Tag Archives: agonists

CB1 receptor activation in the rat paraventricular nucleus induces bi-directional cardiovascular effects via modification of glutamatergic and GABAergic neurotransmission.

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“We have shown previously that the cannabinoid receptor agonist CP55940 microinjected into the paraventricular nucleus of the hypothalamus (PVN) of urethane-anaesthetized rats induces depressor and pressor cardiovascular effects in the absence and presence of the CB1 antagonist AM251, respectively. The aim of our study was to examine whether the hypotension and/or hypertension induced by CP55940 given into the PVN results from its influence on glutamatergic and GABAergic neurotransmission. CP55940 was microinjected into the PVN of urethane-anaesthetized rats twice (S1 and S2, 20 min apart). Antagonists of the following receptors, NMDA (MK801), β2-adrenergic (ICI118551), thromboxane A2-TP (SQ29548), angiotensin II-AT1 (losartan) or GABAA (bicuculline), or the NO synthase inhibitor L-NAME were administered intravenously 5 min before S2 alone or together with AM251. The CP55940-induced hypotension was reversed into a pressor response by AM251, bicuculline and L-NAME, but not by the other antagonists. The CP55940-induced pressor effect examined in the presence of AM251 was completely reversed by losartan, reduced by about 50-60 % by MK801, ICI118551 and SQ29548, prevented by bilateral adrenalectomy but not modified by bicuculline and L-NAME. Parallel, but smaller, changes in heart rate accompanied the changes in blood pressure. The bi-directional CB1 receptor-mediated cardiovascular effects of cannabinoids microinjected into the PVN of anaesthetized rats depend on stimulatory glutamatergic and inhibitory GABAergic inputs to the sympathetic tone; the glutamatergic input is related to AT1, TP and β2-adrenergic receptors and catecholamine release from the adrenal medulla whereas the GABAergic input is reinforced by NO.”

http://www.ncbi.nlm.nih.gov/pubmed/27659492

Cannabinoids: Glutamatergic Transmission and Kynurenines.

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“The endocannabinoid system (ECS) comprises a complex of receptors, enzymes, and endogenous agonists that are widely distributed in the central nervous system of mammals and participates in a considerable number of neuromodulatory functions, including neurotransmission, immunological control, and cell signaling. In turn, the kynurenine pathway (KP) is the most relevant metabolic route for tryptophan degradation to form the metabolic precursor NAD(+).

Recent studies demonstrate that the control exerted by the pharmacological manipulation of the ECS on the glutamatergic system in the brain may offer key information not only on the development of psychiatric disorders like psychosis and schizophrenia-like symptoms, but it also may constitute a solid basis for the development of therapeutic strategies to combat excitotoxic events occurring in neurological disorders like Huntington’s disease (HD).

Part of the evidence pointing to the last approach is based on experimental protocols demonstrating the efficacy of cannabinoids to prevent the deleterious actions of the endogenous neurotoxin and KP metabolite quinolinic acid (QUIN).

These findings intuitively raise the question about what is the precise role of the ECS in tryptophan metabolism through KP and vice versa. In this chapter, we will review basic concepts on the physiology of both the ECS and the KP to finally describe those recent findings combining the components of these two systems and hypothesize the future course that the research in this emerging field will take in the next years.”

 http://www.ncbi.nlm.nih.gov/pubmed/27651254

Cannabinoid Agonists Show Promise for Anorexia

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“Impairments in the endocannabinoid system in the brain could play an important role in the development of anorexia nervosa, say Italian researchers, who report findings that point to novel cannabis-based therapeutic strategies for the eating disorder.

In a mouse model of anorexia, the team found not only that the density of cannabinoid receptors was significantly reduced in areas associated with appetite but also that administration of receptor agonists led to increases in body weight and a reduction in interest in exercise.”

http://www.medscape.com/viewarticle/868990

Comparing the effects of endogenous and synthetic cannabinoid receptor agonists on survival of gastric cancer cells.

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“Anti-neoplastic activity induced by cannabinoids has been extensively documented for a number of cancer cell types; however, this topic has been explored in gastric cancer cells only in a limited number of approaches.

SIGNIFICANCE:

Through a comparative approach, our results support and confirm the therapeutic potential that cannabinoid receptor agonists exert in gastric cancer cells and open possibilities to use cannabinoids as part of a new gastric cancer therapy.”

http://www.ncbi.nlm.nih.gov/pubmed/27640887

Activation of Cannabinoid Receptor Type II by AM1241 Ameliorates Myocardial Fibrosis via Nrf2-Mediated Inhibition of TGF-β1/Smad3 Pathway in Myocardial Infarction Mice.

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“Myocardial interstitial fibrosis is a major histologic landmark resulting in cardiac dysfunction after myocardial infarction (MI).

Activation of cannabinoid receptor type II (CB2 receptor) have been demonstrated to reduce fibrosis in hepatic cirrhotic rat.

In this study, we aimed to investigate the effects of a CB2 receptor selective agonist AM1241 on myocardial fibrosis post MI in mice.

CONCLUSION:

CB2 receptor agonist AM1241 alleviated myocardial interstitial fibrosis via Nrf2 -mediated down-regulation of TGF-β1/Smad3 pathway, which suggested that CB2 receptor activation might represent a promising target for retarding cardiac fibrosis after MI.”

http://www.ncbi.nlm.nih.gov/pubmed/27614871

Spontaneous involution of pediatric low-grade gliomas: high expression of cannabinoid receptor 1 (CNR1) at the time of diagnosis may indicate involvement of the endocannabinoid system.

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“Pediatric low-grade gliomas (P-LGG) consist of a mixed group of brain tumors that correspond to the majority of CNS tumors in children.

Notably, they may exhibit spontaneous involution after subtotal surgical removal (STR). In this study, we investigated molecular indicators of spontaneous involution in P-LGG.

CONCLUSIONS:

The P-LGG, which remained stable or that presented spontaneous involution after STR, showed significantly higher CNR1 expression at the time of diagnosis.

We hypothesize that high expression levels of CNR1 provide tumor susceptibility to the antitumor effects of circulating endocannabinoids like anandamide, resulting in tumor involution.

This corroborates with reports suggesting that CNR1 agonists and activators of the endocannabinoid system may represent therapeutic opportunities for children with LGG.

We also suggest that CNR1 may be a prognostic marker for P-LGG.

This is the first time spontaneous involution of P-LGG has been suggested to be induced by endocannabinoids.”

http://www.ncbi.nlm.nih.gov/pubmed/27613640

Activation of Cannabinoid Receptor 2 Ameliorates DSS-Induced Colitis through Inhibiting NLRP3 Inflammasome in Macrophages.

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“Activation of cannabinoid receptor 2 (CB2R) ameliorates inflammation, but the underlying mechanism remains unclear.

In the present study, we examined whether activation of CB2R could suppress the nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3) inflammasome.

We conclude that activation of CB2R ameliorates DSS-induced colitis through enhancing autophagy that may inhibit NLRP3 inflammasome activation in macrophages.”

http://www.ncbi.nlm.nih.gov/pubmed/27611972

Selective modulator of cannabinoid receptor type 2 reduces memory impairment and infarct size during cerebral hypoperfusion and vascular dementia.

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“Vascular dementia is the highly devastating neurodegenerative disorder after Alzheimer’s disease (AD) and mainly found in aged people but the effectual therapeutic target is still not there.

Chronic cerebral hypoperfusion (CCH) has been broadly found in vascular dementia (VaD) patients. CCH is thought to link with neurodegenerative disorders and their subsequent cognitive deteriorate on.

This study has been framed to examine the role of a selective agonist of cannabinoid receptor type 2(CB2); 1-phenylisatin in CCH induced VaD.

These results indicate that 2VO induced CCH in rats, which was attenuated with the treatment of 1-phenylisatin.

Hence, it may be suggested that modulation of cannabinoid receptor may provide benefits in CCH as cognitive impairment and VaD.

Therefore, selective agonists of CB2 receptors may be a potential research target for the alleviation of VaD.”

http://www.ncbi.nlm.nih.gov/pubmed/27586843

Cannabinoid 2 receptor is a novel anti-inflammatory target in experimental proliferative vitreoretinopathy.

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“Proliferative vitreoretinopathy (PVR) can develop after ocular trauma or inflammation and is a common complication of surgery to correct retinal detachment.

Currently, there are no pharmacological treatments for PVR.

Cannabinoids acting at cannabinoid 2 receptor (CB2R) can decrease inflammation and fibrosis.

The objective of this study was to examine the anti-inflammatory actions of CB2R as a candidate novel therapeutic target in experimental PVR.

In conclusion, our results indicate that intervention at early stage PVR with CB2R agonists reduces ocular inflammation and disease severity.

CB2R may represent a therapeutic target to prevent PVR progression and vision loss.”

http://www.ncbi.nlm.nih.gov/pubmed/27569993

Activation of type 1 cannabinoid receptor (CB1R) promotes neurogenesis in murine subventricular zone cell cultures.

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“The endocannabinoid system has been implicated in the modulation of adult neurogenesis.

Here, we describe the effect of type 1 cannabinoid receptor (CB1R) activation on self-renewal, proliferation and neuronal differentiation in mouse neonatal subventricular zone (SVZ) stem/progenitor cell cultures.

There is an emerging consensus that endocannabinoid signaling plays a major role in adult neurogenesis.

Cannabinoids act on at least two types of receptors, the type 1 and type 2 cannabinoid receptors (CB1R and CB2R), which are, respectively, predominantly distributed in the central nervous system (CNS) and immune system, although some studies have described the presence of low levels of CB2R in the brain.

Taken together, these results demonstrate that CB1R activation induces proliferation, self-renewal and neuronal differentiation from mouse neonatal SVZ cell cultures.

 Collectively, CB1R agonists render neurons less excitable and thus promote neuroprotection.”

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3660454/