The effects of exercise on adolescent hippocampal neurogenesis in a rat model of binge alcohol exposure during the brain growth spurt

Ethanol changes Nestin-promoter induced neural stem cells to disturb newborn dendritic spine remodeling in the hippocampus of mice

Adolescent binge drinking leads to long-lasting disorders of the adult central nervous system, particularly aberrant hippocampal neurogenesis. In this study, we applied in vivo fluorescent tracing using NestinCreERT2::Rosa26-tdTomato mice and analyzed the endogenous neurogenesis lineage progression of neural stem cells (NSCs) and dendritic spine formation of newborn neurons in the subgranular zone of the dentate gyrus. We found abnormal orientation of tamoxifen-induced tdTomato+ (tdTom+) NSCs in adult mice 2 months after treatment with EtOH (5.0 g/kg, i.p.) for 7 consecutive days. EtOH markedly inhibited tdTom+ NSCs activation and hippocampal neurogenesis in mouse dentate gyrus from adolescence to adulthood. EtOH (100 mM) also significantly inhibited the proliferation to 39.2% and differentiation of primary NSCs in vitro. Adult mice exposed to EtOH also exhibited marked inhibitions in dendritic spine growth and newborn neuron maturation in the dentate gyrus, which was partially reversed by voluntary running or inhibition of the mammalian target of rapamycin-enhancer of zeste homolog 2 pathway. In vivo tracing revealed that EtOH induced abnormal orientation of tdTom+ NSCs and spatial misposition defects of newborn neurons, thus causing the disturbance of hippocampal neurogenesis and dendritic spine remodeling in mice.

Alcohol and cannabinoid binges and daily exposure to nicotine in adolescent/young adult rats induce sex-dependent long-term appetitive instrumental learning impairment

Adolescence is a critical developmental period, concerning anatomical, neurochemical and behavioral changes. Moreover, adolescents are more sensitive to the long-term deleterious effects of drug abuse. Binge-like consumption of alcohol and marijuana, along with tobacco smoking, is a dangerous pattern often observed in adolescents during weekends. Nevertheless, the long-term effect of their adolescent co-exposure has not been yet experimentally investigated. Long-Evans adolescent male (n = 20) and female (n = 20) rats from postnatal day 30 (P30) until P60 were daily treated with nicotine (0.3 mg/kg, i.p.), and, on two consecutive 'binging days' per week (for a total of eight times), received an intragastric ethanol solution (3 g/kg) and an intraperitoneal (i.p.) dose of cannabinoid 1/2 receptor agonist WIN55,212-2 (1.2 mg/kg). These rats were tested after treatment discontinuation at > P90 for associative food-rewarded operant learning in the two-lever conditioning chambers for six consecutive days on a fixed ratio 1 (FR1) schedule followed by another six days of daily FR2 schedule testing, after 42 days rest. We found the main effects of sex x treatment interactions in FR1 but not in FR2 experiments. Treated females show attenuated operant responses for food pellets during all FR1 and the FR2 schedule, whilst the treated males show an impairment in FR2 but not in the FR1 schedule. Moreover, the treated females' percentage of learners was significantly lower than female controls in FR1 while treated males were lower than controls in FR2. Our findings suggest that intermittent adolescent abuse of common drugs, such as alcohol and marijuana, and chronic tobacco exposure can cause significant long-term effects on motivation for natural reinforcers later in adulthood in both sexes. Females appear to be sensitive earlier to the deleterious effects of adolescent polydrug abuse, with both sexes having an increased likelihood of developing lifelong brain alterations.

Effects of prenatal alcohol and delta-9-tetrahydrocannabinol exposure via electronic cigarettes on motor development

BACKGROUND

Prenatal alcohol exposure can lead to a wide range of neurological and behavioral deficits, including alterations in motor domains. However, much less is known about the effects of prenatal cannabis exposure on motor development, despite cannabis being the most consumed illicit drug among women. Cannabis use among pregnant women has become increasingly popular given the widespread perception that consumption is safe during pregnancy. Moreover, alcohol and cannabis are commonly used together, even among pregnant women. Yet few studies have explored the potential consequences of combined prenatal exposure on behavioral domains.

METHODS

Using our previously established model, during gestational days 5 to 20, four groups of pregnant Sprague-Dawley rats were exposed to vaporized alcohol, delta-9-Tetrahydrocannabinol (THC) via electronic (e-) cigarettes, the combination of alcohol and THC, or a vehicle. Following birth, offspring were tested on early sensorimotor development, adolescent motor coordination, and adolescent activity levels.

RESULTS

Prenatal THC e-cigarette exposure delayed sensorimotor development early in life and impaired motor coordination later in early adolescence; combined prenatal alcohol and THC exposure did not have additive effects on sensorimotor development. However, combined prenatal exposure produced hyperactivity among male offspring.

CONCLUSIONS

Prenatal cannabis exposure may lead to impaired motor skills throughout early development and combined exposure with alcohol during gestation may lead to hyperactivity in early adolescence. These findings have important implications for informing pregnant women of the risks to the fetus associated with prenatal cannabis exposure, with and without alcohol, and could influence public policy.

Reduced and delayed myelination and volume of corpus callosum in an animal model of Fetal Alcohol Spectrum Disorders partially benefit from voluntary exercise

1 in 20 live births in the United States is affected by prenatal alcohol exposure annually, creating a major public health crisis. The teratogenic impact of alcohol on physical growth, neurodevelopment, and behavior is extensive, together resulting in clinical disorders which fall under the umbrella term of Fetal Alcohol Spectrum Disorders (FASD). FASD-related impairments to executive function and perceptual learning are prevalent among affected youth and are linked to disruptions to corpus callosum growth and myelination in adolescence. Targeted interventions that support neurodevelopment in FASD-affected youth are nonexistent. We evaluated the capacity of an adolescent exercise intervention, a stimulator of myelinogenesis, to upregulate corpus callosum myelination in a rat model of FASD (third trimester-equivalent alcohol exposure). This study employs in vivo diffusion tensor imaging (DTI) scanning to investigate the effects of: (1) neonatal alcohol exposure and (2) an adolescent exercise intervention on corpus callosum myelination in a rodent model of FASD. DTI scans were acquired twice longitudinally (pre- and post-intervention) in male and female rats using a 9.4 Tesla Bruker Biospec scanner to assess alterations to corpus callosum myelination noninvasively. Fractional anisotropy values as well as radial/axial diffusivity values were compared within-animal in a longitudinal study design. Analyses using mixed repeated measures ANOVA’s confirm that neonatal alcohol exposure in a rodent model of FASD delays the trajectory of corpus callosum growth and myelination across adolescence, with a heightened vulnerability in the male brain. Alterations to corpus callosum volume are correlated with reductions to forebrain volume which mediates an indirect relationship between body weight gain and corpus callosum growth. While we did not observe any significant effects of voluntary aerobic exercise on corpus callosum myelination immediately after completion of the 12-day intervention, we did observe a beneficial effect of exercise intervention on corpus callosum volume growth in all rats. In line with clinical findings, we have shown that prenatal alcohol exposure leads to hypomyelination of the corpus callosum in adolescence and that the severity of damage is sexually dimorphic. Further, exercise intervention improves corpus callosum growth in alcohol-exposed and control rats in adolescence.

Cholinergic and Neuroimmune Signaling Interact to Impact Adult Hippocampal Neurogenesis and Alcohol Pathology Across Development

Alcohol (ethanol) use and misuse is a costly societal issue that can affect an individual across the lifespan. Alcohol use and misuse typically initiates during adolescence and generally continues into adulthood. Not only is alcohol the most widely abused drug by adolescents, but it is also one of the most widely abused drugs in the world. In fact, high rates of maternal drinking make developmental ethanol exposure the most preventable cause of neurological deficits in the Western world. Preclinical studies have determined that one of the most consistent effects of ethanol is its disruption of hippocampal neurogenesis. However, the severity, persistence, and reversibility of ethanol’s effects on hippocampal neurogenesis are dependent on developmental stage of exposure and age at assessment. Complicating the neurodevelopmental effects of ethanol is the concurrent development and maturation of neuromodulatory systems which regulate neurogenesis, particularly the cholinergic system. Cholinergic signaling in the hippocampus directly regulates hippocampal neurogenesis through muscarinic and nicotinic receptor actions and indirectly regulates neurogenesis by providing anti-inflammatory regulatory control over the hippocampal environmental milieu. Therefore, this review aims to evaluate how shifting maturational patterns of the cholinergic system and its regulation of neuroimmune signaling impact ethanol’s effects on adult neurogenesis. For example, perinatal ethanol exposure decreases basal forebrain cholinergic neuron populations, resulting in long-term developmental disruptions to the hippocampus that persist into adulthood. Exaggerated neuroimmune responses and disruptions in adult hippocampal neurogenesis are evident after environmental, developmental, and pharmacological challenges, suggesting that perinatal ethanol exposure induces neurogenic deficits in adulthood that can be unmasked under conditions that strain neural and immune function. Similarly, adolescent ethanol exposure persistently decreases basal forebrain cholinergic neuron populations, increases hippocampal neuroimmune gene expression, and decreases hippocampal neurogenesis in adulthood. The effects of neither perinatal nor adolescent ethanol are mitigated by abstinence whereas adult ethanol exposure-induced reductions in hippocampal neurogenesis are restored following abstinence, suggesting that ethanol-induced alterations in neurogenesis and reversibility are dependent upon the developmental period. Thus, the focus of this review is an examination of how ethanol exposure across critical developmental periods disrupts maturation of cholinergic and neuroinflammatory systems to differentially affect hippocampal neurogenesis in adulthood.

Apelin-13 attenuates spatial memory impairment by anti-oxidative, anti-apoptosis, and anti-inflammatory mechanism against ethanol neurotoxicity in the neonatal rat hippocampus

It has been shown that alcohol consumption by pregnant women can have detrimental effects on the developing fetus and lead to fetal alcohol spectrum disorders (FASD). Exposure to alcohol in rat pups during this period causes long-term changes in the structure of the animal's hippocampus, leading to impaired hippocampal-related brain functions such as navigation tasks and spatial memory. Apelin-13, a principal neuropeptide with inhibitory effects on neuroinflammation and brain oxidative stress production, has beneficial properties on memory impairment and neuronal injury. The protective effects of apelin-13 have been evaluated on ethanol-related neurotoxicity in the hippocampus of rat pups. Rat pups from 2 until 10 postnatal day, similar to the third trimester of pregnancy in humans, were intubated total daily dose of ethanol (5/27 g/kg/day). Immediately after intubation, 25 and 50 μg/ kg of apelin-13 was injected subcutaneously. By using Morris water maze task, the hippocampus- dependent memory and spatial learning were evaluated 36 days after birth. Then, Immunohistochemical staining was done to determine the levels of GFAP and caspase-3. ELISA assay was also performed to measure both TNF-α and antioxidant enzymes levels. The current study demonstrates that administration of apelin-13 attenuates spatial memory impairment significantly (P < 0.001). After ethanol neurotoxicity, apelin-13 could also increase the catalase level (P < 0.001), activity of total superoxide dismutase as well as glutathione concentration noticeably (P < 0.05). Other impacts of it could be mentioned as attenuating TNF-α production and also preventing lipid peroxidation (P < 0.001). In addition, the results showed that the level of GFAP as a neuroinflammation factor and the number of active caspase-3 positive cells can be decreased by apelin-13 (P < 0.01). Regarding the protective effects of apelin-13 against ethanol-induced neurotoxicity, it is a promising therapeutic choice for FASD; but more studies are needed.

Exercise and crocin prevent adolescent-stress induced impairment of spatial navigation and dendritic retraction in the hippocampal CA3 area in adult male rats

Adolescent chronic stress has been shown to induce functional, biochemical and morphological modifications of the hippocampus, leading to stress-related disorders in adulthood. The present study investigated the effects of exercise, crocin and their combination on spatial learning and memory impairment and dendritic retraction of the CA3 pyramidal neurons induced by chronic adolescent stress in adult male rats. Rats were exposed to restraint stress 2 h/day for 10 days during postnatal days (PNDs) 30-40. Following this period, separate groups of animals were treated with crocin (25 and 50 mg/kg), exposed to running wheel, and or received the combined treatment during PNDs 41-55. Following the interventions, plasma levels of corticosterone, spatial learning and memory, apical dendritic length of CA3 pyramidal neurons and BDNF levels in the CA3 area were assessed. Findings showed that adolescent stress significantly increased corticosterone levels and caused a tendency to reduce CA3 BDNF levels. Adolescent stress also impaired spatial learning and memory, and retracted apical dendritic length of CA3 pyramidal neurons. Crocin, voluntary exercise, and their combination recovered stress-induced spatial learning and impairment and CA3 pyramidal neurons dendritic length retraction. All treatments also reduced significantly corticosterone levels and enhanced CA3 BDNF levels in the stress groups. Finally, these treatments even increased apical dendritic length of CA3 pyramidal neurons in the non-stress groups. These findings indicate that detrimental effects of adolescent stress on cognitive function and hippocampal morphology in adulthood could be restored by early interventions with physical activity and crocin treatment during adolescent period.

The Influence of Moderate Physical Activity on Brain Monoaminergic Responses to Binge-Patterned Alcohol Ingestion in Female Mice

Monoamine neurotransmitter activity in brain reward, limbic, and motor areas play key roles in the motivation to misuse alcohol and can become modified by exercise in a manner that may affect alcohol craving. This study investigated the influence of daily moderate physical activity on monoamine-related neurochemical concentrations across the mouse brain in response to high volume ethanol ingestion. Adult female C57BL/6J mice were housed with or without 2.5 h of daily access to running wheels for 30 days. On the last 5 days, mice participated in the voluntary binge-like ethanol drinking procedure, “Drinking in the dark” (DID). Mice were sampled immediately following the final episode of DID. Monoamine-related neurochemical concentrations were measured across brain regions comprising reward, limbic, and motor circuits using ultra High-Performance Liquid Chromatography (UHPLC). The results suggest that physical activity status did not influence ethanol ingestion during DID. Moreover, daily running wheel access only mildly influenced alcohol-related norepinephrine concentrations in the hypothalamus and prefrontal cortex, as well as serotonin turnover in the hippocampus. However, access to alcohol during DID eliminated wheel running-related decreases of norepinephrine, serotonin, and 5-HIAA content in the hypothalamus, but also to a lesser extent for norepinephrine in the hippocampus and caudal cortical areas. Finally, alcohol access increased serotonin and dopamine-related neurochemical turnover in the striatum and brainstem areas, regardless of physical activity status. Together, these data provide a relatively thorough assessment of monoamine-related neurochemical levels across the brain in response to voluntary binge-patterned ethanol drinking, but also adds to a growing body of research questioning the utility of moderate physical activity as an intervention to curb alcohol abuse.

Simvastatin attenuates spatial memory impairment via inhibiting microgliosis and apoptotic cell death against ethanol induced neurotoxicity in the developing rat hippocampus

Ethanol is associated with oxidative stress. Exposure to ethanol during childhood may lead to neurological disorders. Congenital disorders induced by alcohol are mainly caused by an oxidative-inflammatory cascade due to extensive apoptotic neurodegeneration in the brain, particularly in the hippocampus. Simvastatin, which acts as an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA), is widely used to manage cardiovascular diseases. Recently, the neuroprotective effects of simvastatin against nervous system disorders have been introduced. In this study, we examined the protective effects of simvastatin on ethanol-related neurotoxicity in the hippocampus of rat pups. Ethanol (5.27 g/kg) in a milk solution (27.8 mL/kg) was administered to male rat pups via intragastric intubation at 2-10 days after birth. Also, 10 and 20 mg/kg of simvastatin were injected to the animals. By using Morris water maze task, the hippocampus-dependent memory and spatial learning was evaluated 36 days after birth. An ELISA assay was performed to investigate the antioxidant and anti-inflammatory effects of simvastatin by measuring the levels of tumor necrosis factor-α (TNF-α), and antioxidant enzymes. To assess the expression levels of Iba1 immunohistochemical staining and caspase-3 immunofluorescence staining was performed. The current study demonstrated that administration of simvastatin significantly attenuates spatial memory impairment (P < 0.01) after ethanol neurotoxicity. Also simvastatin could considerably increase the total superoxide dismutaseand glutathione levels (P < 0.01). Moreover, it was associated with a greater reduction in malondialdehyde (P < 0.05) and TNF-α levels, compared to the ethanol group (P < 0.01). Furthermore, in the simvastatin group, the hippocampal level of caspase-3 and the level of Iba1-positive cells, reduced (P < 0.01). This study demonstrated that apoptotic signaling, mediated by the oxidative-inflammatory cascade, could be inhibited by simvastatin in rat pups with ethanol exposure in the postnatal period.

Ameliorating Effects of Lithium on the Perinatal Ethanol-Induced Behavioral and Cognitive Dysfunction and Brain Oxidative Stress in Postnatal Developing Mice Pups

BACKGROUND

Developmental ethanol (EtOH) exposure can cause lifelong behavioral hyperactivity, cognitive deficits, emotional dysregulation, and more. However, co-treatment with lithium (Li) on the day of EtOH exposure prevents many of the impairments.

METHODS

Experimental groups of pregnant mice were exposed to EtOH (20% v/v solution at a dose of 2.5 g/kg) in their drinking water and the animals were treated with Li (15 and 30 mg/kg) through IP injection on gestational days14, 16, 18, and 20, and post-natal days (PD) 3, 5, 7, and 9. All treatments with EtOH and exposure to Li doses to pregnant mice started on gestational day 14 and continued until post-natal day 9 (PD9). The effects on some developing morphological indices, nerve reflexes during weaning age, and various cognitive dysfunctions at adolescent ages and biochemical changes in the brain tissue indices of below-mentioned neurotransmitters and oxidative stress in post-natal developing offspring at adolescent age, were studied.

RESULTS

Perinatal exposure to EtOH in pregnant mice resulted in several postnatal developing and morphological indices in the developing male pups during their weaning period, like gain in their body weight, delay in appearance of their body hair fuzz and opening of their eyes, and disruptions in their developing motor reflexes.

DISCUSSION

During adolescent age, a significant deficit in their learning capability and cognitive behavior, decline in the neurochemical DA and 5-HT in their brain and some indices of oxidative stress TBARS, GSH, GST, CAT, and SOD was observed.

CONCLUSION

These results indicate that Li ameliorates significantly and dose-dependently EtOH induced developmental toxicities like morphological developments and dysfunctions in cognitive retention and oxidative stress on a long-term basis in brain tissue. However, further detailed studies are required for the clinical use of as an ameliorating agent for perinatal EtOH induced dysfunctions.

Microglial peri-somatic abutments classify two novel types of GABAergic neuron in the inferior colliculus

Emerging evidence suggests functional roles for microglia in the healthy, mature nervous system. However, we know little of the cellular density and ramified morphology of microglia in sensory systems, and even less of their inter-relationship with inhibitory neurons. We therefore conducted fluorescent multi-channel immunohistochemistry and confocal microscopy in guinea pigs of both sexes for Iba1, GAD67, GFAP, calbindin, and calretinin. We explored these markers in the inferior colliculi (IC), which contain sub-regions specialized for different aspects of auditory processing. First, we found that while the density of Iba1+ somata is similar throughout the IC parenchyma, Iba1+ microglia in dorsal cortex are significantly more ramified than those in the central nucleus or lateral cortex. Conversely, Iba1+ ramifications in ventral central nucleus, a region with the highest density of GAD67+ (putative GABAergic) neurons in IC, are longer with fewer ramifications. Second, we observed extensive abutments of ramified Iba1+ processes onto GAD67+ somata throughout the whole IC and developed novel measures to quantify these. Cluster analyses revealed two novel sub-types of GAD67+ neuron that differ in the quantity of Iba1+ somatic abutments they receive. Unlike previous classification schemes for GAD67+ neurons in IC, these clusters are not related to GAD67+ soma size. Taken together, these data demonstrate that microglial ramifications vary between IC sub-regions in the healthy, adult IC, possibly related to the ongoing demands of their niche. Furthermore, Iba1+ abutments onto neuronal somata are a novel means by which GAD67+ neurons can be classified.

Cross-Sectional Analysis of Spatial Working Memory Development in Children with Histories of Heavy Prenatal Alcohol Exposure

BACKGROUND

In children with prenatal alcohol exposure, spatial working memory is affected and brain regions important for spatial working memory performance exhibit atypical neurodevelopment. We therefore hypothesized that children with prenatal alcohol exposure may also have atypical development of spatial working memory ability.

METHODS

We examined the relation between spatial working memory and age using a cross-sectional developmental trajectory approach in youth with and without histories of heavy prenatal alcohol exposure. The Cambridge Neuropsychological Test Automated Battery Spatial Working Memory subtest was administered to children 5.0 to 16.9 years old.

RESULTS

While the controls and children with prenatal alcohol exposure showed similar performance at younger ages, larger group differences were observed in older children. This effect was replicated in a separate sample.

CONCLUSIONS

The atypical brain development that has previously been reported in children with heavy prenatal alcohol exposure may have clinically relevant implications for cognitive development; however, longitudinal cognitive analyses are needed.

Examination of cortically projecting cholinergic neurons following exercise and environmental intervention in a rodent model of fetal alcohol spectrum disorders

BACKGROUND

Up to 1 in 5 infants in the United States are exposed to alcohol prenatally, resulting in neurodevelopmental deficits categorized as fetal alcohol spectrum disorders (FASD). Choline supplementation ameliorates some deficits, suggesting that alcohol exposure (AE) perturbs cholinergic neurotransmission and development. Behavioral interventions, which upregulate cholinergic neurotransmission, rescue cognitive deficits in rodent models of FASD.

METHODS

We investigated the impacts of two interventions (either wheel-running (WR) or "super intervention," WR plus exposure to a complex environment) on cholinergic neuronal morphology in the nucleus basalis of Meynert (NBM), the source of cortical cholinergic input, and prefrontal cortex (PFC) in a rodent model of FASD. One third of the total 47 male pups received intragastric intubation of ethanol in milk substitute during postnatal days (PD) 4-9. Another third served as sham-intubated procedural controls while the final third served as suckle controls. Rats from each group were exposed to either intervention during PD 30-72. Choline acetyltransferase (ChAT⁺ ) and acetylcholinesterase staining were used to quantify cholinergic neuron number, soma volume, and axon number.

RESULTS

Our data indicate a main effect of postnatal treatment on ChAT⁺ neuron number in NBM in adulthood. Post hoc analysis demonstrates that ChAT⁺ neuron number is reduced in AE compared to suckle control rodents (p < .01).

CONCLUSIONS

We examined the cytoarchitectonics of cholinergic neurons in NBM and PFC in adulthood following early postnatal AE and two interventions. We show that AE reduces ChAT⁺ neuron number in NBM, and this is not mitigated by either intervention.

Postnatal alcohol exposure and adolescent exercise have opposite effects on cerebellar microglia in rat

Developmental alcohol exposure results in altered neuroimmune function in both humans and rodents. Given the critical role for the principle neuroimmune cell, microglia, in maintaining synaptic form and function, microglial dysfunction in the cerebellum may be an important mechanism underlying the aberrant cerebellar connectivity observed in rodent models of fetal alcohol spectrum disorders. Using an established rodent model of alcohol exposure during human third-trimester fetal development, we examine the cerebellum of male and female Long Evans rats to determine the impact of early postnatal alcohol exposure on cerebellar microglia, and the potential therapeutic effects of an adolescent intervention consisting of voluntary exercise (running). All cerebelli were examined at postnatal day 42 (i.e., late adolescence), and microglia were labeled with Iba1, a microglia-specific protein. Early postnatal alcohol exposure caused an increase in microglial density throughout cerebellum and a reduction in cerebellar volume, and a reduction in the proportion of fully ramified (often called "resting state") microglia selective to lobules 1-4. In contrast, adolescent exercise decreased microglial density throughout cerebellum and increased cerebellar volume, while activating microglia (as indicated by increases in amoeboid microglia, and reductions in fully and partially ramified microglia) selectively in lobules 1-4. These results suggest that adolescent exercise may be a suitable intervention to ameliorate alcohol-induced neuroimmune dysfunction as it alters microglia density and cerebellar volume in opposite to the effects of developmental alcohol exposure. Importantly, exercise intervention can be flexibly implemented well after the time window of vulnerability to alcohol.

Co-existence of ethanol-related respiratory and motivational learning processes based on a tactile discrimination procedure in neonatal rats

In rats, high ethanol doses during early postnatal life exert deleterious effects upon brain development that impact diverse social and cognitive abilities. This stage in development partially overlaps with the third human gestational trimester, commonly referred to as the brain growth spurt period. At this stage in development, human fetuses and rat neonates (postnatal days [PD] 3-9) exhibit relatively high respiratory rates that are affected by subteratogenic ethanol doses. Recent studies suggest conditioned breathing responses in the developing organism, given that there are explicit associations between exteroceptive stimuli and the state of ethanol intoxication. Furthermore, studies performed with near-term rat fetuses suggest heightened sensitivity to ethanol's motivational effects. The present study was meant to analyze the unconditioned effects of ethanol intoxication and the possible co-occurrence of learning mechanisms that can impact respiratory plasticity, and to analyze the preference for cues that signal the state of intoxication as well as the effects of the drug, related with motor stimulation. Neonatal rats were subjected to differential experiences with salient tactile cues explicitly paired or not paired with the effects of vehicle or ethanol (2.0 g/kg). A tactile discrimination procedure applied during PDs 3, 5, 7, and 9 allowed the identification of the emergence of ethanol-derived non-associative and associative learning processes that affect breathing plasticity, particularly when considering apneic disruptions. Ethanol was found to partially inhibit the disruptions that appeared to be intimately related with stressful circumstances defined by the experimental procedure. Tactile cues paired with the drug's effects were also observed to exert an inhibitory effect upon these breathing disruptions. The level of contingency between a given tactile cue and ethanol intoxication also resulted in significant changes in the probability of seeking this cue in a tactile preference test. In addition, the state of intoxication exerted motor-stimulating effects. When contrasting the data obtained via the analysis of the different dependent variables, it appears that most ethanol-derived changes are modulated by positive and/or negative (anti-anxiety) reinforcing effects of the drug. As a whole, the study indicates co-existence of ethanol-related functional changes in the developing organism that simultaneously affect respiratory plasticity and preference patterns elicited by stimuli that signal ethanol's motivational effects. These results emphasize the need to consider significant alterations due to minimal ethanol experiences that argue against "safe" levels of exposure in a critical stage in brain development.

Assessing the Role of Cannabis Use on Cortical Surface Structure in Adolescents and Young Adults: Exploring Gender and Aerobic Fitness as Potential Moderators

Cannabis use in adolescents and young adults is linked with aberrant brain structure, although findings to date are inconsistent. We examined whether aerobic fitness moderated the effects of cannabis on cortical surface structure and whether gender may play a moderating role. Seventy-four adolescents and young adults completed three-weeks of monitored abstinence, aerobic fitness testing, and structural magnetic resonance imaging (sMRI). Whole-sample linear regressions examined the effects of gender, VO2 max, cannabis use, and their interactions on the surface area (SA) and local gyrification index (LGI). Cannabis use was associated with greater cuneus SA. Gender-by-cannabis predicted precuneus and frontal SA, and precentral, supramarginal, and frontal LGI; female cannabis users demonstrated greater LGI, whereas male cannabis users demonstrated decreased LGI compared to non-users. Aerobic fitness was positively associated with various SA and LGI regions. Cannabis-by-aerobic fitness predicted cuneus SA and occipital LGI. These findings demonstrate that aerobic fitness moderates the impact of cannabis on cortical surface structure, and gender differences are evident. These moderating factors may help explain inconsistencies in the literature and warrant further investigation. Present findings and aerobic fitness literature jointly suggest aerobic intervention may be a low-cost avenue for improving cortical surface structure, although the impact may be gender-specific.

Hydrogen Sulfide Attenuates the Neurotoxicity in the Animal Model of Fetal Alcohol Spectrum Disorders

Fetal alcohol spectrum disorder (FASD), which is caused by prenatal alcohol exposure, can result in cell death in specific brain regions. Alcohol-induced neurocognitive defects offspring's are included with activation of oxidative-inflammatory cascade followed with wide apoptotic neurodegeneration in many brain's regions such as hippocampus. According to the latest studies, H₂S (hydrogen sulfide) can protect neuronal cells via antioxidant, anti-inflammatory, and anti-apoptotic mechanisms in different animal models. Therefore, we aimed to evaluate the protective effects of H₂S on ethanol-induced neuroinflammation and neuronal apoptosis in pup hippocampus with postnatal alcohol exposure. Administration of ethanol (5.27 g/kg) in milk solution (27.8 mL/kg) for each rat pups was performed through intragastric intubation on 2 to 10 postnatal days and NaHS as H₂S donor (1 mg/kg) was injected on similar time, subcutaneously. For examining the antioxidant and anti-inflammatory effects, ELISA assay was performed to determine the levels of TNF-α, IL1β, and antioxidant enzymes. Immunohistochemical staining was performed to evaluate the expression levels of GFAP and caspase-3 also Nissl staining was done for necrotic cell death evaluation. H₂S treatment could significantly increase the activity of total superoxide dismutase, catalase, and glutathione (P < 0.05). It also decreased the levels of TNF-α, IL1β, and malondialdehyde, compared with the ethanol group (P < 0.05). Moreover, the number of hippocampal caspase-3, GFAP-positive cells, and necrotic cells death reduced in the H₂S group (P < 0.01). Based on the findings, H₂S can inhibit apoptotic signaling that is mediated by the oxidative-inflammatory cascade following ethanol exposure of rat pups on postnatal period.

The effect of voluntary wheel running on 129/SvEvTac and C3H/Ibg alcohol consumption

The mesolimbic dopaminergic reward pathway is activated by both alcohol and exercise, suggesting exercise as a possible treatment or preventative method for alcohol-use disorders (AUDs). Prior studies conducted in our lab have demonstrated the hedonic substitution of voluntary alcohol consumption for voluntary wheel running in female C57Bl/6Ibg mice, and a trend in male C57Bl/6Ibg mice. Given the important contribution of genetic background on AUDs, this study aims to assess the effects of voluntary wheel running on voluntary alcohol consumption in two moderate alcohol-consuming strains of mice, C3H/Ibg and 129/SvEvTac. Contrary to our previous studies conducted in C57Bl/6Ibg mice, 129/SvEvTac and male C3H/Ibg mice housed without a wheel consumed significantly more alcohol than mice housed with a free or locked wheel. This suggests that 129/SvEvTac and male C3H/Ibg mice are reducing their alcohol consumption due to an enriched environment and not exercise. Interestingly, the three groups of female C3H/Ibg mice (free wheel, locked wheel, no wheel) did not significantly differ in alcohol consumption, suggesting sex-specific differences in C3H/Ibg mice. In addition, genetic and sex effects were observed for running phenotypes in the presence of alcohol. Female 129/SvEvTac and C57Bl/6Ibg mice ran longer distances than male mice, whereas male and female C3H/Ibg mice did not differ in distance run. C3H/Ibg and female 129/SvEvTav mice with access only to water ran longer distances than mice with access to both alcohol and water. However, this effect was not observed in C57Bl/6Ibg or male 129/SvEvTac mice. The results of this mouse model highlight the importance of genetic background and sex on an animal's response to exercise as an enrichment to reduce voluntary alcohol consumption.

p53-Mediated Activities in NS-5 Neural Stem Cells: Effects of Ethanol

BACKGROUND

Transforming growth factor (TGF) β1 and ethanol (EtOH) powerfully inhibit the proliferation, DNA repair, and survival of neural stem cells (NSCs). The present study tests the hypothesis that the EtOH-induced DNA damage response is mediated through p53 pathways and influenced by growth factor signals.

METHODS

Cultures of nonimmortalized NSCs, NS-5 cells, were transfected with p53 siRNA, exposed to either the mitogenic fibroblast growth factor (FGF) 2 or antimitogenic TGFβ1, and to EtOH. Stage-specific cellular and genomic responses were examined.

RESULTS

p53 status, EtOH exposure, and growth factor significantly affected the expression of transcripts related to the DNA damage response (including those coding for excision repair proteins), mitotic promoters, and regulators of cell death via the tumor necrosis factor pathway. There were significant compensatory increases in p53 family members, p63 and p73, notably in regard to the regulation of cell cycle restriction and apoptosis. Treatment with p53 siRNA potentiated EtOH- and TGFβ1-induced changes in the numbers of proliferating NSCs and increased the proportion of NSCs expressing the apoptotic marker annexin V.

CONCLUSIONS

Thus, it appears that EtOH and TGFβ1 affect proliferation, DNA repair, and survival of NSCs via p53-mediated activities.

Aerobic Fitness Level Moderates the Association Between Cannabis Use and Executive Functioning and Psychomotor Speed Following Abstinence in Adolescents and Young Adults

OBJECTIVES

The high rate of cannabis (CAN) use in emerging adults is concerning given prior research suggesting neurocognitive deficits associated with CAN use in youth. Regular CAN use downregulates endocannabinoid activity, while aerobic exercise upregulates cannabinoid receptor 1 activity and releases endocannabinoids. Here we investigate the influence of regular CAN use on neuropsychological performance, and whether aerobic fitness moderates these effects.

METHODS

Seventy-nine young adults (37 CAN users) aged 16-26 participated. Groups were balanced for aerobic fitness level. Exclusion criteria included: left-handedness, past-year independent Axis-I disorders, major medical/neurologic disorders, prenatal issues, or prenatal alcohol/illicit drug exposure. After 3 weeks of abstinence, participants completed a neuropsychological battery and a maximal oxygen consumption test (VO2 max). Multiple regressions tested whether past-year CAN use, VO2 max, and CAN*VO2 max interaction predicted neuropsychological performance, controlling for past-year alcohol use, cotinine, gender, and depression symptoms.

RESULTS

Increased CAN use was associated with decreased performance on working memory and psychomotor tasks. High aerobic fitness level was related to better performance on visual memory, verbal fluency, and sequencing ability. CAN*VO2 max predicted performance of psychomotor speed, visual memory, and sequencing ability.

CONCLUSIONS

Following monitored abstinence, increased CAN use was associated with poorer performance in working memory and psychomotor speed. Higher aerobic fitness level moderated the impact of CAN on visual memory, executive function and psychomotor speed, as more aerobically fit CAN users demonstrated better performance relative to low-fit users. Therefore, aerobic fitness may present an affordable and efficacious method to improve cognitive functioning in CAN users. (JINS, 2019, 25, 134-145).

Altered brain functional connectivity and behaviour in a mouse model of maternal alcohol binge-drinking

Prenatal and perinatal alcohol exposure caused by maternal alcohol intake during gestation and lactation periods can have long-lasting detrimental effects on the brain development and behaviour of offspring. Children diagnosed with Foetal Alcohol Spectrum Disorders (FASD) display a wide range of cognitive, emotional and motor deficits, together with characteristic morphological abnormalities. Maternal alcohol binge drinking is particularly harmful for foetal and early postnatal brain development, as it involves exposure to high levels of alcohol over short periods of time. However, little is known about the long-term effects of maternal alcohol binge drinking on brain function and behaviour. To address this issue, we used pregnant C57BL/6 female mice with time-limited access to a 20% v/v alcohol solution as a procedure to model alcohol binge drinking during gestation and lactational periods. Male offspring were behaviourally tested during adolescence (30 days) and adulthood (60 days), and baseline neural metabolic capacity of brain regions sensitive to alcohol effects were also evaluated in adult animals from both groups. Our results show that prenatal and postnatal alcohol exposure caused age-dependent changes in spontaneous locomotor activity, increased anxiety-like behaviour and attenuated alcohol-induced conditioned place preference in adults. Also, significant changes in neural metabolic capacity using cytochrome c oxidase (CCO) quantitative histochemistry were found in the hippocampal dentate gyrus, the mammillary bodies, the ventral tegmental area, the lateral habenula and the central lobules of the cerebellum in adult mice with prenatal and postnatal alcohol exposure. In addition, the analysis of interregional CCO activity correlations in alcohol-exposed adult mice showed disrupted functional brain connectivity involving the limbic, brainstem, and cerebellar regions. Finally, increased neurogenesis was found in the dentate gyrus of the hippocampus of alcohol-exposed offspring, suggesting neuroadaptive effects due to early alcohol exposure. Our results demonstrate that maternal binge-like alcohol drinking causes long-lasting effects on motor and emotional-related behaviours associated with impaired neuronal metabolic capacity and altered functional brain connectivity.

Hippocampal neurogenesis in the C57BL/6J mice at early adulthood following prenatal alcohol exposure

We examined the effect of chronic prenatal alcohol exposure (PAE) on the process of adult neurogenesis in C57BL/6J mice at early adulthood (PND 56). Pregnant mice, and their in utero litters, were exposed to alcohol, through oral gavage, on gestational days 7-16, with recorded blood alcohol concentrations averaging 184 mg/dL (CA group). Two control groups, sucrose (CAc) and non-treated (NTc) control groups were also examined. The brains of pups at PND 56 from each experimental group were sectioned in a sagittal plane, and stained for Nissl substance with cresyl violet, and immunostained for Ki-67 which labels proliferative cells and doublecortin (DCX) for immature neurons. Morphologically, the neurogenic pattern was identical in all three groups studied. Populations of Ki-67 immunopositive cells in the dentate gyrus were not statistically significantly different between the experimental groups and there were no differences between the sexes. Thus, the PAE in this study does not appear to have a strong effect on the proliferative process in the adult hippocampus. In contrast, the numbers of immature neurons, labeled with DCX, was statistically significantly lower in the prenatal alcohol exposed mice compared with the two control groups. Alcohol significantly lowered the number of DCX hippocampal cells in the male mice, but not in the female mice. This indicates that the PAE appears to lower the rate of conversion of proliferative cells to immature neurons and this effect of alcohol is sexually dimorphic. This lowered number of immature neurons in the hippocampus appears to mirror hippocampal dysfunctions observed in FASD children.

Epigenetic mechanisms in alcohol- and adversity-induced developmental origins of neurobehavioral functioning

The long-term effects of developmental alcohol and stress exposure are well documented in both humans and non-human animal models. Damage to the brain and attendant life-long impairments in cognition and increased risk for psychiatric disorders are debilitating consequences of developmental exposure to alcohol and/or psychological stress. Here we discuss evidence for a role of epigenetic mechanisms in mediating these consequences. While we highlight some of the common ways in which stress or alcohol impact the epigenome, we point out that little is understood of the epigenome's response to experiencing both stress and alcohol exposure, though stress is a contributing factor as to why women drink during pregnancy. Advancing our understanding of this relationship is of critical concern not just for the health and well-being of individuals directly exposed to these teratogens, but for generations to come.

Binge Drinking's Effects on the Body

Studies have focused on the effects of chronic alcohol consumption and the mechanisms of tissue injury underlying alcoholic hepatitis and cirrhosis, with less focus on the pathophysiological consequences of binge alcohol consumption. Alcohol binge drinking prevalence continues to rise, particularly among individuals ages 18 to 24. However, it is also frequent in individuals ages 65 and older. High blood alcohol levels achieved with this pattern of alcohol consumption are of particular concern, as alcohol can permeate to virtually all tissues in the body, resulting in significant alterations in organ function, which leads to multisystemic pathophysiological consequences. In addition to the pattern, amount, and frequency of alcohol consumption, additional factors, including the type of alcoholic beverage, may contribute differentially to the risk for alcohol-induced tissue injury. Preclinical and translational research strategies are needed to enhance our understanding of the effects of binge alcohol drinking, particularly for individuals with a history of chronic alcohol consumption. Identification of underlying pathophysiological processes responsible for tissue and organ injury can lead to development of preventive or therapeutic interventions to reduce the health care burden associated with binge alcohol drinking.

Exercise as a Positive Modulator of Brain Function

Various forms of exercise have been shown to prevent, restore, or ameliorate a variety of brain disorders including dementias, Parkinson's disease, chronic stress, thyroid disorders, and sleep deprivation, some of which are discussed here. In this review, the effects on brain function of various forms of exercise and exercise mimetics in humans and animal experiments are compared and discussed. Possible mechanisms of the beneficial effects of exercise including the role of neurotrophic factors and others are also discussed.

A proof-of-concept investigation into ketamine as a pharmacological treatment for alcohol dependence: study protocol for a randomised controlled trial

Background

Worldwide, alcohol abuse is a burgeoning problem. Abstinence is key to allow recovery of physical and mental health as well as quality of life, but treatment for alcohol dependence is associated with high relapse rates. Preliminary data have suggested that a combined repeated ketamine and psychological therapy programme may be effective in reducing relapse in severe alcohol use disorder. This non-commercial proof-of-concept trial is aimed at making a preliminary assessment of the effectiveness of this combined treatment in this patient group.

Methods/design

This is a phase II, randomised, double-blind, placebo-controlled, parallel-group clinical trial taking place in two sites in the UK: the South West of England and London. Ninety-six recently detoxified alcoholics, with comorbid depressive symptoms, will be randomised to one of four treatment arms. Patients will receive either three sessions of ketamine (0.8 mg/kg administered intravenously (IV) over 40 minutes) or placebo (50 ml saline 0.9% IV over 40 minutes) plus either seven sessions of manualised psychological therapy or an alcohol education control. Patients will be assessed at 3 and 6 months on a range of psychological and biological variables. The primary endpoints are (1) relapse rates at 6 months and (2) percentage days abstinent at 6 months. Secondary endpoints include 3 and 6 month percentage days abstinence, tolerability (indicated by dropout), adverse events, depressive symptoms, craving and quality of life.

Discussion

This study will provide important information on a new combined psychological and pharmacological intervention aimed at reducing relapse rates in alcoholics. The findings would have broad application given the worldwide prevalence of alcoholism and its associated medical, psychological and social problems.

Trial registration

ClinicalTrials.gov, NCT02649231. Registered on 5 January 2016.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-1895-6) contains supplementary material, which is available to authorized users.

Stress and adolescent hippocampal neurogenesis: diet and exercise as cognitive modulators

Adolescence is a critical period for brain maturation. Deciphering how disturbances to the central nervous system at this time affect structure, function and behavioural outputs is important to better understand any long-lasting effects. Hippocampal neurogenesis occurs during development and continues throughout life. In adulthood, integration of these new cells into the hippocampus is important for emotional behaviour, cognitive function and neural plasticity. During the adolescent period, maturation of the hippocampus and heightened levels of hippocampal neurogenesis are observed, making alterations to neurogenesis at this time particularly consequential. As stress negatively affects hippocampal neurogenesis, and adolescence is a particularly stressful time of life, it is important to investigate the impact of stressor exposure at this time on hippocampal neurogenesis and cognitive function. Adolescence may represent not only a time for which stress can have long-lasting effects, but is also a critical period during which interventions, such as exercise and diet, could ameliorate stress-induced changes to hippocampal function. In addition, intervention at this time may also promote life-long behavioural changes that would aid in fostering increased hippocampal neurogenesis and cognitive function. This review addresses both the acute and long-term stress-induced alterations to hippocampal neurogenesis and cognition during the adolescent period, as well as changes to the stress response and pubertal hormones at this time which may result in differential effects than are observed in adulthood. We hypothesise that adolescence may represent an optimal time for healthy lifestyle changes to have a positive and long-lasting impact on hippocampal neurogenesis, and to protect against stress-induced deficits. We conclude that future research into the mechanisms underlying the susceptibility of the adolescent hippocampus to stress, exercise and diet and the consequent effect on cognition may provide insight into why adolescence may be a vital period for correct conditioning of future hippocampal function.

Wheel Running and Environmental Complexity as a Therapeutic Intervention in an Animal Model of FASD

Aerobic exercise (e.g., wheel running (WR) extensively used in animal research) positively impacts many measures of neuroplastic potential in the brain, such as rates of adult neurogenesis, angiogenesis, and expression of neurotrophic factors in rodents. This intervention has also been shown to mitigate behavioral and neuroanatomical aspects of the negative impacts of teratogens (i.e., developmental exposure to alcohol) and age-related neurodegeneration in rodents. Environmental complexity (EC) has been shown to produce numerous neuroplastic benefits in cortical and subcortical structures and can be coupled with wheel running to increase the proliferation and survival of new cells in the adult hippocampus. The combination of these two interventions provides a robust "superintervention" (WR-EC) that can be implemented in a range of rodent models of neurological disorders. We will discuss the implementation of WR/EC and its constituent interventions for use as a more powerful therapeutic intervention in rats using the animal model of prenatal exposure to alcohol in humans. We will also discuss which elements of the procedures are absolutely necessary for the interventions and which ones may be altered depending on the experimenter's question or facilities.

Binge alcohol alters exercise-driven neuroplasticity

Exercise is increasingly being used as a treatment for alcohol use disorders (AUD), but the interactive effects of alcohol and exercise on the brain remain largely unexplored. Alcohol damages the brain, in part by altering glial functioning. In contrast, exercise promotes glial health and plasticity. In the present study, we investigated whether binge alcohol would attenuate the effects of subsequent exercise on glia. We focused on the medial prefrontal cortex (mPFC), an alcohol-vulnerable region that also undergoes neuroplastic changes in response to exercise. Adult female Long-Evans rats were gavaged with ethanol (25% w/v) every 8h for 4days. Control animals received an isocaloric, non-alcohol diet. After 7days of abstinence, rats remained sedentary or exercised for 4weeks. Immunofluorescence was then used to label microglia, astrocytes, and neurons in serial tissue sections through the mPFC. Confocal microscope images were processed using FARSIGHT, a computational image analysis toolkit capable of automated analysis of cell number and morphology. We found that exercise increased the number of microglia in the mPFC in control animals. Binged animals that exercised, however, had significantly fewer microglia. Furthermore, computational arbor analytics revealed that the binged animals (regardless of exercise) had microglia with thicker, shorter arbors and significantly less branching, suggestive of partial activation. We found no changes in the number or morphology of mPFC astrocytes. We conclude that binge alcohol exerts a prolonged effect on morphology of mPFC microglia and limits the capacity of exercise to increase their numbers.

Neurotrophins in the Brain: Interaction With Alcohol Exposure During Development

Fetal alcohol spectrum disorders (FASDs) are a result of the teratogenic effects of alcohol on the developing fetus. Decades of research examining both individuals with FASDs and animal models of developmental alcohol exposure have revealed the devastating effects of alcohol on brain structure, function, behavior, and cognition. Neurotrophic factors have an important role in guiding normal brain development and cellular plasticity in the adult brain. This chapter reviews the current literature showing that alcohol exposure during the developmental period impacts neurotrophin production and proposes avenues through which alcohol exposure and neurotrophin action might interact. These areas of overlap include formation of long-term potentiation, oxidative stress processes, neuroinflammation, apoptosis and cell loss, hippocampal adult neurogenesis, dendritic morphology and spine density, vasculogenesis and angiogenesis, and behaviors related to spatial memory, anxiety, and depression. Finally, we discuss how neurotrophins have the potential to act in a compensatory manner as neuroprotective molecules that can combat the deleterious effects of in utero alcohol exposure.

Impact of exercise and a complex environment on hippocampal dendritic morphology, Bdnf gene expression, and DNA methylation in male rat pups neonatally exposed to alcohol

Alcohol exposure in utero can result in Fetal Alcohol Spectrums Disorders (FASD). Measures of hippocampal neuroplasticity, including long-term potentiation, synaptic and dendritic organization, and adult neurogenesis, are consistently disrupted in rodent models of FASD. The current study investigated whether third trimester-equivalent binge-like alcohol exposure (AE) [postnatal days (PD) 4-9] affects dendritic morphology of immature dentate gyrus granule cells, and brain-derived neurotrophic factor (Bdnf) gene expression and DNA methylation in hippocampal tissue in adult male rats. To understand immediate impact of alcohol, DNA methylation was measured in the PD10 hippocampus. In addition, two behavioral interventions, wheel running (WR) and environmental complexity (EC), were utilized as rehabilitative therapies for alcohol-induced deficits. AE significantly decreased dendritic complexity of the immature neurons, demonstrating the long-lasting impact of neonatal alcohol exposure on dendritic morphology of immature neurons in the hippocampus. Both housing conditions robustly enhanced dendritic complexity in the AE animals. While Bdnf exon I DNA methylation was lower in the AE and sham-intubated animals compared with suckle controls on PD10, alterations to Bdnf DNA methylation and gene expression levels were not present at PD72. In control animals, exercise, but not exercise followed by housing in EC, resulted in higher levels of hippocampal Bdnf gene expression and lower DNA methylation. These studies demonstrate the long-lasting negative impact of developmental alcohol exposure on hippocampal dendritic morphology and support the implementation of exercise and complex environments as therapeutic interventions for individuals with FASD. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 708-725, 2017.

Behavioral deficits induced by third-trimester equivalent alcohol exposure in male C57BL/6J mice are not associated with reduced adult hippocampal neurogenesis but are still rescued with voluntary exercise

Prenatal alcohol exposure can produce permanent alterations in brain structure and profound behavioral deficits. Mouse models can help discover mechanisms and identify potentially useful interventions. This study examined long-term influences of either a single or repeated alcohol exposure during the third-trimester equivalent on survival of new neurons in the hippocampus, behavioral performance on the Passive avoidance and Rotarod tasks, and the potential role of exercise as a therapeutic intervention. C57BL/6J male mice received either saline or 5g/kg ethanol split into two s.c. injections, two hours apart, on postnatal day (PD)7 (Experiment 1) or on PD5, 7 and 9 (Experiment 2). All mice were weaned on PD21 and received either a running wheel or remained sedentary from PD35-PD80/81. From PD36-45, mice received i.p. injections of 50mg/kg bromodeoxyuridine (BrdU) to label dividing cells. Behavioral testing occurred between PD72-79. Number of surviving BrdU+ cells and immature neurons (doublecortin; DCX+) was measured at PD80-81. Alcohol did not affect number of BrdU+ or DCX+ cells in either experiment. Running significantly increased number of BrdU+ and DCX+ cells in both treatment groups. Alcohol-induced deficits on Rotarod performance and acquisition of the Passive avoidance task (Day 1) were evident only in Experiment 2 and running rescued these deficits. These data suggest neonatal alcohol exposure does not result in long-term impairments in adult hippocampal neurogenesis in the mouse model. Three doses of ethanol were necessary to induce behavioral deficits. Finally, the mechanisms by which exercise ameliorated the neonatal alcohol induced behavioral deficits remain unknown.

Environmental enrichment as a potential intervention for heroin seeking

BACKGROUND

Heroin-related cues can trigger craving and relapse in addicts or heroin seeking in rats. In the present study we investigated whether environmental enrichment (EE) implemented after heroin exposure can reduce cue-induced reinstatement of heroin seeking and expression of heroin conditioned place preference.

METHODS

In Experiment 1, male Long Evans rats that already acquired a heroin self-administration habit, were housed in enriched or non-enriched environments, underwent extinction training and later were tested for cue-induced reinstatement of heroin seeking. In Experiment 2, rats were conditioned with heroin in one compartment of a CPP apparatus and saline in the other, exposed to 30days of enrichment or no enrichment and were later tested for heroin CPP.

RESULTS

The results showed that exposure to EE significantly reduced responding during the reinstatement test (Experiment 1) and prevented the expression of heroin CPP (Experiment 2).

CONCLUSION

Our findings suggest that EE can be an effective behavioral approach to diminish the effects of conditioned cues on heroin seeking.

Effects of maternal hypothyroidism during pregnancy on learning, memory and hippocampal BDNF in rat pups: Beneficial effects of exercise

Hypothyroidism during early development leads to numerous morphological, biochemical and functional changes in developing brain. In this study, we investigated the effects of voluntary and treadmill exercise on learning, memory and hippocampal BDNF levels in both hypothyroid male and female rat pups. To induce hypothyroidism in the mothers, 6-propyl-2-thiouracil (PTU) was added to their drinking water (100mg/L) from their embryonic day 6 to their postnatal day (PND) 21. For 14days, from PNDs 31 to 44, the rat pups were trained with one of the two different exercise protocols, namely the mild treadmill exercise and the voluntary wheel exercise. On PNDs 45-52, a water maze was used for testing their learning and memory ability. The rats were sacrificed one day later and their BDNF levels were then measured in the hippocampus. The findings of the present study indicate that hypothyroidism during the fetal period and the early postnatal period is associated with the impairment of spatial learning and memory and reduced hippocampal BDNF levels in both male and female rat offspring. Both the short-term treadmill exercise and the voluntary wheel exercise performed during the postnatal period reverse the behavioral and neurochemical deficits induced by developmental thyroid hormone insufficiency in both male and female rat offspring. The findings of this study thus demonstrate a marked reversibility of both behavioral and neurochemical disorders induced by developmental thyroid hormone insufficiency through the performance of exercise.

Exercise and cerebrovascular plasticity

Aging impairs cerebrovascular plasticity and subsequently leads cerebral hypoperfusion, which synergistically accelerates aging-associated cognitive dysfunction and neurodegenerative diseases associated with impaired neuronal plasticity. On the other hand, over two decades of researches have successfully demonstrated that exercise, or higher level of physical activity, is a powerful and nonpharmacological approach to improve brain function. Most of the studies have focused on the neuronal aspects and found that exercise triggers improvements in neuronal plasticity, such as neurogenesis; however, exercise can improve cerebrovascular plasticity as well. In this chapter, to understand these beneficial effects of exercise on the cerebral vasculature, we first discuss the issue of changes in cerebral blood flow and its regulation during acute bouts of exercise. Then, how regular exercise improves cerebrovascular plasticity will be discussed. In addition, to shed light on the importance of understanding interactions between the neuron and cerebral vasculature, we describe neuronal activity-driven uptake of circulating IGF-I into the brain.

Effects of pre-natal alcohol exposure on hippocampal synaptic plasticity: Sex, age and methodological considerations

The consumption of alcohol during gestation is detrimental to the developing central nervous system (CNS). The severity of structural and functional brain alterations associated with alcohol intake depends on many factors including the timing and duration of alcohol consumption. The hippocampal formation, a brain region implicated in learning and memory, is highly susceptible to the effects of developmental alcohol exposure. Some of the observed effects of alcohol on learning and memory may be due to changes at the synaptic level, as this teratogen has been repeatedly shown to interfere with hippocampal synaptic plasticity. At the molecular level alcohol interferes with receptor proteins and can disrupt hormones that are important for neuronal signaling and synaptic plasticity. In this review we examine the consequences of prenatal and early postnatal alcohol exposure on hippocampal synaptic plasticity and highlight the numerous factors that can modulate the effects of alcohol. We also discuss some potential mechanisms responsible for these changes as well as emerging therapeutic avenues that are beginning to be explored.

Prenatal ethanol exposure impairs temporal ordering behaviours in young adult rats

Prenatal ethanol exposure (PNEE) causes significant deficits in functional (i.e., synaptic) plasticity in the dentate gyrus (DG) and cornu ammonis (CA) hippocampal sub-regions of young adult male rats. Previous research has shown that in the DG, these deficits are not apparent in age-matched PNEE females. This study aimed to expand these findings and determine if PNEE induces deficits in hippocampal-dependent behaviours in both male and female young adult rats (PND 60). The metric change behavioural test examines DG-dependent deficits by determining whether an animal can detect a metric change between two identical objects. The temporal order behavioural test is thought to rely in part on the CA sub-region of the hippocampus and determines whether an animal will spend more time exploring an object that it has not seen for a larger temporal window as compared to an object that it has seen more recently. Using the liquid diet model of FASD (where 6.6% (v/v) ethanol is provided through a liquid diet consumed ad libitum throughout the entire gestation), we found that PNEE causes a significant impairment in the temporal order task, while no deficits in the DG-dependent metric change task were observed. There were no significant differences between males and females for either task. These results indicate that behaviours relying partially on the CA-region may be more affected by PNEE than those that rely on the DG.

The Benefits of Exercise on Structural and Functional Plasticity in the Rodent Hippocampus of Different Disease Models

In this review, the benefits of physical exercise on structural and functional plasticity in the hippocampus are discussed. The evidence is clear that voluntary exercise in rats and mice can lead to increases in hippocampal neurogenesis and enhanced synaptic plasticity which ultimately result in improved performance in hippocampal-dependent tasks. Furthermore, in models of neurological disorders, including fetal alcohol spectrum disorders, traumatic brain injury, stroke, and neurodegenerative disorders including Alzheimer's, Parkinson's and Huntington's disease exercise can also elicit beneficial effects on hippocampal function. Ultimately this review highlights the multiple benefits of exercise on hippocampal function in both the healthy and the diseased brain.

Exercise Regulation of Cognitive Function and Neuroplasticity in the Healthy and Diseased Brain

Regular exercise broadly enhances physical and mental health throughout the lifespan. Animal models have provided us with the tools to gain a better understanding of the underlying biochemical, physiological, and morphological mechanisms through which exercise exerts its beneficial cognitive effects. One brain region in particular, the hippocampus, is especially responsive to exercise. It is critically involved in learning and memory and is one of two regions in the mammalian brain that continues to generate new neurons throughout life. Exercise prevents the decline of the hippocampus from aging and ameliorates many neurodegenerative diseases, in part by increasing adult hippocampal neurogenesis but also by activating a multitude of molecular mechanisms that promote brain health. In this chapter, we first describe some rodent models used to study effects of exercise on the brain. Then we review the rodent work focusing on the mechanisms behind which exercise improves cognition and brain health in both the normal and the diseased brain, with emphasis on the hippocampus.

Voluntary exercise partially reverses neonatal alcohol-induced deficits in mPFC layer II/III dendritic morphology of male adolescent rats

Developmental alcohol exposure in humans can produce a wide range of deficits collectively referred to as fetal alcohol spectrum disorders (FASD). FASD-related impairments in executive functioning later in life suggest long-term damage to the prefrontal cortex (PFC). In rodent neonates, moderate to high levels of alcohol exposure decreased frontal lobe brain size and altered medial PFC pyramidal neuron dendritic morphology. Previous research in our lab demonstrated that neonatal alcohol exposure decreased basilar dendritic complexity but did not affect spine density in Layer II/III pyramidal neurons in 26- to 30-day-old rats. The current study adds to the literature by evaluating the effect of neonatal alcohol exposure on mPFC Layer II/III basilar dendritic morphology in adolescent male rats. Additionally, it examines the potential for voluntary exercise to mitigate alcohol-induced deficits on mPFC dendritic complexity. An animal model of binge drinking during the third trimester of pregnancy was used. Rats were intubated with alcohol (alcohol-exposed, AE; 5.25 g kg(-1) day(-1)) on postnatal days (PD) 4-9; two control groups were included (suckle control and sham-intubated). Rats were anesthetized and perfused with heparinized saline solution on PD 42, and brains were processed for Golgi-Cox staining. Developmental alcohol exposure decreased spine density and dendritic complexity of basilar dendrites of Layer II/III neurons in the medial PFC (mPFC) compared to dendrites of control animals. Voluntary exercise increased spine density and dendritic length in AE animals resulting in elimination of the differences between AE and SH rats. Thus, voluntary exercise during early adolescence selectively rescued alcohol-induced morphological deficits in the mPFC.

Effects of developmental alcohol exposure vs. intubation stress on BDNF and TrkB expression in the hippocampus and frontal cortex of neonatal rats

Third trimester-equivalent alcohol exposure causes significant deficits in hippocampal and cortical neuroplasticity, resulting in alterations to dendritic arborization, hippocampal adult neurogenesis, and performance on learning tasks. The current study investigated the impact of neonatal alcohol exposure (postnatal days 4-9, 5.25 g/kg/day) on expression of brain-derived neurotrophic factor (BDNF) and the tropomyosin-related kinase B (TrkB) receptor in the hippocampal and frontal cortex of infant Long-Evans rats. Levels of BDNF protein were increased in the hippocampus, but not frontal cortex, of alcohol-exposed rats 24h after the last dose, when compared with undisturbed (but not sham-intubated) control animals. BDNF protein levels showed a trend toward increase in hippocampus of sham-intubated animals as well, suggesting an effect of the intubation procedure. TrkB protein was increased in the hippocampus of alcohol-exposed animals compared to sham-intubated pups, indicating an alcohol-specific effect on receptor expression. In addition, expression of bdnf total mRNA in alcohol-exposed and sham-intubated pups was enhanced in the hippocampus; however, there was a differential effect of alcohol and intubation stress on exon I- and IV-specific mRNA transcripts. Further, plasma corticosterone was found to be increased in both alcohol-exposed and sham-intubated pups compared to undisturbed animals. Upregulation of BDNF could potentially represent a neuroprotective mechanism activated following alcohol exposure or stress. The results suggest that alcohol exposure and stress have both overlapping and unique effects on BDNF, and highlight the need for the stress of intubation to be taken into consideration in studies that implement this route of drug delivery.