The endocannabinoid 2-AG enhances spontaneous remyelination by targeting microglia.

Remyelination is an endogenous process by which functional recovery of damaged neurons is achieved by reinstating the myelin sheath around axons. Remyelination has been documented in multiple sclerosis (MS) lesions and experimental models, although it is often incomplete or fails to affect the integrity of the axon, thereby leading to progressive disability. Microglia play a crucial role in the clearance of the myelin debris produced by demyelination and in inflammation-dependent OPC activation, two processes necessary for remyelination to occur. We show here that following corpus callosum demyelination in the TMEV-IDD viral murine model of MS, there is spontaneous and partial remyelination that involves a temporal discordance between OPC mobilization and microglia activation. Pharmacological treatment with the endocannabinoid 2-AG enhances the clearance of myelin debris by microglia and OPC differentiation, resulting in complete remyelination and a thickening of the myelin sheath. These results highlight the importance of targeting microglia during the repair processes in order to enhance remyelination.

Brain-borne IL-1 adjusts glucoregulation and provides fuel support to astrocytes and neurons in an autocrine/paracrine manner.

It is still controversial which mediators regulate energy provision to activated neural cells, as insulin does in peripheral tissues. Interleukin-1ß (IL-1ß) may mediate this effect as it can affect glucoregulation, it is overexpressed in the 'healthy' brain during increased neuronal activity, and it supports high-energy demanding processes such as long-term potentiation, memory and learning. Furthermore, the absence of sustained neuroendocrine and behavioral counterregulation suggests that brain glucose-sensing neurons do not perceive IL-1ß-induced hypoglycemia. Here, we show that IL-1ß adjusts glucoregulation by inducing its own production in the brain, and that IL-1ß-induced hypoglycemia is myeloid differentiation primary response 88 protein (MyD88)-dependent and only partially counteracted by Kir6.2-mediated sensing signaling. Furthermore, we found that, opposite to insulin, IL-1ß stimulates brain metabolism. This effect is absent in MyD88-deficient mice, which have neurobehavioral alterations associated to disorders in glucose homeostasis, as during several psychiatric diseases. IL-1ß effects on brain metabolism are most likely maintained by IL-1ß auto-induction and may reflect a compensatory increase in fuel supply to neural cells. We explore this possibility by directly blocking IL-1 receptors in neural cells. The results showed that, in an activity-dependent and paracrine/autocrine manner, endogenous IL-1 produced by neurons and astrocytes facilitates glucose uptake by these cells. This effect is exacerbated following glutamatergic stimulation and can be passively transferred between cell types. We conclude that the capacity of IL-1ß to provide fuel to neural cells underlies its physiological effects on glucoregulation, synaptic plasticity, learning and memory. However, deregulation of IL-1ß production could contribute to the alterations in brain glucose metabolism that are detected in several neurologic and psychiatric diseases.

Endocannabinoids drive the acquisition of an alternative phenotype in microglia.

The ability of microglia to acquire diverse states of activation, or phenotypes, reflects different features that are determinant for their contribution to homeostasis in the adult CNS, and their activity in neuroinflammation, repair or immunomodulation. Despite the widely reported immunomodulatory effects of cannabinoids in both the peripheral immune system and the CNS, less is known about how the endocannabinoid signaling system (eCBSS) influence the microglial phenotype. The general aim of the present study was to investigate the role of endocannabinoids in microglia polarization by using microglia cell cultures. We show that alternative microglia (M2a) and acquired deactivated microglia (M2c) exhibit changes in the eCB machinery that favor the selective synthesis of 2-AG and AEA, respectively. Once released, these eCBs might be able to act through CB1 and/or CB2 receptors in order to influence the acquisition of an M2 phenotype. We present three lines of evidence that the eCBSS is critical for the acquisition of the M2 phenotype: (i) M2 polarization occurs on exposure to the two main endocannabinoids 2-AG and AEA in microglia cultures; (ii) cannabinoid receptor antagonists block M2 polarization; and (iii) M2 polarization is dampened in microglia from CB2 receptor knockout mice. Taken together, these results indicate the interest of eCBSS for the regulation of microglial activation in normal and pathological conditions.

Anti-myelin antibodies play an important role in the susceptibility to develop proteolipid protein-induced experimental autoimmune encephalomyelitis.

Multiple sclerosis (MS) is the most common demyelinating disease of the central nervous system. It is an autoimmune disorder in which activated T cells cross the blood-brain barrier (BBB) to initiate an inflammatory response that leads to demyelination and axonal damage. The key mechanisms responsible for disease initiation are still unknown. We addressed this issue in experimental autoimmune encephalomyelitis (EAE), the animal model of MS. It is widely known that EAE manifests only in certain strains when immunized with myelin proteins or peptides. We studied the differential immune responses induced in two mouse strains that are susceptible or resistant to EAE induction when they are immunized with the 139-151 peptide of proteolipid protein, an encephalitogenic peptide capable of inducing EAE in the susceptible strain. The adequate combination of major histocompatibility complex alleles and myelin peptides triggered in susceptible mice a T helper type 17 (Th17) response capable of inducing the production of high-affinity anti-myelin immunoglobulin (Ig)G antibodies. These were not detected in resistant mice, despite immunization with the encephalitogenic peptide in junction with complete Freund's adjuvant and pertussis toxin, which mediate BBB disruption. These data show the pivotal role of Th17 responses and of high-affinity anti-myelin antibodies in EAE induction and that mechanisms that prevent their appearance can contribute to resistance to EAE.

Cannabidiol provides long-lasting protection against the deleterious effects of inflammation in a viral model of multiple sclerosis: a role for A2A receptors.

Inflammation in the central nervous system (CNS) is a complex process that involves a multitude of molecules and effectors, and it requires the transmigration of blood leukocytes across the blood-brain barrier (BBB) and the activation of resident immune cells. Cannabidiol (CBD), a non-psychotropic cannabinoid constituent of Cannabis sativa, has potent anti-inflammatory and immunosuppressive properties. Yet, how this compound modifies the deleterious effects of inflammation in TMEV-induced demyelinating disease (TMEV-IDD) remains unknown. Using this viral model of multiple sclerosis (MS), we demonstrate that CBD decreases the transmigration of blood leukocytes by downregulating the expression of vascular cell adhesion molecule-1 (VCAM-1), chemokines (CCL2 and CCL5) and the proinflammatory cytokine IL-1ß, as well as by attenuating the activation of microglia. Moreover, CBD administration at the time of viral infection exerts long-lasting effects, ameliorating motor deficits in the chronic phase of the disease in conjunction with reduced microglial activation and pro-inflammatory cytokine production. Adenosine A2A receptors participate in some of the anti-inflammatory effects of CBD, as the A2A antagonist ZM241385 partially blocks the protective effects of CBD in the initial stages of inflammation. Together, our findings highlight the anti-inflammatory effects of CBD in this viral model of MS and demonstrate the significant therapeutic potential of this compound for the treatment of pathologies with an inflammatory component.

Regulation of the phosphatase calcineurin by insulin-like growth factor I unveils a key role of astrocytes in Alzheimer's pathology.

Whether insulin-like growth factor I (IGF-I) signaling in Alzheimer's disease (AD) is beneficial or detrimental remains controversial. We now show that a competitive regulation by IGF-I of the phosphatase calcineurin in reactive, but not in quiescent astrocytes drives Alzheimer's pathology. Calcineurin de-phosphorylates the transcription factor Foxo3 in response to tumor necrosis factor-α (TNFα), an inflammatory cytokine increased in AD, activating nuclear factor-κB (NFκB) inflammatory signaling in astrocytes. In turn, IGF-I inactivates and displaces Foxo3 from calcineurin in TNFα-stimulated astrocytes by recruiting the transcription factor peroxisome proliferator-activated receptor-γ, and NFκB signaling is inhibited. This antagonistic mechanism reversibly drives the course of the disease in AD mice, even at advanced stages. As hallmarks of this calcineurin/Foxo3/NFκB pathway are present in human AD brains, treatment with IGF-I may be beneficial by antagonizing it.

Ontogeny of sensorimotor gating and immune impairment induced by prenatal immune challenge in rats: implications for the etiopathology of schizophrenia.

It has been hypothesized that the maternal immune response to infection may influence fetal brain development and lead to schizophrenia. Animal experimentation has supported this notion by demonstrating altered sensorimotor gating (prepulse inhibition, PPI) in adult rats prenatally exposed to an immune challenge. In the present study, pregnant rats were exposed to the bacterial endotoxin lipopolysaccharide (LPS) throughout gestation and the offspring were examined by evaluating the PPI, dopaminergic function, brain protein expression and cytokine serum levels from weaning to late adulthood. Prenatal LPS exposure induced a deficit in PPI that emerged at 'puberty' and that persisted throughout adult life. This prenatal insult caused age-specific changes in accumbal dopamine levels and in synaptophysin expression in the frontal cortex. Moreover, serum cytokine levels were altered in an age- and cytokine-dependent manner. Here we show that prenatal LPS administration throughout pregnancy causes maturation-dependent PPI deficits and age-dependent alterations in dopamine activity, as well as in synaptophysin expression and cytokine levels.

An endocannabinoid tone limits excitotoxicity in vitro and in a model of multiple sclerosis.

The aim of this study was to evaluate how endocannabinoids interact with excitotoxic processes both in vitro, using primary neural cell cultures, and in vivo, in the TMEV-IDD model of multiple sclerosis. First, we observed that neuronal cells respond to excitotoxic challenges by the production of endocannabinoid molecules which in turn exerted neuroprotective effects against excitotoxicity. The inhibitor of endocannabinoid uptake, UCM707, protected specifically against AMPA-induced excitotoxicity, by activating CB(1) and CB(2) cannabinoid receptors, as well as the nuclear factor, PPARgamma. This neuroprotective effect was reverted by blocking the glial glutamate transporter, GLT-1. Mice subjected to the model of multiple sclerosis showed a decrease in the expression of GLT-1. UCM707 reversed this loss of GLT-1 and induced a therapeutic effect. Our data indicate that the enhancement of the endocannabinoid tone leads to neuroprotection against AMPA-induced excitotoxicity and provides therapeutic effects in this model of multiple sclerosis.

A cannabinoid agonist interferes with the progression of a chronic model of multiple sclerosis by downregulating adhesion molecules.

Adhesion molecules are critical players in the regulation of transmigration of blood leukocytes across the blood-brain barrier in multiple sclerosis (MS). Cannabinoids (CBs) are potential therapeutic agents in the treatment of MS, but the mechanisms involved are only partially known. Using a viral model of MS we observed that the cannabinoid agonist WIN55,212-2 administered at the time of virus infection suppresses intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) in brain endothelium, together with a reduction in perivascular CD4+ T lymphocytes infiltrates and microglial responses. WIN55,212-2 also interferes with later progression of the disease by reducing symptomatology and neuroinflammation. In vitro data from brain endothelial cell cultures, provide the first evidence of a role of peroxisome proliferator-activated receptors gamma (PPARgamma) in WIN55,212-2-induced downregulation of VCAM-1. This study highlights that inhibition of brain adhesion molecules by WIN55,212-2 might underline its therapeutic effects in MS models by targeting PPAR-gamma receptors.

CB2 cannabinoid receptors as an emerging target for demyelinating diseases: from neuroimmune interactions to cell replacement strategies.

Amongst the various demyelinating diseases that affect the central nervous system, those induced by an inflammatory response stand out because of their epidemiological relevance. The best known inflammatory-induced demyelinating disease is multiple sclerosis, but the immune response is a common pathogenic mechanism in many other less common pathologies (e.g., acute disseminated encephalomyelitis and acute necrotizing haemorrhagic encephalomyelitis). In all such cases, modulation of the immune response seems to be a logical therapeutic approach. Cannabinoids are well known immunomodulatory molecules that act through CB1 and CB2 receptors. While activation of CB1 receptors has a psychotropic effect, activation of CB2 receptors alone does not. Therefore, to bypass the ethical problems that could result from the treatment of inflammation with psychotropic molecules, considerable effort is being made to study the potential therapeutic value of activating CB2 receptors. In this review we examine the current knowledge and understanding of the utility of cannabinoids as therapeutic molecules for inflammatory-mediated demyelinating pathologies. Moreover, we discuss how CB2 receptor activation is related to the modulation of immunopathogenic states.

Gut microbiota, cannabinoid system and neuroimmune interactions: New perspectives in multiple sclerosis.

The gut microbiota plays a fundamental role on the education and function of the host immune system. Immunological dysregulation is the cause of numerous human disorders such as autoimmune diseases and metabolic disorders frequently associated with inflammatory processes therefore is critical to explore novel mechanisms involved in maintaining the immune system homeostasis. The cannabinoid system and related bioactive lipids participate in multiple central and peripheral physiological processes that affect metabolic, gastrointestinal and neuroimmune regulatory mechanisms displaying a modulatory role and contributing to the maintenance of the organism's homeostasis. In this review, we gather the knowledge on the gut microbiota-endocannabinoids interactions and their impact on autoimmune disorders such as inflammatory bowel disease, rheumatoid arthritis and particularly, multiple sclerosis (MS) as the best example of a CNS autoimmune disorder. Furthermore, we contribute to this field with new data on changes in many elements of the cannabinoid system in a viral model of MS after gut microbiota manipulation by both antibiotics and probiotics. Finally, we highlight new therapeutic opportunities, under an integrative view, targeting the eCBS and the commensal microbiota in the context of neuroinflammation and MS.

Gut dysbiosis and neuroimmune responses to brain infection with Theiler's murine encephalomyelitis virus.

Recent studies have begun to point out the contribution of microbiota to multiple sclerosis (MS) pathogenesis. Theiler's murine encephalomyelitis virus induced demyelinating disease (TMEV-IDD) is a model of progressive MS. Here, we first analyze the effect of intracerebral infection with TMEV on commensal microbiota and secondly, whether the early microbiota depletion influences the immune responses to TMEV on the acute phase (14 dpi) and its impact on the chronic phase (85 dpi). The intracranial inoculation of TMEV was associated with a moderate dysbiosis. The oral administration of antibiotics (ABX) of broad spectrum modified neuroimmune responses to TMEV dampening brain CD4+ and CD8+ T infiltration during the acute phase. The expression of cytokines, chemokines and VP2 capsid protein was enhanced and accompanied by clusters of activated microglia disseminated throughout the brain. Furthermore, ABX treated mice displayed lower levels of CD4+ and CD8+T cells in cervical and mesenteric lymph nodes. Increased mortality to TMEV was observed after ABX cessation at day 28pi. On the chronic phase, mice that survived after ABX withdrawal and recovered microbiota diversity showed subtle changes in brain cell infiltrates, microglia and gene expression of cytokines. Accordingly, the surviving mice of the group ABX-TMEV displayed similar disease severity than TMEV mice.

Adolescent exposure to nicotine modifies acute functional responses to cannabinoid agonists in rats.

We have studied functional interactions between nicotine and the cannabinoid receptor agonist CP 55,940 (CP) in the modulation of behavioural and corticosterone responses of male and female adolescent Wistar rats. The animals underwent a subchronic nicotine treatment (0.4 mg/kg i.p., once daily) during the periadolescent period (postnatal days 34-43). Twenty-four hours after the last injection of nicotine an acute dose of CP (1 or 100 microg/kg i.p.) was administered. Thirty minutes after the cannabinoid injection, the animals were tested individually in the holeboard immediately followed by the elevated plus-maze. We also measured corticosterone levels by radioimmunoassay. In males, neither CP (1 microg/kg) nor nicotine induced any modification in anxiety when administered alone. However, the combination of the two drugs resulted in a significant anxiogenic-like effect. In females, the lower dose of CP was anxiogenic and nicotine, which did not induce any effect per se, prevented this response. In the holeboard, subchronic nicotine and the acute cannabinoid treatment interacted in the modulation of horizontal activity and the nature of this interaction also showed a clear sexual dimorphism. Both, the cannabinoid agonist and nicotine increased corticosterone concentrations and the animals receiving the two drugs showed higher levels than the animals receiving the cannabinoid alone. The data provide evidence for the existence of functional interactions between nicotine and cannabinoids in the modulation of behavioural responses and adrenocortical activity in adolescent rats.

[Cannabinoid system and neuroinflammation:therapeutic perspectives in multiple sclerosis]. / El sistema cannabinoide en situaciones de neuroinflamación: perspectivas terapéuticas en la esclerosis múltiple.

INTRODUCTION: The endocannabinoid system consists of cannabinoid receptors, endogenous ligands and the enzymatic elements involved in their synthesis and breakdown. AIM: To report on currently held knowledge about the functioning of the system as a modulator of the neuroinflammatory processes associated with chronic diseases such as multiple sclerosis. DEVELOPMENT: Cannabinoids are synthesised and released on demand and their production increases in times of neuroinflammation and neural damage. In this context then, their actions in the microglial cells and in the astrocytes are characterised by a lowered expression of inflammatory mediators and pro-inflammatory cytokines. Furthermore, cannabinoids can play a role as neuroprotectors by means of different types of mechanisms and, in experimental models of multiple sclerosis, they slow down the symptoms, reduce inflammation and can favour remyelination. CONCLUSIONS: The clinical use of cannabinoids or pharmacological agents that affect the endogenous cannabinoid system during inflammation of the central nervous system and in multiple sclerosis is currently under consideration and subject to debate. Detailed analysis of the results obtained over the past decade has made it possible to establish the existence of several mechanisms of action of cannabinoids in pathologies affecting the central nervous system that are accompanied by chronic inflammation. Likewise, they also clearly show that the cannabinoid system is an interesting proposal as a new therapeutic tool.

Microglia activation states and cannabinoid system: Therapeutic implications.

Microglial cells are recognized as the brain's intrinsic immune cells, mediating actions that range from the protection against harmful conditions that modify CNS homeostasis, to the control of proliferation and differentiation of neurons and their synaptic pruning. To perform these functions, microglia adopts different activation states, the so-called phenotypes that depending on the local environment involve them in neuroinflammation, tissue repair and even the resolution of the inflammatory process. There is accumulating evidence indicating that cannabinoids (CBs) might serve as a promising tool to modify the outcome of inflammation, especially by influencing microglial activity. Microglia has a functional endocannabinoid (eCB) signaling system, composed of cannabinoid receptors and the complete machinery for the synthesis and degradation of eCBs. The expression of cannabinoid receptors - mainly CB2 - and the production of eCBs have been related to the activation profile of these cells and therefore, the microglial phenotype, emerging as one of the mechanisms by which microglia becomes alternatively activated. Here, we will discuss recent studies that provide new insights into the role of CBs and their endogenous counterparts in defining the profile of microglia activation. These actions make CBs a promising therapeutic tool to avoid the detrimental effects of inflammation and possibly paving the way to target microglia in order to generate a reparative milieu in neurodegenerative diseases.

PDE7 inhibitor TC3.6 ameliorates symptomatology in a model of primary progressive multiple sclerosis.

BACKGROUND AND PURPOSE: cAMP plays an important role in the transduction of signalling pathways involved in neuroprotection and immune regulation. Control of the levels of this nucleotide by inhibition of cAMP-specific PDEs such as PDE7 may affect the pathological processes of neuroinflammatory diseases like multiple sclerosis (MS). In the present study, we evaluated the therapeutic potential of the selective PDE7 inhibitor, TC3.6, in a model of primary progressive multiple sclerosis (PPMS), a rare and severe variant of MS. EXPERIMENTAL APPROACH: Theiler's murine encephalomyelitis virus-induced demyelinated disease (TMEV-IDD) is one of the models used to validate the therapeutic efficacy of new drugs in MS. As recent studies have analysed the effect of PDE7 inhibitors in the EAE model of MS, here the TMEV-IDD model was used to test their efficacy in a progressive variant of MS. Mice were subjected to two protocols of TC3.6 administration: on the pre-symptomatic phase and once the disease was established. KEY RESULTS: Treatment with TC3.6 ameliorated the disease course and improved motor deficits of infected mice. This was associated with down-regulation of microglial activation and reduced cellular infiltrates. Decreased expression of pro-inflammatory mediators such as COX-2 and the cytokines, IL-1ß, TNF-α, IFN-γ and IL-6 in the spinal cord of TMEV-infected mice was also observed after TC3.6 administration. CONCLUSION: These findings support the importance of PDE7 inhibitors, and specifically TC3.6, as a novel class of agents with therapeutic potential for PPMS. Preclinical studies are needed to determine whether their effects translate into durable clinical benefits.

A Sativex(®) -like combination of phytocannabinoids as a disease-modifying therapy in a viral model of multiple sclerosis.

BACKGROUND AND PURPOSE: Sativex(®) is an oromucosal spray, containing equivalent amounts of Δ(9) -tetrahydrocannabinol (Δ(9) -THC) and cannabidiol (CBD)-botanical drug substance (BDS), which has been approved for the treatment of spasticity and pain associated to multiple sclerosis (MS). In this study, we investigated whether Sativex may also serve as a disease-modifying agent in the Theiler's murine encephalomyelitis virus-induced demyelinating disease model of MS. EXPERIMENTAL APPROACH: A Sativex-like combination of phytocannabinoids and each phytocannabinoid alone were administered to mice once they had established MS-like symptoms. Motor activity and the putative targets of these cannabinoids were assessed to evaluate therapeutic efficacy. The accumulation of chondroitin sulfate proteoglycans (CSPGs) and astrogliosis were assessed in the spinal cord and the effect of Sativex on CSPGs production was evaluated in astrocyte cultures. KEY RESULTS: Sativex improved motor activity - reduced CNS infiltrates, microglial activity, axonal damage - and restored myelin morphology. Similarly, we found weaker vascular cell adhesion molecule-1 staining and IL-1ß gene expression but an up-regulation of arginase-1. The astrogliosis and accumulation of CSPGs in the spinal cord in vehicle-infected animals were decreased by Sativex, as was the synthesis and release of CSPGs by astrocytes in culture. We found that CBD-BDS alone alleviated motor deterioration to a similar extent as Sativex, acting through PPARγ receptors whereas Δ(9) -THC-BDS produced weaker effects, acting through CB2 and primarily CB1 receptors. CONCLUSIONS AND IMPLICATIONS: The data support the therapeutic potential of Sativex to slow MS progression and its relevance in CNS repair.

Interleukin-2 induces corticotropin-releasing hormone release from superfused rat hypothalami: influence of glucocorticoids.

The present work shows that interleukin-2 (IL-2) is able to increase in a dose-dependent manner (25-100 U/ml) CRF release from continuous perifused hypothalami. The effects of IL-2 and IL-1 on CRF secretion are potentiated by the simultaneous action of the two cytokines at the hypothalamus. The stimulatory effect of IL-2 on CRF secretion is significantly inhibited by the presence of dexamethasone in the perifusion medium. However, the CRF response to IL-2 was similar in adrenalectomized animals and sham-operated rats. It is suggested that the action of IL-2 on hypothalamic CRF secretion is integrated in the communication between the immune system and the hypothalamic-pituitary-adrenocortical axis, and that such action is subjected to glucocorticoid negative feedback modulation. The mechanism underlying the effect of IL-2 on CRF release is unknown, but arachidonic acid metabolites do not seem to be involved, since neither a lipooxygenase (nordihidrogueretic acid) nor a cyclooxigenase (indomethacin) inhibitor affected the hypothalamic secretory response to IL-2.

The endogenous cannabinoid anandamide potentiates interleukin-6 production by astrocytes infected with Theiler's murine encephalomyelitis virus by a receptor-mediated pathway.

Theiler's murine encephalomyelitis virus (TMEV) infection of a susceptible strain of mice results in virus persistence in the brain and chronic primary immune-mediated demyelination, which resembles multiple sclerosis. Recent attention has focused on the anti-inflammatory and immunosuppressive properties of interleukin-6, a pleiotropic cytokine involved in the regulation of immunological responses, acute phase protein production and hematopoiesis. Anandamide (arachidonoyl ethanolamine) is a natural brain constituent that binds a specific brain cannabinoid receptor. In this study we investigated whether anandamide can modify interleukin-6 production by primary cultures of murine brain cortical astrocytes infected with TMEV. Astrocytes from susceptible (SJL/J) and resistant (BALB/c) strains of mice infected with TMEV (10(5)PFU/well) increased IL-6 release over a period of 24 h. Anandamide caused an enhancement of the release of IL-6 by TMEV-infected astrocytes in a concentration-dependent manner (1-25 microM). Treatment of TMEV-infected astrocytes with 10 microM arachidonyl trifluoromethyl ketone, a potent inhibitor of the amidase that degrades anandamide, was found to potentiate the effects of anandamide on IL-6 release. A novel and selective cannabinoid receptor antagonist, SR 141617A, blocked the enhancing effects of anandamide on IL-6 release by TMEV-infected astrocytes, suggesting a cannabinoid receptor-mediated pathway. The physiological implications of these results are unknown, but may be related to the hypothesis of the protective effects of cannabinoids on neurological disorders like multiple sclerosis.

Role of arachidonic acid metabolism on corticotropin-releasing factor (CRF)-release induced by interleukin-1 from superfused rat hypothalami.

The present work shows that the corticotropin-releasing factor (CRF)-releasing activity of interleukin-1 (IL-1) is partially inhibited by a phospholipase A2 (mepacrine) or a cyclooxygenase (indomethacin) inhibitor, but is not affected by inhibition of the lypoxygenase pathway with norhydroguaiaretic acid. These results indicate that the metabolism of arachidonic acid plays an important role as mediator of the effects of IL-1 on CRF release. It is also shown that products of the cyclooxygenase activity such as prostaglandins can stimulate CRF secretion by a direct action on the hypothalamus. Whereas PGE2 failed to induce increases on CRF release, PGF2 alpha stimulated in a dose-dependent manner (21-340 nM), the CRF release from continuous perifused hypothalami. It is suggested that PGF2 alpha could be involved as a messenger in the hypothalamic CRF secretion induced by IL-1.