Effect of prenatal stress on density of NMDA receptors in rat brain

Prenatal stress and fluoxetine exposure in BTBR and B6 mice differentially affects autism-like behaviors in adult male and female offspring

Autism spectrum disorder (ASD) is characterized by significant heterogeneity in the variety and severity of symptoms. Prenatal stress and/or exposure to antidepressants may be major contributors to ASD heterogeneity. To date, the effects of prenatal stress or selective serotonin reuptake inhibitor exposure have been primarily examined in common laboratory rat and mouse strains as opposed to in rodent models of autism. The present experiments determined in the BTBR mouse model of autism whether restraint stress (30 min session every 2 days during G4 - G18) and/or exposure to the SSRI, fluoxetine (3 mg/kg during G8 - G18) affects repetitive motor behaviors, anxiety and/or behavioral flexibility in offspring at adulthood. Male and female BTBR mice exhibited elevated grooming behavior compared to that of C57BL/6 J (B6) mice. The prenatal manipulations did not affect grooming in male BTBR mice, but the combination increased rearing and jumping. Prenatal stress, fluoxetine and the combination significantly reduced self-grooming, while concomitantly increasing locomotion in female BTBR mice. These prenatal manipulations also increased rearing and jumping behavior in female BTBR mice. In B6 mice, the prenatal stress conditions increased grooming behavior. In addition, male BTBR mice exposed to prenatal stress and fluoxetine along with female BTBR mice prenatally exposed to fluoxetine were impaired on reversal learning. The prenatal manipulations had no effect on anxiety in either mouse strain. The pattern of results suggest that prenatal exposure to stress and/or a SSRI have long-term effects on autism-like behaviors and may contribute to the heterogeneity and co-morbidity observed in autism.

Agmatine mitigates hyperexcitability of ventral tegmental area dopaminergic neurons in prenatally stressed male offspring

Prenatal stress (PS) alters development of the brain, resulting in heightening the risk in offspring of cognitive deficits and addiction behaviors. The ventral tegmental area (VTA) plays a crucial role in processing stressful events, and promoting cognitively based motivational behavior. Previous research, including our own, has shown that PS affects the development of VTA dopaminergic (DA) neurons, leading to functional differences. In this study PS was induced in pregnant mice using both psychological and physical methods. Psychological stress involved placing the mice in a communication stress box to observe others under physical stress, while physical stress was applied by immersion in water for 5 min daily for 7 days. Agmatine, a neuromodulator with neuroprotective properties, was examined for its effects on the electrophysiological functioning of VTA DA neurons in the male offspring of stressed mice. Patch-clamp recordings of VTA DA cells from offspring maternally exposed to psychological or physical stress revealed enhanced cellular excitability, evidenced by increased firing frequency and greater firing following inhibition. Additionally, a decrease in action potential half-width and latency to the first spike were observed, indicating altered firing properties. Prenatal administration of agmatine mitigated these effects, preventing the PS-induced hyperexcitability of the VTA DA cells. Our findings extend previous work by demonstrating that both physical and psychological PS can significantly alter the electrophysiological functionality of VTA DA neurons, resulting in increased excitability. Agmatine effectively reduced these electrophysiological changes, highlighting its potential as a neuroprotective agent against neural alterations caused by negative maternal events during gestation.

Inhibition of FLT1 Attenuates Neurodevelopmental Abnormalities and Cognitive Impairment in Offspring Caused by Maternal Prenatal Stress

Fms-like tyrosine kinase 1 (FLT1) has been shown to regulate processes such as angiogenesis, neurogenesis, and cognitive impairment. However, the role of FLT1 in prenatal stress (PS) is unclear. The purpose of this study was to investigate the role of FLT1 in PS mothers and their offspring. Wire mesh restrainers were used to construct PS rat model. The levels of FLT1, IL-1β, IL-6, and ROS in clinical samples and rat samples were detected by qRT-PCR, ELisa kit, and DCFH-DA fluorescence kit. Morris water maze assay and forced swimming assay were used to test the cognitive function of offspring young rats. The apoptosis level of hippocampal neurons and the expression of NMDARs were detected by MTT assay, TUNEL assay, and Western blot. The results showed that FLT1 was upregulated in PS mothers and positively correlated with PS degree. The level of FLT1 was elevated in PS model rats. Knockdown of FLT1 reduced maternal ROS and MDA levels and increased SOD levels in PS rats. Knockdown of FLT1 also reduced the secretion of IL-1β, IL-6, and cortisol in PS rats. Inhibition of FTL1 alleviated cognitive impairment in PS offspring pups. Inhibition of FTL1 reduced hippocampal neuronal apoptosis and increased the expression of NMDARs in PS progeny. In conclusions, we demonstrated that knockdown of FLT1 inhibits maternal oxidative stress, inflammation, and cortisol secretion in PS rats. In addition, knockdown of FLT1 also alleviated cognitive dysfunction and neurodevelopmental abnormalities in PS offspring pups.

Effect of postnatal environmental enrichment on LTP induction in the CA1 area of hippocampus of prenatally traffic noise-stressed female rats

Early-life stress negatively alters mammalian brain programming. Environmental enrichment (EE) has beneficial effects on brain structure and function. This study aimed to evaluate the effects of postnatal environmental enrichment on long-term potentiation (LTP) induction in the hippocampal CA1 area of prenatally stressed female rats. The pregnant Wistar rats were housed in a standard animal room and exposed to traffic noise stress 2 hours/day during the third week of pregnancy. Their offspring either remained intact (ST) or received enrichment (SE) for a month starting from postnatal day 21. The control groups either remained intact (CO) or received enrichment (CE). Basic field excitatory post-synaptic potentials (fEPSPs) were recorded in the CA1 area; then, LTP was induced by high-frequency stimulation. Finally, the serum levels of corticosterone were measured. Our results showed that while the prenatal noise stress decreased the baseline responses of the ST rats when compared to the control rats (P < 0.001), the postnatal EE increased the fEPSPs of both the CE and SE animals when compared to the respective controls. Additionally, high-frequency stimulation (HFS) induced LTP in the fEPSPs of the CO rats (P < 0.001) and failed to induce LTP in the fEPSPs of the ST animals. The enriched condition caused increased potentiation of post-HFS responses in the controls (P < 0.001) and restored the disrupted synaptic plasticity of the CA1 area in the prenatally stressed rats. Likewise, the postnatal EE decreased the elevated serum corticosterone of prenatally stressed offspring (P < 0.001). In conclusion, the postnatal EE restored the stress induced impairment of synaptic plasticity in rats' female offspring.

A short pre-conception bout of predation risk affects both children and grandchildren

Traumatic events that affect physiology and behavior in the current generation may also impact future generations. We demonstrate that an ecologically realistic degree of predation risk prior to conception causes lasting changes in the first filial (F1) and second filial (F2) generations. We exposed male and female mice to a live rat (predator stress) or control (non-predator) condition for 5 min. Ten days later, stressed males and females were bred together as were control males and females. Adult F1 offspring from preconception-stressed parents responded to a mild stressor with more anxiety-like behavior and hyperarousal than offspring from control parents. Exposing these F1 offspring to the mild stressor increased neuronal activity (cFOS) in the hippocampus and altered glucocorticoid system function peripherally (plasma corticosterone levels). Even without the mild stressor, F1 offspring from preconception-stressed parents still exhibited more anxiety-like behaviors than controls. Cross-fostering studies confirmed that preconception stress, not maternal social environment, determined offspring behavioral phenotype. The effects of preconception parental stress were also unexpectedly persistent and produced similar behavioral phenotypes in the F2 offspring. Our data illustrate that a surprisingly small amount of preconception predator stress alters the brain, physiology, and behavior of future generations. A better understanding of the 'long shadow' cast by fearful events is critical for understanding the adaptive costs and benefits of transgenerational plasticity. It also suggests the intriguing possibility that similar risk-induced changes are the rule rather than the exception in free-living organisms, and that such multigenerational impacts are as ubiquitous as they are cryptic.

Enhancing the Neuroprotection Potential of Edaravone in Transient Global Ischemia Treatment with Glutathione- (GSH-) Conjugated Poly(methacrylic acid) Nanogel as a Promising Carrier for Targeted Brain Drug Delivery

Ischemic stroke is the most common among various stroke types and the second leading cause of death, worldwide. Edaravone (EDV) is one of the cardinal antioxidants that is capable of scavenging reactive oxygen species, especially hydroxyl molecules, and has been already used for ischemic stroke treatment. However, poor water solubility, low stability, and bioavailability in aqueous media are major EDV drawbacks. Thus, to overcome the aforementioned drawbacks, nanogel was exploited as a drug carrier of EDV. Furthermore, decorating the nanogel surface with glutathione as targeting ligands would potentiate the therapeutic efficacy. Nanovehicle characterization was assessed with various analytical techniques. Size (199 nm, hydrodynamic diameter) and zeta potential (-25 mV) of optimum formulation were assessed. The outcome demonstrated a diameter of around 100 nm, sphere shape, and homogenous morphology. Encapsulation efficiency and drug loading were determined to be 99.9% and 37.5%, respectively. In vitro drug release profile depicted a sustained release process. EDV and glutathione presence in one vehicle simultaneously made the possibility of antioxidant effects on the brain in specific doses, which resulted in elevated spatial memory and learning along with cognitive function in Wistar rats. In addition, significantly lower MDA and PCO and higher levels of neural GSH and antioxidant levels were observed, while histopathological improvement was approved. The developed nanogel can be a suited vehicle for drug delivery of EDV to the brain and improve ischemia-induced oxidative stress cell damage.

Tualang Honey: A Decade of Neurological Research

Tualang honey has been shown to protect against neurodegeneration, leading to improved memory/learning as well as mood. In addition, studies have also demonstrated its anti-inflammatory and antioxidant properties. However, a substantial part of this research lacks systematization, and there seems to be a tendency to start anew with every study. This review presents a decade of research on Tualang honey with a particular interest in the underlying mechanisms related to its effects on the central nervous system. A total of 28 original articles published between 2011 and 2020 addressing the central nervous system (CNS) effects of Tualang honey were analysed. We identified five main categories, namely nootropic, antinociceptive, stress-relieving, antidepressant, and anxiolytic effects of Tualang honey, and proposed the underlying mechanisms. The findings from this review may potentially be beneficial towards developing new therapeutic roles for Tualang honey and help in determining how best to benefit from this brain supplement.

Prenatal stress and increased susceptibility to anxiety-like behaviors: role of neuroinflammation and balance between GABAergic and glutamatergic transmission

Neuroplasticity during the prenatal period allows neurons to regenerate anatomically and functionally for re-programming the brain development. During this critical period of fetal programming, the fetus phenotype can change in accordance with environmental stimuli such as stress exposure. Prenatal stress (PS) can exert important effects on brain development and result in permanent alterations with long-lasting consequences on the physiology and behavior of the offspring later in life. Neuroinflammation, as well as GABAergic and glutamatergic dysfunctions, has been implicated as potential mediators of behavioral consequences of PS. Hyperexcitation, due to enhanced excitatory transmission or reduced inhibitory transmission, can promote anxiety. Alterations of the GABAergic and/or glutamatergic signaling during fetal development lead to a severe excitatory/inhibitory imbalance in neuronal circuits, a condition that may account for PS-precipitated anxiety-like behaviors. This review summarizes experimental evidence linking PS to an elevated risk to anxiety-like behaviors and interprets the role of the neuroinflammation and alterations of the brain GABAergic and glutamatergic transmission in this phenomenon. We hypothesize this is an imbalance in GABAergic and glutamatergic circuits (as a direct or indirect consequence of neuroinflammation), which at least partially contributes to PS-precipitated anxiety-like behaviors and primes the brain to be vulnerable to anxiety disorders. Therefore, pharmacological interventions with anti-inflammatory activities and with regulatory effects on the excitatory/inhibitory balance can be attributed to the novel therapeutic target for anxiety disorders.

Is personality linked to season of birth?

The environment is a very significant factor in early childhood development. Season of birth (SOB) is a proxy viable for the environment to which the babies are exposed, thus also significant in early development. This study investigates the association between SOB and personality. A total 2,962 college students were included as study participants. The participants were classified into four seasonal groups based on their birth month and underwent a personality assessment using the Temperament and Character Inventory (TCI). Statistical analysis was performed using one-way analysis of variance (ANOVA) and multinomial logistic regression analysis. The male participants born in autumn scored high on the Disorderliness (NS4) subscale (β = 0.055, P = 0.042) and the male participants born in summer and winter scored high on the Extravagance (NS3) subscale (summer: β = 0.072, P = 0.01, winter: β = 0.078, P = 0.003). The difference observed indicates a relationship between the SOB and temperament, especially NS. Our findings suggest that environmental factors may affect temperament in early development, although further research is likely needed to clarify the causality between them.

Vitamin E reduces spasms caused by prenatal stress by lowering calpain expression

BACKGROUND

Prenatal stress increases the susceptibility of infants to seizures and is known to be associated with oxidative stress. Recent studies suggest that vitamin E has beneficial effects in various neurological diseases due to its antioxidant properties. In this study, we investigated the relationship between prenatal stress and vitamin E treatment on N-methyl-D-aspartate (NMDA)-induced spasms.

METHODS

We used pregnant female Sprague Dawley rats and induced prenatal stress with an injection of betamethasone on G15. They were then treated orally with 200 mg/kg vitamin E or saline twice a day from G15-G21. On postnatal day 15, NMDA was administered to trigger spasms in offspring. The total number of spasms and latency to the first spasm were recorded. We also measured oxidative stress in the medial cortex using western blot, and calpain activity, thiobarbituric acid reactive substances (TBARS), glutathione (GSH)/GSH/glutathione disulfide (GSSG), superoxide dismutase (SOD) activity, catalase activity, and nitric oxide (NO) assays.

RESULTS

We observed that rats treated with vitamin E while exposed to prenatal stress demonstrated reduced total number and frequency of spasms. Expression of glutamate decarboxylase 67 (GAD67) and K⁺/Cl^- co-transporter (KCC2) were reduced after prenatal stress; this recovered in the vitamin E treated group. Further, expression of calpain 2 was decreased and various markers of oxidative stress (malondialdehyde (MDA), GSH/GSSG, SOD, catalase, and NO) were reduced in the vitamin E treated group.

CONCLUSIONS

Our results provide evidence that vitamin E lowers oxidative stress and decreases seizure susceptibility in rat offspring exposed to prenatal stress. Given the well-known safety profile of vitamin E, these results indicate its potential as a strategy for preventing seizures.

Sex differences in the neurochemistry of frontal cortex: Impact of early life stress

Traumatic events during early life have been linked with later life psychopathology. To understand this risk factor, researchers have studied the effects of prenatal and postnatal early life stress on neurochemical changes. Here we review the rodent literature on sex differences and sex-specific impact of early life stress on frontal cortex neurochemistry. This region is implicated in regulating motivation and emotion, which are often disrupted in psychological disorders. The prefrontal cortex (PFC) in particular is one of the last brain regions to develop, and there are sex differences in the rate of this development. To draw direct comparisons between sexes, our review of the literature was restricted to studies where the effects of prenatal or postnatal stress had been described in male and female littermates. This literature included research describing glutamate, γ-amino butyric acid (GABA), corticosteroids, monoamines, and cannabinoids. We found that sex-dependent effects of stress are mediated by the age at which stress is experienced, age at test, and type of stress endured. More research is required, particularly into the effects of adolescent stress on male and female littermates. We hope that a greater understanding of sex-specific susceptibilities in response to stress across development will help to uncover risk factors for psychological disorders in vulnerable populations.

Oxytocin protects against 3-NP induced learning and memory impairment in rats: Sex differences in behavioral and molecular responses to the context of prenatal stress

Learning and memory impairment manifests years before the onset of motor impairments in Huntington's disease (HD). Oxytocin (OXT), as a neurohypophyseal neuropeptide has a key role in both learning and memory. Hence, we investigated possible protective effect of OXT on instrumental fear conditioning memory impairment by 3-Nitropropionic acid (3-NP) induced HD, considering sex and prenatal stress effects. Pregnant Wistar rats were exposed to restraint stress for 45 min three times a day, from the gestational day 8 to parturition. 3-NP was injected intraperitoneally (20 mg/kg) for 5-7 days after OXT (10 μg/μl. icv) injection in the male and female offspring rats respectively. One day after the last 3-NP injection, the rotarod and passive avoidance task were conducted. As the key molecular determinants in metabolism and memory processes, we measured the activity of acetylcholinesterase (AChE) and the amount of receptor interacting protein3 (RIP3) in the hippocampus, prefrontal cortex, striatum and amygdala using spectrophotometry and western blotting respectively. Besides, the activity of glutamate dehydrogenase was measured (GDH) as a chain between metabolism and memory formation. The results indicated that OXT improved learning and memory impairment caused by 3-NP or prenatal stress in both sexes. It was along with a significant decrease in the level of RIP3, AChE and GDH activities. However, in the presence of prenatal stress, the OXT could improve 3-NP induced learning and memory impairments just in female rats. So it could be suggested as an effective neurotherapeutic agent in diseases such as HD, but its sex and context dependency should be considered carefully.

Stress during pregnancy affected neonatal outcomes and changed cortisol and leptin levels both in mothers and newborns

BACKGROUND

The present study aimed to determine the effect of perceived stress during pregnancy on neonatal outcomes and cortisol and leptin levels in mothers and their newborns.

METHODS

This longitudinal study was carried out on 110 pregnant women in Miandoab city, Iran. Mothers, who had singleton pregnancies and gestational age of 24 to 28 weeks, were included in the study. The participants were asked to fill out Cohen's Perceived Stress Scale (PSS). The mothers were then tracked in gestational ages of 28-32 weeks, 32-36 weeks, and the time of delivery. The maternal and umbilical cord blood samples were obtained during labor in order to measure leptin and cortisol levels.

RESULTS

Umbilical cortisol level was significantly higher in newborns who had meconium stained amniotic fluid than those who did not. Maternal blood leptin levels at delivery were significantly higher in the mothers whose neonates had respiratory distress, low birth weight, low head circumference, low Apgar score, and were premature than those whose neonates did not have such problems. The level of leptin in umbilical cord blood was significantly higher in neonates who had respiratory distress than those who did not. The results also showed a significant correlation between maternal cortisol levels and PSS during weeks 24-28 and the entire pregnancy. A significant relationship was observed between umbilical leptin and maternal leptin levels.

CONCLUSIONS

It can be concluded that stress during pregnancy is accompanied by fetal distress. The probable reason for newborns distress may be related to increased maternal leptin levels.

Long-time effects of prenatal morphine, tramadol, methadone, and buprenorphine exposure on seizure and anxiety in immature rats

Purpose: This study aimed to investigate seizures and anxiety-like behaviors in immature rats prenatally exposed to opiate drugs.Materials and methods: Pregnant rats were randomly divided into five groups: saline, morphine, tramadol, methadone, and buprenorphine. Administrations were performed intraperitoneally once a day for the last seven days of pregnancy. Neonatal rats were subdivided into ten groups, split according to sex. Anxiety-like behavior was tested on postnatal day (PD) 19. On PD 20, seizure was induced by PTZ injection.Results: Morphine in male rats had an increased time to onset (p < 0.005), whereas there was a decreased number of tonic-clonic seizures in females (p < 0.05). Tramadol had an increased duration of tonic-clonic seizures compared to morphine and methadone in males (p < 0.005). Moreover, tramadol decreased open arm time and locomotor activity in males more than in females (p < 0.05). Methadone decreased open arm time in males (p < 0.05). Furthermore, buprenorphine and tramadol decreased open arm entrance in male rats (p < 0.05).Conclusions: It was demonstrated that prenatal tramadol significantly increases both the duration of seizures and anxiety-like behaviors in immature male rats, whereas morphine decreases both of them. The effects of tramadol on seizure and anxiety-like behavior may be due to the comorbid occurrence of the symptoms of these two disorders.

Prenatal stress and elevated seizure susceptibility: Molecular inheritable changes

Stressful episodes are common during early-life and may have a wide range of negative effects on both physical and mental status of the offspring. In addition to various neurobehavioral complications induced by prenatal stress (PS), seizure is a common complication with no fully explained cause. In this study, the association between PS and seizure susceptibility was reviewed focusing on sex differences and various underlying mechanisms. The role of drugs in the initiation of seizure and the effects of PS on the nervous system that prone the brain for seizure, especially the hypothalamic-pituitary-adrenal (HPA) axis, are also discussed in detail by reviewing the papers studying the effect of PS on glutamatergic, gamma-aminobutyric acid (GABA)ergic, and adrenergic systems in the context of seizure and epilepsy. Finally, epigenetic changes in epilepsy are described, and the underlying mechanisms of this change are expanded. As the effects of PS may be life-lasting, it is possible to prevent future psychiatric and behavioral disorders including epilepsy by preventing avoidable PS risk factors.

Interactive Effects of Exercise, Sex Hormones, and Transient Congenital Hypothyroidism on Long-Term Potentiation in Hippocampal Slices of Rat Offspring

Introduction:

The long-term adverse effects of transient thyroid function abnormalities at birth on intellectual development are proven. The effect of exercise increases in the presence of sex hormones. The current study aimed at investigating the possibility that a combination of sex hormones and exercise has synergistic effects on neural plasticity in Transient Congenital Hypothyroidism (TCH) rats.

Methods:

To induce hypothyroidism in the mothers, Propylthiouracil (PTU) was added to drinking water (100 mg/L) on the 6th day of gestation and continued until the 21^st Postnatal Day. From Postnatal Day (PND) 28 to 47, the female and male pups received 17β-estradiol and testosterone, respectively. The mild treadmill exercise began 30 minutes after the sex hormones or vehicle administration. On PND 48, electrophysiological experiments were performed on brain slices.

Results:

Increase of Long-Term Potentiation (LTP) was observed in sedentary-non-hormone female rats of TCH group, compared with that of the control. The exercise enhanced LTP in control rats, but the hormones showed no significant effect. The effect of exercise and sex hormone was not significant in the TCH group. The combination of exercise and testosterone enhanced LTP in TCH male rats, while the combination of exercise and estradiol or each of them individually did not produce such an effect on LTP in TCH female rats.

Conclusion:

The study findings showed an increase in excitatory transmission despite the returning of thyroid hormone levels to normal range in TCH female rats. Also a combination treatment including exercise and testosterone enhanced LTP in male rats of TCH group, which was a gender-specific event.

Blockade of GluN2B-containing NMDA receptors reduces short-term brain damage induced by early-life status epilepticus

Status epilepticus (SE) during developmental periods can cause short- and long-term consequences to the brain. Brain damage induced by SE is associated to NMDA receptors (NMDAR)-mediated excitotoxicity. This study aimed to investigate whether blockade of GluN2B-containing NMDAR is neuroprotective against SE-induced neurodegeneration and neuroinflammation in young rats. Forty-eight Wistar rats (16 days of life) were injected with pilocarpine (60 mg/kg; i.p.) 12-18 h after LiCl (3 mEq/kg; i.p.). Fifteen minutes after pilocarpine administration, animals received i.p. injections of saline solution (0.9% NaCl; SE + SAL group), ketamine (a non-selective and noncompetitive NMDAR antagonist; 25 mg/kg; SE + KET), CI-1041 (a GluN2B-containing NMDAR antagonist; 10 mg/kg; SE + CI group) or CP-101,606 (a NMDAR antagonist with great selectivity for NMDAR composed by GluN1/GluN2B diheteromers; 10 mg/kg; SE + CP group). Seven days after SE, brains were removed for Fluoro-Jade C staining and Iba1/ED1 immunolabeling. GluN2B-containing NMDAR blockade by CI-1041 or CP-101,606 did not terminate LiCl-pilocarpine-induced seizures. SE + SAL group presented intense neurodegeneration and Iba1⁺/ED1⁺ double-labeling in hippocampus (CA1 and dentate gyrus; DG) and amygdala (MePV nucleus). Administration of CP-101,606 did not alter this pattern. However, GluN2B-containing NMDAR blockade by CI-1041 reduced neurodegeneration and Iba1⁺/ED1⁺ double-labeling in hippocampus and amygdala similar to the reduction observed for SE + KET group. Our results indicate that GluN2B-containing NMDAR are involved in SE-induced neurodegeneration and microglial recruitment and activation, and suggest that stopping epileptic activity is not a condition required to prevent short-term brain damage in young animals.

Effects of Tualang honey in modulating nociceptive responses at the spinal cord in offspring of prenatally stressed rats

OBJECTIVE

This study was done to determine whether Tualang honey could prevent the altered nociceptive behaviour, with its associated changes of oxidative stress markers and morphology of the spinal cord, among the offspring of prenatally stressed rats.

METHODS

Pregnant rats were divided into three groups: control, stress, and stress treated with Tualang honey. The stress and stress treated with Tualang honey groups were subjected to restraint stress from day 11 of pregnancy until delivery. Ten week old male offspring (n = 9 from each group) were given formalin injection and their nociceptive behaviours were recorded. After 2 h, the rats were sacrificed, and their spinal cords were removed to assess oxidative stress activity and morphology. Nociceptive behaviour was analysed using repeated measures analysis of variance (ANOVA), while the levels of oxidative stress parameters and number of Nissl-stained neurons were analysed using a one-way ANOVA.

RESULTS

This study demonstrated that prenatal stress was associated with increased nociceptive behaviour, changes in the oxidative stress parameters and morphology of the spinal cord of offspring exposed to prenatal stress; administration of Tualang honey reduced the alteration of these parameters.

CONCLUSION

This study provides a preliminary understanding of the beneficial effects of Tualang honey against the changes in oxidative stress and neuronal damage in the spinal cord of the offspring of prenatally stressed rats.

The Impact and Mechanism of Methylated Metabotropic Glutamate Receptors 1 and 5 in the Hippocampus on Depression-Like Behavior in Prenatal Stress Offspring Rats

An increasing number of epidemiological investigations and animal models research suggest that prenatal stress (PS) could cause depression-like behavior in the offspring, which is sex specific. However, the underlying mechanisms remain to be elucidated. This study is to investigate the promoter methylation of metabotropic glutamate receptor 1 (mGluR1) and metabotropic Glutamate Receptor 5 (mGluR5) gene modification on PS induced depression-like behavior in offspring rats (OR). PS models were established, with or without 5-aza-2′-deoxycytidine (5-azaD, decitabine) treatment. Animal behavior was assessed by the sucrose preference test (SPT), forced swimming test (FST), and open field test (OFT). The mRNA and protein expression levels of mGluR1 and mGluR5 in the hippocampus of offspring were detected with quantitative real-time PCR and Western blot analysis, respectively. The promoter methylation in the hippocampus of mGluR1 and mGluR5 OR were also analyzed. SPT showed significantly reduced sucrose preference in PS induced OR. FST showed significantly prolonged immobility time in PS induced OR. OFT showed significantly reduced central residence time in PS induced OR and no significantly influence in rearing as well as in frequency of micturition. Moreover, the mRNA, protein expression levels, and gene promoter methylation level of mGluR1 and mGluR5 in the hippocampus were significantly increased in the PS induced male OR, while no significantly influence in the PS induced female OR. Furthermore, the PS induced effects in male OR could be reversed by the microinjection of 5-azaD. In conclusion, our results showed that the promoter methylation of mGluR1 and mGluR5 gene modification is only involved in PS induced depression-like behavior in male OR in a sex-specific manner. These findings might contribute to the understanding of the disease pathogenesis and clinical treatment in future.

Effect of prenatal stress on ɑ5 GABAA receptor subunit gene expression in hippocampus and pilocarpine induced seizure in rats

The GABAergic synapses go through structural and functional maturation during early brain development. Maternal stress alters GABAergic synapses in developing brain, which are associated with the pathophysiology of neuropsychiatric disorders in adults. The present study aimed to investigate the effect of prenatal restraint stress (PS) on pilocarpine-induced seizure and ɑ5 subunit of γ-amino butyric acid type A (GABA_A) receptor expression in hippocampus. Pregnant Wistar rats were subjected to PS at gestational days 15-17 and the pups were examined for susceptibility to seizure and ɑ5 subunit of GABA_A receptor expression in hippocampus at postnatal days 14 and 21 (P14 and PND 21). Quantitative real-time PCR was used for evaluating the gene expression in the pups. Pilocarpine was injected intraperitoneally into the pups and seizure behaviors were recorded. The results showed that ɑ5 subunit mRNA expression significantly increased in hippocampus at both the P14 and P21 in the stressed rats. However, ɑ5 subunit level was greater at the P21 than at the P14 in both the groups. Latency of first tonic-clonic seizure significantly decreased in the PS group compared to the control pups. Number and duration of tonic-clonic seizures increased in the PS rats compared to the controls. PS led to an increase in total score of seizure at the P14 and P21. It can be concluded that PS increases the seizure susceptibility and GABA_A receptor ɑ5 subunit gene expression in offspring; it is likely that the mechanism of increased seizure susceptibility by PS, at least in part, can increase the GABA_A receptor ɑ5 subunit gene expression in hippocampus.

Correlation of nerve fibers in corpus callosum and number of neurons in cerebral cortex: an innovative mathematical model

Purpose/aim: It is estimated that 10⁹ bits/s information are processed in the human brain. The transmission of this huge amount of information requires all connections in the brain to be highly accurate and have order. The current study attempted to present a new aspect of order and proportion in the ultra-structure of the human brain and to calculate the degree of neural interdependence between the two hemispheres.

MATERIALS AND METHODS

In this model, intensity of interdependence of the brain to hemispheres is estimated to be equal to the mathematical proportion of number of neurons in cerebral cortex divided by 2 (number of hemispheres), divided by number of nerve fibers in the human corpus callosum.

RESULTS

The calculated number is equal to 30-50 and it indicates that for every 30-50 neurons between the two hemispheres, there is a neural interconnecting bridge.

CONCLUSIONS

This connection indicates that the brain's function output follows a mathematical relation.

Pregestational stress attenuated fertility rate in dams and increased seizure susceptibility in offspring

Many studies have found that stress during pregnancy is linked to an increased incidence of epileptic behaviors and reproductive disorders. However, few works have investigated the effect of pregestational stress on seizure susceptibility in the offspring. We investigated the effect of pregestational stress on epileptic behaviors in the offspring as well as fertility rate in dams. The male and female rats were randomly divided into four groups to form a combination of control and stressed groups for each sex. The rats were subjected to predatory stress (exposed to a cat) twice per day for 50 (male) and 15 (female) consecutive days. At the end of the stress procedure, the rats were coupled as follows: both male and female control (M_C-F_C), male stressed/female control (M_S-F_C), male control/female stressed (M_C-F_S), and both male and female stressed (M_S-F_S). Then, the puppies born from these groups were counted and evaluated for pentylentetrazole (PTZ)-induced seizure. There was no significant difference between the male and female pups in each identical group in terms of litter size and epileptic behaviors, except duration of tail rigidity and duration of immobility. The total score of seizure increased in all the stressed groups, but more severely in the M_S-F_S group. However, the onset of the first epileptic behavior and tonic-clonic seizure significantly decreased in the stressed groups. Moreover, fertility rate significantly decreased in the stressed groups compared with the control group, but there was no significant difference in terms of litter size between the groups. These data revealed the impact of pregestational stress during spermatogenesis and oogenesis on fertility rate in dams and epileptic behaviors in the offspring.

Winter birth, urbanicity and immigrant status predict psychometric schizotypy dimensions in adolescents

BACKGROUND

Urbanicity, immigration and winter-birth are stable epidemiological risk factors for schizophrenia, but their relationship to schizotypy is unknown. This is a first examination of the association of these epidemiological risk factors with positive schizotypy, in nonclinical adolescents, controlling for a range of potential and known confounders.

METHODS

We collected socio-demographics, life-style, family and school circumstances, positive schizotypy dimensions and other personality traits from 445 high school pupils (192 males, 158 immigrants) from 9 municipalities in Athens and Heraklion, Greece, which covered a range of host population and migrant densities. Using multivariate hierarchical linear regressions models, we estimated the association of schizotypy dimensions with: (1) demographics of a priori interest (winter-birth, immigrant status, urban characteristics), including family financial and mental health status; (2) factors resulting from principal component analysis (PCA) of the demographic and personal data; (3) factors resulting from PCA of the personality questionnaires.

RESULTS

Adolescent women scored higher on schizotypy than men. High anxiety/neuroticism was the most consistent and significant predictor of all schizotypy dimensions in both sexes. In the fully adjusted models, urbanicity predicted magical thinking and unusual experiences in women, while winter-birth and immigration predicted paranoid ideation and unusual experiences respectively in men.

CONCLUSIONS

These results support the continuum hypothesis and offer potential insights in the nature of risk conferred by winter-birth, urbanicity and immigration and the nature of important sex differences. Controlling for a wide range of potential confounding factors increases the robustness of these results and confidence that these were not spurious associations.

Are changes in excitability in the hippocampus of adult male rats induced by prenatal methamphetamine exposure or stress?

Prenatal stress and drug exposure induce permanent alterations of the brain. Even though different brain structures are involved, alterations almost always refer to the hippocampus. The aim of this study was to investigate the excitability of hippocampal slices in low-magnesium epilepsy model of prenatally methamphetamine (MA, 5mg/kg sc.) or saline (sc., stress model) exposed animals in adult male rats. The second aim was to investigate, if a low dose of MA (1ml/kgs.c.) administered in adulthood changes the hippocampal activity of these animals. Adult Wistar male rats were divided into groups according to their prenatal treatment (C - naïve control; Sa - saline; MA - MA administration). One half of the animals was treated with a challenge dose of MA (1mg/kg sc.) 45min before hippocampal slices were cut. The activity of 350μ thick transversal slices of CA1 hippocampi was recorded (latencies of the first epileptiform discharge and the regular epileptiform activity) and evaluated in ACSF with low-magnesium concentration. Effects of prenatal exposure: The highest excitability was found in the Sa (prenatally stressed) group in respect to C and MA groups. This group developed also the highest number of seizure-like events. In addition, the prenatally MA treated group had also higher excitability than C group. Effects of the MA challenge dose: The challenge dose decreased the excitability of prenatally SA- exposed group. To conclude, even a mild prenatal stress significantly increases hippocampal excitability in adulthood and a challenge dose of MA is able to dampen it.

Prenatal stress potentiates febrile seizure and leads to long-lasting increase in cortisol blood levels in children under 2years old

Neurological disorders can be exacerbated in an offspring that is exposed to stress prenatally. This study is aimed to investigate the severity of febrile seizures (FS) in the offspring under 2years old that were prenatally stressed. In this study, 158 children below 2years old with FS were selected. Information about convulsion including seizure lasting, recurrence of seizure, age of the first seizure and type of FS was gathered. Blood samples were obtained from the offspring to measure the cortisol blood levels. Questionnaire was filled in to evaluate the perceived stress and exposure or non-exposure to major stresses during pregnancy. Results of this study showed that both high Perceived Stress Scores (PSS) during pregnancy and exposure to major stresses during pregnancy significantly increased seizure duration and seizure intensity. Also, the appearance of complex FS was significantly higher in prenatally stressed children than the unexposed ones. Further, cortisol blood levels were significantly higher in prenatally stressed subjects. It can be concluded that both higher PSS and/or exposure to major stresses during pregnancy potentiate FS parameters and lead to long lasting increase in cortisol blood levels in the offspring.

Effect of prenatal restraint stress and morphine co-administration on plasma vasopressin concentration and anxiety behaviors in adult rat offspring

Stressful events and exposure to opiates during gestation have important effects on the later mental health of the offspring. Anxiety is among the most common mental disorders. The present study aimed to identify effects of prenatal restraint stress and morphine co-administration on plasma vasopressin concentration (PVC) and anxiety behaviors in rats. Pregnant rats were divided into four groups (n = 6, each): saline, morphine, stress + saline and stress + morphine treatment. The stress procedure consisted of restraint twice per day, two hours per session, for three consecutive days starting on day 15 of pregnancy. Rats in the saline and morphine groups received either 0.9% saline or morphine intraperitoneally on the same days. In the morphine/saline + stress groups, rats were exposed to restraint stress and received either morphine or saline intraperitoneally. All offspring were tested in an elevated plus maze (EPM) on postnatal day 90 (n = 6, each sex), and anxiety behaviors of each rat were recorded. Finally, blood samples were collected to determine PVC. Prenatal morphine exposure reduced anxiety-like behaviors. Co-administration of prenatal stress and morphine increased locomotor activity (LA) and PVC. PVC was significantly lower in female offspring of the morphine and morphine + stress groups compared with males in the same group, but the opposite was seen in the saline + stress group. These data emphasize the impact of prenatal stress and morphine on fetal neuroendocrine development, with long-term changes in anxiety-like behaviors and vasopressin secretion. These changes are sex specific, indicating differential impact of prenatal stress and morphine on fetal neuroendocrine system development. Lay Summary Pregnant women are sometimes exposed to stressful and painful conditions which may lead to poor outcomes for offspring. Opiates may provide pain and stress relief to these mothers. In this study, we used an experimental model of maternal exposure to stress and morphine in pregnant rats. The findings indicated that maternal stress increased anxiety in offspring while morphine decreased such effects, but had negative effects on the levels of a hormone controlling blood pressure, and activity of offspring. Hence morphine should not be used in pregnancy for pain and stress relief.

Interactive effects of prenatal exposure to restraint stress and alcohol on pentylenetetrazol-induced seizure behaviors in rat offspring

Prenatal exposure to stress or alcohol increases vulnerability of brain regions involved in neurobehavioral development and programs susceptibility to seizure. To examine how prenatal alcohol interferes with stress-sensitive seizures, corticosterone (COS) blood levels and pentylenetetrazol (PTZ)-induced seizure behaviors were investigated in rat pups, prenatally exposed to stress, alcohol, or both. Pregnant rats were exposed to stress and saline/alcohol on 17, 18, and 19 days of pregnancy and divided into four groups of control-saline (CS), control-alcohol (CA), restraint stress-saline (RS), and restraint stress-alcohol (RA). In CS/CA groups, rats received saline/alcohol (20%, 2 g/kg, intraperitoneally [i.p.]). In RS/RA groups, rats were exposed to restraint stress by being held immobile in a Plexiglas^® tube (twice/day, 1 h/session), and received saline/alcohol, simultaneously. After parturition, on postnatal days 6 and 15 (P6 & P15), blood samples were collected from the pups to determine COS level. On P15 and P25, PTZ (45 mg/kg) was injected into the rest of the pups and seizure behaviors were then recorded. COS levels increased in pups of the RS group but not in pups of the RA group. Both focal and tonic-clonic seizures were prevalent and severe in pups of the RS group, whereas only focal seizures were prominent in pups of the CA group. However, pups prenatally exposed to co-administration of alcohol and stress, unexpectedly, did not show additive epileptic effects. The failure of pups prenatally exposed to alcohol to show progressive or facilitatory epileptic responses to stressors, indicates decreased plasticity and adaptability, which may negatively affect HPA-axis performance or hippocampal structure/function.

Neuroplasticity Changes of Rat Brain by Musical Stimuli during Fetal Period

OBJECTIVE

Fetal development of the central nervous system is an important and sensitive stage which is affected by many external and internal stimuli. This study aimed to investigate effect of musical stimuli on fetal rat brain.

MATERIALS AND METHODS

In this experimental study, twelve female Wistar rats were selected and evenly assigned to control and musical groups. The females were mated with a male rat of the same genotype. Musical group was exposed to classic music with 60 dB power for 90 minutes twice per day from 2(nd) to 20(th) day of gestation. The control rats were handled similar to the musical group, but were not exposed to music. Before parturition, all the dams were anesthetized, and their blood samples were obtained and used for corticosterone (COS) measurement. They were transcardially perfused by electron microscope (EM) fixative agent. The fetal brains were extracted intact and used for slice preparation. Horizontal slices were made for electron microscope preparation, and images were taken and analyzed in terms of cell density and morphological changes.

RESULTS

EM observation indicated significant morphological difference in cellular and intercellular spaces between the two groups. Music-treated fetuses had significantly higher cell density in parietal cortex and music-treated dams had lower COS level.

CONCLUSION

It was concluded that prenatal music would have a great impact on neuroplasticity of fetal rat brain, at least indirectly. Although the rat fetuses cannot hear until birth, music-induced reduction in COS blood level of dams might be the reason for neuroplasticity of fetal brain.

Psychological or physical prenatal stress differentially affects cognition behaviors

INTRODUCTION

Prenatal stress is proposed as a major risk factor in the development of cognitive impairments in the offspring. The objective of the current study was to evaluate the effect of prenatal physical or psychological stress on the motor and cognitive functions of male and female offspring.

METHODS

Adult female rats were stressed during their conception using a novel method to induced whether physical or psychological stress. Animal offspring were then kept until adulthood. Elevated plus maze (EPM) was used to evaluate their anxiety-like behavior. Rotarod and wire grip were used to evaluate muscle strength and balance function. Morris water maze (MWM) and passive avoidance (PA) learning and memory paradigm were used to evaluate the cognitive function of the offspring.

RESULTS

Female offspring of both physical and psychological stress had an increased anxiety-like behavior in the EPM test in comparison to female control rats. Balance function was impaired in physical stressed female offspring in comparison to the control and male offspring. Muscle strength was reduced in physical male and female offspring. Both male and female offspring groups that underwent prenatal physical and psychological stress had an impaired spatial learning and memory. PA learning and memory were impaired in both male and female offspring except for the psychological stress female offspring in PA learning.

CONCLUSION

Results of our study revealed that prenatal physical or psychological stress have different effects on motor and cognitive functions of the offspring. Male and female offspring were differentially affected by prenatal stress. We suggest more studies to evaluate the role of sex hormones on the effects of prenatal physical or psychological stress on cognitive and motor functions of the offspring.

Altered expression of Alzheimer's disease-related genes in the cerebellum of autistic patients: a model for disrupted brain connectome and therapy

Autism and Alzheimer's disease (AD) are, respectively, neurodevelopmental and degenerative diseases with an increasing epidemiological burden. The AD-associated amyloid-β precursor protein-α has been shown to be elevated in severe autism, leading to the 'anabolic hypothesis' of its etiology. Here we performed a focused microarray analysis of genes belonging to NOTCH and WNT signaling cascades, as well as genes related to AD and apoptosis pathways in cerebellar samples from autistic individuals, to provide further evidence for pathological relevance of these cascades for autism. By using the limma package from R and false discovery rate, we demonstrated that 31% (116 out of 374) of the genes belonging to these pathways displayed significant changes in expression (corrected P-values <0.05), with mitochondria-related genes being the most downregulated. We also found upregulation of GRIN1, the channel-forming subunit of NMDA glutamate receptors, and MAP3K1, known activator of the JNK and ERK pathways with anti-apoptotic effect. Expression of PSEN2 (presinilin 2) and APBB1 (or F65) were significantly lower when compared with control samples. Based on these results, we propose a model of NMDA glutamate receptor-mediated ERK activation of α-secretase activity and mitochondrial adaptation to apoptosis that may explain the early brain overgrowth and disruption of synaptic plasticity and connectome in autism. Finally, systems pharmacology analyses of the model that integrates all these genes together (NOWADA) highlighted magnesium (Mg(2+)) and rapamycin as most efficient drugs to target this network model in silico. Their potential therapeutic application, in the context of autism, is therefore discussed.

Prenatal maternal factors in the development of cognitive impairments in the offspring

Different environmental factors acting during sensitive prenatal periods can have a negative impact on neurodevelopment and predispose the individual to the development of various psychiatric conditions that often share cognitive impairments as a common component. As cognitive symptoms remain one of the most challenging and resistant aspects of mental illness to be treated pharmacologically, it is important to investigate the mechanisms underlying such cognitive deficits, with particular focus on the impact of early life adverse events that predispose the individual to mental disorders. Multiple clinical studies have, in fact, repeatedly confirmed that prenatal maternal factors, such as infection, stress or malnutrition, are pivotal in shaping behavioral and cognitive functions of the offspring, and in the past decade many preclinical studies have investigated this hypothesis. The purpose of this review is to describe recent preclinical studies aimed at dissecting the relative impact of various prenatal maternal factors on the development of cognitive impairments in offspring, focusing on animal models of prenatal stress and prenatal infection. These recent studies point to the pivotal role of prenatal stressful experiences in shaping memory and learning functions associated with specific brain structures, such as the hippocampus and the prefrontal cortex. More importantly, such experimental evidence suggests that different insults converge on similar downstream functional targets, such as cognition, which may therefore represent an endophenotype for several pathological conditions. Future studies should thus focus on investigating the mechanisms contributing to the convergent action of different prenatal insults in order to identify targets for novel therapeutic intervention.