Increased apoptosis and reduced neuronal and glial densities in the hippocampus due to nicotine and ethanol exposure in adolescent mice

Adolescent intermittent alcohol exposure produces strain-specific cross-sensitization to nicotine and other behavioral adaptations in adulthood in C57BL/6J and DBA/2J mice

Adolescent alcohol exposure is associated with lasting behavioral changes in humans and in mice. Prior work from our laboratory and others have demonstrated that C57BL/6J and DBA/2J mice differ in sensitivity to some effects of acute alcohol exposure during adolescence and adulthood. However, it is unknown if these strains differ in cognitive, anxiety-related, and addiction-related long-term consequences of adolescent intermittent alcohol exposure. This study examined the impact of a previously validated adolescent alcohol exposure paradigm (2-3 g/kg, i.p., every other day PND 30-44) in C57BL/6J and DBA/2J male and female mice on adult fear conditioning, anxiety-related behavior (elevated plus maze), and addiction-related phenotypes including nicotine sensitivity (hypothermia and locomotor depression) and alcohol sensitivity (loss of righting reflex; LORR). Both shared and strain-specific long-term consequences of adolescent alcohol exposure were found. Most notably, we found a strain-specific alcohol-induced increase in sensitivity to nicotine's hypothermic effects during adulthood in the DBA/2J strain but not in the C57BL/6J strain. Conversely, both strains demonstrated a robust increased latency to LORR during adulthood after adolescent alcohol exposure. Thus, we observed strain-dependent cross-sensitization to nicotine and strain-independent tolerance to alcohol due to adolescent alcohol exposure. Several strain and sex differences independent of adolescent alcohol treatment were also observed. These include increased sensitivity to nicotine-induced hypothermia in the C57BL/6J strain relative to the DBA/2J strain, in addition to DBA/2J mice showing more anxiety-like behaviors in the elevated plus maze relative to the C57BL/6J strain. Overall, these results suggest that adolescent alcohol exposure results in altered adult sensitivity to nicotine and alcohol with some phenotypes mediated by genetic background.

Omega-3 fatty acids prevent nicotine withdrawal-induced impairment of learning and memory via affecting oxidative status, inflammatory response, cholinergic activity, BDNF and amyloid-B in rat hippocampal tissues

In the present study, the main objective was to reveal whether treatment by Omega-3 fatty acids could prevent the adverse effects of adolescent nicotine withdrawal on spatial and avoidance memory in male rats. For this purpose, Morris water maze and passive avoidance tests were performed on male Wistar rats and the hippocampal levels of oxidative stress markers, inflammatory indices, brain-derived neurotrophic factor, nitrite, amyloid-B and acetylcholinesterase (AChE) were measured. Moreover, density of dark neurons were assessed in CA1 and CA3 regions. Results showed that adolescent nicotine exposure followed by a period of drug cessation exacerbates the behavioral indices of learning and memory through affecting a variety of biochemical markers within the hippocampal tissues. These changes lead to elevation of oxidative and inflammatory markers, reduction of neurotrophic capacity and increased AChE activity in hippocampal tissues. In addition, it was observed that co-administration of nicotine with Omega-3 fatty acids significantly prevents nicotine withdrawal-induced adverse effects through restoration of the mentioned biochemical disturbances. Therefore, we suggest administration of Omega-3 fatty acids as a safe, inexpensive and effective therapeutic strategy for prevention of memory dysfunctions associated with nicotine abstinence during adolescence.

Region- and age-specific effects of perinatal phthalate exposure on developmental cell death and adult anatomy of dorsal and ventral hippocampus and associated cognitive behaviors

Humans are exposed to phthalates, a class of endocrine-disrupting chemicals used in food packaging/processing, PVC plastics, and personal care products. Gestational exposure may lead to adverse neurodevelopmental outcomes. In a rat model, perinatal exposure to an environmentally relevant mixture and dose of phthalates leads to increased developmental apoptosis in the medial prefrontal cortex (mPFC) and a subsequent reduction in neurons and in cognitive flexibility measured in adults of both sexes (Sellinger et al., 2021b; Kougias et al., 2018b). However, whether these effects generalize to other cognitive regions, like the hippocampus, is less well understood as existing studies used single phthalates at large doses, unrepresentative of human exposure. In the current study, patterns of naturally occurring cell death were first established in the dorsal and ventral hippocampal subfields (CA3 and CA1). Both dorsal and ventral CA3 reached high levels of cell death on P2 while levels in dorsal and ventral CA1 peaked on P5 in both sexes. Exposure to a phthalate mixture (0.2 and 1 mg/kg/day) throughout gestation through postnatal day 10 resulted in subtle age- and region-specific decreases in developmental cell death, however there were no significant changes in adult neuron number or associated behaviors: the Morris water maze and social recognition. Therefore, perinatal exposure to a low dose mixture of phthalates does not result in the dramatic structural and behavioral changes seen with high doses of single phthalates. This study also adds to our understanding of the distinct neurodevelopmental effects of phthalates on different brain regions.

Impact of in-utero electronic cigarette exposure on neonatal neuroinflammation, oxidative stress and mitochondrial function

Introduction: Despite the prevalence of the perception that electronic cigarettes (e-cig) are a safer alternative to tobacco smoke, growing concern about their potential toxic impact warrants adequate investigation focusing on special populations like maternal and pediatric groups. This study evaluated the consequences of maternal e-cig use on neonatal neuroinflammation, oxidative stress, and mitochondrial function in primary cultured neurons and postnatal day (PD) 7 and 90 brain. Methodology: Pregnant CD1 mice were exposed to e-cig vapor (2.4% nicotine) from gestational day 5 (E5) till PD7, and the primary neurons were isolated from pups at E16/17. Cellular total reactive oxygen species (ROS) and mitochondrial superoxide were measured in primary neurons using CM-H2DCFDA and Mitosox red, respectively. Mitochondrial function was assessed by Seahorse XF Cell Mitostress analysis. The level of pro-inflammatory cytokines was measured in primary neurons and PD7 and PD90 brains by RT-PCR and immunobead assay. Western blot analysis evaluated the expression of antioxidative markers (SOD-2, HO-1, NRF2, NQO1) and that of the proinflammatory modulator NF-κB. Results: Significantly higher level of total cellular ROS (p < 0.05) and mitochondrial superoxide (p < 0.01) was observed in prenatally e-cig-exposed primary neurons. We also observed significantly reduced antioxidative marker expression and increased proinflammatory modulator and cytokines expression in primary neurons and PD7 (p < 0.05) but not in PD90 postnatal brain. Conclusion: Our findings suggest that prenatal e-cig exposure induces postnatal neuroinflammation by promoting oxidative stress (OS), increasing cytokines' levels, and disrupting mitochondrial function. These damaging events can alter the fetal brain's immune functions, making such offspring more vulnerable to brain insults.

Nicotine on the developing brain

Developmental periods such as gestation and adolescence have enhanced plasticity leaving the brain vulnerable to harmful effects from nicotine use. Proper brain maturation and circuit organization is critical for normal physiological and behavioral outcomes. Although cigarette smoking has declined in popularity, noncombustible nicotine products are readily used. The misperceived safety of these alternatives lead to widespread use among vulnerable populations such as pregnant women and adolescents. Nicotine exposure during these sensitive developmental windows is detrimental to cardiorespiratory function, learning and memory, executive function, and reward related circuitry. In this review, we will discuss clinical and preclinical evidence of the adverse alterations in the brain and behavior following nicotine exposure. Time-dependent nicotine-induced changes in reward related brain regions and drug reward behaviors will be discussed and highlight unique sensitivities within a developmental period. We will also review long lasting effects of developmental exposure persisting into adulthood, along with permanent epigenetic changes in the genome which can be passed to future generations. Taken together, it is critical to evaluate the consequences of nicotine exposure during these vulnerable developmental windows due to its direct impact on cognition, potential trajectories for other substance use, and implicated mechanisms for the neurobiology of substance use disorders.

Investigating the causal nature of the relationship of subcortical brain volume with smoking and alcohol use

BACKGROUND

Structural variation in subcortical brain regions has been linked to substance use, including the most commonly used substances nicotine and alcohol. Pre-existing differences in subcortical brain volume may affect smoking and alcohol use, but there is also evidence that smoking and alcohol use can lead to structural changes.

AIMS

We assess the causal nature of the complex relationship of subcortical brain volume with smoking and alcohol use, using bi-directional Mendelian randomisation.

METHOD

Mendelian randomisation uses genetic variants predictive of a certain 'exposure' as instrumental variables to test causal effects on an 'outcome'. Because of random assortment at meiosis, genetic variants should not be associated with confounders, allowing less biased causal inference. We used summary-level data of genome-wide association studies of subcortical brain volumes (nucleus accumbens, amygdala, caudate, hippocampus, pallidum, putamen and thalamus; n = 50 290) and smoking and alcohol use (smoking initiation, n = 848 460; cigarettes per day, n = 216 590; smoking cessation, n = 378 249; alcoholic drinks per week, n = 630 154; alcohol dependence, n = 46 568). The main analysis, inverse-variance weighted regression, was verified by a wide range of sensitivity methods.

RESULTS

There was strong evidence that liability to alcohol dependence decreased amygdala and hippocampal volume, and smoking more cigarettes per day decreased hippocampal volume. From subcortical brain volumes to substance use, there was no or weak evidence for causal effects.

CONCLUSIONS

Our findings suggest that heavy alcohol use and smoking can causally reduce subcortical brain volume. This adds to accumulating evidence that alcohol and smoking affect the brain, and likely mental health, warranting more recognition in public health efforts.

Nicotine Prevents Oxidative Stress-Induced Hippocampal Neuronal Injury Through α7-nAChR/Erk1/2 Signaling Pathway

Oxidative stress-induced neuronal damage has been implicated to play a dominant role in neurodegenerative disorders, such as Alzheimer’s disease (AD). Nicotine, a principal additive compound for tobacco users, is thought as a candidate to attenuate amyloid-β-mediated neurotoxicity and NMDA-induced excitotoxicity. Previous studies demonstrated that nicotine exerted this neuroprotective action on oxidative stress. However, the mechanisms underlying how nicotine contributes on oxidative injury in immortalized hippocampal HT-22 cells remain largely unknown. Therefore, in this study we investigated that the potential effects of nicotine on hydrogen peroxide (H₂O₂)-induced oxidative injury and underlying mechanisms in HT-22 cells. We found that pretreatment with nicotine at low concentrations markedly recovered the cell cycle that was arrested at the G2/M phase in the presence of H₂O₂ through reduced intracellular ROS generation. Moreover, nicotine attenuated H₂O₂-induced mitochondrial dysfunctions. Mechanistically, the application of nicotine significantly upregulated the levels of phosphorylated Erk1/2. The neuroprotective effects of nicotine, in turn, were abolished by PD0325901, a selective Erk1/2 inhibitor. Further obtained investigation showed that nicotine exerted its neuroprotective effects via specifically activating α7 nicotinic acetylcholine receptors (α7-nAChRs). A selective inhibitor of α7-nAChRs, methyllycaconitine citrate (MLA), not only completely prevented nicotine-mediated antioxidation but also abolished expression of p-Erk1/2. Taken together, our findings suggest that nicotine suppresses H₂O₂-induced HT-22 cell injury through activating the α7-nAChR/Erk1/2 signaling pathway, which indicates that nicotine may be a novel strategy for the treatment of neurodegenerative disorders.

Effects of endurance exercise and Urtica dioica on the functional, histological and molecular aspects of the hippocampus in STZ-Induced diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Many body systems and organs, including the hippocampus, are affected by diabetes, and undergo changes that may increase the risk of cognitive decline. Urtica dioica (UD) has long been recognized as a medicinal plant with beneficial effects on blood glucose control in diabetes.

AIM OF THE STUDY

The present study aimed to investigate the effect of endurance exercise (Ex), along with Urtica dioica (UD) hydro-alcoholic extract on some functional, histological, and molecular aspects of the hippocampus in streptozotocin (STZ)-induced diabetic rats.

MATERIALS AND METHODS

60 male Wistar rats were divided into five groups (N = 12): healthy control (H-C), diabetes control (D-C), diabetes exercise (D-Ex), diabetes Urtica dioica (D-UD), and diabetes exercise Urtica dioica (D-Ex-UD). Diabetes was induced intraperitoneally by STZ (45 mg/kg) injection. Two weeks after the injection by STZ, Ex (moderate intensity/5day/week) and gavage of UD extract (50mg/kg/day) was performed for six weeks. Cognitive functions were evaluated by the Morris Water Maze test, routine histological examination, and molecular studies were done via Hematoxylin & Eosin stain, and Western blot.

RESULTS

Diabetic rats showed spatial learning and memory deficits, as well as negatively affects to the tissue and structure of the hippocampus in the dentate gyrus (DG) and cornu ammonis (CA) areas. Ex + UD treatment caused a decrease of neural disorganization, an increase of neural-microglial density, and thickness of the pyramidal-molecular layer in the hippocampus. In addition, Ex + UD caused a rise of GAP-43 protein levels, a reduction of CAP-1 protein levels, improved hippocampal structure, and improved learning and memory function.

CONCLUSIONS

These results show that Ex, along with the UD extract, may decrease levels of the central neural complications of diabetes. Given the importance of recognizing non-pharmacological complementary therapies in this field, future studies are warranted.

Comparative study on the effects of cigarette smoke exposure, ethanol consumption and association: Behavioral parameters, apoptosis, glial fibrillary acid protein and S100β immunoreactivity in different regions of the rat hippocampus

Exposure to cigarette smoke and ethanol are proposed to trigger neurotoxicity, apoptosis, and to impair neuronal signaling. However, it is little known how the combination of both might trigger astrogliosis and the morphological changes capable of affecting a differential susceptibility of hippocampal regions to these licit drugs. The present study investigated the chronic effects of exposure to cigarette smoke and/or ethanol on behavioral parameters, apoptosis, and alteration in immunoreactivity of glial fibrillary acid protein (GFAP) and S100β in the CA1, CA3, and dentate gyrus (DG) of the rat hippocampus. Adult male Wistar rats (n = 32) were divided into four groups: vehicle (VE, glucose 3% in water, 10 mL/kg), cigarette smoke (TOB, total 12 cigarettes per day), ethanol (ethanol, 2 g/kg), and cigarette smoke plus ethanol (TOB plus ethanol, total 12 cigarettes per day plus ethanol 2 g/kg) for 54 days. The groups were submitted to tail-flick, open-field, and inhibitory avoidance tasks. The results showed that ethanol per se worsened the short-term memory. The association between TOB and ethanol increased the immunoreactivity of cleaved caspase-3 in the CA3 and DG regions. The TOB plus ethanol group showed a lower immunoreactivity to GFAP in all regions of the hippocampus. In addition, ethanol and TOB per se also reduced the immunoreactivity for GFAP in the DG. Ethanol increased S100β immunoreactivity only in the DG. In conclusion, this study showed that only ethanol worsened short-term memory, and the DG became more susceptible to changes in the markers investigated. This evidence suggests that DG is more sensitive to neurotoxicity induced by cigarette smoke and ethanol.

Pulcinelli R, Bandiera S, Caletti G, Bitencourt PER, Quincozes-Santos A, Gomez R. Combined Exposure to Alcohol and Tobacco Smoke Changes Oxidative, Inflammatory, and Neurotrophic Parameters in Different Areas of the Brains of Rats

Devastating effects of exposure to alcohol and tobacco smoke on health are extensively reported in the literature. However, few studies have attempted to elucidate the consequences of their combined use on the central nervous system. Here we studied the effect of this combined use on some oxidative, inflammatory, and neurotrophic parameters in the hippocampus, striatum, and frontal cortex of rats. Adult Wistar rats were allocated into control (CT), alcohol (AL), tobacco smoke (TB), or combined (ALTB) groups. Rats were exposed to environmental air (CT and AL groups) or to the smoke from six cigarettes (TB and ALTB groups) immediately after tap water (CT and TB) or 2 g of alcohol/kg (AL and ALTB) oral gavage administration, twice a day, for 4 weeks. On day 28, rats were euthanized and areas of the brain were dissected to evaluate some cellular redox parameters, pro-inflammatory cytokine levels, and brain-derived neurotrophic factor (BDNF) levels. A one-way analysis of variance showed that the ALTB combined treatment significantly increased oxidative stress levels in the hippocampus. ALTB also increased interleukin-1β levels in the striatum and frontal cortex and tumoral necrosis factor-α levels in the frontal cortex compared with those of AL, TB, and CT rats. Combined treatment also decreased the BDNF levels in the frontal cortex of rats. Oxidative damage was found, more importantly, in the hippocampus, and inflammatory parameters were extended to all areas of the brain that were studied. Our results showed an interaction between alcohol and tobacco smoke according to the area of the brain, suggesting an additional risk of neural damage in alcoholics who smoke.

Tobacco smoke and ethanol during adolescence: Both combined- and single-drug exposures lead to short- and long-term disruption of the serotonergic system in the mouse brain

The impairment of the serotonergic system contributes to nicotine and ethanol effects on mood, suggesting that this system is targeted by each of these drugs and that co-exposure possibly worsens the disruption. Here, we tested this hypothesis in an adolescent mice model of tobacco smoke and/or ethanol exposure. From postnatal day (PN) 30-45, Swiss mice were exposed to one of the following: 1) tobacco smoke (SMK; research cigarettes 2R1F, whole-body exposure, 8 h/daily); 2) ethanol (ETOH; 2 g/kg i.p., every other day); 3) SMK + ETOH; 4) Control (VEH). At PN45 (end-of-exposure), hippocampal serotonin transporter (5 H TT) binding was increased in SMK and decreased in ETOH male mice. At PN50 (short-term deprivation), cortical 5 H TT was reduced in all drug-exposed mice. In the hippocampus, similar deficits were identified in females. In both brain regions, the effects of SMK + ETOH deprivation on 5 H TT were equivalent to the damage caused by either drug. At PN50, hippocampal 5 H T1A receptor binding was reduced in ETOH and SMK + ETOH mice. Similar results were observed in the male cortex. In females, deficits were identified in SMK mice. In both brain regions, SMK + ETOH 5 H T1A deficits reflected the summation of SMK and ETOH outcomes. At PN75 (long-term deprivation), there was a late-emergent increase in cortical 5 H T1A binding in SMK mice, while cortical 5 H T2 receptor binding was similarly increased in SMK and SMK + ETOH groups. Adolescent SMK and/or ETOH serotonergic impairment is sex-dependent and most evident during short-term deprivation. SMK + ETOH deprivation evokes serotonergic disruption that is at least equivalent to that caused by either drug alone.

Taurine Ameliorates Arsenic-Induced Apoptosis in the Hippocampus of Mice Through Intrinsic Pathway

Our group previously reported that arsenic (As) exposure induced apoptosis in hippocampus neurons. The aim of the present study was to clarify the protective capacity of taurine (Tau) on As-induced neuronal apoptosis and the related mechanism in mouse hippocampus. Mice were divided into: control group, Tau control group, As exposure group and Tau protective group, randomly. The apoptotic rate of mouse hippocampus was determined by TUNEL staining. The levels of Bcl-2 and Bax gene and protein were analyzed by real time RT-PCR and WB, respectively. Furthermore, cytochrome c (Cyt C) release, and the activity of caspase-8 and caspase-3 were also determined. The results showed that Tau treatment induced the decrease of TUNEL-positive cells, prohibited the disturbance of Bcl-2 and Bax expression, and inhibited Cyt C release and caspase-8 and caspase-3 activation significantly. The results indicated that Tau supplement markedly ameliorates As-induced apoptosis by mitochondria-related pathway in mouse hippocampus.

Alcohol and the Developing Brain: Why Neurons Die and How Survivors Change

The consequences of alcohol drinking during pregnancy are dramatic and usually referred to as fetal alcohol spectrum disorders (FASD). This condition is one of the main causes of intellectual disability in Western countries. The immature fetal brain exposed to ethanol undergoes massive neuron death. However, the same mechanisms leading to cell death can also be responsible for changes of developmental plasticity. As a consequence of such a maladaptive plasticity, the functional damage to central nervous system structures is amplified and leads to permanent sequelae. Here we review the literature dealing with experimental FASD, focusing on the alterations of the cerebral cortex. We propose that the reciprocal interaction between cell death and maladaptive plasticity represents the main pathogenetic mechanism of the alcohol-induced damage to the developing brain.

Chronic ethanol exposure induces SK-N-SH cell apoptosis by increasing N-methyl-D-aspartic acid receptor expression and intracellular calcium

It has been identified that chronic ethanol exposure damages the nervous system, particularly neurons. There is scientific evidence suggesting that neuronal loss caused by chronic ethanol exposure has an association with neuron apoptosis and intracellular calcium oscillation is one of the primary inducers of apoptosis. Therefore, the present study aimed to investigate the inductive effects of intracellular calcium oscillation on apoptosis in SK-N-SH human neuroblastoma cells and the protective effects of the N-methyl-D-aspartic acid receptor (NMDAR) antagonist, memantine, on SK-N-SH cell apoptosis caused by chronic ethanol exposure. SK-N-SH cells were treated with 100 mM ethanol and memantine (4 µM) for 2 days. Protein expression of NR1 was downregulated by RNA interference (RNAi). Apoptosis was detected by Annexin V/propidium iodide (PI) double-staining and flow cytometry and cell viability was detected using an MTS kit. Fluorescence dual wavelength spectrophotometry was used to determine the intracellular calcium concentration and the levels of NR1 and caspase-3 were detected using western blotting. NR1 mRNA levels were also detected using qPCR. It was found that chronic ethanol exposure reduced neuronal cell viability and caused apoptosis of SK-N-SH cells, and the extent of damage in SK-N-SH cells was associated with ethanol exposure concentration and time. In addition, chronic ethanol exposure increased the concentration of intracellular calcium in SK-N-SH cells by inducing the expression of NMDAR, resulting in apoptosis, and memantine treatment reduced ethanol-induced cell apoptosis. The results of the present study indicate that the application of memantine may provide a novel strategy for the treatment of alcoholic dementia.

Bidirectional Regulation of Mouse Embryonic Stem Cell Proliferation by Nicotine Is Mediated Through Wnt Signaling Pathway

Introduction:

Nicotine is a key biologically active compound of cigarettes. Although nicotine is a risk factor for various health issues, it may also be beneficial when treated at moderate concentrations. Nicotine has been shown to bidirectionally regulate stem cell proliferation and differentiation depending on the doses applied. It is not clear whether or how nicotine regulates mouse embryonic stem cell (mESC) survival and proliferation.

Methods:

Mouse embryonic stem cells were cultured in the presence of 0.01, 0.1, 1, or 10 μM nicotine. The effects of nicotine on cell survival and proliferation were examined. The signaling pathway that mediated these effects was analyzed.

Results:

Cell viability was not affected by nicotine at all 4 concentrations examined. The proliferation of mESCs was promoted by 0.01 and 0.1 μM nicotine and suppressed by 1 and 10 μM. This dose-dependent regulation was mediated through the Wnt/β-catenin pathway. Modulation of Wnt/β-catenin activity either worsens or reverses the effects of nicotine.

Conclusions:

We have identified a bidirectional function of nicotine on mESC proliferation through regulation of the Wnt/β-catenin pathway and this is associated with different doses. This study suggests that concentration of nicotine is a crucial aspect for consideration when designing research or therapeutic strategies.

Long-Lasting Effects of Chronic Intermittent Alcohol Exposure in Adolescent Mice on Object Recognition and Hippocampal Neuronal Activity

BACKGROUND

Binge drinking is popular and highly prevalent in teenagers. However, the long-term cognitive and neurobiological consequences of such practices are not yet fully understood. In this context, we therefore assessed in mice whether a chronic intermittent alcohol (CIA) exposure in adolescence had long-term consequences on object discrimination and memory performances, emotional behaviors, brain activity, and morphology.

METHODS

C57BL/6JRj mice were treated with either saline or ethanol (EtOH) (2 g/kg/d, i.p., from postnatal days [PND] 30 to PND 44 every other day). The day following the last administration or later in adulthood (PND 71) mice were tested for different behavioral tests (novel object recognition, spontaneous alternation, light-dark box, elevated plus-maze, actimeter test), to assess object recognition, working memory performances, anxiety-like behavior, and locomotor activity. We also investigated neuronal activation of hippocampus, prefrontal and perirhinal cortices, and anatomical changes using immediate-early gene expression and longitudinal brain magnetic resonance imaging.

RESULTS

Our results showed that adolescent mice exposed to CIA present a critical and persistent impairment of short-term object recognition performances. By contrast, spatial working memory was not impaired, nor was anxiety-like behavior. This altered object discrimination was associated with a biphasic change in neuronal activity in the hippocampus but without morphological changes. Indeed, c-Fos expression was specifically increased in the dorsal dentate gyrus (DG) of the hippocampus after the binge exposure, but then became significantly lower in adulthood both in the DG and the CA1 part of the hippocampus compared with adult saline pretreated mice.

CONCLUSIONS

These findings provide evidence for adolescent vulnerability to the effects of intermittent binge EtOH exposure on object discrimination and hippocampal activity with long-lasting consequences.

Long-term effects of chronic nicotine on emotional and cognitive behaviors and hippocampus cell morphology in mice: comparisons of adult and adolescent nicotine exposure

Nicotine dependence is associated with increased risk for emotional, cognitive and neurological impairments later in life. This study investigated the long-term effects of nicotine exposure during adolescence and adulthood on measures of depression, anxiety, learning and hippocampal pyramidal cell morphology. Mice (C57BL/6J) received saline or nicotine for 12 days via pumps implanted on postnatal day 32 (adolescent) or 54 (adults). Thirty days after cessation of nicotine/saline, mice were tested for learning using contextual fear conditioning, depression-like behaviors using the forced swim test or anxiety-like behaviors with the elevated plus maze. Brains from nicotine- or saline-exposed mice were processed with Golgi stain for whole neuron reconstruction in the CA1 and CA3 regions of the hippocampus. Results demonstrate higher depression-like responses in both adolescent and adult mice when tested during acute nicotine withdrawal. Heightened depression-like behaviors persisted when tested after 30 days of nicotine abstinence in mice exposed as adolescents, but not adults. Adult, but not adolescent, exposure to nicotine resulted in increased open-arm time when tested after 30 days of abstinence. Nicotine exposure during adolescence caused deficits in contextual fear learning indicated by lower levels of freezing to the context as compared with controls when tested 30 days later. In addition, reduced dendritic length and complexity in the apical CA1 branches in adult mice exposed to nicotine during adolescence were found. These results demonstrate that nicotine exposure and withdrawal can have long-term effects on emotional and cognitive functioning, particularly when nicotine exposure occurs during the critical period of adolescence.

Developmental cigarette smoke exposure II: Hippocampus proteome and metabolome profiles in adult offspring

Exposure to cigarette smoke during development is linked to neurodevelopmental delays and cognitive impairment including impulsivity, attention deficit disorder, and lower IQ. Utilizing a murine experimental model of "active" inhalation exposure to cigarette smoke spanning the entirety of gestation and through human third trimester equivalent hippocampal development [gestation day 1 (GD1) through postnatal day 21 (PD21)], we examined hippocampus proteome and metabolome alterations present at a time during which developmental cigarette smoke exposure (CSE)-induced behavioral and cognitive impairments are evident in adult animals from this model system. At six month of age, carbohydrate metabolism and lipid content in the hippocampus of adult offspring remained impacted by prior exposure to cigarette smoke during the critical period of hippocampal ontogenesis indicating limited glycolysis. These findings indicate developmental CSE-induced systemic glucose availability may limit both organism growth and developmental trajectory, including the capacity for learning and memory.

Activation of γ-aminobutyric Acid (A) Receptor Protects Hippocampus from Intense Exercise-induced Synapses Damage and Apoptosis in Rats

BACKGROUND

Our previous study has confirmed that one bout of exhaustion (Ex) can cause hippocampus neurocyte damage, excessive apoptosis, and dysfunction. Its initial reason is intracellular calcium overload in hippocampus triggered by N-methyl-D-aspartic acid receptor (NMDAR) over-activation. NMDAR activation can be suppressed by γ-aminobutyric acid (A) receptor (GABAAR). Whether GABAAR can prevent intense exercise-induced hippocampus apoptosis, damage, or dysfunction will be studied in this study.

METHODS

According to dose test, rats were randomly divided into control (Con), Ex, muscimol (MUS, 0.1 mg/kg) and bicuculline (BIC, 0.5 mg/kg) groups, then all rats underwent once swimming Ex except ones in Con group only underwent training. Intracellular free calcium concentration ([Ca2+]i) was measured by Fura-2-acetoxymethyl ester; glial librillary acidic protein (GFAP) and synaptophysin (SYP) immunofluorescence were also performed; apoptosis were displayed by dUTP nick end labeling (TUNEL) stain; endoplasmic reticulum stress-induced apoptosis pathway was detected by Western blotting analysis; Morris water maze was used to detect learning ability and spatial memory.

RESULTS

The appropriate dose was 0.1 mg/kg for MUS and 0.5 mg/kg for BIC. Ex group showed significantly increased [Ca2+]i and astrogliosis; TUNEL positive cells and levels of GFAP, B cell lymphoma-2 (Bcl-2) associated X protein (Bax), caspase-3, caspase-12 cleavage, CCAAT/enhancer binding protein homologous protein (CHOP), and p-Jun amino-terminal kinase (p-JNK) in Ex group also raised significantly compared to Con group, while SYP, synapse plasticity, and Bcl-2 levels in Ex group were significantly lower than those in Con group. These indexes were back to normal in MUS group. BIC group had the highest levels of [Ca2+]i, astrogliosis, TUNEL positive cell, GFAP, Bax, caspase-3, caspase-12 cleavage, CHOP, and p-JNK, it also gained the lowest SYP, synapse plasticity, and Bcl-2 levels among all groups. Water maze test showed that Ex group had longer escape latency (EL) and less quadrant dwell time than Con group; all indexes between MUS and Con groups had no significant differences; BIC had the longest EL and least quadrant dwell time among all groups.

CONCLUSIONS

Activation of GABAA R could prevent intense exercise-induced synapses damage, excessive apoptosis, and dysfunction of hippocampus.

Tobacco nitrosamines as culprits in disease: mechanisms reviewed

The link between tobacco abuse and cancer is well-established. However, emerging data indicate that toxins in tobacco smoke cause cellular injury due to enhanced toxic/metabolic effects of metabolites, disruption of intracellular signaling mechanisms, and formation of DNA, protein, and lipid adducts that impair function and promote oxidative stress and inflammation. These effects of smoking, which are largely non-carcinogenic, can be produced by tobacco-specific nitrosamines and their metabolites. These factors could account for the increased rates of neurodegeneration and insulin resistance diseases among smokers. Herein, we review nicotine and tobacco-specific nitrosamine metabolism, mechanisms of adduct formation, DNA damage, mutagenesis, and potential mechanisms of disease.

Cytoplasmic phospholipase A₂ modulation of adolescent rat ethanol-induced protein kinase C translocation and behavior

Ethanol consumption typically begins during adolescence, a developmental period which exhibits many age-dependent differences in ethanol behavioral sensitivity. Protein kinase C (PKC) activity is largely implicated in ethanol-behaviors, and our previous work indicates that regulation of novel PKC isoforms likely contributes to decreased high-dose ethanol sensitivity during adolescence. The cytoplasmic Phospholipase A2 (cPLA2) signaling cascade selectivity modulates novel and atypical PKC isoform activity, as well as adolescent ethanol hypnotic sensitivity. Therefore, the current study was designed to ascertain adolescent cPLA2 activity both basally and in response to ethanol, as well as it's involvement in ethanol-induced PKC isoform translocation patterns. cPLA2 expression was elevated during adolescence, and activity was increased only in adolescents following high-dose ethanol administration. Novel, but not atypical PKC isoforms translocate to cytosolic regions following high-dose ethanol administration. Inhibiting cPLA2 with AACOCF3 blocked ethanol-induced PKC cytosolic translocation. Finally, inhibition of novel, but not atypical, PKC isoforms when cPLA2 activity was elevated, modulated adolescent high-dose ethanol-sensitivity. These data suggest that the cPLA2/PKC pathway contributes to the acute behavioral effects of ethanol during adolescence.

Biobanking of Cerebrospinal Fluid for Biomarker Analysis in Neurological Diseases

Cerebrospinal fluid (CSF) reflects pathophysiological aspects of neurological diseases, where neuroprotective strategies and biomarkers are urgently needed. Therefore, biobanking is very relevant for biomarker discovery and evaluation for these neurological diseases.An important aspect of CSF biobanking is quality control, needed for e.g. consistent patient follow-up and the exchange of patient samples between research centers. Systematic studies to address effects of pre-analytical and storage variation on a broad range of CSF proteins are needed and initiated.Important features of CSF biobanking are intensive collaboration in international networks and the tight application of standardized protocols. The current adoption of standardized protocols for CSF and blood collection and for biobanking of these samples, as presented in this chapter, enables biomarker studies in large cohorts of patients and controls.In conclusion, biomarker research in neurodegenerative diseases has entered a new era due to the collaborative and multicenter efforts of many groups. The streamlining of biobanking procedures, including sample collection, quality control, and the selection of optimal control groups for investigating biomarkers is an important improvement to perform high quality biomarker studies.

The link between cardiovascular risk, Alzheimer's disease, and mild cognitive impairment: support from recent functional neuroimaging studies

OBJECTIVE

To review functional neuroimaging studies about the relationship between cardiovascular risk factors (CVRFs), Alzheimer's disease (AD), and mild cognitive impairment (MCI).

METHODS

We performed a comprehensive literature search to identify articles in the neuroimaging field addressing CVRF in AD and MCI. We included studies that used positron emission tomography (PET), single photon emission computerized tomography (SPECT), or functional magnetic resonance imaging (fMRI).

RESULTS

CVRFs have been considered risk factors for cognitive decline, MCI, and AD. Patterns of AD-like changes in brain function have been found in association with several CVRFs (both regarding individual risk factors and also composite CVRF measures). In vivo assessment of AD-related pathology with amyloid imaging techniques provided further evidence linking CVRFs and AD, but there is still limited information resulting from this new technology.

CONCLUSION

There is a large body of evidence from functional neuroimaging studies supporting the hypothesis that CVRFs may play a causal role in the pathophysiology of AD. A major limitation of most studies is their cross-sectional design; future longitudinal studies using multiple imaging modalities are expected to better document changes in CVRF-related brain function patterns and provide a clearer picture of the complex relationship between aging, CVRFs, and AD.

Lumbrokinase attenuates side-stream-smoke-induced apoptosis and autophagy in young hamster hippocampus: correlated with eNOS induction and NFκB/iNOS/COX-2 signaling suppression

Recent studies have found that cigarette smoke is epidemiologically linked to an increased risk for impaired cognitive development in adolescents. This study evaluated the influence of side stream smoke (SSS) exposure on hippocampal apoptosis and of the lumbrokinase (LK) effects on SSS induced apoptosis in young hamster hippocampus. Twenty male hamsters at six weeks of age were randomly divided into control group, SSS group (exposed to tobacco cigarettes smoke at doses of 10 cigarettes for 30 min twice a day for 1 month), and SSS hamsters with LK treatment (1.2 mg/kg, ip) for twice a week for 1 month. TUNEL assay and Western blotting were performed. The TUNEL-positive apoptotic cells, as well as Fas-dependent activity and mitochondria-dependent apoptotic pathways, such as Fas, FADD, activated caspase-8, t-Bid, activated caspase-9, and activated caspase-3, were significantly increased in the SSS-exposed hippocampus compared to the control and highly attenuated in the LK treatment group. Additionally, SSS exposure significantly increased the autophagy marker proteins, Beclin-1, ATG7, and LC3-II levels, in the hippocampus compared to those in the control group and obviously attenuated after LK treatment. LK also reduced hippocampus injury by enhancing eNOS expression and remarkably inhibited the proinflammatory NFκB/iNOS/COX-2 signaling activity. We found that the detrimental effects of SSS on the hippocampus are truly mediated by cell apoptosis and autophagy. However, LK reduced the hippocampus apoptosis and autophagy related injuries induced by SSS in a widespread manner. We suggest that LK presents protective effects on hippocampus apoptosis and has therapeutic potential against abnormal hippocampal function.

How cigarette smoking may increase the risk of anxiety symptoms and anxiety disorders: a critical review of biological pathways

Multiple studies have demonstrated an association between cigarette smoking and increased anxiety symptoms or disorders, with early life exposures potentially predisposing to enhanced anxiety responses in later life. Explanatory models support a potential role for neurotransmitter systems, inflammation, oxidative and nitrosative stress, mitochondrial dysfunction, neurotrophins and neurogenesis, and epigenetic effects, in anxiety pathogenesis. All of these pathways are affected by exposure to cigarette smoke components, including nicotine and free radicals. This review critically examines and summarizes the literature exploring the role of these systems in increased anxiety and how exposure to cigarette smoke may contribute to this pathology at a biological level. Further, this review explores the effects of cigarette smoke on normal neurodevelopment and anxiety control, suggesting how exposure in early life (prenatal, infancy, and adolescence) may predispose to higher anxiety in later life. A large heterogenous literature was reviewed that detailed the association between cigarette smoking and anxiety symptoms and disorders with structural brain changes, inflammation, and cell-mediated immune markers, markers of oxidative and nitrosative stress, mitochondrial function, neurotransmitter systems, neurotrophins and neurogenesis. Some preliminary data were found for potential epigenetic effects. The literature provides some support for a potential interaction between cigarette smoking, anxiety symptoms and disorders, and the above pathways; however, limitations exist particularly in delineating causative effects. The literature also provides insight into potential effects of cigarette smoke, in particular nicotine, on neurodevelopment. The potential treatment implications of these findings are discussed in regards to future therapeutic targets for anxiety. The aforementioned pathways may help mediate increased anxiety seen in people who smoke. Further research into the specific actions of nicotine and other cigarette components on these pathways, and how these pathways interact, may provide insights that lead to new treatment for anxiety and a greater understanding of anxiety pathogenesis.

Ethanol promotes cytotoxic effects of tumor necrosis factor-related apoptosis-inducing ligand through induction of reactive oxygen species in prostate cancer cells

BACKGROUND

Effective treatment of prostate cancer (PCa) remains a major challenge due to chemoresistance to drugs including tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Ethanol and ethanol extracts are known apoptosis inducers. However, cytotoxic effects of ethanol on PCa cells are unclear.

METHODS

In this study we utilized PC3 and LNCaP cell culture models. We used immunohistochemical analysis, western blot analysis, reactive oxygen species (ROS) measurement, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) Cell Proliferation Assay, Annexin-V staining and flow cytometry for quantification of apoptosis. In vitro soft agar colony formation and Boyden chamber invasion assays were used. Tumorigenicity was measured in a xenotransplantation mouse model.

RESULTS

Here, we demonstrate that ethanol enhances the apoptosis-inducing potential of TRAIL in androgen-resistant PC3 cells and sensitizes TRAIL-resistant, androgen sensitive LNCaP cells to apoptosis through caspase activation, and a complete cleavage of poly (ADP)-ribose polymerase, which was in association with increased production of ROS. The cytotoxicity of ethanol was suppressed by an antioxidant N-acetyl cystein pretreatment. Furthermore, ethanol in combination with TRAIL increased the expression of cyclin-dependent kinase inhibitor p21 and decreased the levels of Bcl-2 and phosphorylated-AKT. These molecular changes were accompanied by decreased proliferation, anchorage-independent growth and invasive potential of PC3 and LNCaP cells. In vivo studies using a xenotransplantation mouse model with PC3 cells demonstrated significantly increased apoptosis in tumors treated with ethanol and TRAIL in combination.

CONCLUSIONS

Taken together, use of ethanol in combination with TRAIL may be an effective strategy to augment sensitivity to TRAIL-induced apoptosis in PCa cells.

Positive and negative effects of alcohol and nicotine and their interactions: a mechanistic review

Nicotine and alcohol are two of the most commonly abused legal substances. Heavy use of one drug can often lead to, or is predictive of, heavy use of the other drug in adolescents and adults. Heavy drinking and smoking alone are of significant health hazard. The combination of the two, however, can result in synergistic adverse effects particularly in incidences of various cancers (e.g., esophagus). Although detrimental consequences of smoking are well established, nicotine by itself might possess positive and even therapeutic potential. Similarly, alcohol at low or moderated doses may confer beneficial health effects. These opposing findings have generated considerable interest in how these drugs act. Here we will briefly review the negative impact of drinking-smoking co-morbidity followed by factors that appear to contribute to the high rate of co-use of alcohol and nicotine. Our main focus will be on what research is telling us about the central actions and interactions of these drugs, and what has been elucidated about the mechanisms of their positive and negative effects. We will conclude by making suggestions for future research in this area.

Gene x disease interaction on orbitofrontal gray matter in cocaine addiction

CONTEXT

Long-term cocaine use has been associated with structural deficits in brain regions having dopamine-receptive neurons. However, the concomitant use of other drugs and common genetic variability in monoamine regulation present additional structural variability.

OBJECTIVE

To examine variations in gray matter volume (GMV) as a function of lifetime drug use and the genotype of the monoamine oxidase A gene, MAOA, in men with cocaine use disorders (CUD) and healthy male controls.

DESIGN

Cross-sectional comparison.

SETTING

Clinical Research Center at Brookhaven National Laboratory.

PATIENTS

Forty individuals with CUD and 42 controls who underwent magnetic resonance imaging to assess GMV and were genotyped for the MAOA polymorphism (categorized as high- and low-repeat alleles).

MAIN OUTCOME MEASURES

The impact of cocaine addiction on GMV, tested by (1) comparing the CUD group with controls, (2) testing diagnosis × MAOA interactions, and (3) correlating GMV with lifetime cocaine, alcohol, and cigarette smoking, and testing their unique contribution to GMV beyond other factors.

RESULTS

(1) Individuals with CUD had reductions in GMV in the orbitofrontal, dorsolateral prefrontal, and temporal cortex and the hippocampus compared with controls. (2) The orbitofrontal cortex reductions were uniquely driven by CUD with low- MAOA genotype and by lifetime cocaine use. (3) The GMV in the dorsolateral prefrontal cortex and hippocampus was driven by lifetime alcohol use beyond the genotype and other pertinent variables.

CONCLUSIONS

Long-term cocaine users with the low-repeat MAOA allele have enhanced sensitivity to gray matter loss, specifically in the orbitofrontal cortex, indicating that this genotype may exacerbate the deleterious effects of cocaine in the brain. In addition, long-term alcohol use is a major contributor to gray matter loss in the dorsolateral prefrontal cortex and hippocampus, and is likely to further impair executive function and learning in cocaine addiction.

Modified apolipoprotein (apo) A-I by artificial sweetener causes severe premature cellular senescence and atherosclerosis with impairment of functional and structural properties of apoA-I in lipid-free and lipid-bound state

Long-term consumption of artificial sweeteners (AS) has been the recent focus of safety concerns. However, the potential risk of the AS in cardiovascular disease and lipoprotein metabolism has not been investigated sufficiently. We compared the influence of AS (aspartame, acesulfame K, and saccharin) and fructose in terms of functional and structural correlations of apolipoprotein (apo) A-I and high-density lipoproteins (HDL), which have atheroprotective effects. Long-term treatment of apoA-I with the sweetener at physiological concentration (3 mM for 168 h) resulted in loss of antioxidant and phospholipid binding activities with modification of secondary structure. The AS treated apoA-I exhibited proteolytic cleavage to produce 26 kDa-fragment. They showed pro-atherogenic properties in acetylated LDL phagocytosis of macrophages. Each sweetener alone or sweetener-treated apoA-I caused accelerated senescence in human dermal fibroblasts. These results suggest that long-term consumption of AS might accelerate atherosclerosis and senescence via impairment of function and structure of apoA-I and HDL.

Toxic effects of low alcohol and nicotine combinations in SH-SY5Y cells are apoptotically mediated

It is well established that combination of heavy drinking and smoking has severe health consequences. However, at relatively low concentrations, both alcohol and nicotine may have beneficial effects including neuroprotection. Thus, protective effects of low alcohol concentration against beta-amyloid-induced toxicity in organotypic hippocampal slices and protective effects of nicotine against salsolinol-induced toxicity in human-derived neuroblastoma cells (SH-SY5Y) have been reported. In this study, we sought to determine whether alcohol might also be protective against salsolinol-induced toxicity in SH-SY5Y cells and whether the combination of low doses of alcohol and nicotine might have an additive or synergistic effect. Pre-exposure of SH-SY5Y cells to either ethanol (1 or 10 mM) or nicotine (20 or 50 μM) significantly attenuated salsolinol-induced toxicity. However, contrary to the expectation the combination of low doses of alcohol and nicotine not only did not provide any synergistic or additive protective effect, but exacerbated salsolinol-induced toxicity. Indeed, simple combination of low alcohol and nicotine resulted in significant toxicity in SH-SY5Y cells. This toxicity, reflected in a reduction in cell viability was associated with an increase in apoptosis as determined by caspase-3 measurement. These in vitro results suggest that combination of even low concentrations of alcohol and nicotine may activate apoptotic mechanisms that can lead to cell toxicity and detrimental consequences.

Effects of exogenous agents on brain development: stress, abuse and therapeutic compounds

The range of exogenous agents likely to affect, generally detrimentally, the normal development of the brain and central nervous system defies estimation although the amount of accumulated evidence is enormous. The present review is limited to certain types of chemotherapeutic and "use-and-abuse" compounds and environmental agents, exemplified by anesthetic, antiepileptic, sleep-inducing and anxiolytic compounds, nicotine and alcohol, and stress as well as agents of infection; each of these agents have been investigated quite extensively and have been shown to contribute to the etiopathogenesis of serious neuropsychiatric disorders. To greater or lesser extent, all of the exogenous agents discussed in the present treatise have been investigated for their influence upon neurodevelopmental processes during the period of the brain growth spurt and during other phases uptill adulthood, thereby maintaining the notion of critical phases for the outcome of treatment whether prenatal, postnatal, or adolescent. Several of these agents have contributed to the developmental disruptions underlying structural and functional brain abnormalities that are observed in the symptom and biomarker profiles of the schizophrenia spectrum disorders and the fetal alcohol spectrum disorders. In each case, the effects of the exogenous agents upon the status of the affected brain, within defined parameters and conditions, is generally permanent and irreversible.

Hippocampal increased cell death and decreased cell density elicited by nicotine and/or ethanol during adolescence are reversed during drug withdrawal

We have recently identified hippocampal cell death and reduced neuronal and glial cells densities during adolescent nicotine and ethanol exposures and outcomes reduced in severity when nicotine and ethanol are co-administered during this developmental period. In the present study, we investigated the effects of adolescent nicotine and/or ethanol withdrawal on the following regions of the hippocampus: Granular layer of the Dentate Gyrus (GrDG), Molecular layer (Mol), CA1, CA2 and CA3. From the 30th to the 45th postnatal day (PN30-PN45), C57BL/6 male and female mice were exposed to nicotine free base (NIC) and/or ethanol (ETOH). Four groups were analyzed: (1) concomitant NIC (50 microg/ml in 2% saccharin to drink) and ETOH (25%, 2 g/kg i.p. injected every other day) exposure; (2) NIC exposure; (3) ETOH exposure; (4) vehicle. We evaluated cell degeneration (TUNEL assay), neuronal and glial densities (optical Disector) and region thicknesses two (PN47) and five (PN50) days post-exposure. On PN47, there were increases in the number of TUNEL+ cells in most hippocampal regions of both ETOH and NIC groups. In the NIC+ETOH group there were less severe effects. These results were paralleled by reductions in neuronal and glial cells densities for all treatment groups. In contrast, on PN50, ethanol and/or nicotine withdrawal were associated with compensatory reductions in TUNEL+ cells in all hippocampal regions. These results were paralleled by a reversal of effects on neuronal and glial densities so that there were no longer differences between groups. There were no effects on region thicknesses. These results suggest that deleterious effects of nicotine and/or ethanol are reversed during prolonged withdrawal.

Developmental aspects of the cholinergic system

Beyond its importance in sustaining or modulating different aspects of the activity of the central nervous system (CNS), the cholinergic system plays important roles during development. In the current review, we focus on the developmental aspects associated with major components of the cholinergic system: Acetylcholine, choline acetyltransferase, vesicular acetylcholine transporter, high-affinity choline transporter, acetylcholinesterase, nicotinic and muscarinic receptors. We describe when and where each one of these components is first identified in the CNS and the changes in their levels that occur during the course of prenatal and postnatal development. We also describe how these components are relevant to many events that occur during the development of the CNS, including progenitor cells proliferation and differentiation, neurogenesis, gliogenesis, neuronal maturation and plasticity, axonal pathfinding, regulation of gene expression and cell survival. It will be noticed that evidence regarding the developmental aspects of the cholinergic system comes mostly from studies that used agonists, such as nicotine, and antagonists, such as hemicholinium-3. Studies using immunohistochemistry and genetically altered mice also provided valuable information.