miRNA Expression Analysis of the Hippocampus in a Vervet Monkey Model of Fetal Alcohol Spectrum Disorder Reveals a Potential Role in Global mRNA Downregulation.

MicroRNAs (miRNAs) are short-length non-protein-coding RNA sequences that post-transcriptionally regulate gene expression in a broad range of cellular processes including neuro- development and have previously been implicated in fetal alcohol spectrum disorders (FASD). In this study, we use our vervet monkey model of FASD to follow up on a prior multivariate (developmental age × ethanol exposure) mRNA analysis (GSE173516) to explore the possibility that the global mRNA downregulation we observed in that study could be related to miRNA expression and function. We report here a predominance of upregulated and differentially expressed miRNAs. Further, the 24 most upregulated miRNAs were significantly correlated with their predicted targets (Target Scan 7.2). We then explored the relationship between these 24 miRNAs and the fold changes observed in their paired mRNA targets using two prediction platforms (Target Scan 7.2 and miRwalk 3.0). Compared to a list of non-differentially expressed miRNAs from our dataset, the 24 upregulated and differentially expressed miRNAs had a greater impact on the fold changes of their corresponding mRNA targets across both platforms. Taken together, this evidence raises the possibility that ethanol-induced upregulation of specific miRNAs might contribute functionally to the general downregulation of mRNAs observed by multiple investigators in response to prenatal alcohol exposure.

Age and Sex-Related Changes in Retinal Function in the Vervet Monkey.

Among the deficits in visual processing that accompany healthy aging, the earliest originate in the retina. Moreover, sex-related differences in retinal function have been increasingly recognized. To better understand the dynamics of the retinal aging trajectory, we used the light-adapted flicker electroretinogram (ERG) to functionally assess the state of the neuroretina in a large cohort of age- and sex-matched vervet monkeys (N = 35), aged 9 to 28 years old, with no signs of obvious ocular pathology. We primarily isolated the cone-bipolar axis by stimulating the retina with a standard intensity light flash (2.57 cd/s/m2) at eight different frequencies, ranging from 5 to 40 Hz. Sex-specific changes in the voltage and temporal characteristics of the flicker waveform were found in older individuals (21-28 years-old, N = 16), when compared to younger monkeys (9-20 years-old, N = 19), across all stimulus frequencies tested. Specifically, significantly prolonged implicit times were observed in older monkeys (p < 0.05), but a significant reduction of the amplitude of the response was only found in old male monkeys (p < 0.05). These changes might reflect ongoing degenerative processes targeting the retinal circuitry and the cone subsystem in particular. Altogether, our findings corroborate the existing literature in humans and other species, where aging detrimentally affects photopic retinal responses, and draw attention to the potential contribution of different hormonal environments.

Dose-Related Reduction in Hippocampal Neuronal Populations in Fetal Alcohol Exposed Vervet Monkeys.

Fetal alcohol spectrum disorder (FASD) is a chronic debilitating condition resulting in behavioral and intellectual impairments and is considered the most prevalent form of preventable mental retardation in the industrialized world. We previously reported that 2-year-old offspring of vervet monkey (Chlorocebus sabeus) dams drinking, on average, 2.3 ± 0.49 g ethanol per Kg maternal body weight 4 days per week during the last third of pregnancy had significantly lower numbers of CA1 (-51.6%), CA2 (-51.2%) and CA3 (-42.8%) hippocampal neurons, as compared to age-matched sucrose controls. Fetal alcohol-exposed (FAE) offspring also showed significantly lower volumes for these structures at 2 years of age. In the present study, we examined these same parameters in 12 FAE offspring with a similar average but a larger range of ethanol exposures (1.01-2.98 g/Kg/day; total ethanol exposure 24-158 g/Kg). Design-based stereology was performed on cresyl violet-stained and doublecortin (DCX)-immunostained sections of the hippocampus. We report here significant neuronal deficits in the hippocampus with a significant negative correlation between daily dose and neuronal population in CA1 (r2 = 0.486), CA2 (r2 = 0.492), and CA3 (r2 = 0.469). There were also significant correlations between DCX population in the dentate gyrus and daily dose (r2 = 0.560). Both correlations were consistent with linear dose-response models. This study illustrates that neuroanatomical sequelae of fetal ethanol exposure are dose-responsive and suggests that there may be a threshold for this effect.

mRNA expression analysis of the hippocampus in a vervet monkey model of fetal alcohol spectrum disorder.

BACKGROUND: Fetal alcohol spectrum disorders (FASD) are common, yet preventable developmental disorders that stem from prenatal exposure to alcohol. This exposure leads to a wide array of behavioural and physical problems with a complex and poorly defined biological basis. Molecular investigations to date predominantly use rodent animal models, but because of genetic, developmental and social behavioral similarity, primate models are more relevant. We previously reported reduced cortical and hippocampal neuron levels in an Old World monkey (Chlorocebus sabaeus) model with ethanol exposure targeted to the period of rapid synaptogenesis and report here an initial molecular study of this model. The goal of this study was to evaluate mRNA expression of the hippocampus at two different behavioural stages (5 months, 2 years) corresponding to human infancy and early childhood. METHODS: Offspring of alcohol-preferring or control dams drank a maximum of 3.5 g ethanol per kg body weight or calorically matched sucrose solution 4 days per week during the last 2 months of gestation. Total mRNA expression was measured with the Affymetrix GeneChip Rhesus Macaque Genome Array in a 2 × 2 study design that interrogated two independent variables, age at sacrifice, and alcohol consumption during gestation. RESULTS AND DISCUSSION: Statistical analysis identified a preferential downregulation of expression when interrogating the factor 'alcohol' with a balanced effect of upregulation vs. downregulation for the independent variable 'age'. Functional exploration of both independent variables shows that the alcohol consumption factor generates broad functional annotation clusters that likely implicate a role for epigenetics in the observed differential expression, while the variable age reliably produced functional annotation clusters predominantly related to development. Furthermore, our data reveals a novel connection between EFNB1 and the FASDs; this is highly plausible both due to the role of EFNB1 in neuronal development as well as its central role in craniofrontal nasal syndrome (CFNS). Fold changes for key genes were subsequently confirmed via qRT-PCR. CONCLUSION: Prenatal alcohol exposure leads to global downregulation in mRNA expression. The cellular interference model of EFNB1 provides a potential clue regarding how genetically susceptible individuals may develop the phenotypic triad generally associated with classic fetal alcohol syndrome.

FGF21 suppresses alcohol consumption through an amygdalo-striatal circuit.

Excessive alcohol consumption is a major health and social issue in our society. Pharmacologic administration of the endocrine hormone fibroblast growth factor 21 (FGF21) suppresses alcohol consumption through actions in the brain in rodents, and genome-wide association studies have identified single nucleotide polymorphisms in genes involved with FGF21 signaling as being associated with increased alcohol consumption in humans. However, the neural circuit(s) through which FGF21 signals to suppress alcohol consumption are unknown, as are its effects on alcohol consumption in higher organisms. Here, we demonstrate that administration of an FGF21 analog to alcohol-preferring non-human primates reduces alcohol intake by 50%. Further, we reveal that FGF21 suppresses alcohol consumption through a projection-specific subpopulation of KLB-expressing neurons in the basolateral amygdala. Our results illustrate how FGF21 suppresses alcohol consumption through a specific population of neurons in the brain and demonstrate its therapeutic potential in non-human primate models of excessive alcohol consumption.

The Influence of Tobacco Smoke/Nicotine on CYP2A Expression in Human and African Green Monkey Lungs.

CYP2A enzymes metabolically inactivate nicotine and activate tobacco-derived procarcinogens [e.g., 4-[methylnitrosamino]-1-(3-pyridyl)-1-butanone]. Smoking decreases nicotine clearance, and chronic nicotine reduces hepatic CYP2A activity. However, little is known about the impact of smoking or nicotine on the expression of CYP2A in the lung. We investigated 1) the levels of human lung CYP2A mRNA in smokers versus nonsmokers and 2) the impact of daily nicotine treatment on lung CYP2A protein levels in African green monkeys (AGMs). Lung CYP2A13, CYP2A6, and CYP2A7 (and CYP1A2) mRNA levels in smokers and nonsmokers were assessed in Gene Expression Omnibus data sets (GSE30063, GSE108134, and GSE11784). The impact of chronic, twice-daily, subcutaneous nicotine at two doses (0.3 and 0.5 mg/kg) versus vehicle on lung CYP2A protein levels was assessed. The impact of ethanol self-administration was also investigated, with and without nicotine treatment. Smokers versus nonsmokers (from GSE30063 and GSE108134) had lower (1.04- to 1.12-fold) levels of lung CYP2A13, CYP2A6, and CYP2A7 (and higher CYP1A2) mRNA. Both doses of nicotine tested decreased AGM lung CYP2A protein (3- to 7-fold). Ethanol self-administration had no effect on AGM lung CYP2A protein, and there was no interaction between ethanol and nicotine. Our results suggest that smoking was associated with a reduction in human lung CYP2A13, CYP2A6, and CYP2A7 mRNA, consistent with the role of nicotine treatment in reducing AGM lung CYP2A protein. This regulation by smoking/nicotine will increase interindividual variation in lung CYP2A levels, which may impact the localized metabolism of inhaled drugs and tobacco smoke procarcinogens. SIGNIFICANCE STATEMENT: CYP2A13 and CYP2A6 are expressed in the lung and may contribute to local procarcinogen activation. Smokers had lower lung CYP2A mRNA levels compared with nonsmokers. Lung CYP2A protein expression was decreased by systemic treatment with nicotine. Decreased lung CYP2A expression may alter smoking-related lung cancer risk and tissue damage from other inhaled toxins. This novel regulatory impact of nicotine, including nicotine found in smoking-cessation nicotine-replacement therapies, may have potential benefits on smoking-related lung cancer risk.

Transient receptor potential vanilloid type 1 is expressed in the horizontal pathway of the vervet monkey retina.

The ubiquitous distribution of the classic endocannabinoid system (cannabinoid receptors CB1 and CB2) has been demonstrated within the monkey nervous system, including the retina. Transient receptor potential vanilloid type 1 (TRPV1) is a cannabinoid-like non-selective cation channel receptor that is present in the retina and binds to endovannilloids and endocannabinoids, like anandamide, 2-arachidonoylglycerol and N-arachidonoyl dopamine. Retinal expression patterns of TRPV1 are available for rodents and data in higher mammals like humans and monkeys are scarce. We therefore thoroughly examined the expression and localization of TRPV1 in the retina, at various eccentricities, of the vervet (Chlorocebus sabeus) monkey, using Western blots and immunohistochemistry. Our results demonstrate that TRPV1 is found mainly in the outer and inner plexiform layers, and in the retinal ganglion cell (RGC) layer with a higher density in the periphery. Co-immunolabeling of TRPV1 with parvalbumin, a primate horizontal cell marker, revealed a clear overlap of expression throughout the entire cell structure with most prominent staining in the cell body membrane and synaptic terminals. Furthermore, double labeling of TRPV1 and syntaxin was found throughout amacrine cells in the inner plexiform layer. Finally, double staining of TRPV1 and Brn3a allowed us to confirm its previously reported expression in the cell bodies and dendrites of RGCs. The presence of TRPV1 in the horizontal pathway suggests a function of this receptor in lateral inhibition between photoreceptors through the horizontal cells, and between bipolar cells through amacrine cells.

l-Serine Reduces Spinal Cord Pathology in a Vervet Model of Preclinical ALS/MND.

The early neuropathological features of amyotrophic lateral sclerosis/motor neuron disease (ALS/MND) are protein aggregates in motor neurons and microglial activation. Similar pathology characterizes Guamanian ALS/Parkinsonism dementia complex, which may be triggered by the cyanotoxin ß-N-methylamino-l-alanine (BMAA). We report here the occurrence of ALS/MND-type pathological changes in vervets (Chlorocebus sabaeus; n = 8) fed oral doses of a dry powder of BMAA HCl salt (210 mg/kg/day) for 140 days. Spinal cords and brains from toxin-exposed vervets were compared to controls fed rice flour (210 mg/kg/day) and to vervets coadministered equal amounts of BMAA and l-serine (210 mg/kg/day). Immunohistochemistry and quantitative image analysis were used to examine markers of ALS/MND and glial activation. UHPLC-MS/MS was used to confirm BMAA exposures in dosed vervets. Motor neuron degeneration was demonstrated in BMAA-dosed vervets by TDP-43+ proteinopathy in anterior horn cells, by reactive astrogliosis, by activated microglia, and by damage to myelinated axons in the lateral corticospinal tracts. Vervets dosed with BMAA + l-serine displayed reduced neuropathological changes. This study demonstrates that chronic dietary exposure to BMAA causes ALS/MND-type pathological changes in the vervet and coadministration of l-serine reduces the amount of reactive gliosis and the number of protein inclusions in motor neurons.

Retinal structure and function in monkeys with fetal alcohol exposure.

Exposure to ethanol in utero leads to several brain development disorders including retinal abnormalities whose underlying cellular pathogenesis remains elusive. We recently reported that fetal alcohol exposure (FAE) in vervet monkeys induces anomalies of full-field electroretinogram (ERG) waveforms that suggest premature aging of the retina. The goal of this study is to characterize the anatomo-functional mechanisms underlying the retinal changes observed in fetal alcohol exposed (FAE) monkeys, and age- and sex-matched normals. First, we examined in vivo the fundus of the eyes, measured intraocular pressure (IOP) and assessed cone activity using flicker ERG. Second, we investigated ex vivo, protein expression and anatomical organization of the retina using Western blotting, classical histology and immunohistochemistry. Our results indicated that the fundus of the eyes showed both, increased vascularization (tessellated fundus) and IOP in FAE monkeys. Furthermore, light-adapted flicker responses above 15 Hz were also significantly higher in FAE monkeys. Although there were no obvious changes in the overall anatomy in the FAE retina, Glial Fibrillary Acidic Protein (GFAP, a potent marker of astrocytes) immunoreactivity was increased in the FAE retinal ganglion cell layer indicating a strong astrogliosis. These alterations were present in juvenile (2 years old) monkeys and persist in adults (8 years old). Moreover, using specific cell type markers, no significant modifications in the morphology of the photoreceptors, horizontal cells, bipolar cells, and amacrine cells were observed. Our data indicate that FAE does indeed induce anatomical changes within the retinal ganglion cell layer that are reflected in the increased photosensitivity of the cone photoreceptors.

Perinatal MAO Inhibition Produces Long-Lasting Impairment of Serotonin Function in Offspring.

In addition to transmitter functions, many neuroamines have trophic or ontogenetic regulatory effects important to both normal and disordered brain development. In previous work (Mejia et al., 2002), we showed that pharmacologically inhibiting monoamine oxidase (MAO) activity during murine gestation increases the prevalence of behaviors thought to reflect impulsivity and aggression. The goal of the present study was to determine the extent to which this treatment influences dopamine and serotonin innervation of murine cortical and subcortical areas, as measured by regional density of dopamine (DAT) and serotonin transporters (SERT). We measured DAT and SERT densities at 3 developmental times (PND 14, 35 and 90) following inhibition of MAO A, or MAO B or both throughout murine gestation and early post-natal development. DAT binding was unaltered within the nigrostriatal pathway, but concurrent inhibition of MAO-A and MAO-B significantly and specifically reduced SERT binding by 10⁻25% in both the frontal cortex and raphe nuclei. Low levels of SERT binding persisted (PND 35, 90) after the termination (PND 21) of exposure to MAO inhibitors and was most marked in brain structures germane to the previously described behavioral changes. The relatively modest level of enzyme inhibition (25⁻40%) required to produce these effects mandates care in the use of any compound which might inhibit MAO activity during gestation.

Hematologic and biochemical RIs for an aged population of captive African Green monkeys (Chlorocebus aethiops sabaeus).

BACKGROUND: Established RIs for geriatric African Green monkeys (Chlorocebus aethiops sabaeus) are critical for clinical differentiation of normal aging from disease-related changes in this population. OBJECTIVE: The aim of this study was to establish hematologic and serum biochemical RIs for a Caribbean captive population of geriatric (≥ 15 years of age) African Green monkeys, or Vervets. METHODS: Inclusion and exclusion criteria were defined for a cohort of 109 healthy, aged (15- to 30-year-old, median 19-year-old) Vervets. Both male (34) and female (75) monkeys were included in RI generation. Complete manual and analyzer-generated blood counts and serum biochemistry profiles were performed at Ross University School of Veterinary Medicine, West Farm, St. Kitts, West Indies. All results were evaluated using Reference Value Advisor. Isolated outliers were identified using Dixon's outlier range statistic and not included in determination of RIs for individual analytes. Reference intervals were determined using parametric and nonparametric methods depending on the distribution. Data, including mean, median, maximum, and minimum values, were tabulated. RESULTS: Of the 109 animals, 12 monkeys were excluded due to abnormal physical examination results (2 monkeys), and ≥ 2 confirmed outliers (9 monkeys), or evidence of disease based on laboratory data (one monkey). CONCLUSIONS: This study provides useful RIs for assessment of hematology and serum biochemical variables in a geriatric population of African Green monkeys in the Caribbean.

Prenatal Alcohol Exposure Affects Progenitor Cell Numbers in Olfactory Bulbs and Dentate Gyrus of Vervet Monkeys.

Fetal alcohol exposure (FAE) alters hippocampal cell numbers in rodents and primates, and this may be due, in part, to a reduction in the number or migration of neuronal progenitor cells. The olfactory bulb exhibits substantial postnatal cellular proliferation and a rapid turnover of newly formed cells in the rostral migratory pathway, while production and migration of postnatal neurons into the dentate gyrus may be more complex. The relatively small size of the olfactory bulb, compared to the hippocampus, potentially makes this structure ideal for a rapid analysis. This study used the St. Kitts vervet monkey (Chlorocebus sabeus) to (1) investigate the normal developmental sequence of post-natal proliferation in the olfactory bulb and dentate gyrus and (2) determine the effects of naturalistic prenatal ethanol exposure on proliferation at three different ages (neonate, five months and two years). Using design-based stereology, we found an age-related decrease of actively proliferating cells in the olfactory bulb and dentate gyrus for both control and FAE groups. Furthermore, at the neonatal time point, the FAE group had fewer actively proliferating cells as compared to the control group. These data are unique with respect to fetal ethanol effects on progenitor proliferation in the primate brain and suggest that the olfactory bulb may be a useful structure for studies of cellular proliferation.

Hippocampal neuron populations are reduced in vervet monkeys with fetal alcohol exposure.

Prenatal exposure to beverage alcohol is a major cause of mild mental retardation and developmental delay. In nonendangered alcohol-preferring vervet monkeys, we modeled the most common nondysmorphic form of fetal alcohol syndrome disorder with voluntary drinking during the third trimester of pregnancy. Here, we report significant numerical reductions in the principal hippocampal neurons of fetal alcohol-exposed (FAE) offspring, as compared to age-matched, similarly housed conspecifics with isocaloric sucrose exposure. These deficits, particularly marked in CA1 and CA3, are present neonatally and persist through infancy (5 months) and juvenile (2 years) stages. Although the volumes of hippocampal subdivisions in FAE animals are not atypical at birth, by age 2, they are only 65-70% of those estimated in age-matched controls. These data suggest that moderate, naturalistic alcohol consumption during late pregnancy results in a stable loss of hippocampal neurons and a progressive reduction of hippocampal volume.

A deficit in face-voice integration in developing vervet monkeys exposed to ethanol during gestation.

Children with fetal alcohol spectrum disorders display behavioural and intellectual impairments that strongly implicate dysfunction within the frontal cortex. Deficits in social behaviour and cognition are amongst the most pervasive outcomes of prenatal ethanol exposure. Our naturalistic vervet monkey model of fetal alcohol exposure (FAE) provides an unparalleled opportunity to study the neurobehavioral outcomes of prenatal ethanol exposure in a controlled experimental setting. Recent work has revealed a significant reduction of the neuronal population in the frontal lobes of these monkeys. We used an intersensory matching procedure to investigate audiovisual perception of socially relevant stimuli in young FAE vervet monkeys. Here we show a domain-specific deficit in audiovisual integration of socially relevant stimuli. When FAE monkeys were shown a pair of side-by-side videos of a monkey concurrently presenting two different calls along with a single audio track matching the content of one of the calls, they were not able to match the correct video to the single audio track. This was manifest by their average looking time being equally spent towards both the matching and non-matching videos. However, a group of normally developing monkeys exhibited a significant preference for the non-matching video. This inability to integrate and thereby discriminate audiovisual stimuli was confined to the integration of faces and voices as revealed by the monkeys' ability to match a dynamic face to a complex tone or a black-and-white checkerboard to a pure tone, presumably based on duration and/or onset-offset synchrony. Together, these results suggest that prenatal ethanol exposure negatively affects a specific domain of audiovisual integration. This deficit is confined to the integration of information that is presented by the face and the voice and does not affect more elementary aspects of sensory integration.

Standardized full-field electroretinography in the Green Monkey (Chlorocebus sabaeus).

Full-field electroretinography is an objective measure of retinal function, serving as an important diagnostic clinical tool in ophthalmology for evaluating the integrity of the retina. Given the similarity between the anatomy and physiology of the human and Green Monkey eyes, this species has increasingly become a favorable non-human primate model for assessing ocular defects in humans. To test this model, we obtained full-field electroretinographic recordings (ERG) and normal values for standard responses required by the International Society for Clinical Electrophysiology of Vision (ISCEV). Photopic and scotopic ERG recordings were obtained by full-field stimulation over a range of 6 log units of intensity in dark-adapted or light-adapted eyes of adult Green Monkeys (Chlorocebus sabaeus). Intensity, duration, and interval of light stimuli were varied separately. Reproducible values of amplitude and latency were obtained for the a- and b-waves, under well-controlled adaptation and stimulus conditions; the i-wave was also easily identifiable and separated from the a-b-wave complex in the photopic ERG. The recordings obtained in the healthy Green Monkey matched very well with those in humans and other non-human primate species (Macaca mulatta and Macaca fascicularis). These results validate the Green Monkey as an excellent non-human primate model, with potential to serve for testing retinal function following various manipulations such as visual deprivation or drug evaluation.

Pyroglutamate-3 amyloid-ß deposition in the brains of humans, non-human primates, canines, and Alzheimer disease-like transgenic mouse models.

Amyloid-ß (Aß) peptides, starting with pyroglutamate at the third residue (pyroGlu-3 Aß), are a major species deposited in the brain of Alzheimer disease (AD) patients. Recent studies suggest that this isoform shows higher toxicity and amyloidogenecity when compared to full-length Aß peptides. Here, we report the first comprehensive and comparative IHC evaluation of pyroGlu-3 Aß deposition in humans and animal models. PyroGlu-3 Aß immunoreactivity (IR) is abundant in plaques and cerebral amyloid angiopathy of AD and Down syndrome patients, colocalizing with general Aß IR. PyroGlu-3 Aß is further present in two nontransgenic mammalian models of cerebral amyloidosis, Caribbean vervets, and beagle canines. In addition, pyroGlu-3 Aß deposition was analyzed in 12 different AD-like transgenic mouse models. In contrast to humans, all transgenic models showed general Aß deposition preceding pyroGlu-3 Aß deposition. The findings varied greatly among the mouse models concerning age of onset and cortical brain region. In summary, pyroGlu-3 Aß is a major species of ß-amyloid deposited early in diffuse and focal plaques and cerebral amyloid angiopathy in humans and nonhuman primates, whereas it is deposited later in a subset of focal and vascular amyloid in AD-like transgenic mouse models. Given the proposed decisive role of pyroGlu-3 Aß peptides for the development of human AD pathology, this study provides insights into the usage of animal models in AD studies.

Ethanol self-administration and nicotine treatment induce brain levels of CYP2B6 and CYP2E1 in African green monkeys.

CYP2B6 and CYP2E1 are enzymes responsible for the metabolism of many centrally acting drugs, toxins and endogenous compounds. Human smokers and alcoholics have elevated levels of CYP2B6 and CYP2E1 in certain brain regions, which may contribute to altered drug efficacy, neurotoxicity and metabolic tolerance. The objective of this study was to determine the effects of ethanol self-administration and nicotine treatment, alone and in combination, on brain CYP2B6 and CYP2E1 levels in monkeys. Monkeys were randomized into four groups (N = 10/group): an ethanol-only group, a nicotine-only group, an ethanol + nicotine group and a control (no drug) group. Ethanol (10% alcohol in sucrose solution) was voluntarily self-administered by the monkeys and nicotine was given as subcutaneous injections (0.5 mg/kg bid). Immunocytochemistry revealed induction of both CYP2B6 and CYP2E1 protein in certain brain regions and cells within monkey brain as a result of ethanol self-administration, nicotine treatment and combined exposure to both drugs. Immunoblotting analyses demonstrated CYP2B6 induction by ethanol in the caudate, putamen and cerebellum (1.5-3.2 fold, P < 0.05), and CYP2E1 induction by nicotine in the frontal cortex and putamen (1.6-2.0 fold, P < 0.05). Combined ethanol and nicotine exposure induced CYP2B6 in the caudate, putamen, thalamus and cerebellum (1.4-2.4 fold, P < 0.05), and CYP2E1 in the frontal cortex and putamen (1.5-1.8, P < 0.05). CYP2B6 and CYP2E1 mRNA levels were unaffected by ethanol or nicotine exposure. In summary, ethanol and nicotine can induce CYP2B6 and CYP2E1 protein in the primate brain, which could potentially result in altered sensitivity to centrally acting drugs and toxins.

The effect of naltrexone on alcohol's stimulant properties and self-administration behavior in social drinkers: influence of gender and genotype.

BACKGROUND: Few pharmacological treatments for alcohol dependence are available. Moreover, the best supported treatment, naltrexone hydrochloride, appears to work for only some. METHODS: To investigate potential predictors of these differential responses, 40 social drinkers (20 women) were administered 6 days of treatment with naltrexone vs. placebo in a double-blind, counterbalanced, crossover design. At the end of each treatment period, participants received a single dose of their preferred alcoholic beverage followed by the opportunity to work for additional alcohol units using a progressive ratio (PR) breakpoint paradigm. All subjects but one were genotyped for the A118G polymorphism of the mu opioid receptor gene (OPRM1). RESULTS: Naltrexone decreased the ethanol-induced 'euphoria' to a priming dose of alcohol in two subgroups: (i) in women, and (ii) in subjects with the A118G polymorphism of the mu opioid receptor gene (OPRM1). Naltrexone did not decrease motivation to work for additional alcoholic beverages on the PR task regardless of gender or genotype. CONCLUSIONS: The results add to the evidence that naltrexone decreases positive subjective effects of alcohol, with preferential effects in distinct subgroups. Similar effects in heavier drinkers might decrease alcohol use.

Neuronal reduction in frontal cortex of primates after prenatal alcohol exposure.

Children with fetal alcohol spectrum disorders (FASD) show behavioral and intellectual impairments that indicate frontal lobe dysfunction, but the extent of damage to this region has not been clarified by brain imaging studies. This study uses the St Kitts vervet monkey, a species that voluntarily consumes beverage alcohol, to examine the effects of prenatal ethanol exposure. Pregnant vervets were allowed to drink the equivalent of 3-5 standard drinks four times a week during the third trimester. Using unbiased stereology, we estimated neuronal reduction and found significantly fewer cells in the frontal lobes of FASD offspring as well as an increased density of interstitial white matter neurons. These cytoarchitectonic effects are consistent with the behavioral and cognitive changes observed in FASD.

The dopamine D4 receptor gene and moderation of the association between externalizing behavior and IQ.

BACKGROUND: Dopaminergic neurotransmission is implicated in externalizing behavior problems, such as aggression and hyperactivity. Externalizing behavior is known to be negatively associated with cognitive ability. Activation of dopamine D4 receptors appears to inhibit the functioning of the prefrontal cortex, a brain region implicated in cognitive ability. The 7-repeat allele of the dopamine D4 receptor gene produces less efficient receptors, relative to other alleles, and this may alter the effects of dopamine on cognitive function. OBJECTIVE: To examine the influence of a polymorphism in the third exon of the dopamine D4 receptor gene on the association between externalizing behavior and IQ. DESIGN: In 1 community sample and 2 clinical samples, the presence or absence of the 7-repeat allele was examined as a moderator of the association between externalizing behavior and IQ; the strength of this effect across samples was estimated meta-analytically. PATIENTS: Eighty-seven boys from a longitudinal community study, 48 boys referred clinically for aggression, and 42 adult males diagnosed with attention-deficit/hyperactivity disorder. MAIN OUTCOME MEASURES: IQ scores and observer ratings of externalizing behavior were taken from existing data sets. RESULTS: Among individuals lacking the 7-repeat allele, externalizing behavior was negatively correlated with IQ (mean r = -0.43; P<.001). Among individuals having at least 1 copy of the 7-repeat allele, externalizing behavior and IQ were uncorrelated (mean r = 0.02; P = .45). The difference between these correlations was significant (z = -2.99; P<.01). CONCLUSIONS: Allelic variation of the dopamine D4 receptor gene appears to be a genetic factor moderating the association between externalizing behavior and cognitive ability. This finding may help to elucidate the adaptive value of the 7-repeat allele.