Microplastics ingestion and endocrine disrupting chemicals (EDCs) by breeding seabirds in the east tropical Atlantic: Associations with trophic and foraging proxies (δ15N and δ13C)

In this study we found that endocrine disrupting chemicals (EDCs) were omnipresent in a tropical seabird community comprising diverse ecological guilds and distinct foraging and trophic preferences. Because EDCs tend to bioaccumulate within the food web and microplastics can absorb and release harmful chemical compounds, our findings draw attention to the potential threats to wildlife. Thus, the goal of this study was to investigate the role of plastic ingestion, trophic and foraging patterns (δ15N and δ13C) of five tropical seabird species breeding in sympatry, on the exposure to EDCs, namely Polybrominated diphenyl ethers (PBDEs), methoxylated polybrominated diphenyl ethers (MeO-PBDEs) and personal care products (PCPs, e.g., musk fragrances and UV-filters). Results indicated that microplastics occurrence and EDCs detection frequency varied among species. Microplastics occurrence was higher in species with dual and coastal foraging strategies. Preen oil had higher levels of MeO-PBDEs and PCPs, while serum had higher levels of PBDEs. In brown boobies, the correlation between microplastics and ∑PBDEs levels was significant, suggesting that microplastics ingestion is a key PBDEs route. Trophic position (δ15N) plays a key role in PBDEs accumulation, particularly in Bulwer's petrel, which occupies a high trophic position and had more specialized feeding ecology than the other species. MeO-PBDEs were linked to foraging habitat (δ13C), although the link to foraging locations deserves further investigation. Overall, our findings not only fill key gaps in our understanding of seabirds' exposure to microplastics and EDCs, but also provide an essential baseline for future research and monitoring efforts. These findings have broader implications for the marine wildlife conservation and pollution management in sensitive environments, such as the tropical regions off West Africa.

Anthropogenic debris ingestion in a tropical seabird community: Insights from taxonomy and foraging distribution

Oceans have been considered as an unlimited supply of goods and services, but resource extraction and waste disposal became ubiquitous and have been damaging the health of marine ecosystems. Finding suitable sentinel species of the human impacts on the oceans is thus imperative, since they may work as early warnings of disruptive situations. In this study, we investigated how taxonomy and foraging distribution influenced the occurrence of anthropogenic debris among five seabird species inhabiting the tropical Atlantic region. Occurrence of anthropogenic debris was assessed using faeces of breeding individuals as a proxy of ingestion. A total of 268 particles were extracted from all samples. The categories "fragments" and "fibres", as well as the colour "blue", were the most prevalent characteristics across species. There was a high diversity of polymers from cellulosic particles to synthetic plastics (Anthropogenic Cellulosic 26.9 %; Polyester 7.7 %; Varnish 5.8 %; Polypropylene 1.9 %). Species with a more coastal foraging strategy exhibited higher occurrence and number of anthropogenic debris when compared to species foraging comparably more in pelagic areas. This suggests that anthropogenic debris are more prevalent in coastal foraging areas, where human activities occur in higher number and frequency (e.g., fisheries) and sources of freshwater input from inland are at close distance. These results provide more evidence to the growing perception on the ubiquity and diversity of anthropogenic debris in the marine environment, and further support the usefulness of using seabirds as bio-indicators of anthropogenic pollution in both neritic and oceanic regions.

Effects of stress exposure in captivity on physiology and infection in avian hosts: no evidence of increased Borrelia burgdorferi s.l. infectivity to vector ticks

Exposure to environmental stressors, an increasingly recurring event in natural communities due to anthropogenic-induced environmental change, profoundly impacts disease emergence and spread. One mechanism through which this occurs is through stress-induced immunosuppression increasing disease susceptibility, prevalence, intensity and reactivation in hosts. We experimentally evaluated how exposure to stressors affected both the physiology of avian hosts and the prevalence of the zoonotic bacteria Borrelia burgdorferi sensu lato (s.l.), in two model species-the blackbird Turdus merula and the robin Erithacus rubecula captured in the wild, using xenodiagnoses and analysis of skin biopsies and blood. Although exposure to stressors in captivity induced physiological stress in birds (increased the number of circulating heterophils), there was no evidence of increased infectivity to xenodiagnostic ticks. However, Borrelia detection in the blood for both experimental groups of blackbirds was higher by the end of the captivity period. The infectivity and efficiency of transmission were higher for blackbirds than robins. When comparing different methodologies to determine infection status, xenodiagnosis was a more sensitive method than skin biopsies and blood samples, which could be attributed to mild levels of infection in these avian hosts and/or dynamics and timing of Borrelia infection relapses and redistribution in tissues.

The Taq IA polymorphism linked to the DRD2 gene is related to lower attention and less inhibitory control in alcoholic patients

The TaqIA polymorphism linked to the DRD2 gene has been associated with alcoholism. The aim of this work is to study attention and inhibitory control as per the continuous performance test and the stop task in a sample of 50 Spanish male alcoholic patients split into two groups according to the presence of the TaqIA1 allele in their genotype. Our results show that alcoholics carrying the TaqIA1 allele present lower sustained attention and less inhibitory control than those patients without such allele.

Identification of Affine Linear Parameter Varying Models for Adaptive Interventions in Fibromyalgia Treatment

There is good evidence that naltrexone, an opioid antagonist, has a strong neuroprotective role and may be a potential drug for the treatment of fibromyalgia. In previous work, some of the authors used experimental clinical data to identify input-output linear time invariant models that were used to extract useful information about the effect of this drug on fibromyalgia symptoms. Additional factors such as anxiety, stress, mood, and headache, were considered as additive disturbances. However, it seems reasonable to think that these factors do not affect the drug actuation, but only the way in which a participant perceives how the drug actuates on herself. Under this hypothesis the linear time invariant models can be replaced by State-Space Affine Linear Parameter Varying models where the disturbances are seen as a scheduling signal signal only acting at the parameters of the output equation. In this paper a new algorithm for identifying such a model is proposed. This algorithm minimizes a quadratic criterion of the output error. Since the output error is a linear function of some parameters, the Affine Linear Parameter Varying system identification is formulated as a separable nonlinear least squares problem. Likewise other identification algorithms using gradient optimization methods several parameter derivatives are dynamical systems that must be simulated. In order to increase time efficiency a canonical parametrization that minimizes the number of systems to be simulated is chosen. The effectiveness of the algorithm is assessed in a case study where an Affine Parameter Varying Model is identified from the experimental data used in the previous study and compared with the time-invariant model.

Diversity and seasonal patterns of ticks parasitizing wild birds in western Portugal

The diversity and abundance of questing ticks and ticks parasitizing birds was assessed during 1 year in two recreational forests in western Portugal, a suburban forest and an enclosed game area. The aim of this study was to assess the distribution and seasonality of tick species and to understand the role of bird species as hosts for ticks. Ixodes ricinus was the most abundant questing tick collected in the enclosed game area, whereas in the suburban forest, only three ticks were collected by blanket dragging. Tick species parasitizing birds included I. ricinus, I. frontalis, I. arboricola, I. acuminatus, Haemaphysalis punctata, Hyalomma marginatum and H. lusitanicum. This is the first record of I. arboricola in Portugal. Tick prevalence and intensity of infestation differed between study areas and was higher in birds from the game area where a large population of deer and wild boar may support tick populations. Ground and shrub dwelling bird species such as Turdus merula, Erithacus rubecula and Sylvia melanocephala were the most heavily parasitized by ticks, but the importance of different bird species as hosts of larvae and nymphs of I. ricinus and I. frontalis differed. Therefore, different bird species may contribute differently for tick population maintenance.

Surface Over-Melt During Laser Polishing of Indirect-SLS Metal Parts

Laser polishing of indirect-SLS parts made from 420 stainless powder infiltrated with bronze has been achieved using CO2 and Nd:YAG lasers. Two mechanisms have been previously proposed for the reduction in surface roughness, namely: shallow surface melting (SMM) and surface over-melt (SOM). In SMM reflow of the molten surface minimizes the peak-valley height driven by capillary pressure and liquid curvature. On the other hand, during SOM the melting depth is such that the entire surface becomes liquid and formation of surface periodical structures dominates driven by a surface tension gradient. This surface morphology was identified by means of optical and scanning electron microscopy (SEM). The onset of this regime is dictated by the energy density (i.e., ratio of laser power to scan speed and beam diameter) as well as the initial roughness Ra value prior to laser surface polishing. In contrast with SMM, onset of the latter mechanism increases the roughness Ra with speed reduction. A thermo-physical model is presented, signaling good agreement with roughness Ra and characteristic surface wavelength results obtained for varying laser beam scan speeds. Understanding the surface over-melt mechanism is critical for determining the optimum polishing conditions that minimize roughness.

Are great tits (Parus major) inhabiting the vicinity of a pulp mill healthy? Impacts on physiology and breeding performance

The evaluation of pollution effects on wildlife provides biologically meaningful information concerning environmental quality and possible impacts on populations and can be used as an early warning of environmental change. We aimed to assess the potential effects of exposure to atmospheric pollution from pulp mill emissions on the morphology, physiology, and reproductive performance of the great tit (Parus major). Great tits from a population inhabiting the vicinity of a pulp mill had significantly higher feather mercury levels and were physiologically distinct from other birds not under the direct influence of the pollution source. This distinction, due to significantly higher levels of red blood cell-glutathione peroxidase antioxidant activity, in birds from the vicinity of the pulp mill, was observed both in autumn and winter and was repeatable between years. No detectable effects were observed on breeding performance or nestling morphology and physiology. The effects of pollution in this study seem to be related to increased levels of oxidative stress.

[Symptoms that contribute to the perception of depressive symptom intensity. A preliminary study]

INTRODUCTION

Psychiatrists use few symptoms when diagnosing depression. This study has aimed to know what symptoms are used by the psychiatrists to evaluate the severity of a depressive person compared to how they are evaluated when using a standardized instrument such as Hamilton's Rating Scale for Depression (HRSD-17).

METHODOLOGY

A total of 100 depressed outpatients attended consecutively who met the ICD-10 criteria for depressive episode, dysthymia or adjustment disorders depressive types were studied. The depressed outpatients expressed their clinical situation on a Visual Analogue Scale (VAS) whose extreme values were the adjectives WELL and BAD. The psychiatrist evaluated them using a Clinical Global Impression (CGI) scale on the state of the patient's depressed mood, and Hamilton's Rating Scale for Depression (HRSD-17). The total scores obtained with those instruments and with the partial scores of the melancholic and anxious factors of the HRSD-17 were correlated (Pearson's R).

RESULTS

Psychiatrists give more importance to melancholic symptoms than to anxious ones to establish the severity of a depressed outpatient. Depressed outpatients give the same importance to their anxious and melancholic symptoms. In addition, the total score of the HRSD-17 is more influenced and shares a larger variance proportion with anxious symptoms than with melancholic ones. All the correlations calculated are statistically significant (p = 0.000).

CONCLUSIONS

The authors discuss the influence that the HRSD-17 can have on seemingly precocious results offered by some clinical trials of antidepressants drugs.

Immunohistologic diagnosis of avian listeriosis

Listeriosis in a chicken from a small farm was diagnosed by the per-oxidase-antiperoxidase (PAP) method. The animal had diffuse myocarditis and necrotic foci in the liver and in the spleen. PAP technique performed on formalin-fixed tissues confirmed the presumptive diagnosis. Serological and microbiological studies were also done. It is concluded that PAP method is useful for the diagnosis of avian listeriosis allowing retrospective studies with formalin-fixed, paraffin-embedded tissues, avoiding cumbersome microbiological culture.

Effects on development

This chapter will review the effects produced on neural development by maternal consumption of cannabinoids during gestation and lactation, with emphasis in the maturation of several neurotransmitter systems (dopamine, serotonin, opioids, cannabinoids, etc.) and possible modifications in their functional expression at the behavioral or neuroendocrine levels. In addition, we have analyzed the possible existence of a sexual dimorphism in these ontogenic effects of cannabinoids, as well as the possible molecular mechanism underlying such effects. In general, the results discussed support the view that exposure to cannabinoids during critical periods of development produces marked modifications in the functional expression of diverse neuronal systems in adulthood. Furthermore, the functions of endocannabinoids in the brain are large not only in adulthood, but also in the period of prenatal and postnatal development. Thus, endocannabinoids have been reported to be present in early ages and to play a role in the process of brain development: neural proliferation and migration, axonal elongation, synaptogenesis and/or myelogenesis.

Prenatal cannabinoid exposure down- regulates glutamate transporter expressions (GLAST and EAAC1) in the rat cerebellum

Efficient reuptake of synaptically released glutamate is essential for preventing glutamate receptor overstimulation and neuronal death. Glutamate transporters play a vital role in removing extracellular glutamate from the synaptic cleft. This study analyzed the expression of the glial (GLAST) and neuronal (EAAC1) subtypes of glutamate transporter in the cerebellum of male and female offspring exposed pre- and postnatally to Delta9-tetrahydrocannabinol (THC, the main component of marijuana). Pregnant rats were administered saline or THC from gestational day 5 to postnatal day 20 (PD20). The expression of glutamate transporters was examined at PD20, PD30 and PD70 (10 and 50 days after THC withdrawal) to analyze the short- and long-term effects of prenatal THC exposure. The expression of the glutamate transporter GLAST in astroglial cells and EAAC1 in Purkinje neurons decreased in THC-exposed offspring compared to controls. This reduction was observed at all ages but mainly in males. Moreover, the glial glutamate transporter level in THC-exposed rats (quantified by Western blot) was lower than in control rats. These results suggest that THC exposure during cerebellar development may alter the glutamatergic system not only during the period of drug exposure but in the postnatal stage following withdrawal. The down-regulation reported here might reflect an abnormal maturation of the glutamatergic neuron-glia circuitry.

[Large-scale genotyping in research into autism spectrum disorders and attention deficit hyperactivity disorder]

INTRODUCTION AND DEVELOPMENT

Autism spectrum disorder (ASD) and attention deficit hyperactivity disorder (ADHD) are two neuropsychiatric disorders beginning in childhood that present a high degree of familial aggregation. ASD is characterised by social interaction and communication disorders, whereas patients with ADHD display persistent inattention and/or hyperactive-impulsive behaviour. With the exception of a few cases of autism in which cytogenetic anomalies or mutations have been reported in specific genes, the aetiology of these diseases remains unknown. This is a group of multifactorial diseases with several genes having a lesser effect and there is also an environmental component. Genetic linkage studies have pointed to about 20 chromosomal regions that could well contain genes that grant susceptibility to autism, to ADHD or to both disorders. The challenge to researchers lies in the clinical characterisation, recruitment of patients with ASD and ADHD, gene dosage quantification studies, comparative genomic methylation and hybridisation in order to identify chromosomal rearrangements in patients with autism and severe mental retardation.

CONCLUSIONS

Genotyping large SNP-type collections that are potentially functional in genes that are candidates for these disorders, based on pharmacological, biochemical and neuropathological data together with that coming from animal models and linkage studies in a wide collection of samples from patients and controls, will enable us to identify the genetic components of these pathologies and to define their biological foundations.

IDRD2 TaqIA polymorphism is associated with urinary homovanillic acid levels in a sample of Spanish male alcoholic patients

The TaqIA1 allele of the dopamine receptor gene D2 (DRD2) has been associated with alcoholism, as well as with other addictive behaviours. The exact nature of how the presence of this allele can be a vulnerability factor in the development of alcoholism remains unclear. In this study we found that the presence in the DRD2 genotype of the TaqIA1 allele in Spanish alcoholics is associated with higher levels of urine homovanillic acid (HVA) when compared to patients homozygous for the TaqIA2 allele. A sample of 142 Spanish male alcoholic patients was split into 2 groups on the basis of the presence or absence of the A1 allele in their genotype. The urine sample was analyzed by high performance liquid cromatography (HPLC), and the concentration of homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HIAA) and vanilylmandelic acid (VMA) was determined. We found a statistical difference in the concentration of HVA between the groups, that suggests this polymorphism could be related to the variance of urine HVA levels.

The A1 allele of the DRD2 gene (TaqI A polymorphisms) is associated with antisocial personality in a sample of alcohol-dependent patients

BACKGROUND

Presence of A1 allele of the DRD2 gene has been associated with a predisposition for alcoholism although there are limited data about its phenotypic expression in alcoholism.

OBJECTIVES

To determine the importance of the A1 allele in clinical variables of alcohol dependence.

METHODOLOGY

A sample of 103 alcohol-dependent males was studied. All patients were recruited consecutively from the general hospital and community settings. The diagnostics were made with the structured clinical interview for DSM-III-R (SCID); and the International Personality Disorder Examination (IPDE). Diagnosis of family alcoholism was made by direct interview or with the Research Diagnostic Criteria-Family History (RDC-FH). The Addiction Severity Index (ASI) and the Severity of Alcohol Dependence Scale (SADS) were used to assess alcohol dependence severity. Genotyping was done by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) methods.

RESULTS

Approximately 39% of the sample carried the A1 allele (A1+ group). This group had higher prevalences of antisocial personality disorder (60% vs. 15.9%); and alcoholism family history (72.5% vs. 52.4%). Also A1+ had early onset alcohol abuse and more drinking problems. The presence of A1+ was the main factor to explain the diagnosis of antisocial personality disorder, but the weight of this factor was not sufficient to explain the complications assessed by the ASI.

CONCLUSIONS

Our results support the existence of an association between the A1 allele and factors resulting from dopaminergic deficiency, otherwise denominated reward deficiency syndrome.

Reduced glial fibrillary acidic protein and glutamine synthetase expression in astrocytes and Bergmann glial cells in the rat cerebellum caused by delta(9)-tetrahydrocannabinol administration during development

In this study we analyzed the responses of cerebellar astroglial cells to pre- and perinatal delta(9)-tetrahydrocannabinol (THC) exposure in three postnatal ages and both sexes. To determine whether THC during development directly modifies astroglial growth, this study investigated the effects of THC on astroglial morphological changes and on the expression of specific astroglial markers (glial fibrillary acidic protein: GFAP and glutamine synthetase: GS). Our results demonstrated that the administration of THC during development has deleterious effects on astroglial maturation in the cerebellum. These results also indicate that THC might interfere with astroglial differentiation in a way dependent on sex. The effect of cannabinoids on the development of cerebellar astroglial cells (astrocytes and Bergmann glial cells) is to reduce protein synthesis, since both GFAP and GS decreased in astroglial cells, not only during THC exposure but also in adult ages. Our data suggest that pre- and perinatal THC exposure directly interferes with astroglial maturation by disrupting normal cytoskeletal formation, as indicated by the irregular disposition of GFAP and the lower GFAP expression observed at all the ages studied. THC exposure during development may also modulate glutamatergic nervous activity since GS expression is reduced in THC-exposed brains. GS expression increased progressively after THC withdrawal, but GS expression had still not reached control values two months after THC withdrawal. This indicates that glutamate uptake is lower in glial cells exposed to THC, since GS expression is lower than in older controls. Consequently, glutamatergic neurotransmission may be affected by cannabinoid exposure during gestation. Therefore, cannabinoids exert developmental toxicity, at least on astroglial cells, which could contribute to fetal brain growth retardation.

Loss of mRNA levels, binding and activation of GTP-binding proteins for cannabinoid CB1 receptors in the basal ganglia of a transgenic model of Huntington's disease

Data obtained from the basal ganglia of postmortem Huntington's disease (HD) brains have revealed that the level of cannabinoid CB1 receptors in striatal efferent neurons decreases in parallel to the dysfunction and subsequent degeneration of these neurons. These findings, and others from rat models of HD generated by lesions with mitochondrial toxins, suggest that the loss of CB1 receptors may be involved in the pathogenesis of the disease. To explore further the changes in the endocannabinoid system, as well as the potential of endocannabinoid-related compounds, we examined the status of CB1 receptors in the HD94 transgenic mouse model of HD. These mice express huntingtin exon 1 with a polyglutamine tract of 94 repeats in a tissue-specific and conditional manner using the tet regulatable system. They develop many features of HD, such as striatal atrophy, intraneuronal aggregates and progressive dystonia. In these animals, we analyzed mRNA levels for the CB1 receptor, in addition to the number of specific binding sites and the activation of GTP-binding proteins by CB1 receptor agonists. mRNA transcripts of the CB1 receptor were significantly decreased in the caudate-putamen of HD transgenic mice compared to age-matched littermate controls. The decrease concurred with a marked reduction in receptor density in both the caudate-putamen and its projection areas such as the globus pallidus, entopeduncular nucleus and substantia nigra pars reticulata. Furthermore, the efficacy of CB1 receptor activation was reduced in the globus pallidus, as determined by agonist-induced [35S]GTPgammaS binding, and tended towards a decrease in the substantia nigra. None of these changes was seen in the cerebral cortex and hippocampus, despite high levels of expression of the mutant protein in these regions. The decrease in CB1 receptor levels was accompanied by a decrease in the proenkephalin-mRNA levels but not in substance P-mRNA levels. Taken together, these results suggest that the loss of CB1 receptor might be preferential to the enkephalinergic CB1 receptor-containing striatopallidal neurons, and further implicate the CB1 receptor to the subsequent HD symptomatology and neuropathology.

Endocannabinoids and basal ganglia functionality

In recent years, our knowledge on the cannabinoid pharmacology has shown a significant rise in terms of both quantity (more compounds and more targets) and quality (more selective compounds). This allows to consider cannabinoids and related compounds as a promising new line of research for therapeutic treatment of a variety of conditions, such as brain injury, chronic pain, glaucoma, asthma, cancer and AIDS-associated effects and other pathologies. Motor disorders are another promising field for the therapeutic application of cannabinoid-related compounds, since the control of movement is one of the more relevant physiological roles of the endocannabinoid transmission in the brain. There are two pathologies, Parkinson's disease and Huntington's chorea, which are particularly interesting from a clinical point of view due to the direct relationship of endocannabinoids and their receptors with neurons that degenerate in those disorders. However, other neurological pathologies, such as Alzheimer's disease or multiple sclerosis, which are not motor disorders in origin, but present a strong alteration in the control of movement, have also been a subject of interesting research for a cannabinoid therapy. This review will summarize our current knowledge on the role of these endogenous substances in the control of movement and, in particular, on the possible therapeutic usefulness of these compounds in the treatment of motor pathologies.

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.

Increased cannabinoid CB1 receptor binding and activation of GTP-binding proteins in the basal ganglia of patients with Parkinson's syndrome and of MPTP-treated marmosets

Recent evidence obtained in rat models of Parkinson's disease showed that the density of cannabinoid CB1 receptors and their endogenous ligands increase in basal ganglia. However, no data exists from post-mortem brain of humans affected by Parkinson's disease or from primate models of the disorder. In the present study, we examined CB1 receptor binding and the magnitude of the stimulation by WIN55,212-2, a specific CB1 receptor agonist, of [35S]GTPgammaS binding to membrane fractions from the basal ganglia of patients affected by Parkinson's disease. In Parkinson's disease, WIN55,212-2-stimulated [35S]GTPgammaS binding in the caudate nucleus, putamen, lateral globus pallidus and substantia nigra was increased, thus indicating a more effective activation of GTP-binding protein-coupled signalling mechanisms via CB1 receptors. This was accompanied by an increase in CB1 receptor binding in the caudate nucleus and the putamen, although no changes were observed in the lateral globus pallidus and the substantia nigra. Because Parkinson's disease patients had been chronically treated with l-DOPA, brains were studied from normal common marmosets and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated animals with and without chronic L-DOPA treatment. MPTP-lesioned marmosets had increased CB1 receptor binding in the caudate nucleus and the putamen compared to control marmosets, as well as increased stimulation of [35S]GTPgammaS binding by WIN55,212-2. However, following l-DOPA treatment these parameters returned towards control values. The results indicate that a nigro-striatal lesion is associated with an increase in CB1 receptors in the basal ganglia in humans and nonhuman primates and that this increase could be reversed by chronic l-DOPA therapy. The data suggest that CB1 receptor blockade might be useful as an adjuvant for the treatment of parkinsonian motor symptoms.

Rapid degradation of auxin/indoleacetic acid proteins requires conserved amino acids of domain II and is proteasome dependent

Auxin rapidly induces auxin/indoleacetic acid (Aux/IAA) transcription. The proteins encoded are short-lived nucleus-localized transcriptional regulators that share four conserved domains. In a transient assay measuring protein accumulation, an Aux/IAA 13-amino acid domain II consensus sequence was sufficient to target firefly luciferase (LUC) for low protein accumulation equivalent to that observed previously for full-length PSIAA6. Single amino acid substitutions in these 13 amino acids, corresponding to known auxin response mutants, resulted in a sixfold to 20-fold increase in protein accumulation. Naturally occurring variant amino acids had no effect. Residues identified as essential by single alanine substitutions were not sufficient when all flanking amino acids were alanine, indicating the importance of flanking regions. Using direct protein degradation measurements in transgenic Arabidopsis seedlings, full-length IAA1, PSIAA6, and the N-terminal 73 PSIAA6 amino acids targeted LUC for rapid degradation with 8-min half-lives. The C-terminal 109 amino acids did not affect LUC half-life. Smaller regions containing domain II also targeted LUC for rapid degradation, but the rates were not equivalent to those of the full-length protein. A single domain II substitution in the context of full-length PSIAA6 increased half-life 30-fold. Proteasome inhibitors affected Aux/IAA::LUC fusion protein accumulation, demonstrating the involvement of the proteasome.

Rapid degradation of auxin/indoleacetic acid proteins requires conserved amino acids of domain II and is proteasome dependent

Auxin rapidly induces auxin/indoleacetic acid (Aux/IAA) transcription. The proteins encoded are short-lived nucleus-localized transcriptional regulators that share four conserved domains. In a transient assay measuring protein accumulation, an Aux/IAA 13-amino acid domain II consensus sequence was sufficient to target firefly luciferase (LUC) for low protein accumulation equivalent to that observed previously for full-length PSIAA6. Single amino acid substitutions in these 13 amino acids, corresponding to known auxin response mutants, resulted in a sixfold to 20-fold increase in protein accumulation. Naturally occurring variant amino acids had no effect. Residues identified as essential by single alanine substitutions were not sufficient when all flanking amino acids were alanine, indicating the importance of flanking regions. Using direct protein degradation measurements in transgenic Arabidopsis seedlings, full-length IAA1, PSIAA6, and the N-terminal 73 PSIAA6 amino acids targeted LUC for rapid degradation with 8-min half-lives. The C-terminal 109 amino acids did not affect LUC half-life. Smaller regions containing domain II also targeted LUC for rapid degradation, but the rates were not equivalent to those of the full-length protein. A single domain II substitution in the context of full-length PSIAA6 increased half-life 30-fold. Proteasome inhibitors affected Aux/IAA::LUC fusion protein accumulation, demonstrating the involvement of the proteasome.

Changes in cannabinoid CB(1) receptors in striatal and cortical regions of rats with experimental allergic encephalomyelitis, an animal model of multiple sclerosis

Data, initially anecdotal, but recently supported on more solid experimental evidence, suggest that cannabinoids might be beneficial in the treatment of some of the symptoms of multiple sclerosis (MS). Despite this evidence, there are no data on the possible changes in cannabinoid CB(1) or CB(2) receptors, the main molecular targets for the action of cannabinoids, either in the postmortem brain of patients with MS or in animal models of this disease. The present study addressed this question using the model of experimental allergic encephalomyelitis (EAE) in Lewis rats generated by inoculation of guinea pig myelin basic protein in Freund's adjuvant. After inoculation, animals were examined daily to detect the appearance of neurological signs. The first signs appeared around day 10 after inoculation, reaching the highest degree by day 13, when animals were sacrificed and their brains removed and used for analysis of CB(1) receptor binding, mRNA levels, and activation of GTP-binding proteins. CB(1) receptor binding and mRNA levels were not affected in EAE rats in brain areas such as the hippocampus, limbic structures, and cerebellum. However, there was a marked decrease in both parameters in the caudate-putamen, both in the lateral and medial parts, although this decrease did not correspond with decreases in binding in the nuclei recipient of striatal output neurons, which suggests that changes in CB(1) receptors are exclusively located in the cell bodies of striatal neurons. In addition, CB(1) receptor binding, but not mRNA levels, also decreased in the cerebral cortex, both in the deep and the superficial layers. The analysis of [(35)S]GTPgammaS binding after activation of CB(1) receptors with WIN55,212-2, a synthetic agonist, revealed that, despite the decrease in the number of CB(1) receptors in EAE rats, these were more efficiently coupled to GTP-binding protein-mediated signaling mechanisms in both the caudate-putamen and the cerebral cortex of these animals. In summary, these data suggest that the generation of EAE in Lewis rats would be associated with changes in CB(1) receptors in striatal and cortical neurons, which might be related to the alleviation of some motor signs observed after the treatment with cannabinoid receptor agonists in similar models of MS in rodents.

Changes in endocannabinoid transmission in the basal ganglia in a rat model of Huntington's disease

Recent studies have demonstrated a loss of cannabinoid CB1 receptors in the basal ganglia in Huntington's disease (HD), but there are no data on endocannabinoid levels in this disease. In the present study, we have addressed this question by using rats with bilateral intrastriatal injections of 3-nitropropionic acid (3-NP), a toxin that, through the selective damage of striatal GABAergic efferent neurons, produces a useful model of HD. Twelve days after the lesion, 3-NP-lesioned rats exhibited motor disturbances, characterized by an ambulatory hyperactivity accompanied by a loss of guided activities. Analysis of GABA contents in the basal ganglia showed a trend towards a reduction compatible with motor hyperactivity. In addition, CB1 receptor binding and, to a greater extent, CB1 receptor activation of GTP-binding proteins, were also reduced in the basal ganglia. These changes were paralleled by a decrease of the contents of the two endocannabinoids, anandamide and 2-arachidonoylglycerol, in the striatum, and by an increase, particularly of anandamide, in the ventral mesencephalon where the substantia nigra is located. Both CB1 receptors and endocannabinoid levels were not altered in the cerebral cortex, an area not affected by the lesion. In summary, behavioral and biochemical changes observed in rats intrastriatally lesioned with 3-NP were similar to those occurring in the brain of HD patients. As expected, a loss of CB1 receptor function was evident in the basal ganglia of these rats and this was accompanied by different changes in endocannabinoid levels.

Decreased cannabinoid CB1 receptor mRNA levels and immunoreactivity in pituitary hyperplasia induced by prolonged exposure to estrogens

Recent studies have demonstrated that cannabinoid CB1 receptor gene expression in the anterior pituitary gland is under the influence of estrogens. Because these receptors have been recently involved in the development of several types of cancer, it would be interesting to examine the changes produced in these receptors by the development of pituitary hyperplasia after a chronic exposure to estrogens. To this end, we measured mRNA levels and immunoreactivity for the CB1 receptor in the anterior pituitary gland of rats implanted with silastic capsules containing diethylstilbestrod (DES), a synthetic estrogen, or empty capsules. Results were as follows. Induction of pituitary hyperplasia with DES produced the expected body weight loss (-38.4%) and increase in pituitary weight (5-fold) and plasma prolactin (PRL) levels (90-fold). In hyperplastic pituitaries, both CB1 receptor mRNA levels and immunoreactivity decreased significantly (-79.4% and -63.2% respectively). Double immuno-labelling studies demonstrated that CB1 receptors colocalized, in hyperplastic pituitaries, with PRL- or luteinizing hormone-containing cells, as they did in normal pituitaries. In summary, estrogen-induced pituitary hyperplastia was associated with a marked reduction in CB1 receptors, despite the fact that these receptors were located, among others, on lactotroph cells which develop hyperplasia during DES exposure. Whether this decrease is involved in the ethiology of pituitary hyperplasia and whether the pharmacological activation of these receptors might affect this process are presently unknown, but this will be subjected of further research.

Neuronal and astroglial response to pre- and perinatal exposure to delta-9-tetra- hydrocannabinol in the rat substantia nigra

The responses of neurons and astroglial cells to pre- and perinatal exposure to Delta(9)-tetrahydrocannabinol (Delta(9)-THC) were evaluated in the substantia nigra (SN) of male and female rats, at three postnatal ages (PD21, PD30 and PD70), by immunohistochemical detection of tyrosine hydroxylase (TH) in dopaminergic neurons and of glial fibrillary acidic protein (GFAP) in astrocytes. Our results showed that the effects of pre- and perinatal exposure to Delta(9)-THC on neuronal and astroglial immunoreactivities in the SN (compacta and reticulata) varied with sex, with male rats being more susceptible than females. Prenatal exposure to Delta(9)-THC decreased TH immunoreactivity in the SN of males on PD21 when compared to both their controls and Delta(9)-THC-exposed females of the same age. Furthermore, the TH expression decreased with age in Delta(9)-THC-exposed males in the SNc pars compacta, whereas it increased in controls. On the contrary, TH expression was maintained stable in the SN pars compacta of Delta(9)-THC-exposed females from PD21. These differences in neuronal development caused by prenatal Delta(9)-THC exposure were associated with significant differences in GFAP expression by astroglial cells in both sexes. On PD21, GFAP immunoreactivity decreased in the SN in Delta(9)-THC-exposed male rats. Although GFAP expression increased in Delta(9)-THC-exposed males with age, it did not reach control levels by PD70. On the contrary, significantly increased GFAP expression in the Delta(9)-THC-exposed females on PD21 was observed, compared to their controls and also to Delta(9)-THC-exposed male rats; however, the GFAP expression shown by Delta(9)-THC-exposed females stabilized from PD21. These Delta(9)-THC-induced changes in the glial development could indicate that Delta(9)-THC accelerated the maturation of astrocytes in female rats, whereas Delta(9)-THC delayed astrocytic maturation in Delta(9)-THC-exposed males. These findings suggest that pre- and perinatal exposure to Delta(9)-THC can lead to long-term effects in both neurons and glial cells.

Unilateral 6-hydroxydopamine lesions of nigrostriatal dopaminergic neurons increased CB1 receptor mRNA levels in the caudate-putamen

It has been recently suggested that the effects of cannabinoids on motor behavior might be different in rats with lesions of nigrostriatal dopaminergic neurons than in controls. In the present study, we examined the possible alteration in the status of cannabinoid CB1 receptors in the basal ganglia of rats with unilateral lesions of those neurons caused by 6-hydroxydopamine. We used two different experimental groups depending on the duration of the period of recovery after the lesion, and comparisons were done between the lesioned and nonlesioned sides at the level of the basal ganglia. Both groups of lesioned rats exhibited a similar marked reduction in tyrosine hydroxylase (TH)-mRNA levels, measured by in situ hybridization, in the substantia nigra of the lesioned side. In the same way, lesioned rats exhibited the characteristic rotational behavior after a single injection of apomorphine and the intensity of this rotation was stable at the two times analyzed after the lesion. Also as expected, lesioned rats exhibited an increase in proenkephalin mRNA levels in the caudate-putamen, whereas mRNA levels of substance P decreased, although differences between the two times of recovery analyzed were observed in this case. We did not find any significant changes in CB1 receptor binding, measured by [3H]WIN-55,212,2 autoradiography, or in the activation of signal transduction mechanisms, measured by WIN-55,212,2-stimulated [35S]GTPgammaS binding autoradiography, between the lesioned and nonlesioned sides at the level of the lateral caudate-putamen, globus pallidus and substantia nigra in both groups of lesioned rats. However, we found a significant increase in levels of CB1 receptor-mRNA transcripts, measured by in situ hybridization, in the lesioned side in both the lateral and medial caudate-putamen. This occurred 7-10 weeks after the lesion, but the increase was markedly waned after 17-18 weeks. In summary, the unilateral 6-hydroxydopamine lesion of nigrostriatal dopaminergic neurons originated a marked increase in CB1 receptor-mRNA levels in cell bodies of striatal efferent neurons, although accompanied by no changes in CB1 receptor binding and activation of signal transduction mechanisms. This supports a critical role for dopamine in the control of CB1 receptor gene expression. However, the magnitude of the effect significantly waned as a function of the duration of the period after lesion.

First pharmacophoric hypothesis for 5-HT7 antagonism

In order to make the first contribution to the elucidation of essential structural features for 5-HT7 antagonism, a set of thirty 5-HT7 antagonists were selected from the literature. A pharmacophore model was built using Molecular Modeling studies with Catalyst program. The information contained in this model was validated with new synthesized compounds.

Sex steroid influence on cannabinoid CB(1) receptor mRNA and endocannabinoid levels in the anterior pituitary gland

Recent studies have demonstrated the occurrence of endocannabinoid synthesis and of gene expression and immunoreactivity for the cannabinoid CB(1) receptor in the anterior pituitary gland. Since the activity of this gland is under the influence of circulating sex steroids, the present study was designed to elucidate whether expression of the CB(1) receptor gene in the anterior pituitary gland is also under the influence of these steroids. To this aim, we first examined the possible changes in the levels of CB(1) receptor-mRNA transcripts in the anterior pituitary gland of intact male rats and normal cycling female rats at the different stages of the ovarian cycle. We observed that males had higher levels of CB(1) receptor-mRNA transcripts than females. In addition, these transcripts fluctuated in females during the different phases of the ovarian cycle, with the highest values observed on the second day of diestrus and the lowest on estrus. In these animals, we also measured the content of endocannabinoids in the anterior pituitary gland and the hypothalamus. We observed that females had higher contents of anandamide than males in both cases. The content of anandamide in females also fluctuated during the ovarian cycle in both the anterior pituitary gland and the hypothalamus. The highest values in the anterior pituitary gland were found in the estrus and the lowest on the first day of diestrus and proestrus, whereas the inverse tendency was found in the hypothalamus. No changes were observed in the other major endocannabinoid, 2-arachidonoyl-glycerol, between males and females and during the ovarian cycle. To further explore the potential influence of circulating sex steroids on CB(1) receptor gene expression in the anterior pituitary gland, as a second objective, we examined the possible changes in the amount of transcripts for this receptor in gonadectomized and sex steroid-replaced gonadectomized rats of both sexes. We observed that orchidectomy (ORCHX) in males reduced CB(1) receptor-mRNA levels, whereas replacement with dihydrotestosterone also maintained low levels of this messenger. In females, estradiol-replaced ovariectomized (OVX) rats exhibited significantly lower CB(1) receptor-mRNA levels than OVX animals that had not been replaced with this estrogen. In this experiment, we also examined if the previously reported response of the CB(1) receptor gene in the anterior pituitary lobe to chronic administration of Delta(9)-tetrahydrocannabinol (Delta(9)-THC) is under sex steroid influence. We observed that chronic Delta(9)-THC treatment decreased CB(1) receptor-mRNA levels in intact and ORCHX males, but not in dihydrotestosterone-replaced ORCHX males. In females, Delta(9)-THC treatment produced no effect in both OVX- and estradiol-replaced OVX rats. In summary, these data collectively support that expression of the CB(1) receptor gene in the anterior pituitary gland is regulated by sex steroids in both males and females. Furthermore, gonadal steroids appear to affect the response of this gene to chronic cannabinoid administration. We have also observed that anandamide contents in the anterior pituitary gland and the hypothalamus might be controlled by circulating sex steroids. The functional implications of these data are discussed.

Enhancement of anandamide formation in the limbic forebrain and reduction of endocannabinoid contents in the striatum of delta9-tetrahydrocannabinol-tolerant rats

Recent studies have shown that the pharmacological tolerance observed after prolonged exposure to synthetic or plant-derived cannabinoids in adult rats is accompanied by down-regulation/desensitization of brain cannabinoid receptors. However, no evidence exists on possible changes in the contents of the endogenous ligands of cannabinoid receptors in the brain of cannabinoid-tolerant rats. The present study was designed to elucidate this possibility by measuring, by means of isotope dilution gas chromatography/mass spectrometry, the contents of both anandamide (arachidonoylethanolamide; AEA) and its biosynthetic precursor, N-arachidonoylphosphatidylethanolamine (NArPE), and 2-arachidonoylglycerol (2-AG) in several brain regions of adult male rats treated daily with delta9-tetrahydrocannabinol (delta9-THC) for a period of 8 days. The areas analyzed included cerebellum, striatum, limbic forebrain, hippocampus, cerebral cortex, and brainstem. The same regions were also analyzed for cannabinoid receptor binding and WIN-55,212-2-stimulated guanylyl-5'-O-(gamma-[35S]thio)-triphosphate ([35S]GTPgammaS) binding to test the development of the well known down-regulation/desensitization phenomenon. Results were as follows: As expected, cannabinoid receptor binding and WIN-55,212-2-stimulated [35S]GTPgammaS binding decreased in most of the brain areas of delta9-THC-tolerant rats. The only region exhibiting no changes in both parameters was the limbic forebrain. This same region exhibited a marked (almost fourfold) increase in the content of AEA after 8 days of delta9-THC treatment. By contrast, the striatum exhibited a decrease in AEA contents, whereas no changes were found in the brainstem, hippocampus, cerebellum, or cerebral cortex. The increase in AEA contents observed in the limbic forebrain was accompanied by a tendency of NArPE levels to decrease, whereas in the striatum, no significant change in NArPE contents was found. The contents of 2-AG were unchanged in brain regions from delta9-THC-tolerant rats, except for the striatum where they dropped significantly. In summary, the present results show that prolonged activation of cannabinoid receptors leads to decreased endocannabinoid contents and signaling in the striatum and to increased AEA formation in the limbic forebrain. The pathophysiological implications of these findings are discussed in view of the proposed roles of endocannabinoids in the control of motor behavior and emotional states.

Prenatal Delta(9)-tetrahydrocannabinol exposure modifies proenkephalin gene expression in the fetal rat brain: sex-dependent differences

Perinatal Delta(9)-tetrahydrocannabinol (Delta(9)-THC) exposure in rats resulted in enhanced morphine self-administration behavior, naloxone-precipitated withdrawal signs or changes in pain sensitivity, which have been related to changes in micro-opioid receptor binding and/or proenkephalin mRNA levels in several brain regions. However, despite exposure of these animals to Delta(9)-THC from fetal ages, the effects were studied only when animals matured, whereas there is no study on possible changes caused by this cannabinoid during the prenatal ontogeny of opioidergic neurons. The purpose of the present study was to examine the changes in proenkephalin mRNA levels, measured by using in situ hybridization, in several brain nuclei of rat fetuses that had been daily exposed to Delta(9)-THC from the 5th day of gestation. Results were as follows. Prenatal Delta(9)-THC exposure altered proenkephalin mRNA levels in most of the brain areas studied at different fetal ages, but the effects were different between sexes. Thus, proenkephalin mRNA levels increased in females, but decreased in males that had been prenatally exposed to Delta(9)-THC. This was observed in the caudate-putamen, hypothalamic paraventricular and ventromedial nuclei and cerebral cortex. No changes were observed, however, in the subventricular zones of the caudate-putamen, neocortex and nucleus accumbens. In summary, prenatal Delta(9)-THC exposure produced a sex-dependent effect in proenkephalin mRNA levels in several brain structures of rat fetuses.

Cannabinoid CB(1) receptors colocalize with tyrosine hydroxylase in cultured fetal mesencephalic neurons and their activation increases the levels of this enzyme

The incubation of cultured fetal mesencephalic neurons with Delta(9)-tetrahydrocannabinol (Delta(9)-THC) increased the activity of tyrosine hydroxylase (TH) and this increase was reversed by SR141716A, a specific antagonist for cannabinoid CB(1) receptors. In the present work, we extended these earlier observations by addressing two objectives. First, we characterized at a molecular level the presence of CB(1) receptors in cultured fetal mesencephalic neurons using two strategies: (i) analyzing the presence of CB(1) receptor gene transcripts by Northern blot, and (ii) measuring [3H]WIN-55,212-2 binding in membrane fractions obtained from these cells, as well as evaluating the potential increase in [35S]-guanylyl-5'-O-(gamma-thio)-triphosphate ([35S]GTPgammaS) binding caused by the activation of these receptors with WIN-55,212-2, a synthetic agonist. Northern blot analyses demonstrated the presence of small, but measurable levels of CB(1) receptor mRNA in cultured fetal mesencephalic neurons. The presence of these transcripts was accompanied by the presence of receptor binding protein, as revealed by a small, but specific, [3H]WIN-55, 212-2 binding in membrane fractions obtained from these cells. These CB(1) receptors are coupled to GTP-binding proteins, as the incubation of membrane fractions obtained from these cells with WIN-55,212-2 slightly, but significantly increased [35S]GTPgammaS binding. This fact indicated the existence, not only of receptor binding, but also of a functional receptor transduction pathway. As a second objective, we examined the potential colocalization of CB(1) receptors and TH in these cells by double-labelling immunocytochemistry. We also determined by Western blotting whether the previously observed Delta(9)-THC-induced increase in TH activity was accompanied by increased TH protein levels. Cultured fetal mesencephalic neurons exhibit diverse cell phenotypes, with CB(1) receptors localized only on TH-containing neurons. In addition, we found that the incubation of fetal mesencephalic neurons with medium containing Delta(9)-THC increased TH protein levels, in concordance with the previously reported increase in TH activity. Collectively, our results support the notion that CB(1) receptors are present in cultured fetal mesencephalic TH-containing neurons, despite their absence in the corresponding neurons in the adult brain. Thus, it is likely that the effects of cannabinoids on TH activity are direct. All this data strengthen the view that cannabinoid receptors are atypically located during brain development and that they might play an important role during this process, in particular on the phenotypical expression of TH-containing neurons.

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.

Immunocytochemical demonstration of CB1 cannabinoid receptors in the anterior lobe of the pituitary gland

Both exogenous and endogenous cannabinoids can influence hormone secretion from the anterior pituitary gland. A large body of information proves that the primary target of these effects is the neuroendocrine hypothalamus. However, recent studies using cannabinoid (CB) receptor autoradiography, messenger RNA in-situ hybridization and in-vitro analysis, indicate direct effects of cannabinoids at the level of the anterior pituitary gland itself. In the present paper, the immunocytochemical distribution of CB in the adult rat anterior pituitary was studied using specific polyclonal antibodies against CB1 (central) and CB2 (peripheral) receptors. Due to its resolution, this method allowed identification of individual anterior pituitary cells possessing cannabinoid receptors. The specific hormone immunoreactive cells with receptor-like immunoreactivity were compared on adjacent sections. CB1-like immunoreactivity (CB1ir) was found in the lactotroph cells as well as in luteinizing hormone (LH) secreting gonadotrophs. The CB1ir positive material present in the cytoplasm of these cells was less homogeneous than the hormone immunoreactive material, and it was also seen at the periphery of the cells, presumably on the cell membrane. No CB1ir was found in growth hormone (GH) secreting cells and it was hardly seen in the corticotrophs. No CB1ir was detected in the posterior pituitary. CB2ir was not observed in any part of the pituitary gland. The results support the view that the site of action of cannabinoids on neuroendocrine regulatory mechanisms may be both at pituitary and hypothalamic levels. We suggest that at least the direct effect of cannabinoids on the regulation of LH and prolactin secretion is mediated via CB1 cannabinoid receptors in the anterior pituitary.

Analysis of cannabinoid receptor binding and mRNA expression and endogenous cannabinoid contents in the developing rat brain during late gestation and early postnatal period

Cannabinoid CB(1) receptors emerge early in the rat brain during prenatal development, supporting their potential participation in events related to neural development. In the present investigation, we completed earlier studies, analyzing CB(1) receptor binding and mRNA expression by using autoradiography and in situ hybridization, respectively, in the brain of rat fetuses at gestational day (GD) 21 and of newborns at postnatal days (PND) 1 and 5, in comparison with the adult brain. These analyses were paralleled by quantitation of levels of anandamide and its precursor, N-arachidonoyl-phosphatidylethanolamine (NAPE), and of 2-arachidonoyl-glycerol (2-AG), carried out by using gas chromatography / mass spectrometry of the tri-methyl-sylyl-ether derivatives. As expected, CB(1) receptor binding was detected at GD21 in a variety of brain structures. In most of them, such as the hippocampus, cerebral cortex, cerebellum, basal ganglia, and limbic nuclei, there were no marked differences in the density of CB(1) receptors in animals at GD21 as compared to early newborns (PND1 and 5), although it markedly increased in these regions in adulthood. However, with the exception of the cerebellum and, in part, the caudate-putamen, the pattern observed for binding in these regions was clearly different from that observed for mRNA expression of the CB(1) receptor, which currently exhibited the highest levels at PND1 and the lowest in the adult brain. This was also seen in the basolateral amygdaloid nucleus, ventromedial hypothalamic nucleus, medial habenula, and other structures. In the caudate-putamen and, particularly, in the cerebellum, mRNA expression was higher in the adult brain as compared with other ages. As previously reported, specific binding for CB(1) receptors was also detected at GD21 in white matter areas, such as the corpus callosum, anterior commissure, fornix, fimbria, stria medullaris, stria terminalis, and fasciculus retroflexum. With the exception of the anterior commissure and the fimbria, specific binding progressively decreased at PND1 and PND5 until disappearing in the adult brain. In the fimbria, the highest values of binding were seen at PND1, but binding also completely disappeared in the adult brain, whereas in the anterior commissure, specific binding at PND1 and PND5 was lesser than that observed at GD21 and, particularly, in adulthood. CB(1) receptor mRNA expression was not detected in these white matter areas, thus dismissing the possible presence of these receptors in glial cells rather than in neuronal axons. However, mRNA expression was detected in the brainstem, an area also rich in white matter, and it mostly correlated with receptor binding, exhibiting a progressive decrease from GD21 up to adulthood. CB(1) receptor mRNA expression was also detected at GD21 in atypical areas where binding was not detected. These areas are proliferative regions, such as the subventricular zones of the neocortex, striatum, and nucleus accumbens. This atypical location only persisted at PND1 and PND5 in the striatal subventricular zone, but disappeared in the adult brain. We also found measurable levels of different endogenous cannabinoids in the developing brain. High levels of 2-AG, comparable to those found in the adult brain, were measured at GD21, whereas significantly lower levels were measured for anandamide and NAPE at this fetal age compared with the levels found in the adult brain. Levels of anandamide and NAPE increased during the early postnatal period until reaching the maximum in the adult brain. By contrast, 2-AG levels peaked at PND1, with values approximately twofold higher than those found at the other ages. In summary, all these data demonstrate that the endogenous cannabinoid system, constituted by endogenous ligands and receptor signaling pathways, is present in the developing brain, which suggests a possible specific role of this system in key processes of neural development. (c) 1999 Wiley-Liss, Inc.

Role of endocannabinoids in brain development

In addition to those functions that have been extensively addressed in this special issue, such as nociception, motor activity, neuroendocrine regulation, immune function and others, the endogenous cannabinoid system seems to play also a role in neural development. This view is based on a three-fold evidence. A first evidence emerges from neurotoxicological studies that showed that synthetic and plant-derived cannabinoids, when administered to pregnant rats, produced a variety of changes in the maturation of several neurotransmitters and their associated-behaviors in their pups, changes that were evident at different stages of brain development. A second evidence comes from studies that demonstrated the early appearance of elements of the endogenous cannabinoid system (receptors and ligands) during the brain development. The atypical location of these elements during fetal and early postnatal periods favours the notion that this system may play a role in specific molecular events related to neural development. Finally, a third evidence derives from studies using cultures of fetal glial or neuronal cells. Cannabinoid receptors are present in some of these cultured cells and their activation produced a set of cellular effects consistent with a role of this system in the process of neural development. All this likely supports that endocannabinoids, early synthesized in nervous cells, play a role in events related to development, by acting through the activation of second messenger-coupled cannabinoid receptors.

Extrapyramidal and neuroendocrine effects of AM404, an inhibitor of the carrier-mediated transport of anandamide

A selective inhibitor of the carrier-mediated transport of endogenous cannabinoids, N-(4-hydroxyphenyl)-arachidonylethanolamide (AM404), has been recently synthesized and proposed as a useful tool for studying the physiological effects of endogenous cannabinoids and as a potential therapeutic agent in a variety of diseases. In the present study, we have examined the effects of this compound in two important brain processes in which a role for anandamide and other endogenous cannabinoids has been claimed: neuroendocrine regulation and extrapyramidal motor activity. A single and well-characterized dose of AM404, which presumably resulted in a significant elevation of the levels of endogenous cannabinoids, produced a marked decrease in plasma prolactin (PRL) levels, with no changes in luteinizing hormone (LH) levels. This decrease in PRL levels was accompanied by an increase in the activity of tyrosine hydroxylase (TH) in the medial basal hypothalamus. Both decreased PRL secretion and increased hypothalamic TH activity have been reported to occur after the administration of anandamide. Administration of AM404 also produced a marked motor inhibition in the open-field test, as also reported for anandamide, with a decrease in ambulatory and exploratory activities and an increase in the time spent in inactivity. This was accompanied by a decrease in the activity of TH in the substantia nigra, an effect also previously observed for anandamide.

Identification of endocannabinoids and cannabinoid CB(1) receptor mRNA in the pituitary gland

Most data on effects of natural and synthetic cannabinoids on anterior pituitary hormone secretion point out to a primary impact on the hypothalamus. There is also some evidence, however, of possible direct actions of these compounds on the anterior pituitary, although the presence of cannabinoid receptors in the pituitary has not been documented as yet. In the present study, we evaluated the presence of cannabinoid CB(1) receptor-mRNA transcripts in the pituitary gland by in situ hybridization. We observed CB(1) receptor-mRNA transcripts in the anterior pituitary and to a lesser extent in the intermediate lobe whereas they were absent in the neural lobe. We then examined whether CB(1) receptor-mRNA levels in both pituitary lobes responded to chronic activation by a specific agonist, as did receptors located in adjacent hypothalamic nuclei and in other brain regions. Daily administration of CP-55,940 for 18 days produced a small, but statistically significant paradoxical increase in CB(1) receptor-mRNA levels in the anterior pituitary, with no changes in the intermediate lobe, in contrast to reduced CB(1) receptor-mRNA levels observed in the ventromedial hypothalamic nucleus (VMN), and to decreased CB(1) receptor binding in the VMN and the arcuate nucleus. The time-course of up-regulation of CB(1) receptor-mRNA transcripts in the anterior lobe was biphasic; daily administration of Delta(9)-tetrahydrocannabinol produced an early and marked decrease in CB(1) receptor-mRNA levels after 1 and 3 days, followed by normalization after 7 days and by a small increase after 14 days. We also checked whether endogenous cannabinoid ligands are present in the anterior pituitary and the hypothalamus. Although anandamide itself was detected only in trace amounts, concentrations of its precursor N-arachidonoyl-phosphatidyl-ethanolamine and of 2-arachidonoyl-glycerol were found in both tissues, suggesting that endocannabinoids may be synthetized in the anterior pituitary. In summary, CB(1) receptors and corresponding ligands seem to be expressed in cells of the anterior and intermediate lobes of the pituitary, but the response of CB(1) receptor-mRNA transcripts in the anterior lobe to chronic agonist activation is different than the desensitization observed in hypothalamic nuclei.