Biological characterization of PM226, a chromenoisoxazole, as a selective CB2 receptor agonist with neuroprotective profile.

Cannabinoids have emerged as promising neuroprotective agents due to their capability to activate specific targets, which are involved in the control of neuronal homeostasis and survival. Specifically, those ligands that selectively target and activate the CB2 receptor may be useful for their anti-inflammatory and neuroprotective properties in various neurological disorders, with the advantage of being devoid of psychotropic effects associated with the activation of CB1 receptors. The aim of this work has been to investigate the neuroprotective properties of 7-(1,1-dimethylheptyl)-4,4-dimethyl-9-methoxychromeno[3,4-d]isoxazole (PM226), a compound derived from a series of chromeno-isoxazoles and -pyrazoles, which seems to have a promising profile related to the CB2 receptor. The compound binds selectively to this receptor with an affinity in the nanomolar range (Ki=12.8±2.4nM). It has negligible affinity for the CB1 receptor (Ki>40000nM) and no activity at the GPR55. PM226 was also evaluated in GTPγS binding assays specific to the CB2 receptor showing agonist activity (EC50=38.67±6.70nM). In silico analysis of PM226 indicated that it has a good pharmacokinetic profile and a predicted ability to cross the blood-brain barrier. Next, PM226 was investigated in an in vitro model to explore its anti-inflammatory/neuroprotective properties. Conditioned media were collected from LPS-stimulated cultures of BV2 microglial cell line in the absence or presence of different doses of PM226, and then media were added to cultured M213-2O neuronal cells to record their influence on cell viability evaluated using MTT assays. As expected, cell viability was significantly reduced by the exposure to these conditioned media, while the addition of PM226 attenuated this reduction in a dose-dependent manner. This effect was reversed by co-incubating with the CB2 antagonist SR144528, thus confirming the involvement of CB2 receptors, whereas the addition of PM226 to neuronal cultures instead cultured BV2 cells was not effective. PM226 has also been studied in an in vivo model of mitochondrial damage generated by intrastriatal application of malonate in rats. MRI analysis showed that PM226 administration decreased the volume of the striatal lesion caused by malonate, effect that was confirmed after the histopathological evaluation (Nissl staining, Iba-1 immunostaining and TUNEL assay) of striatal sections derived from malonate-lesioned rats in the absence or presence of PM226. Again, the beneficial effects of PM226 were dependent on the activation of CB2 receptors as they were reversed by blocking these receptors with AM630. Overall, PM226 has shown to have a promising neuroprotective profile derived from its ability to selectively activate CB2 receptor, so that it could be a useful disease-modifying agent in those neurodegenerative pathologies in which the activation of these receptors may have therapeutic value.

Control of experimental spasticity by targeting the degradation of endocannabinoids using selective fatty acid amide hydrolase inhibitors.

BACKGROUND: It has been previously shown that CB1 cannabinoid receptor agonism using cannabis extracts alleviates spasticity in both a mouse experimental autoimmune encephalomyelitis (EAE) model and multiple sclerosis (MS) in humans. However, this action can be associated with dose-limiting side effects. OBJECTIVE: We hypothesised that blockade of anandamide (endocannabinoid) degradation would inhibit spasticity, whilst avoiding overt cannabimimetic effects. METHODS: Spasticity eventually developed following the induction of EAE in either wild-type or congenic fatty acid amide hydrolase (FAAH)-deficient Biozzi ABH mice. These animals were treated with a variety of different FAAH inhibitors and the effect on the degree of limb stiffness was assessed using a strain gauge. RESULTS: Control of spasticity was achieved using FAAH inhibitors CAY100400, CAY100402 and URB597, which was sustained following repeated administrations. Therapeutic activity occurred in the absence of overt cannabimimetic effects. Importantly, the therapeutic value of the target could be definitively validated as the treatment activity was lost in FAAH-deficient mice. Spasticity was also controlled by a selective monoacyl glycerol lipase inhibitor, JZL184. CONCLUSIONS: This study demonstrates definitively that FAAH inhibitors provide a new class of anti-spastic agents that may have utility in treating spasticity in MS and avoid the dose-limiting side effects associated with cannabis use.

Cervical Spinal Cord Degeneration in Spinocerebellar Ataxia Type 7.

BACKGROUND AND PURPOSE: Spinocerebellar ataxia type 7 is an autosomal dominant neurodegenerative disease caused by a cytosine-adenine-guanine (CAG) repeat expansion. Clinically, spinocerebellar ataxia type 7 is characterized by progressive cerebellar ataxia, pyramidal signs, and macular degeneration. In vivo MR imaging studies have shown extensive gray matter degeneration in the cerebellum and, to a lesser extent, in a range of cortical cerebral areas. The purpose of this study was to evaluate the impact of the disease in the spinal cord and its relationship with the patient's impairment. MATERIALS AND METHODS: Using a semiautomated procedure applied to MR imaging data, we analyzed spinal cord area and eccentricity in a cohort of 48 patients with spinocerebellar ataxia type 7 and compared them with matched healthy controls. The motor impairment in the patient group was evaluated using the Scale for Assessment and Rating of Ataxia. RESULTS: Our analysis showed a significantly smaller cord area (t = 9.04, P < .001, d = 1.31) and greater eccentricity (t = -2.25, P =. 02, d = 0.32) in the patient group. Similarly, smaller cord area was significantly correlated with a greater Scale for Assessment and Rating of Ataxia score (r = -0.44, P = .001). A multiple regression model showed that the spinal cord area was strongly associated with longer CAG repetition expansions (P = .002) and greater disease duration (P = .020). CONCLUSIONS: Our findings indicate that cervical spinal cord changes are progressive and clinically relevant features of spinocerebellar ataxia type 7, and future investigation of these measures as candidate biomarkers is warranted.

Cannabinoid receptor CB2 ablation protects against TAU induced neurodegeneration.

Tauopathies are a group of neurodegenerative diseases characterized by the alteration/aggregation of TAU protein, for which there is still no effective treatment. Therefore, new pharmacological targets are being sought, such as elements of the endocannabinoid system (ECS). We analysed the occurrence of changes in the ECS in tauopathies and their implication in the pathogenesis. By integrating gene expression analysis, immunofluorescence, genetic and adeno-associated virus expressing TAU mouse models, we found a TAU-dependent increase in CB2 receptor expression in hippocampal neurons, that occurs as an early event in the pathology and was maintained until late stages. These changes were accompanied by alterations in the endocannabinoid metabolism. Remarkably, CB2 ablation in mice protects from neurodegeneration induced by hTAUP301L overexpression, corroborated at the level of cognitive behaviour, synaptic plasticity, and aggregates of insoluble TAU. At the level of neuroinflammation, the absence of CB2 did not produce significant changes in concordance with a possible neuronal location rather than its classic glial expression in these models. These findings were corroborated in post-mortem samples of patients with Alzheimer's disease, the most common tauopathy. Our results show that neurons with accumulated TAU induce the expression of the CB2 receptor, which enhances neurodegeneration. These results are important for our understanding of disease mechanisms, providing a novel therapeutic strategy to be investigated in tauopathies.

The neuroprotective effect of cannabidiol in an in vitro model of newborn hypoxic-ischemic brain damage in mice is mediated by CB(2) and adenosine receptors.

To investigate the mechanisms involved in cannabidiol (CBD)-induced neuroprotection in hypoxic-ischemic (HI) immature brain, forebrain slices from newborn mice underwent oxygen and glucose deprivation in the presence of vehicle, or CBD alone or with selective antagonists of cannabinoid CB(1) and CB(2), and adenosine A(1) and A(2) receptors. CBD reduced acute (LDH efflux to the incubation medium) and apoptotic (caspase-9 concentration in tissue) HI brain damage by reducing glutamate and IL-6 concentration, and TNFalpha, COX-2, and iNOS expression. CBD effects were reversed by the CB(2) antagonist AM630 and by the A(2A) antagonist SCH58261. The A(1A) antagonist DPCPX only counteracted the CBD reduction of glutamate release, while the CB(1) antagonist SR141716 did not modify any effect of CBD. In conclusion, CBD induces robust neuroprotection in immature brain, by acting on some of the major mechanisms underlying HI cell death; these effects are mediated by CB(2) and adenosine, mainly A(2A), receptors.

Identification of putative miRNA biomarkers in early rheumatoid arthritis by genome-wide microarray profiling: A pilot study.

Despite the existing research, the etiology of rheumatoid arthritis (RA), an autoimmune disease remains poorly understood with early and accurate diagnosis difficult to achieve. MicroRNAs (miRNAs) play an important role in biological processes as modulators of transcription and translation. Previous studies have demonstrated a downregulation of several genes in early RA stages and in addition, miRNAs may serve as early biomarkers of subclinical changes in early RA. When comparing the four groups (ANOVA P < 0.01, fold change > 4), we found 253 differentially expressed miRNAs. Of these, 97 miRNAs were identified as overexpressed in early rheumatoid arthritis. The validation of miRNA microarray expression was performed in a set by RT-qPCR and showed strong agreement with microarray expression data. The putative targets of overexpressed microRNAs in early RA were significantly enriched in apoptosis, tolerance loss and Wnt pathways. Moreover, ROC analysis showed values of AUC 0.76 and P < 0.05 for miR 361-5p, identifying this miRNA as a potential biomarker of disease. We identified specific microRNAs associated with early rheumatoid arthritis and proposed them as early biomarkers of disease. Our results provide novel insight into immune disease physiopathology and describe unreported microRNAs in RA with potential for clinical use.

Ophthalmic features of spinocerebellar ataxia type 7.

PurposeTo analyze the relation between ophthalmologic and motor changes in spinocerebellar ataxia type 7 (SCA7).Patients and methodsThis was a case series study. Sixteen SCA7 patients underwent a comprehensive ophthalmic examination, including ocular extrinsic motility testing, color vision test, and optical coherence tomography of the optic nerve and macula. Changes in the corneal endothelium, electroretinographic patterns, and a complete neurologic evaluation using the Scale for the Assessment and Rating of Ataxia (SARA) were evaluated. Correlations of endothelial cell density (ECD) with number of CAG repetitions and the SARA scores were estimated.ResultsAll patients showed various degrees of visual impairment mainly due to macular deterioration. Notably, they also presented decreased ECD. Pairwise correlations of ECD with number of CAG repeats and severity of motor symptoms quantified with the SARA scores were inverse (r=-0.46, P=0.083 and r=-0.64, P=0.009, respectively). Further analyses indicated an average ECD decrease of 48 cells/mm2 (P=0.006) per unit of change on the number of CAG repeats, and of 75 cells/mm2 (P=0.001) per unit of change on the SARA scores.ConclusionsThe results agree with previous ophthalmological findings regarding the widespread effect of SCA7 mutation on the patient's visual system. However, the results also show a significant negative correlation of decreased ECD with both CAG repetitions and SARA scores. This suggests that motor systems could degenerate in parallel with visual systems, although more research is needed to determine whether the degeneration is caused by the same mechanisms.

The endogenous cannabinoid system and brain development.

Cannabinoid receptors and their endogenous ligands constitute a novel modulatory system that is involved in specific brain functions, such as nociception, control of movement, memory and neuroendocrine regulation. Recently, it has also been suggested that this system is involved in brain development. Studies have used a variety of techniques to elucidate the effects of cannabinoids during development, as well as to characterize the presence of elements of the endogenous cannabinoid system (receptors and ligands) in the developing brain. Collectively, they suggest that endocannabinoids participate in brain development through the activation of second-messenger-coupled cannabinoid receptors.

[Satisfaction of principal caregivers of patients followed-up by palliative care teams]. / Grado de satisfacción de los cuidadores principales de pacientes seguidos por los equipos de cuidados paliativos.

OBJECTIVE: To determine the satisfaction of main caregivers of deceased patients followed-up by palliative care teams. METHOD: Web research on electronic data bases: PubMed and MEDES, using "Palliative Care" and "Patient Satisfaction" as main descriptors, and "Family", "Professional-Family Relations", "Quality of Health Care" and "Quality Assurance, Health Care" as secondary descriptors. Studies written in Spanish and English were included. RESULTS: Profile of principal caregiver: a woman between her mid-forties and her mid-fifties, usually related with the patient as a daughter, and of primary educational level. The items that the main caregivers valued the most were: a kind manner, feeling free to ask questions about problems during the process, tactful explanations, receiving information, pain management, time for answering questions, interest for emotional problems, and information about treatment. The worse valued items were: symptoms control, lack of psychological support after death, preparation for a death of a relative, keeping in touch after death, help to resolve outstanding issues, and help during grief. In general, a great majority of palliative care teams achieved excellent results. CONCLUSION: In spite of the good results obtained in satisfaction surveys from caregivers with regard to palliative care teams, it is essential to improve the quality of scientific-technical training (both from the medical and the psychological point of view), as well as to improve communicational skills among palliative care staff.

Tractography at 3T MRI of Corpus Callosum Tracts Crossing White Matter Hyperintensities.

BACKGROUND AND PURPOSE: The impact of white matter hyperintensities on the diffusion characteristics of crossing tracts is unclear. This study used quantitative tractography at 3T MR imaging to compare, in the same individuals, the diffusion characteristics of corpus callosum tracts that crossed white matter hyperintensities with the diffusion characteristics of corpus callosum tracts that did not pass through white matter hyperintensities. MATERIALS AND METHODS: Brain T2 fluid-attenuated inversion recovery-weighted and diffusion tensor 3T MR imaging scans were acquired in 24 individuals with white matter hyperintensities. Tractography data were generated by the Fiber Assignment by Continuous Tracking method. White matter hyperintensities and corpus callosum tracts were manually segmented. In the corpus callosum, the fractional anisotropy, radial diffusivity, and mean diffusivity of tracts crossing white matter hyperintensities were compared with the fractional anisotropy, radial diffusivity, and mean diffusivity of tracts that did not cross white matter hyperintensities. The cingulum, long association fibers, corticospinal/bulbar tracts, and thalamic projection fibers were included for comparison. RESULTS: Within the corpus callosum, tracts that crossed white matter hyperintensities had decreased fractional anisotropy compared with tracts that did not pass through white matter hyperintensities (P = .002). Within the cingulum, tracts that crossed white matter hyperintensities had increased radial diffusivity compared with tracts that did not pass through white matter hyperintensities (P = .001). CONCLUSIONS: In the corpus callosum and cingulum, tracts had worse diffusion characteristics when they crossed white matter hyperintensities. These results support a role for white matter hyperintensities in the disruption of crossing tracts.

Ataxia Severity Correlates with White Matter Degeneration in Spinocerebellar Ataxia Type 7.

BACKGROUND AND PURPOSE: There is a scarcity of information on the effect of white matter degeneration in patients with spinocerebellar ataxia type 7. Therefore, we investigated the WM integrity in a large group of patients with spinocerebellar ataxia type 7 by using Tract-Based Spatial Statistics. MATERIALS AND METHODS: Thirty-three patients with a molecular diagnosis of spinocerebellar ataxia type 7 and their age- and sex-matched healthy controls participated in this study. The patients' ataxia severity was evaluated with the Scale for the Assessment and Rating of Ataxia. Voxelwise analyses of diffusion metrics, including fractional anisotropy and mean diffusivity, were performed with Tract-Based Spatial Statistics. The correlation between WM abnormalities and ataxia severity was then calculated. RESULTS: Tract-Based Spatial Statistics analysis revealed WM abnormalities in the cerebellum and the cerebellar peduncles, as well as in other major cortical and subcortical pathways. Further analysis between the Scale for the Assessment and Rating of Ataxia score and WM mean diffusivity showed significant associations only in key areas related to motor control and visuospatial processing, including the cerebellar WM, the middle occipital WM, the superior cerebellar peduncle, and bilateral anterior thalamic radiation. No significant associations between fractional anisotropy and the Scale for the Assessment and Rating of Ataxia were found. CONCLUSIONS: These results suggest a significant contribution of local cerebellar and cerebellar-midbrain connections to ataxic impairment in spinocerebellar ataxia type 7. The results also suggest an involvement of cortical WM abnormalities including tracts within the occipital and frontal cortices. These findings contribute to a more comprehensive view of the clinical impact of the white matter degeneration in spinocerebellar ataxia type 7.

Changes in cannabinoid receptor binding and mRNA levels in several brain regions of aged rats.

We have recently found that cannabinoid receptor binding and gene expression markedly decreased in extrapyramidal structures of aged rats. The present study was designed to analyze the possible existence of similar aging-induced changes in cannabinoid receptor binding and gene expression in brain regions other than extrapyramidal areas, but that also contain a significant population of cannabinoid receptors, such as the cerebellum, hippocampal structures, limbic and hypothalamic nuclei, the cerebral cortex and others. To this end, we analyzed cannabinoid receptor binding, using autoradiography, and cannabinoid receptor mRNA levels, using in situ hybridization, in slide-mounted brain sections obtained from young (3 month old) and aged (> 2 year old) rats. Results were as follows. In the cerebellum, aged rats exhibited a marked decrease in cannabinoid receptor binding in the molecular layer (-33.3%), although accompanied by no changes in mRNA levels in the granular layer. In the cerebral cortex, a small, although statistically significant, decrease in binding was found in the deep layer (VI) (-18.3%) of aged rats, whereas no changes were found in the superficial layer (I). As in the case of the cerebellum, mRNA levels did not change in the cerebral cortex layers (II-III and V-VI). The different regions of the Ammon's horn of the hippocampus exhibited similar cannabinoid receptor binding levels in aged and young rats. Interestingly, mRNA levels decreased in aged rats to a small, but statistically significant, extent (CA1: -26.1%; CA2: -21.6%; CA3: -14.4%). This was also seen in another hippocampal structure, the dentate gyrus (-14.6%), although in this region binding levels increased in aged rats (+28.4%). Two hypothalamic structures, the arcuate nucleus and the ventromedial hypothalamic nucleus, exhibited decreased cannabinoid receptor binding in aged rats (-31.1% and -30.3%, respectively), but this was not seen in the medial preoptic area. This was accompanied by no changes in mRNA levels in the ventromedial hypothalamic nucleus. In the limbic structures, aged rats exhibited similar binding levels to young rats. This was seen in the nucleus accumbens, septum nuclei and basolateral amygdaloid nucleus. However, mRNA levels slightly decreased in the basolateral amygdaloid nucleus (-13.4%), whereas they were not altered in the septum nuclei. Finally, other brain structures, such as the central gray substance and the brainstem, exhibited similar binding levels in aged and young rats. However, it is important to note that mRNA levels increased significantly (+211.2%) in the brainstem of aged rats, an area where the levels of binding and mRNA were very low in young rats. This marked increase may be related to an increase in the presence of glial elements in this region, as revealed by the increase in the immunoreactivity for glial fibrillary acidic protein observed in the brainstem of aged rats as compared to young animals. In summary, senescence was associated with changes in cannabinoid receptors in the cerebellum, the cerebral cortex, limbic and hypothalamic structures, the hippocampus and other brain regions. However, the changes observed (i) were not as marked and relevant as those early reported in extrapyramidal areas, and (ii) exhibited regional differences that might be attributed to the different roles played by these receptors in each region. Of particular relevance by their magnitude were the aging-induced decrease in binding found in the cerebellum and the hypothalamus, and the increase in mRNA levels observed in the brainstem. The latter might be related to an increase in the presence of glial cells which might contain cannabinoid receptor mRNA.

Pharmacological and biochemical interactions between opioids and cannabinoids.

Opioids and cannabinoids are among the most widely consumed drugs of abuse in humans. A number of studies have shown that both types of drugs share several pharmacological properties, including hypothermia, sedation, hypotension, inhibition of both intestinal motility and locomotor activity and, in particular, antinociception. Moreover, phenomena of cross-tolerance or mutual potentiation of some of these pharmacological effects have been reported. In recent years, these phenomena have supported the possible existence of functional links in the mechanisms of action of both types of drugs. The present review addresses the recent advances in the study of pharmacological interactions between opioids and cannabinoids, focusing on two aspects: antinociception and drug addiction. The potential biochemical mechanisms involved in these pharmacological interactions are also discussed together with possible therapeutic implications of opioid-cannabinoid interactions.

Cannabinoid control of motor function at the basal ganglia.

Classic and novel data strengthen the idea of a prominent role for the endocannabinoid signaling system in the control of movement. This finding is supported by three-fold evidence: (1) the abundance of the cannabinoid CB1 receptor subtype, but also of CB2 and vanilloid VR1 receptors, as well as of endocannabinoids in the basal ganglia and the cerebellum, the areas that control movement; (2) the demonstration of a powerful action, mostly of an inhibitory nature, of plant-derived, synthetic, and endogenous cannabinoids on motor activity, exerted by modulating the activity of various classic neurotransmitters; and (3) the occurrence of marked changes in endocannabinoid transmission in the basal ganglia of humans affected by several motor disorders, an event corroborated in animal models of these neurological diseases. This three-fold evidence has provided support to the idea that cannabinoid-based compounds, which act at key steps of the endocannabinoid transmission [receptors, transporter, fatty acid amide hydrolase (FAAH)], might be of interest because of their potential ability to alleviate motor symptoms and/or provide neuroprotection in a variety of neurological pathologies directly affecting basal ganglia structures, such as Parkinson's disease and Huntington's chorea, or indirectly, such as multiple sclerosis and Alzheimer's disease. The present chapter will review the knowledge on this issue, trying to establish future lines for research into the therapeutic potential of the endocannabinoid system in motor disorders.

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.

Sex- and age-related changes in catecholamine metabolism and release of rat adrenal gland.

To examine the possible existence of changes in the adrenal catecholaminergic activity during aging, we analyzed the adrenal content of catecholamines (CA) and the activities of selected enzymes involved in their metabolism as well as the basal and the K+-stimulated release of these CA in incubated adrenal tissue of aged (greater than 22 months) and young (2 months) rats of both sexes. Adrenal contents of norepinephrine (NE) and epinephrine (E) of male rats were unaltered in aging, although aged males showed an increased activity of tyrosine hydroxylase (TH) and a decrease in phenylethanolamine-N-methyl transferase (PNMT) activity. In addition, the in vitro release of both CA as well as their content in the incubated adrenal tissue were higher in aged males than in young animals. However, the response of the adrenal of aged males to incubation with stimulatory concentrations of K+ was significantly lower than that observed in young males. Aged females showed increases in the adrenal content of E, although the activities of TH and PNMT were unaltered. As in aged males, the in vitro release of CA from incubated adrenal tissue was higher in aged females than in young rats, but the CA amounts measured in the incubated tissues were similar. Moreover, the response to stimulatory concentrations of K+ was lower in aged females than in young animals. In summary, these results clearly indicate that adrenal catecholaminergic activity is enhanced during aging, which could have important consequences for physiological functions regulated by the adrenal secretion. Also, some differences in the effects of aging could be observed between males and females.

Comparisons between brain dopaminergic neurons of juvenile and aged rats: sex-related differences.

It is known that several aspects of dopaminergic neurotransmission deteriorate with advanced age. In the present report, we have studied the possible existence of sexual differences in these aging-induced changes. Thus, we measured several pre- and postsynaptic biochemical parameters, indicative of the activity of dopaminergic neurons, in striatum, limbic forebrain and hypothalamic-anterior pituitary area of aged (24-26 months) and young (2 months) rats of both sexes. Tyrosine hydroxylase (TH) activity, as well as the number of D2-dopaminergic receptors, decreased in the striatum of aged rats, especially in the males in which the decrease in the number of receptors was associated with an increase in their affinity. In addition, the ratio between dopamine (DA) and its intraneuronal metabolite, L-3,4-dihydroxyphenyl-acetic acid (DOPAC), which can be used as an index of neurotransmitter turnover, was increased in aged females in parallel with a decreased DA content. In the limbic forebrain, TH activity was also decreased during aging, but only in males, whereas the DOPAC/DA ratio was increased in females, although in parallel with an increased DOPAC production. Finally, in the hypothalamic-anterior pituitary area, aging only affected the females, in which increased plasma prolactin levels were observed. This effect might be the result of a low responsiveness of pituitary lactotrophs to DA released from hypothalamic neurons, in spite of high prolactin levels producing a constant, although ineffective, stimulation of the activity of these neurons, as reflected by the high DOPAC content and DOPAC/DA ratio observed in the medial basal hypothalamus. In summary, these data allow us to suggest that the activity of brain dopaminergic neurons is modified with aging and there are significant differences as a function of sex and brain area.

The endocannabinoid system and Huntington's disease.

The research in Huntington's disease (HD) has been growing exponentially during the last decade, since the discovery of the genetic basis that leads to neurodegeneration. HD is one of several progressive neurodegenerative disorders, in which the underlying mutation is a CAG expansion encoding a polyglutamine tract in a specific protein, which in the case of HD, is called huntingtin. The first clinical symptoms of HD are generally psychiatric abnormalities, most commonly depression and mood disturbances. Involuntary choreiform movements and dementia develop over the next 15-20 years, and death generally results from complications derived from immobility. There is currently no cure, or even an effective therapy to offset the decline in mental and motor capabilities suffered by those affected by HD, but recent studies have started to examine the usefulness of different classes of new compounds. Among these, plant-derived, synthetic or endogenous cannabinoids have been proposed to have therapeutic value for the treatment of HD, since they act on cannabinoid CB(1) receptors located in the basal ganglia circuitry, that is affected by the striatal atrophy typical of HD. Recent studies have characterized the changes in these receptors, as well as their endogenous ligands, in the basal ganglia in a variety of animal models of HD. The results are indicative that the endocannabinoid system becomes hypofunctional in this disease, which could be related to the hyperkinesia typical of the earliest phases of this disease. In addition, it has been proposed that the loss of these receptors might be involved in the process of pathogenesis itself. This, together with the well-known protective properties of cannabinoid-related compounds, suggest that, in addition to a symptomatic usefulness, cannabinoids might also serve to delay or to arrest the development of this disease. The present article will review all recent data dealing with the biochemical, pharmacological and therapeutic bases that support a potential role of cannabinoids in the pathogenesis and/or therapeutic treatment of this motor disorder.

Design, synthesis and biological evaluation of novel arachidonic acid derivatives as highly potent and selective endocannabinoid transporter inhibitors.

In the present work, we have designed and synthesized a series of arachidonic acid derivatives of general structure I which have been characterized as highly potent and selective inhibitors of anandamide transporter (IC(50) = 24-0.8 microM, K(i) > 1000-5000 nM for CB(1) and CB(2) cannabinoid receptors and vanilloid VR(1) receptor). Among them, N-(3-furylmethyl)eicosa-5,8,11,14-tetraenamide deserves special attention as being the most potent endocannabinoid transporter inhibitor (IC(50) = 0.8 microM) described to date.