Erythropoietin Ameliorates Neonatal Hypoxia-Ischemia-Induced Neurobehavioral Deficits,Neuroinflammation, and Hippocampal Injury in the Juvenile Rat

The hematopoietic growth factor erythropoietin (EPO) has been shown to be neuroprotective against hypoxia-ischemia (HI) in Postnatal Day 7 (P7)–P10 or adult animal models. The current study was aimed to determine whether EPO also provides long-lasting neuroprotection against HI in P5 rats, which is relevant to immature human infants. Sprague-Dawley rats at P5 were subjected to right common carotid artery ligation followed by an exposure to 6% oxygen with balanced nitrogen for 1.5 h. Human recombinant EPO (rEPO, at a dose of 5 units/g) was administered intraperitoneally one hour before or immediately after insult, followed by additional injections at 24 and 48 h post-insult. The control rats were injected with normal saline following HI. Neurobehavioral tests were performed on P8 and P20, and brain injury was examined on P21. HI insult significantly impaired neurobehavioral performance including sensorimotor, locomotor activity and cognitive ability on the P8 and P20 rats. HI insult also resulted in brain inflammation (as indicated by microglia activation) and neuronal death (as indicated by Jade B positive staining) in the white matter, striatum, cortex, and hippocampal areas of the P21 rat. Both pre- and post-treatment with rEPO significantly improved neurobehavioral performance and protected against the HI-induced neuronal death, microglia activation (OX42+) as well as loss of mature oligodendrocytes (APC-CC1+) and hippocampal neurons (Nissl+). The long-lasting protective effects of rEPO in the neonatal rat HI model suggest that to exert neurotrophic activity in the brain might be an effective approach for therapeutic treatment of neonatal brain injury induced by hypoxia-ischemia.     

Sex-Specific Alterations in Dopamine Metabolism in the Brain after Methamphetamine Self-Administration

Methamphetamine (METH) use disorder affects both sexes, with sex differences occurring in behavioral, structural, and biochemical consequences. The molecular mechanisms underlying these differences are unclear. Herein, we used a rat model to identify potential sex differences in the effects of METH on brain dopaminergic systems. Rats were trained to self-administer METH for 20 days, and a cue-induced drug-seeking test was performed on withdrawal days 3 and 30. Dopamine and its metabolites were measured in the prefrontal cortex (PFC), nucleus accumbens (NAc), dorsal striatum (dSTR), and hippocampus (HIP). Irrespective of conditions, in comparison to females, male rats showed increased 3,4-dihydroxyphenylalanine (DOPA) in the PFC, dSTR, and HIP; increased cys-dopamine in NAc; and increased 3,4-dihydroxyphenylethanol (DOPET) and 3,4-dihydroxyphenylacetic acid (DOPAC) in dSTR. Males also showed METH-associated decreases in DA levels in the HIP but increases in the NAc. Female rats showed METH-associated decreases in DA, DOPAL, and DOPAC levels in the PFC but increases in DOPET and DOPAC levels in the HIP. Both sexes showed METH-associated decreases in NAc DA metabolites. Together, these data document sex differences in METH SA-induced changes in DA metabolism. These observations provide further support for using sex as an essential variable when discussing therapeutic approaches against METH use disorder in humans.     

Effects of β-Phenylethylamine on Psychomotor,Rewarding, and Reinforcing Behaviors and Affective State: The Role of Dopamine D1 Receptors

Beta-phenylethylamine (β-PEA) is a well-known and widespread endogenous neuroactive trace amine found throughout the central nervous system in humans. In this study, we demonstrated the effects of β-PEA on psychomotor, rewarding, and reinforcing behaviors and affective state using the open-field test, conditioned place preference (CPP), self-administration, and ultrasonic vocalizations (USVs) paradigms. We also investigated the role of the dopamine (DA) D1 receptor in the behavioral effects of β-PEA in rodents. Using enzyme-linked immunosorbent assay (ELISA) and Western immunoblotting, we also determined the DA concentration and the DA-related protein levels in the dorsal striatum of mice administered with acute β-PEA. The results showed that acute β-PEA increased stereotypic behaviors such as circling and head-twitching responses in mice. In the CPP experiment, β-PEA increased place preference in mice. In the self-administration test, β-PEA significantly enhanced self-administration during a 2 h session under fixed ratio (FR) schedules (FR1 and FR3) and produced a higher breakpoint during a 6 h session under progressive ratio schedules of reinforcement in rats. In addition, acute β-PEA increased 50-kHz USV calls in rats. Furthermore, acute β-PEA administration increased DA concentration and p-DAT and TH expression in the dorsal striatum of mice. Finally, pretreatment with SCH23390, a DA D1 receptor antagonist, attenuated β-PEA-induced circling behavior and β-PEA-taking behavior in rodents. Taken together, these findings suggest that β-PEA has rewarding and reinforcing effects and psychoactive properties, which induce psychomotor behaviors and a positive affective state by activating the DA D1 receptor in the dorsal striatum.     

Sex Hormones Function as Sex Attractant Pheromones in House Mice and Brown Rats

Sex hormones of mammals control the expression of sexual characteristics and bodily functions. The male hormone testosterone and the female hormones progesterone and estradiol are known to occur in urine markings of mice. Here, we show that all three hormones are also present in urine of brown rats, and that they are effective sexual communication signals (pheromones) that elicit attraction behavior of prospective mates in both brown rats and house mice. When added as lures to trap boxes in field experiments, synthetic testosterone, for example, increased captures of adult female mice 15‐fold, and a blend of progesterone and estradiol increased captures of male mice eightfold and male rats 13‐fold. Remarkably, these hormones increased captures even though the food‐ and pheromone‐based baits to which they were added had previously been shown to be superior to current commercial rodent attractants. We predict that these sex hormones will function as sex attractant pheromones in diverse taxa.     

Effects of Three Different Doses of Inter-Alpha Inhibitor Proteins on Severe Hypoxia–Ischemia-Related Brain Injury in Neonatal Rats

Hypoxia–ischemia (HI)-related brain injury is an important cause of morbidity and long-standing disability in newborns. We have previously shown that human plasma-derived inter-alpha inhibitor proteins (hIAIPs) attenuate HI-related brain injury in neonatal rats. The optimal dose of hIAIPs for their neuroprotective effects and improvement in behavioral outcomes remains to be determined. We examined the efficacy of 30, 60, or 90 mg/kg of hIAIPs administered to neonatal rats after exposure to HI for 2 h. Postnatal day 7 (P7) Wistar rats were exposed to either sham-surgery or unilateral HI (right carotid artery ligation, 2 h of 8% O₂) brain injury. A placebo, 30, 60, or 90 mg/kg of hIAIPs were injected intraperitoneally at 0, 24 and 48 h after HI (n = 9–10/sex). We carried out the following behavioral analyses: P8 (righting reflex), P9 (negative geotaxis) and P10 (open-field task). Rats were humanely killed on P10 and their brains were stained with cresyl violet. Male extension/contraction responses and female righting reflex times were higher in the HI placebo groups than the sham groups. Female open-field exploration was lower in the HI placebo group than the sham group. hIAIPs attenuated these behavioral deficits. However, the magnitude of the responses did not vary by hIAIP dose. hIAIPs reduced male brain infarct volumes in a manner that correlated with improved behavioral outcomes. Increasing the hIAIP dose from 30 to 90 mg/kg did not further accentuate the hIAIP-related decreases in infarct volumes. We conclude that larger doses of hIAIPs did not provide additional benefits over the 30 mg/kg dose for behavior tasks or reductions in infarct volumes in neonatal rats after exposure to severe HI.     

Exposure to Atrazine during Gestation and Lactation Periods: Toxicity Effects on Dopaminergic Neurons in Offspring by Downregulation of Nurr1 and VMAT2

High atrazine (2-chloro-4-ethytlamino-6-isopropylamine-1,3,5-triazine; ATR) contents in the environment threaten the health conditions of organisms. We examined the effects of ATR exposure on Sprague-Dawley rats during gestation and on the dopaminergic neurons of offspring during lactation. Pregnant dams were orally treated with 0 mg/kg/day to 50 mg/kg/day of ATR from gestational day 5 to postnatal day 22. Afterward, neither offspring nor dams received ATR. Dopamine (DA) content was examined in striatum samples by HPLC-FL; the mRNA expressions of tyrosine hydroxylase (TH), orphan nuclear hormone (Nurr1), dopamine transporter (DAT), and vesicular monoamine transporter 2 (VMAT2) in the ventral midbrain samples were examined by fluorescence PCR when the offspring reached one year of age. After the pregnant rats were exposed to ATR, the DA concentrations and mRNA levels of Nurr1 were decreased in their offspring. Decreased Nurr1 levels were also accompanied by changes in the mRNA levels of VMAT2, which controls the transport and reuptake of DA.     

Enhanced Fear Memories and Altered Brain Glucose Metabolism (18F-FDG-PET) following Subanesthetic Intravenous Ketamine Infusion in Female Sprague–Dawley Rats

Although women and men are equally likely to receive ketamine following traumatic injury, little is known regarding sex-related differences in the impact of ketamine on traumatic memory. We previously reported that subanesthetic doses of an intravenous (IV) ketamine infusion following fear conditioning impaired fear extinction and altered regional brain glucose metabolism (BGluM) in male rats. Here, we investigated the effects of IV ketamine infusion on fear memory, stress hormone levels, and BGluM in female rats. Adult female Sprague–Dawley rats received a single IV ketamine infusion (0, 2, 10, or 20 mg/kg, over a 2-h period) following auditory fear conditioning (three pairings of tone and footshock). Levels of plasma stress hormones, corticosterone (CORT) and progesterone, were measured after the ketamine infusion. Two days after ketamine infusion, fear memory retrieval, extinction, and renewal were tested over a three-day period. The effects of IV ketamine infusion on BGluM were determined using ¹⁸F-fluoro-deoxyglucose positron emission tomography (¹⁸F-FDG-PET) and computed tomography (CT). The 2 and 10 mg/kg ketamine infusions reduced locomotor activity, while 20 mg/kg infusion produced reduction (first hour) followed by stimulation (second hour) of activity. The 10 and 20 mg/kg ketamine infusions significantly elevated plasma CORT and progesterone levels. All three doses enhanced fear memory retrieval, impaired fear extinction, and enhanced cued fear renewal in female rats. Ketamine infusion produced dose-dependent effects on BGluM in fear- and stress-sensitive brain regions of female rats. The current findings indicate that subanesthetic doses of IV ketamine produce robust effects on the hypothalamic–pituitary–adrenal (HPA) axis and brain energy utilization that may contribute to enhanced fear memory observed in female rats.     

Behavioral Effects of Exposure to Phthalates in Female Rodents: Evidence for Endocrine Disruption?

Phthalates have been widely studied for their reprotoxic effects in male rodents and in particular on testosterone production, for which reference doses were established. The female rodent brain can also represent a target for exposure to these environmental endocrine disruptors. Indeed, a large range of behaviors including reproductive behaviors, mood-related behaviors, and learning and memory are regulated by sex steroid hormones. Here we review the experimental studies addressing the effects and mechanisms of phthalate exposure on these behaviors in female rodents, paying particular attention to the experimental conditions (period of exposure, doses, estrous stage of analyses etc.). The objective of this review is to provide a clear picture of the consistent effects that can occur in female rodents and the gaps that still need to be filled in terms of effects and mode(s) of action for a better risk assessment for human health.     

Alteration of Ethanol Reward by Prior Mephedrone Exposure: The Role of Age and Matrix Metalloproteinase-9 (MMP-9)

Mephedrone, a synthetic cathinone, is widely abused by adolescents and young adults. The aim of this study was to determine: (i) whether prior mephedrone exposure would alter ethanol reward and (ii) whether age and matrix metalloproteinase-9 (MMP-9) are important in this regard. In our research, male Wistar rats at postnatal day 30 (PND30) received mephedrone at the dose of 10 mg/kg, i.p., 3 times a day for 7 days. To clarify the role of MMP-9 in the mephedrone effects, one mephedrone-treated group received minocycline, as an MMP-9 antagonist. Animals were then assigned to conditioned place preference (CPP) procedure at PND38 (adolescent) or at PND69 (adult). After the CPP test (PND48/79), expression of dopamine D1 receptors (D1R), Cav1.2 (a subtype of L-type calcium channels), and MMP-9 was quantified in the rat ventral striatum (vSTR). The influence of mephedrone administration on the N-methyl-D-aspartate glutamate receptors (NMDAR) subunits (GluN1, GluN2A, and GluN2B) was then assessed in the vSTR of adult rats (only). These results indicate that, in contrast with adolescent rats, adult rats with prior mephedrone administration appear to be more sensitive to the ethanol effect in the CPP test under the drug-free state. The mephedrone effect in adult rats was associated with upregulation of D1R, NMDAR/GluN2B, MMP-9, and Cav1.2 signaling. MMP-9 appears to contribute to these changes in proteins expression because minocycline pretreatment blocked mephedrone-evoked sensitivity to ethanol reward. Thus, our results suggest that prior mephedrone exposure differentially alters ethanol reward in adolescent and adult rats.     

Testing a short-term feeding trial to assess compositional and histopathological changes in hearts of rats fed vegetable oils

Male, female and castrated rats, three wk of age, were fed a low-fat diet for 14 wk followed by high-fat diets (20% by weight) for one wk containing graded levels of erucic acid from 1 to 50%, to evaluate the effect of short-term feeding and interaction of male sex hormones on formation of heart lesions. Some rats within each group were returned to the low-fat diet for one wk after the test period. For comparison, one group of three-wk-old male rats was fed the high fat 50% erucic acid diet for 15 wk. Erucic acid depressed growth rate and food consumption and increased cardiac lipidosis and triglycerides proportional to the erucic acid content of the diet. There were no sex differences, and the effects disappeared once rats were returned to the low-fat diet for one week. There was a significance (P<0.05) in the incidence of myocardial necrosis among male rats fed increased levels of erucic acid for one week, but the response was not linear to the increase in dietary erucic acid. Furthermore, the response was much less than in males fed the 50% erucic acid diet continually for 15 weeks. These results suggest that the short-term model is not a suitable substitute for the long-term feeding trial to test the cardiopathogenicity of a vegetable oil. The significantly lower incidence in myocardial lesions in female and castrated male rats compared with male rats suggests involvement of sex hormones. However, the process appears to be long term, since changes in cardiac lipids and their fatty acid pattern between sexes became evident after one wk on diet but was significant only after long-term feeding. Deceased.     

Pioglitazone Ameliorates Lipopolysaccharide-Induced Behavioral Impairment,Brain Inflammation,White Matter Injury and Mitochondrial Dysfunction in Neonatal Rats

Previous studies have demonstrated that pioglitazone, a peroxisome proliferator-activated receptor gamma (PPARγ) agonist, inhibits ischemia-induced brain injury. The present study was conducted to examine whether pioglitazone can reduce impairment of behavioral deficits mediated by inflammatory-induced brain white matter injury in neonatal rats. Intraperitoneal (i.p.) injection of lipopolysaccharide (LPS, 2 mg/kg) was administered to Sprague–Dawley rat pups on postnatal day 5 (P5), and i.p. administration of pioglitazone (20 mg/kg) or vehicle was performed 5 min after LPS injection. Sensorimotor behavioral tests were performed 24 h after LPS exposure, and changes in biochemistry of the brain was examined after these tests. The results show that systemic LPS exposure resulted in impaired sensorimotor behavioral performance, reduction of oligodendrocytes and mitochondrial activity, and increases in lipid peroxidation and brain inflammation, as indicated by the increment of interleukin-1β (IL-1β) levels and number of activated microglia in the neonatal rat brain. Pioglitazone treatment significantly improved LPS-induced neurobehavioral and physiological disturbances including the loss of body weight, hypothermia, righting reflex, wire-hanging maneuver, negative geotaxis, and hind-limb suspension in neonatal rats. The neuroprotective effect of pioglitazone against the loss of oligodendrocytes and mitochondrial activity was associated with attenuation of LPS-induced increment of thiobarbituric acid reactive substances (TBARS) content, IL-1β levels and number of activated microglia in neonatal rats. Our results show that pioglitazone prevents neurobehavioral disturbances induced by systemic LPS exposure in neonatal rats, and its neuroprotective effects are associated with its impact on microglial activation, IL-1β induction, lipid peroxidation, oligodendrocyte production and mitochondrial activity.     

Chronic dietary n-3 polyunsaturated fatty acids deficiency affects the fatty acid composition of plasmenylethanolamine and phosphatidylethanolamine differently in rat frontal cortex, striatum, and cerebellum

As chronic consumption of a diet devoid of n-3 fatty acid induced modification of neurotransmission pathways in the frontal cortex of rats, plasmalogen alteration could occur in this area. Because of the propensity to facilitate membrane fusion, plasmenylethanolamine (PmE), a major plasmalogen of brain, may be involved in synaptic transmission. Female rats were fed diet containing peanut oil [(n-3)-deficient diet] through two generations. Two weeks before mating, half of the female rats of the second generation received a diet containing peanut oil and rapeseed oil (control group). The distribution and acyl composition of major phospholipids, phosphatidylethanolamine and PmE, were measured in the frontal cortex, striatum, and cerebellum of the male progeny of the two groups at 60 d of age. The n-3 polyunsaturated fatty acid (PUFA) deficiency had no effect on the distribution of phospholipids in all brain regions but affected their acyl composition differently. The level of 22∶6n-3 was significantly lower and compensated for by higher levels of n-6 fatty acids in all regions and phospholipids studied. However, docosahexaenoic acid, being more concentrated in the PmE of frontal cortex, is also more decreased in the n-3-deficient rats compared to the striatum. By contrast, striatum PmE has retained more 22∶6n-3 than PmE of the other regions. In addition, the increase of n-6 PUFA was significantly lower in frontal cortex PmE compared to the striatum and cerebellum PmE. In association with altered neurotransmission observed in frontal cortex of n-3-deficient rats, our results suggest that frontal cortex PmE might be more affected in chronically α-linolenic-deficient rats. However, by retaining 22∶6n-3, striatum PmE could be most resilient.     

Towards Novel Treatments for Schizophrenia: Molecular and Behavioural Signatures of the Psychotropic Agent SEP-363856

Schizophrenia is a complex psychopathology whose treatment is still challenging. Given the limitations of existing antipsychotics, there is urgent need for novel drugs with fewer side effects. SEP-363856 (SEP-856) is a novel psychotropic agent currently under phase III clinical investigation for schizophrenia treatment. In this study, we investigated the ability of an acute oral SEP-856 administration to modulate the functional activity of specific brain regions at basal levels and under glutamatergic or dopaminergic-perturbed conditions in adult rats. We found that immediate-early genes (IEGs) expression was strongly upregulated in the prefrontal cortex and, to a less extent, in the ventral hippocampus, suggesting an activation of these regions. Furthermore, SEP-856 was effective in preventing the hyperactivity induced by an acute injection of phencyclidine (PCP), but not of d-amphetamine (AMPH). The compound effectively normalized the PCP-induced increase in IEGs expression in the PFC at all doses tested, whereas only the highest dose determined the major modulations on AMPH-induced changes. Lastly, SEP-856 acute administration corrected the cognitive deficits produced by subchronic PCP administration. Taken together, our data provide further insights on SEP-856, suggesting that modulation of the PFC may represent an important mechanism for the functional and behavioural activity of this novel compound.     

Heterozygote Dopamine Transporter Knockout Rats Display Enhanced Cocaine Locomotion in Adolescent Females

Cocaine is a powerful psychostimulant that is one of the most widely used illicit addictive. The dopamine transporter (DAT) plays a major role in mediating cocaine’s reward effect. Decreases in DAT expression increase rates of drug abuse and vulnerability to comorbid psychiatric disorders. We used the novel DAT transgenic rat model to study the effects of cocaine on locomotor behaviors in adolescent rats, with an emphasis on sex. Female rats showed higher response rates to cocaine at lower acute and chronic doses, highlighting a higher vulnerability and perceived gender effects. In contrast, locomotor responses to an acute high dose of cocaine were more marked and sustained in male DAT heterozygous (HET) adolescents. The results demonstrate the augmented effects of chronic cocaine in HET DAT adolescent female rats. Knockout (KO) DAT led to a level of hyperdopaminergia which caused a marked basal hyperactivity that was unchanged, consistent with a possible ceiling effect. We suggest a role of alpha synuclein (α-syn) and PICK 1 protein expressions to the increased vulnerability in female rats. These proteins showed a lower expression in female HET and KO rats. This study highlights gender differences associated with mutations which affect DAT expression and can increase susceptibility to cocaine abuse in adolescence.     

Influence of dietary fat on renal function,lipid profile,sex hormones,and electrolyte balance in rats

Evidence from animal and human studies indicates that abnormal lipid profile may contribute to renal disease progression. The effect of dietary fat level on renal function, electrolyte balance, cholesterol, triacylglycerol, and sex hormones was examined in 54 male and female adult rats. The rats were fed either low/high fat diet (3/20 g/100 g diet) for 12 weeks. In rats fed the high fat diet (HF), the kidney weight/body weight ratio was significantly increased in comparison with low fat diet (LF). Rats fed the LF diet had significantly lower mean of feed intake and body weight gain percentage compared with both HF and control groups (p<0.05). HF diets enhanced cholesterol and triacylglycerol significantly in male and female rats, and this increase was associated with a significant increase of testosterone and estradiol levels relative to controls. Uric acid, urea nitrogen and creatinine were increased significantly in HF diet groups for male and female rats. The results indicate that uric acid was increased 100% relative to the control group in male rats when switched to HF diets. In the female group uric acid was increased 35% relative to the control, and for urea nitrogen, 53.4 and 9.6% increase was observed for male and female rats, respectively. Lipid profile in the female group was better than male rats. Significant increase in sodium ions was detected in the serum of male and female rats fed (HF) high fat diets, and the opposite was noticed in potassium ions levels of male and female rats fed HF. Microscopically, examined kidneys of HF diet rats revealed two types of histopathological alterations in both sexes.     

Cholesteryl ester hydrolysis in rat liver cytosol. Modulation by female sex hormones

The regulation of cholesterol ester hydrolase activity by female sex hormones was studied in cytosolic preparations from female rat liver. The investigation was undertaken in order to determine whether a reduction in the enzyme activity might be responsible for the increased content of esterified cholesterol found in rat liver after estradiol or progesterone treatments. The single injection of estradiol (0.75 mg/100 g) or progesterone (1.50mg/100g) produced respectively significant decreases and increases in sterol hydrolase activity. Both opposite effects were noted after a similar lag period of 3–4 hr and were of short duration. No alterations were observed in rats receiving short-term treatments. When hormones were added to the incubation medium, the activity of cholesterol ester hydrolase decreased progressively with increasing concentrations of hormones. Kinetic studies demonstrate that both estradiol and progesterone compete with the substrate (cholesteryl oleate) for the active center. The findings of the present paper exclude a direct relationship between hepatic hydrolytic activity and lipid deposition. However, they provide evidences that female sex hormones act as modulatory agents of the hydrolysis of cholesteryl esters in rat liver cytosol and suggest that other factors besides competitive inhibition are involved in such regulatory effects.     

The Impact of Nicotine along with Oral Contraceptive Exposure on Brain Fatty Acid Metabolism in Female Rats

Smoking-derived nicotine (N) and oral contraceptive (OC) synergistically exacerbate ischemic brain damage in females, and the underlying mechanisms remain elusive. In a previous study, we showed that N + OC exposure altered brain glucose metabolism in females. Since lipid metabolism complements glycolysis, the current study aims to examine the metabolic fingerprint of fatty acids in the brain of female rats exposed to N+/−OC. Adolescent and adult Sprague–Dawley female rats were randomly (n = 8 per group) exposed to either saline or N (4.5 mg/kg) +/−OC (combined OC or placebo delivered via oral gavage) for 16–21 days. Following exposure, brain tissue was harvested for unbiased metabolomic analysis (performed by Metabolon Inc., Morrisville, NC, USA) and the metabolomic profile changes were complemented with Western blot analysis of key enzymes in the lipid pathway. Metabolomic data showed significant accumulation of fatty acids and phosphatidylcholine (PC) metabolites in the brain. Adolescent, more so than adult females, exposed to N + OC showed significant increases in carnitine-conjugated fatty acid metabolites compared to saline control animals. These changes in fatty acyl carnitines were accompanied by an increase in a subset of free fatty acids, suggesting elevated fatty acid β-oxidation in the mitochondria to meet energy demand. In support, β-hydroxybutyrate was significantly lower in N + OC exposure groups in adolescent animals, implying a complete shunting of acetyl CoA for energy production via the TCA cycle. The reported changes in fatty acids and PC metabolism due to N + OC could inhibit post-translational palmitoylation of membrane proteins and synaptic vesicle formation, respectively, thus exacerbating ischemic brain damage in female rats.     

The Regulatory Role of H19/miR-181a/ATG5 Signaling in Perinatal Nicotine Exposure-Induced Development of Neonatal Brain Hypoxic-Ischemic Sensitive Phenotype

Nicotine exposure either from maternal cigarette smoking or e-cigarette vaping is one of the most common risk factors for neurodevelopmental disease in offspring. Previous studies revealed that perinatal nicotine exposure programs a sensitive phenotype to neonatal hypoxic-ischemic encephalopathy (HIE) in postnatal life, yet the underlying mechanisms remain undetermined. The goal of the present study was to determine the regulatory role of H19/miR-181a/ATG5 signaling in perinatal nicotine exposure-induced development of neonatal brain hypoxic-ischemic sensitive phenotype. Nicotine was administered to pregnant rats via subcutaneous osmotic minipumps. All experiments were conducted in offspring pups at postnatal day 9 (P9). Perinatal nicotine exposure significantly enhanced expression of miR-181a but attenuated autophagy-related protein 5 (ATG5) mRNA and protein levels in neonatal brains. Of interest, miR-181a mimicking administration in the absence of nicotine exposure also produced dose-dependent increased hypoxia/ischemia (H/I)-induced brain injury associated with a decreased ATG5 expression, closely resembling perinatal nicotine exposure-mediated effects. Locked nucleic acid (LNA)-miR-181a antisense reversed perinatal nicotine-mediated increase in H/I-induced brain injury and normalized aberrant ATG5 expression. In addition, nicotine exposure attenuated a long non-coding RNA (lncRNA) H19 expression level. Knockdown of H19 via siRNA increased the miR-181a level and enhanced H/I-induced neonatal brain injury. In conclusion, the present findings provide a novel mechanism that aberrant alteration of the H19/miR-181a/AGT5 axis plays a vital role in perinatal nicotine exposure-mediated ischemia-sensitive phenotype in offspring and suggests promising molecular targets for intervention and rescuing nicotine-induced adverse programming effects in offspring.     

Exposure to 2.45 GHz Radiation Triggers Changes in HSP-70, Glucocorticoid Receptors and GFAP Biomarkers in Rat Brain

Brain tissue may be especially sensitive to electromagnetic phenomena provoking signs of neural stress in cerebral activity. Fifty-four adult female Sprague-Dawley rats underwent ELISA and immunohistochemistry testing of four relevant anatomical areas of the cerebrum to measure biomarkers indicating induction of heat shock protein 70 (HSP-70), glucocorticoid receptors (GCR) or glial fibrillary acidic protein (GFAP) after single or repeated exposure to 2.45 GHz radiation in the experimental set-up. Neither radiation regime caused tissue heating, so thermal effects can be ruled out. A progressive decrease in GCR and HSP-70 was observed after acute or repeated irradiation in the somatosensory cortex, hypothalamus and hippocampus. In the limbic cortex; however, values for both biomarkers were significantly higher after repeated exposure to irradiation when compared to control animals. GFAP values in brain tissue after irradiation were not significantly different or were even lower than those of nonirradiated animals in all brain regions studied. Our results suggest that repeated exposure to 2.45 GHz elicited GCR/HSP-70 dysregulation in the brain, triggering a state of stress that could decrease tissue anti-inflammatory action without favoring glial proliferation and make the nervous system more vulnerable.