB1 by using triple-transgenic mice.

These results demonstrate that CB1 expressed in NSCs and their progeny controls neurogenesis in adult mice to regulate the NSC stem cell pool, dendritic morphology, activity-dependent plasticity, and behavior.”

https://www.ncbi.nlm.nih.gov/pubmed/30307491

https://academic.oup.com/cercor/advance-article/doi/10.1093/cercor/bhy258/5126794

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[Should ophtalmologists recommend medical cannabis to patients with glaucoma?]

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“Cannabis has been widely used for various medical purposes since before year 2000 BC. Its effects are mediated by cannabinoids and stimulation of mainly G-protein coupled cannabinoid receptors.

In 1971, subjects who smoked marihuana, showed a decrease in the intraocular pressure.

Later investigations additionally revealed a neuroprotective effect of both ∆-9-tetrahydrocannabinol and cannabidiol (CBD).

Furthermore, CBD was found to promote neurogenesis. The aim of this review is to provide an overview of the potential use of cannabinoids in the treatment of glaucoma.”

https://www.ncbi.nlm.nih.gov/pubmed/30020072

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Modulation of the Cannabinoid System: A New Perspective for the Treatment of the Alzheimer’s Disease.

“The pathogenesis of Alzheimer’s disease (AD) is somewhat complex and has yet to be fully understood. As the effectiveness of the therapy currently available for AD has proved to be limited, the need for new drugs has become increasingly urgent.

The modulation of the endogenous cannabinoid system (ECBS) is one of the potential therapeutic approaches that is attracting a growing amount of interest. The ECBS consists of endogenous compounds and receptors. The receptors CB1 and CB2 have already been well characterized: CB1 receptors, which are abundant in the brain, particularly in the hippocampus, basal ganglia and cerebellum, regulate memory function and cognition.

It has been suggested that the activation of CB1 receptors reduces intracellular Ca concentrations, inhibits glutamate release and enhances neurotrophin expression and neurogenesis. CB2 receptors are expressed, though to a lesser extent, in the central nervous system, particularly in microglia and in immune system cells involved in the release of cytokines. CB2 receptors have been shown to be upregulated in neuritic plaque-associated migroglia in the hippocampus and entorhinal cortex of patients, which suggests that these receptors play a role in the inflammatory pathology of AD.

The role of the ECBS in AD is supported by cellular and animal models. By contrast, few clinical studies designed to investigate therapies aimed at reducing behaviour disturbances, especially night-time agitation, eating behaviour and aggressiveness, have yielded positive results. In this review, we will describe how the manipulation of the ECBS offers a potential approach to the treatment of AD.”

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Brain endocannabinoid signaling exhibits remarkable complexity.

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“The endocannabinoid (eCB) signaling system is one of the most extensive of the mammalian brain. Despite the involvement of only few specific ligands and receptors, the system encompasses a vast diversity of triggered mechanisms and driven effects. It mediates a wide range of phenomena, including the regulation of transmitter release, neural excitability, synaptic plasticity, impulse spread, long-term neuronal potentiation, neurogenesis, cell death, lineage segregation, cell migration, inflammation, oxidative stress, nociception and the sleep cycle. It is also known to be involved in the processes of learning and memory formation. This extensive scope of action is attained by combining numerous variables. In a properly functioning brain, the correlations of these variables are kept in a strictly controlled balance; however, this balance is disrupted in many pathological conditions. However, while this balance is known to be disrupted by drugs in the case of addicts, the stimuli and mechanisms influencing the neurodegenerating brain remain elusive. This review examines the multiple factors and phenomena affecting the eCB signaling system in the brain. It evaluates techniques of controlling the eCB system to identify the obstacles in their applications and highlights the crucial interdependent variables that may influence biomedical research outcomes.”

https://www.ncbi.nlm.nih.gov/pubmed/29953913

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