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Development of cannabinoid 1 receptor protein and messenger RNA in monkey dorsolateral prefrontal cortex.

ABSTRACT: Adolescent cannabis use is associated with an increased risk of schizophrenia and with impairments in cognitive processes reliant on the circuitry of the dorsolateral prefrontal cortex (DLPFC). Additionally, maternal cannabis use is associated with cognitive dysfunction in offspring. The effects of cannabis are mediated by the cannabinoid 1 receptor (CB1R), which is present in high density in the primate DLPFC. In order to determine how developmental changes in CB1Rs might render DLPFC circuitry vulnerable to cannabis exposure, we examined the density and innervation patterns of CB1R-immunoreactive (IR) axons and the expression of CB1R mRNA in the DLPFC from 81 macaque monkeys, ranging in age from embryonic 82 days to 18 years. Overall CB1R immunoreactivity in the gray matter robustly increased during the perinatal period and achieved adult levels by 1 week postnatal. However, laminar analyses revealed that CB1R-IR axon density significantly decreased with age in layers 1-2 but significantly increased in layer 4, especially during adolescence. In contrast, CB1R mRNA levels were highest 1 week postnatal, declined over the next 2 months, and then remained unchanged into adulthood. These findings provide a potential substrate for discrete, age-dependent effects of cannabis exposure on the maturation of primate DLPFC circuitry.

SUBMITTER: Eggan SM

PROVIDER: S-EPMC2852503 | biostudies-literature | 2010 May

REPOSITORIES: biostudies-literature

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Development of cannabinoid 1 receptor protein and messenger RNA in monkey dorsolateral prefrontal cortex.

Eggan Stephen M SM Mizoguchi Yoshito Y Stoyak Samuel R SR Lewis David A DA

Cerebral cortex (New York, N.Y. : 1991) 20090824 5

Adolescent cannabis use is associated with an increased risk of schizophrenia and with impairments in cognitive processes reliant on the circuitry of the dorsolateral prefrontal cortex (DLPFC). Additionally, maternal cannabis use is associated with cognitive dysfunction in offspring. The effects of cannabis are mediated by the cannabinoid 1 receptor (CB1R), which is present in high density in the primate DLPFC. In order to determine how developmental changes in CB1Rs might render DLPFC circuitry ...[more]

PMID: 19703937

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Project description:Exposure to cannabis impairs cognitive functions reliant on the circuitry of the dorsolateral prefrontal cortex (DLPFC) and increases the risk of schizophrenia. The actions of cannabis are mediated via the brain cannabinoid 1 receptor (CB1R), which in rodents is heavily localized to the axon terminals of cortical GABA basket neurons that contain cholecystokinin (CCK). Differences in the laminar distribution of CB1R-immunoreactive (IR) axons have been reported between rodent and monkey neocortex, suggesting that the cell type(s) containing CB1Rs, and the synaptic targets of CB1R-IR axon terminals, may differ across species; however, neither the relationship of CB1Rs to CCK-containing interneurons, nor the postsynaptic targets of CB1R and CCK axon terminals, have been examined in primate DLPFC. Consequently, we compared the distribution patterns of CB1R- and CCK-IR structures, determined the proportions of CB1R and CCK neurons that were dual-labeled, and identified the synaptic types and postsynaptic targets of CB1R- and CCK-IR axon terminals in macaque monkey DLPFC. By light microscopy, CB1R- and CCK-IR axons exhibited a similar laminar distribution, with their greatest densities in layer 4. Dual-label fluorescence experiments demonstrated that 91% of CB1R-IR neurons were immunopositive for CCK, whereas only 51% of CCK-IR neurons were immunopositive for CB1R. By electron microscopy, all synapses formed by CB1R-IR axon terminals were symmetric, whereas CCK-IR axon terminals formed both symmetric (88%) and asymmetric (12%) synapses. The primary postsynaptic target of both CB1R- and CCK-IR axon terminals forming symmetric synapses was dendritic shafts (81-88%), with the remainder targeting cell bodies or dendritic spines. Thus, despite species differences in laminar distribution, CB1Rs are principally localized to CCK basket neuron axons in both rodent neocortex and monkey DLPFC. These axons target the perisomatic region of pyramidal neurons, providing a potential anatomical substrate for the impaired function of the DLPFC associated with cannabis use and schizophrenia.

Project description:ContextCannabis use is associated with both impaired cognitive functions, including working memory, and an increased risk of schizophrenia. Schizophrenia is characterized by impairments in working memory that are associated with reduced gamma-aminobutyric acid (GABA) neurotransmission in the dorsolateral prefrontal cortex. The cannabinoid 1 receptor (CB1R) is highly expressed in the dorsolateral prefrontal cortex, is contained in the axon terminals of a subpopulation of perisomatic-targeting GABA neurons, and, when activated, suppresses the release of GABA.ObjectiveTo determine the potential relationship between CB1R signaling and altered GABA neurotransmission in schizophrenia by evaluating CB1R messenger RNA (mRNA) and protein expression in the dorsolateral prefrontal cortex.DesignIn situ hybridization and immunocytochemistry techniques were used to examine the cortical levels of CB1R mRNA and protein, respectively.SettingBrain specimens were obtained from autopsies conducted at the Allegheny County Medical Examiner's Office, Pittsburgh, Pennsylvania.ParticipantsPostmortem brain specimens from 23 pairs of subjects with schizophrenia and age-, sex-, and postmortem interval-matched comparison subjects, as well as brain specimens from 18 macaque monkeys with long-term exposure to haloperidol, olanzapine, or placebo.Main outcome measuresOptical density measures of CB1R mRNA expression and protein levels and correlations with previously reported glutamic acid decarboxylase 67 and cholecystokinin mRNA measures.ResultsLevels of CB1R mRNA were significantly lower by 14.8% in the subjects with schizophrenia. Similarly, CB1R protein levels, assessed by radioimmunocytochemistry and standard immunocytochemistry, were significantly decreased by 11.6% and 13.9%, respectively. Group differences in CB1R mRNA levels were significantly correlated with those in glutamic acid decarboxylase 67 and cholecystokinin mRNA levels. Expression of CB1R mRNA was not changed in antipsychotic-exposed monkeys, and neither CB1R mRNA levels nor protein levels were affected by potential confounding factors in the subjects with schizophrenia.ConclusionsThis combination of findings suggests the testable hypothesis that reduced CB1R mRNA and protein levels in schizophrenia represent a compensatory mechanism to increase GABA transmission from perisomatic-targeting cholecystokinin interneurons with impaired GABA synthesis.

Project description:The pathophysiology of schizophrenia includes altered neurotransmission, dysregulated intracellular signaling pathway activity, and abnormal dendritic morphology that contribute to deficits of synaptic plasticity in the disorder. These processes all require dynamic protein-protein interactions at cell membranes. Lipid modifications target proteins to membranes by increasing substrate hydrophobicity by the addition of a fatty acid or isoprenyl moiety, and recent evidence suggests that dysregulated posttranslational lipid modifications may play a role in multiple neuropsychiatric disorders, including schizophrenia. Consistent with these emerging findings, we have recently reported decreased protein S-palmitoylation in schizophrenia. Protein prenylation is a lipid modification that occurs upstream of S-palmitoylation on many protein substrates, facilitating membrane localization and activity of key intracellular signaling proteins. Accordingly, we hypothesized that, in addition to palmitoylation, protein prenylation may be abnormal in schizophrenia. To test this, we assayed protein expression of the five prenyltransferase subunits (FNTA, FNTB, PGGT1B, RABGGTA, and RABGGTB) in postmortem dorsolateral prefrontal cortex from patients with schizophrenia and paired comparison subjects (n = 13 pairs). We found decreased levels of FNTA (14%), PGGT1B (13%), and RABGGTB (8%) in schizophrenia. To determine whether upstream or downstream factors may be driving these changes, we also assayed protein expression of the isoprenoid synthases FDPS and GGPS1 and prenylation-dependent processing enzymes RCE and ICMT. We found these upstream and downstream enzymes to have normal protein expression. To rule out effects from chronic antipsychotic treatment, we assayed FNTA, PGGT1B, and RABGGTB in the cortex from rats treated long-term with haloperidol decanoate and found no change in the expression of these proteins. Given the role prenylation plays in localization of key signaling proteins found at the synapse, these data offer a potential mechanism underlying abnormal protein-protein interactions and protein localization in schizophrenia.

Project description:BackgroundMethamphetamine (MA), is an extremely addictive stimulant that adversely affects the central nervous system. Accumulating evidence indicates that molecular mechanisms such as oxidative stress, apoptosis, and autophagy are involved in the toxicity of MA. Considering experimental animal studies exhibiting MA-induced neurotoxicity, the relevance of these findings needs to be evidently elucidated in human MA users. It is generally assumed that multiple chemical substances released in the brain following MA-induced metabolic activation are primary factors underlying damage of neural cells. Hence, this study aimed to investigate the role of autophagy and apoptosis as well as oxidative stress in the brain of postmortem MA-induced toxicity.Materials and methodsIn this study, we determine the gene expression of autophagy and apoptosis, including BECN1, MAP1ALC3, CASP8, TP53, and BAX genes in ten healthy controls and ten chronic users of MA postmortem dorsolateral prefrontal cortex (DLPFC) by real-time polymerase chain reaction. Also, we applied immunohistochemistry in formalin-fixed and paraffin-embedded human brain samples to analyze brain-derived neurotrophic factor (BDNF). Also, spectrophotometry was performed to measure glutathione (GSH) content.ResultsThe expression level of apoptotic and autophagic genes (BECN1, MAP1ALC3, CASP8, TP53, and BAX) were significantly elevated, while GSH content and BDNF showed substantial reductions in DLPFC of chronic MA users. Discussion: Our data showed that MA addiction provokes transduction pathways, namely apoptosis and autophagy, along with oxidative mechanisms in DLPFC. Also, MA induces multiple functional and structural perturbations in the brain, determining its toxicity and possibly contributing to neurotoxicity.DiscussionOur study showed BDNF-positive cells as well as GSH amount, displayed significant declines in DLPFC of MA user. MA addiction provokes transduction pathways, namely apoptosis and autophagy, along with oxidative mechanisms in DLPFC. However, further investigations are needed to throw light on the cellular and molecular mechanisms that act in the various regions of the addicted brain, especially in DLPFC.

Dataset Information

Development of cannabinoid 1 receptor protein and messenger RNA in monkey dorsolateral prefrontal cortex.

Publications

Development of cannabinoid 1 receptor protein and messenger RNA in monkey dorsolateral prefrontal cortex.

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