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Dillenia indica (Linn.) has been reported by several biological activities, including anti-inflammatory, antioxidant, antidiabetic, anti-hyperglycemic, antiproliferative, antimutagenic, anticholinesterase, and antimicrobial. In Brazilian traditional medicine, the fruits of D. indica have been used to treat general topical pain and inflammation, but with no scientific validation. Thus, aiming to study its chemical constitution and antinociceptive properties, the crude extract (CE) and fractions obtained from the fruits of D. indica were submitted to an in vivo pharmacological evaluation and a dereplication study by LC-MS/MS analysis, assisted by the Global Natural Product Social Molecular Networking (GNPS). The oral antinociceptive activity of the fruits of D. indica and the possible participation of the opioid and cannabinoid systems were demonstrated in the formalin-induced nociception model. The chemical dereplication study led us to identify several known chemical constituents, including flavonoids, such as caffeoylmalic acid, naringenin, quercetin, and kaempferol. According to literature data, our results are compatible with significant antinociceptive and anti-inflammatory activities. Therefore, the flavonoid constituents of the fruits of D. indica are probably responsible for its antioxidant, anti-inflammatory, and antinociceptive effects mediated by both opioid and cannabinoid systems, confirming its folk use in the treatment and relief of pain.

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It has already been shown that serotonin can release endocannabinoids at the spinal cord level, culminating in inhibition of the dorsal horn. At the peripheral level, cannabinoid receptors modulate primary afferent neurons by inhibiting calcium conductance and increasing potassium conductance. Studies have shown that after the activation of opioid receptors and cannabinoids, there is also the activation of the NO/cGMP/KATP pathway, inducing cellular hyperpolarization. In this study, we evaluated the participation of the cannabinoid system with subsequent activation of the NO/cGMP/KATP pathway in the peripheral antinociceptive effect of serotonin. The paw pressure test of mice was used in animals that had their sensitivity to pain increased due to an intraplantar injection of PGE2 (2 µg). Serotonin (250 ng/paw), administered locally in the right hind paw, induced antinociceptive effect. CB1 and CB2 cannabinoid receptors antagonists, AM251 (20, 40 and 80 µg) and AM630 (25, 50 and 100 µg), respectively, reversed the serotonin-induced antinociceptive effect. MAFP (0.5 µg), an inhibitor of the FAAH enzyme that degrades anandamide, and JZL184 (3.75 µg), an inhibitor of the enzyme MAGL that degrades 2-AG, as well as the VDM11 (2.5 µg) inhibitor of anandamide reuptake, potentiated the antinociceptive effect induced by a low dose (62. 5 ng) of serotonin. In the evaluation of the participation of the NO/cGMP/KATP pathway, the antinociceptive effect of serotonin was reversed by the administration of the non-selective inhibitor of NOS isoforms L-NOarg (12.5, 25 and 50 µg) and by the selective inhibitor for the neuronal isoform LNPA (24 µg), as well as by the soluble guanylate cyclase inhibitor ODQ (25, 50 and 100 µg). Among potassium channel blockers, only Glibenclamide (20, 40 and 80 µg), an ATP-sensitive potassium channel blocker, reversed the effect of serotonin. In addition, intraplantar administration of serotonin (250 ng) was shown to induce a significant increase in nitrite levels in the homogenate of the plantar surface of the paw of mice. Taken together, these data suggest that the antinociceptive effect of serotonin occurs by activation of the cannabinoid system with subsequent activation of the NO/cGMP/KATP pathway.

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The components of the endogenous cannabinoid system are widely expressed in the gastrointestinal tract contributing to local homeostasis. In general, cannabinoids exert inhibitory actions in the gastrointestinal tract, inducing anti-inflammatory, antiemetic, antisecretory, and antiproliferative effects. Therefore, cannabinoids are interesting pharmacological compounds for the treatment of several acute intestinal disorders, such as dysmotility, emesis, and abdominal pain. Likewise, the role of cannabinoids in the treatment of chronic intestinal diseases, such as irritable bowel syndrome and inflammatory bowel disease, is also under investigation. Patients with chronic intestinal inflammatory diseases present impaired quality of life, and mental health issues are commonly associated with long-term chronic diseases. The complex pathophysiology of these diseases contributes to difficulties in diagnosis and, therefore, in the choice of a satisfactory treatment. Thus, this article reviews the involvement of the cannabinoid system in chronic inflammatory diseases that affect the gastrointestinal tract and highlights possible therapeutic approaches related to the use of cannabinoids.

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RESUMEN El sistema cannabinoide endógeno es un nuevo sistema de comunicación intercelular que constituye una pieza crucial en la regulación de la función intestinal. Se realizó una revisión bibliográfica con el objetivo de describir cómo el sistema cannabinoide endógeno modula la función intestinal. Se consultaron un total de 31 referencias bibliográficas entre libros, revistas, tesis doctorales y artículos en internet. Se encontró que los endocannabinoides son inmunomoduladores a nivel intestinal, que el sistema cannabinoide endógeno regula la composición de la microbiota intestinal y esta a su vez determina la concentración de los endocannabinoides, además tanto la secreción como la motilidad intestinal disminuyen por estimulación del sistema cannabinoide endógeno. Los receptores de cannabinoides, los endocannabinoides anandamida y 2-araquidonoilglirerol y las proteínas responsables de su síntesis y degradación están ampliamente distribuidos en el intestino en condiciones fisiológicas, aumentando su expresión en la enfermedad inflamatoria intestinal lo que le permite regular la función intestinal en ambas condiciones. El sistema cannabinoide endógeno tiene un enorme potencial terapéutico en la enfermedad inflamatoria intestinal debido a los efectos inmunosupresores, antiinflamatorios y analgésicos que posee.

ABSTRACT The endogenous cannabinoid system is a new intercellular communication system that constitutes a crucial piece in the regulation of intestinal function. A bibliographic review was carried out in order to describe how the endogenous cannabinoid system modulates intestinal function. A total of 31 bibliographic references were consulted between books, magazines, doctoral theses and articles on the internet. It was found that endocannabinoids are immunomodulatory at the intestinal level, that the endogenous cannabinoid system regulates the composition of the intestinal microbiota and this in turn determines the concentration of endocannabinoids, in addition both secretion and intestinal motility decrease by stimulation of the endogenous cannabinoid system. The cannabinoid receptors, the endocannabinoids anandamide and 2-arachidonoylglirerol, and the proteins responsible for their synthesis and degradation are widely distributed in the intestine under physiological conditions, increasing their expression in inflammatory bowel disease, which allows it to regulate intestinal function in both conditions. The endogenous cannabinoid system has enormous therapeutic potential in inflammatory bowel disease due to its immunosuppressive, anti-inflammatory and analgesic effects.

RESUMO O sistema canabinoide endógeno é umnovo sistema de comunicação intercelular que constitui uma peça crucial na regulação da função intestinal. Foi realizada uma revisão bibliográfica para descrever como o sistema canabinoide endógeno modula a função intestinal. Foram consultadas 31referências bibliográficas entre livros, revistas, teses de doutorado e artigosna internet. Verificou-se que os endocanabinoides são imunomoduladores em nível intestinal, que o sistema canabinoide endógeno regula a composição da microbiota intestinal e esta, por sua vez, determina a concentração de endocanabinoides, além da diminuição da secreção e da motilidade intestinal pela estimulação do sistema canabinoide endógeno. Os receptores canabinoides, os endocanabinoides anandamida e 2-araquidonoilglirerol e as proteínas responsáveis ​​por sua síntese e degradação estão amplamente distribuídos no intestino em condições fisiológicas, aumentando sua expressão em doenças inflamatórias intestinais que permitem regular a função intestinal em ambas as condições. O sistema canabinoide endógeno apresenta enorme potencial terapêutico na doença inflamatória intestinal devido aos seus efeitos imunossupressores, antiinflamatórios e analgésicos.

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Kahweol is a compound derived from coffee with reported antinociceptive effects. Based on the few reports that exist in the literature regarding the mechanisms involved in kahweol-induced peripheral antinociceptive action, this study proposed to investigate the contribution of the endocannabinoid system to the peripheral antinociception induced in rats by kahweol. Hyperalgesia was induced by intraplantar injection of prostaglandin E2(PGE2) and was measured with the paw pressure test. Kahweol and the drugs to test the cannabinoid system were administered locally into the right hind paw. The endocannabinoids were purified by open-bed chromatography on silica and measured by LC-MS. Kahweol (80 µg/paw) induced peripheral antinociception against PGE2-induced hyperalgesia. This effect was reversed by the intraplantar injection of the CB1 cannabinoid receptor antagonist AM251 (20, 40, and 80 μg/paw), but not by the CB2 cannabinoid receptor antagonist AM630 (100 μg/paw). Treatment with the endocannabinoid reuptake inhibitor VDM11 (2.5 μg/paw) intensified the peripheral antinociceptive effect induced by low-dose kahweol (40 μg/paw). The monoacylglycerol lipase (MAGL) inhibitor, JZL184 (4 μg/paw), and the dual MAGL/fatty acid amide hydrolase (FAAH) inhibitor, MAFP (0.5 μg/paw), potentiated the peripheral antinociceptive effect of low-dose kahweol. Furthermore, kahweol increased the levels of the endocannabinoid anandamide, but not of the other endocannabinoid 2-arachidonoylglycerol nor of anandamide-related N-acylethanolamines, in the plantar surface of the rat paw. Our results suggested that kahweol induced peripheral antinociception via anandamide release and activation of CB1 cannabinoid receptors and this compound could be used to develop new drugs for pain relief.

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The understanding that hyper-excitability and hyper-synchronism in epilepsy are indissociably bound by a cause-consequence relation has only recently been challenged. Thus, therapeutic strategies for seizure suppression have often aimed at inhibiting excitatory circuits and/or activating inhibitory ones. However, new approaches that aim to desynchronize networks or compromise abnormal coupling between adjacent neural circuitry have been proven effective, even at the cost of enhancing local neuronal activation. Although most of these novel perspectives targeting circuitry desynchronization and network coupling have been implemented by non-pharmacological devices, we argue that there may be endogenous neurochemical systems that act primarily in the desynchronization component of network behavior rather than dampening excitability of individual neurons. This review explores the endocannabinoid system as one such possible pharmacological landmark for mimicking a form of "on-demand" desynchronization analogous to those proposed by deep brain stimulation in the treatment of epilepsy. This essay discusses the evidence supporting the role of the endocannabinoid system in modulating the synchronization and/or coupling of distinct local neural circuitry; which presents obvious implications on the physiological setting of proper sensory-motor integration. Accordingly, the process of ictogenesis involves pathological circuit coupling that could be avoided, or at least have its spread throughout the containment of other areas, if such endogenous mechanisms of control could be activated or potentiated by pharmacological intervention. In addition, we will discuss evidence that supports not only a weaker role played on neuronal excitability but the potential of the endocannabinoid system strengthening its modulatory effect, only when circuitry coupling surpasses a level of activation.

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Animal venoms are an almost inexhaustible source for promising molecules with biological activity and the venom of Phoneutria nigriventer spider is a good example of this. Among several other toxins obtained from this venom, PnTx4(6-1), also called δ-Ctenitoxin-Pn1a, was isolated and initially described as an insect toxin that binds to the site 3 of sodium channels in cockroach nerve cord synaptosomes (Periplaneta americana) and slows down sodium current inactivation in isolated axons of this animal. This toxin did not cause any apparent toxicity to mice when intracerebroventricularly injected (30 µg). Subsequently, it was demonstrated that PnTx4(6-1) has an antinociceptive effect in three different pain models: inflammatory, induced by carrageenan; nociceptive, induced by prostaglandin E2 and neuropathic, induced by sciatic nerve constriction. Using diverse antagonists from receptors, it was shown that the cannabinoid system, via the CB1 receptor, and the opioid system, through the µ and δ receptors, are both involved in the antinociceptive effect of PnTx4(6-1). In the present work, it was synthesized a peptide, named PnAn13, based on the amino acid sequence of PnTx4(6-1) in order to try to reproduce or increase the analgesic effect of the toxin. As it was seen for the toxin, PnAn13 had antinociceptive activity, when intrathecally injected, and this effect involved the cannabinoid and opioid systems. In addition, when it was evaluated the peripheral effect of PnAn13, via intraplantar administration, this peptide was able to reverse the hyperalgesic threshold, evoked by prostaglandin E2. Therefore, using different pharmacological tools, it was shown the participation of cannabinoid and opioid systems in this effect.

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Cannabinoid receptor type 1 (CB1R) modulates synaptic activity and is widely distributed in brain areas such as the hippocampus, cerebellum, cerebral cortex, and striatum, among others. CB1R is involved in processes such as memory, learning, motor coordination, and mood. Genetic deletion of CB1R causes behavioral alterations. In this work, we evaluated neuronal morphology and synaptic structure in the hippocampus of adult male CB1R knockout mice (CB1R-/- ). Morphological changes in the CB1R-/- hippocampus evidenced a decrease in the expression of cytoskeletal proteins neurofilaments 160 KDa, neurofilaments 200 KDa, and microtubule-associated protein 2. CA1 neurons showed decreased arborization and changes in synaptic structure such as lower thickness of postsynaptic density and a reduction in synaptophysin levels. Results obtained in the present work provide evidence of the participation of CB1R in the establishment of neuronal structure and networks that could have an important role in neuronal plasticity. In addition, these changes observed in CB1R-/- could be correlated with behavioral alterations reported.

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Lavandula angustifolia (LaEO) essential oil has been widely used by aromatherapy in the treatment of various clinical conditions, with evidence of its analgesic and anti-inflammatory potential. Our results demonstrate that sixty-five substances were identified in LaEO. Among the compounds found, the major ones were linalool (30.61%) and linalyl acetate (20.36%). We found that LaEO inhalation reduces mechanical hyperalgesia in conditions of chronic inflammatory and neuropathic pain. Furthermore, this effect seems to be mediated by peripheral and central opioid and cannabinoid 2 receptors. The findings of the present study suggests that the LaEO inhalation is effective on the chronic pain treatment.

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Parkinson's disease (PD) and L-DOPA-induced dyskinesia (LID) are motor disorders with significant impact on the patient's quality of life. Unfortunately, pharmacological treatments that improve these disorders without causing severe side effects are not yet available. Delay in initiating L-DOPA is no longer recommended as LID development is a function of disease duration rather than cumulative L-DOPA exposure. Manipulation of the endocannabinoid system could be a promising therapy to control PD and LID symptoms. In this way, phytocannabinoids and synthetic cannabinoids, such as cannabidiol (CBD), the principal non-psychotomimetic constituent of the Cannabis sativa plant, have received considerable attention in the last decade. In this review, we present clinical and preclinical evidence suggesting CBD and other cannabinoids have therapeutic effects in PD and LID. Here, we discuss CBD pharmacology, as well as its neuroprotective effects and those of other cannabinoids. Finally, we discuss the modulation of several pro- or anti-inflammatory factors as possible mechanisms responsible for the therapeutic/neuroprotective potential of Cannabis-derived/cannabinoid synthetic compounds in motor disorders.

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Abstract Background The endocannabinoid system (eCBs) is one of the modulatory systems widely expressed in the brain. It consists of receptors expressed in the cytoplasmic (CB1 and CB2), the mitochondrial membrane (CB1), and the endogenous ligands known as endocannabinoids, such as anandamide, 2AG and oleamide. CB1 has been found in excitatory and inhibitory neurons in the pre- and post-synaptic membranes. It is expressed in several brain areas such as the hippocampus, dorsal, and ventral striatum, amygdala and prefrontal cortex. The eCBs has been involved in the regulation of learning and memory, mood, energy balance, sleep, and drug addiction. Objective Integrate existing information about the eCBs and its role in brain function and mental health. Method Review of the information of basic and clinical relevance obtained from indexed scientific journals (PubMed/Medline, Scopus). Results Basic and clinical research on eCBs related to central nervous system function is described. Discussion and conclusion At present, the study of eCBs is of importance. The development of drugs that affect this system may be clinically useful to control different debilitating diseases. This is an area of interest to the scientific community and health care providers.

Resumen Antecedentes El sistema de endocannabinoides (eCBs) es uno de los sistemas moduladores más ampliamente expresados en el cerebro. Se compone de receptores expresados en la membrana citoplasmática (CB1 y CB2) y en la membrana mitocondrial (CB1) y ligandos endógenos conocidos como endocannabinoides, como anandamida, 2AG y oleamida. El CB1 se ha encontrado en neuronas excitadoras e inhibidoras, en las membranas pre- y pos-sináptica, en varias áreas cerebrales como el hipocampo, el estriado dorsal y ventral, y en la amígdala y la corteza prefrontal. El eCBs se ha relacionado con la regulación del aprendizaje y la memoria, del estado afectivo, del equilibrio energético, del sueño y del proceso de la adicción a las drogas. Objetivo Integrar la información existente sobre el eCBs y su función sobre los procesos cerebrales y la salud mental. Método Revisión de la información de relevancia básica y clínica obtenida de revistas científicas indexadas (PubMed/Medline, Scopus). Resultados Se describe de manera concisa información de interés básico y clínico de la investigación sobre el eCBs relacionada con la función del sistema nervioso central. Discusión y conclusión En la actualidad, el estudio del eCBs es indispensable debido a su potencial terapéutico. El desarrollo de fármacos que afecten este sistema puede ser clínicamente útil para controlar diferentes enfermedades debilitantes. Ésta es un área de interés para la comunidad científica y los proveedores de salud.

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3-Methylglutaric acid (3MGA) is an organic acid that accumulates in various organic acidemias whose patients present neurodegeneration events in children coursing with metabolic acidurias. Limited evidence describes the toxic mechanisms elicited by 3MGA in the brain. Herein, we explored the effects of 3MGA on different toxic endpoints in synaptosomal and mitochondrial-enriched fractions of adult rat brains to provide novel information on early mechanisms evoked by this metabolite. At 1 and 5 mM concentration, 3MGA increased lipid peroxidation, but decreased mitochondrial function only at 5 mM concentration. Despite less intense effects were obtained at 1 mM concentration, its co-administration with the kynurenine pathway (KP) metabolite and N-methyl-D-aspartate receptor (NMDAr) agonist, quinolinic acid (QUIN, 50 and 100 µM), produced toxic synergism on markers of oxidative stress and mitochondrial function. The toxicity of 3MGA per se (5 mM) was prevented by the cannabinoid receptor agonist WIN55,212-2 and the NMDAr antagonist kynurenic acid (KYNA), suggesting cannabinoid and glutamatergic components in the 3MGA pattern of toxicity. The synergic model (3MGA + QUIN) was also sensitive to KYNA and the antioxidant S-allylcysteine, but not to the nitric oxide synthase inhibitor L-nitroarginine methyl ester. These findings suggest various underlying mechanisms involved in the neurotoxicity of 3MGA that may possibly contribute to the neurodegeneration observed in acidemias.

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Nonsteroidal anti-inflammatory drugs (NSAIDs) have been used extensively to control inflammatory pain. Several peripheral antinociceptive mechanisms have been described, such as opioid system and NO/cGMP/KATP pathway activation. There is evidence that the cannabinoid system can also contribute to the in vivo pharmacological effects of ibuprofen and indomethacin. However, there is no evidence of the involvement of the endocannabinoid system in the peripheral antinociception induced by NSAIDs. Thus, the aim of this study was to investigate the participation of the endocannabinoid system in the peripheral antinociceptive effect of NSAIDs. All experiments were performed on male Wistar rats (160-200 g; N = 4 per group). Hyperalgesia was induced by a subcutaneous intraplantar (ipl) injection of prostaglandin E2 (PGE2, 2 μg/paw) in the rat’s hindpaw and measured by the paw pressure test 3 h after injection. The weight in grams required to elicit a nociceptive response, paw flexion, was determined as the nociceptive threshold. The hyperalgesia was calculated as the difference between the measurements made before and after PGE2, which induced hyperalgesia (mean = 83.3 ± 4.505 g). AM-251 (80 μg/paw) and AM-630 (100 μg/paw) were used as CB1 and CB2 cannabinoid receptor antagonists, respectively. Ipl injection of 40 μg dipyrone (mean = 5.825 ± 2.842 g), 20 μg diclofenac (mean = 4.825 ± 3.850 g) and 40 μg indomethacin (mean = 6.650 ± 3.611 g) elicited a local peripheral antinociceptive effect. This effect was not antagonized by ipl CB1 cannabinoid antagonist to dipyrone (mean = 5.00 ± 0.9815 g), diclofenac (mean = 2.50 ± 0.8337 g) and indomethacin (mean = 6.650 ± 4.069 g) or CB2 cannabinoid antagonist to dipyrone (mean = 1.050 ± 6.436 g), diclofenac (mean = 6.675 ± 1.368 g) and indomethacin (mean = 2.85 ± 5.01 g). Thus, cannabinoid receptors do not seem to be involved in the peripheral antinociceptive mechanism of the NSAIDs dipyrone, diclofenac and indomethacin.

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