Modafinil ameliorates cognitive deficits induced by maternal separation and sleep deprivation

Maternal Substance Use and Early-Life Adversity: Inducing Drug Dependence in Offspring, Interactions, Mechanisms, and Treatments

The likelihood of substance dependency in offspring is increased in cases when there is a family history of drug or alcohol use. Mothering is limited by maternal addiction because of the separation. Maternal separation (MS) leads to the development of behavioural and neuropsychiatric issues in the future. Despite the importance of this issue, empirical investigations of the influences of maternal substance use and separation on substance use problems in offspring are limited, and studies that consider both effects are rare. This study aims to review a few studies on the mechanisms, treatments, genetics, epigenetics, molecular and psychological alterations, and neuroanatomical regions involved in the dependence of offspring who underwent maternal addiction and separation. The PubMed database was used. A total of 95 articles were found, including the most related ones in the review. The brain's lateral paragigantocellularis (LPGi), nucleus accumbens (NAc), caudate-putamen (CPu), prefrontal cortex (PFC), and hippocampus, can be affected by MS. Dopamine receptor subtype genes, alcohol biomarker minor allele, and preproenkephalin mRNA may be affected by alcohol or substance use disorders. After early-life adversity, histone acetylation in the hippocampus may be linked to brain-derived neurotrophic factor (BDNF) gene epigenetics and glucocorticoid receptors (GRs). The adverse early-life experiences differ in offspring›s genders and rewire the brain›s dopamine and endocannabinoid circuits, making offspring more susceptible to dependence. Related psychological factors rooted in early-life stress (ELS) and parental substance use disorder (SUD). Treatments include antidepressants, histone deacetylase inhibitors, lamotrigine, ketamine, choline, modafinil, methadone, dopamine, cannabinoid 1 receptor agonists/antagonists, vitamins, oxytocin, tetrahydrocannabinol, SR141716A, and dronabinol. Finally, the study emphasizes the need for multifaceted strategies to prevent these outcomes.

Solriamfetol enhances wakefulness and improves cognition and anxiety in a murine model of OSA

BACKGROUND

Obstructive sleep apnea (OSA) is a chronic condition characterized by intermittent hypoxia (IH). Excessive daytime sleepiness (EDS) is a common consequence of OSA and is associated with cognitive deficits and anxiety. Modafinil (MOD) and Solriamfetol (SOL) are potent wake-promoting agents clinically used to improve wakefulness in OSA patients with EDS.

METHODS

Male C57Bl/6J mice were exposed to either IH or room air (RA) controls during the light phase for 16 weeks. Both groups were then randomly assigned to receive once-daily intraperitoneal injections of SOL (200 mg/kg), MOD (200 mg/kg) or vehicle (VEH) for 9 days while continuing IH exposures. Sleep/wake activity was assessed during the dark (active) phase. Novel object recognition (NOR), elevated-plus maze test (EPMT), and forced swim test (FST) were performed before and after drug treatment.

RESULTS

IH exposure increased dark phase sleep percentage and reduced wake bouts lengths and induced cognitive deficits and anxiogenic effects. Both SOL and MOD treatments decreased sleep propensity under IH conditions, but only SOL promoted improvements in NOR performance (explicit memory) and reduced anxiety-like behaviors.

CONCLUSION

Chronic IH, a hallmark feature of OSA, induces EDS in young adult mice that is ameliorated by both SOL and MOD. SOL, but not MOD, significantly improves IH-induced cognitive deficits and promotes anxiolytic effects. Thus, SOL could potentially benefit OSA patients beyond EDS management.

Solriamfetol improves chronic sleep fragmentation-induced increases in sleep propensity and ameliorates explicit memory in male mice

Obstructive sleep apnea (OSA) is a highly prevalent condition characterized by episodes of partial or complete breath cessation during sleep that induces sleep fragmentation (SF). One of the frequent manifestations of OSA is the presence of excessive daytime sleepiness (EDS) associated with cognitive deficits. Solriamfetol (SOL) and modafinil (MOD) are wake-promoting agents commonly prescribed to improve wakefulness in OSA patients with EDS. This study aimed to assess the effects of SOL and MOD in a murine model of OSA characterized by periodic SF. Male C57Bl/6J mice were exposed to either control sleep (SC) or SF (mimicking OSA) during the light period (06:00 h to 18:00 h) for 4 weeks, which consistently induces sustained excessive sleepiness during the dark phase. Both groups were then randomly assigned to receive once-daily intraperitoneal injections of SOL (200 mg/kg), MOD (200 mg/kg), or vehicle for 1 week while continuing exposures to SF or SC. Sleep/wake activity and sleep propensity were assessed during the dark phase. Novel Object Recognition test, Elevated-Plus Maze Test, and Forced Swim Test were performed before and after treatment. SOL or MOD decreased sleep propensity in SF, but only SOL induced improvements in explicit memory, while MOD exhibited increased anxiety behaviors. Chronic SF, a major hallmark of OSA, induces EDS in young adult mice that is mitigated by both SOL and MOD. SOL, but not MOD, significantly improves SF-induced cognitive deficits. Increased anxiety behaviors are apparent in MOD-treated mice. Further studies aiming to elucidate the beneficial cognitive effects of SOL are warranted.

Risky Decision-taking Task: a novel paradigm to assess the risk-taking behaviour in rats predisposed to early-life stress

One of the characteristic features of adolescence is risk-taking behavioural traits. Uncontrolled risk-taking without proper assessment may have harmful impact on mental health later in life. Therefore, it is essential to identify it early for the preventable health problems. In the present study, we have designed a novel paradigm, viz. Risky Decision-taking Task (RDTT), to evaluate the spontaneous risk-taking behavioural repertoire in adolescent rodents. The task was designed based on both risk and cognitive factors. To validate and compare the risk-taking tendency, we have used early maternal separation and isolation (MS) stress model, as it is known to increase anxiety and curiosity-like behaviour at adolescence. We have used Sprague-Dawley rats of both sexes. Rats were exposed to MS stress for 10 days daily for six hours during stress hyporesponsive period (SHRP) from postnatal day 4 to 13. These rats were subjected to RDTT during adolescence. This task is a reward-based task where the latency to collect reward in the presence or absence of a risk factor is assessed. It consists of habituation, training to find the location of small and large rewards, reward preference for small and large reward and testing period under risky situation. Rats were trained individually to retrieve the valuation-based rewards under the risky, but innate aversive environments. The results from RDTT showed that as compared to controls, MS rats from both sexes showed reduced latency to collect large reward in the presence of a risk element and a reduced risk-index which is indicative of a higher risk-taking tendency in these rats. In addition, MS rats showed a trend towards anxiety-like behaviour as compared to controls in the Light-Dark Test. These results together show decreased risk latency for the large reward and reduced risk assessment in MS rats which is suggestive of more risk-taking tendency in these rats. Thus, we propose that RDTT paradigm can be used to evaluate the spontaneous risk-taking behavioural repertoire based on innate, spontaneous aversion and cognitive factors in rats.

Effects of early life adversities upon memory processes and cognition in rodent models

Exposure to stressors in early postnatal life induces long-lasting modifications in brainfunction.Thisplasticity,an essential characteristic of the brain that enables adaptation to the environment, may also induce impairments in some psychophysiological functions, including learning and memory. Early life stress (ELS) has long-term effects on thehypothalamic-pituitary-adrenal axisresponse to stressors, and has been reported to lead toneuroinflammation,altered levelsof neurotrophic factors, modifications inneurogenesis andsynaptic plasticity,with changes in neurotransmitter systems and network functioning. In this review, we focus on early postnatal stress in animal models and their effects on learning and memory.Many studies have reported ELS-induced impairments in different types of memories, including spatial memory, fear memory, recognition (both for objects and social) memory, working memory and reversal learning. Studies are not always in agreement, however, no effects, or sometimes facilitation, being reported, depending on the nature and intensity of the early intervention, as well as the age when the outcome was evaluated and the sex of the animals. When considering processes occurring after consolidation, related with memory maintenance or modification, there are a very reduced number of reports. Future studies addressing the mechanisms underlying memory changes for ELS should shed some light on the understanding of the different effects induced by stressors of different types and intensities on cognitive functions.

Modafinil rescues repeated morphine-induced synaptic and behavioural impairments via activation of D1R-ERK-CREB pathway in medial prefrontal cortex

Long-term opioid abuse causes a variety of long-lasting cognitive impairments such as attention, impulsivity and working memory. These cognitive impairments undermine behavioural treatment for drug abuse and lead to poor treatment retention and outcomes. Modafinil is a wake-promoting drug that shows potential in improving attention and memory in humans and animals. However, modafinil's effect on opioid-induced cognitive impairments remains unclear, and the underlying mechanism is poorly understood. This study showed that repeated morphine administration significantly impairs attention, increases impulsivity and reduces motivation to natural rewards in mice. Systemic modafinil treatment at low dose efficiently ameliorates morphine-induced attention dysfunction and improves motivation and working memory in mice. High dose of modafinil has adverse effects on impulsive action and attention. Local infusion of D1R antagonist SCH-23390 reverses the morphine-induced synaptic abnormalities and activation of the D1R-ERK-CREB pathway in medial prefrontal cortex (mPFC). This study demonstrated a protective effect of modafinil in mPFC neurons and offered a therapeutic potential for cognitive deficits in opioid abuse.

Effects of postnatal ethanol exposure and maternal separation on mood, cognition and hippocampal arborization in adolescent rats

Ethanol exposure and early life stress during brain development are associated with an increased risk of developing psychiatric disorders. We used a third-trimester equivalent model of fetal alcohol spectrum disorders combined with a maternal separation (MS) protocol to evaluate whether these stressors cause sexually dimorphic behavioral and hippocampal dendritic arborization responses in adolescent rats. Wistar rat pups were divided into four experimental groups: 1) Control; 2) MS (MS, for 3 h/day from postnatal (PND) 2 to PND14); 3) EtOH (EtOH, 5 g/kg/day, i.p., PND2, 4, 6, 8, and 10); 4) EtOH + MS. All animals were divided into two cohorts and subjected to a battery of behavioral tests when they reached adolescence (PND37-44). Animals from cohort 1 were submitted to: 1) the open field test; 2) self-cleaning behavior (PND38); and 3) the motivation test (PND39-41). Animals from cohort 2 were submitted to: 1) the novel object recognition (PND37-39); 2) social investigation test (PND40); and 3) Morris water maze test (PND41-44). At PND45, the animals were euthanized, and the brains were collected for subsequent dendritic analysis. Postnatal ethanol exposure (PEE) caused anxiety-like behavior in females and reduced motivation, and increased hippocampal dendritic arborization in both sexes. MS reduced body weight, increased locomotor activity in females, and increased motivation, and hippocampal dendritic arborization in both sexes. We found that males from the EtOH + MS groups are more socially engaged than females, who were more interested in sweets than males. Altogether, these data suggest that early life adverse conditions may alter behavior in a sex-dependent manner in adolescent rats.

Memory improvement by modafinil at cost of metabolic hazards? A study to decipher the benefits and risks of modafinil in rats

BACKGROUND

Modafinil is approved for narcolepsy and achieved high success in off-label indications in memory-related disorders. However, chronic indiscriminate use of modafinil imposes several health hazards like hyperglycaemia, obesity and metabolic syndrome, owing to impairment of sleep-wake cycle, circadian-rhythm, and neurotransmission. The present protocol elucidates the effects of modafinil per se and diabetic complications apropos.

METHODS

Modafinil (100 and 200 mg/kg) was administered in rats from day 5-26. To induce type-2 diabetes, streptozotocin (STZ) was given on day 1, and blood glucose assessed on day 5. CPP (combination propranolol and phentolamine) was administered to antagonize sympathetic activity. After evaluation of cognitive functions, serum lipid profile, and biomarkers of oxidative stress and acetylcholinesterase (AChE) activity were assessed.

RESULTS

Subacute dosing of modafinil significantly elevated blood glucose levels, albeit considerably less than diabetic group, and attenuated brain oxidative stress and AChE activity. Modafinil caused significant dyslipidaemia, increased body weight, whereas modestly altered abdominal circumference (AC) and thoracic circumference (TC) in rats. Significant hyperglycaemia, derangement of serum lipid-profile, brain lipid peroxidation, cholinergic hypofunction, and decrease in body weight and ACTC was noted in diabetic rats. Modafinil (100 mg/kg) significantly potentiated the hyperglycaemia and dyslipidaemia, however, attenuated oxidative stress and AChE activity in diabetic rats. Modafinil increased short-term (working) memory but not long-term spatial memory in normal and diabetic rats. CPP infusion attenuated these effects of modafinil.

CONCLUSION

Subacute dosing of modafinil differentially modulates long-term and short-term memory subtypes, and also predisposes towards metabolic derangements.

Effects of BDNF Signaling on Anxiety-Related Behavior and Spatial Memory of Adolescent Rats in Different Length of Maternal Separation

As an adverse form of early-life stress (ELS), maternal separation (MS) can interfere with the development of cognition and behaviors of adolescent rodents. Brain-derived neurotrophic factor (BDNF) is involved in the regulation of brain development and function, but the molecular mechanisms by which BDNF regulates brain function and behavior in MS with different stressor strengths remain unclear. This descriptive study characterized the levels of BDNF in the prefrontal cortex (PFC) and plasma corticosterone (CORT) from the offspring of rats exposed to early handling (EH, 15-min separation per day) and prolonged MS (PMS, 180-min separation per day), during postnatal days (PND) 1‑21. The behavioral and biochemical analyses were performed during adolescence (PND 42‑56). PMS resulted in reduced weight and decreased locomotor activity in the open field test and Y-maze task compared to control (CON) group, with EH showing an intermediate phenotype. BDNF protein levels in the PFC were lower in PMS compared to EH and further reduced in CON male rats. Plasma CORT levels were higher in PMS compared to CON with EH again showing intermediate levels. Neither PMS or EH affected spatial learning in the Y-maze task. These findings indicate that longer periods of maternal separation are necessary to increase anxiety-like behavior, elevate CORT levels, and further suppress BDNF levels in the PFC, providing a possible mechanism to explain why more severe forms of ELS lead to more significant psychiatric and medical consequences later in life.

The interfaces between vitamin D, sleep and pain

The role of vitamin D in osteomineral metabolism is well known. Several studies have suggested its action on different biological mechanisms, such as nociceptive sensitivity and sleep-wake cycle modulation. Sleep is an important biological process regulated by different regions of the central nervous system, mainly the hypothalamus, in combination with several neurotransmitters. Pain, which can be classified as nociceptive, neuropathic and psychological, is regulated by both the central and peripheral nervous systems. In the peripheral nervous system, the immune system participates in the inflammatory process that contributes to hyperalgesia. Sleep deprivation is an important condition related to hyperalgesia, and recently it has also been associated with vitamin D. Poor sleep efficiency and sleep disorders have been shown to have an important role in hyperalgesia, and be associated with different vitamin D values. Vitamin D has been inversely correlated with painful manifestations, such as fibromyalgia and rheumatic diseases. Studies have demonstrated a possible action of vitamin D in the regulatory mechanisms of both sleep and pain. The supplementation of vitamin D associated with good sleep hygiene may have a therapeutic role, not only in sleep disorders but also in the prevention and treatment of chronic pain conditions.

Cognitive impairment effects of early life stress in adolescents can be predicted with early biomarkers: Impacts of sex, experience, and cytokines

Childhood adversity increases vulnerability to psychiatric disorders that emerge in adolescence, in a sex-dependent manner. Early adversity modeled in rodents with maternal separation (MS) affects cognition and medial prefrontal cortex (mPFC) circuitry. Humans and animals exposed to early life adversity also display heightened circulating inflammatory cytokines, however the predictive relationship of these early measures with later behavioral deficits is unknown. Here, male and female rats were exposed to MS or control rearing during the postnatal period (P2-21). Blood samples were taken at distinct developmental time points for analysis of the pro-inflammatory cytokine IL-1β and the anti-inflammatory cytokines IL-4, and IL-10, followed by win-shift cognitive testing and analysis of mPFC parvalbumin (PVB) immunofluorescent interneurons in adolescence. Regression analyses were conducted to explore the relationship between early cytokines and adolescent behavioral measures. We observed sex- and age-dependent effects of MS on circulating cytokines. MS also yielded adolescent decreases in mPFC PVB and cognitive deficits, which were predicted by early cytokine expression in a sex- and experience-dependent manner. Taken together, the present data reveals that circulating cytokines and PVB levels are predictive of adolescent cognitive deficits, and therefore provide compelling evidence for a putative role of early biomarkers in mediating MS-induced behavioral dysfunction. Importantly, predictive relationships often depended on sex and on MS history, suggesting that early life experiences may yield individualistic mechanisms of vulnerability compared to the general population.

The Preeminence of Early Life Trauma as a Risk Factor for Worsened Long-Term Health Outcomes in Women

Early life trauma (ELT) comprises an array of disturbingly common distressing experiences between conception and the beginning of adulthood with numerous and significant potential long-term, even transgenerational, health consequences of great public health concern, including depression, cardiovascular disease, and other psychiatric and medical disorders, and neurobiological, psychological, and behavioral effects which are sufficiently robust to confound many types of biomedical research. The impact of ELT on a woman's health trajectory appears to vary with the specific characteristics of the ELT (e.g., type, number of different types, severity, and timing), the individual (e.g., age, genetics, epigenetics, personality, and cognitive factors), and the individual's environment (e.g., level of social support and ongoing stressors) and to be mediated to a significant extent by persistent changes in a number of biological systems, dysregulation of those governing the stress response chief among them. Growing knowledge of the risk factors and pathophysiological mechanisms by which ELT confers diathesis to various poor health outcomes and the unique treatment-response profiles of women with ELT will lead to much needed improvements in prevention, diagnostic, and therapeutic efforts, including more effective psychotherapy and pharmacotherapy approaches, hopefully making strides toward improvements in the lives of women everywhere and ending countless cycles of intergenerational trauma-associated pathology. This article attempts to broadly summarize the current state of knowledge about the long-term sequelae of ELT for women's health.

Effects of maternal separation on behavior and brain damage in adult rats exposed to neonatal hypoxia-ischemia

Animal studies suggest that maternal separation, a widely used paradigm to study the effects of early life adversity, exerts a profound and life-long impact on both brain and behavior. The aim of the current study was to investigate whether adverse early life experiences interact with neonatal hypoxia-ischemia, affecting the outcome of this neurological insult at both functional and structural levels during adulthood. Rat pups were separated from their mothers during postnatal days 1-6, for either a short (15 min) or prolonged (180 min) period, while another group was left undisturbed. On postnatal day 7, a subgroup from each of the three postnatal manipulations was exposed to a hypoxic-ischemic episode. Behavioral examination took place approximately at three months of age and included tests of learning and memory (Morris water maze, novel object and novel place recognition), as well as motor coordination (rota-rod). We found that both prolonged maternal separation and neonatal hypoxia-ischemia impaired the animals' spatial learning and reference memory. Deficits in spatial but not visual recognition memory were detected only in hypoxic-ischemic rats. Interestingly, prolonged maternal separation prior to neonatal hypoxia-ischemia augmented the reference memory impairments. Histological analysis of infarct size, hippocampal area and thickness of corpus callosum did not reveal any exacerbation of damage in hypoxic-ischemic rats that were maternally separated for a prolonged period. These are the first data suggesting that an adverse postnatal environmental manipulation of just 6 days causes long-term effects on spatial learning and memory and may render the organism more vulnerable to a subsequent insult.

"Messing with the mind": evolutionary challenges to human brain augmentation

The issue of brain augmentation has received considerable scientific attention over the last two decades. A key factor to brain augmentation that has been widely overlooked are the complex evolutionary processes which have taken place in evolving the human brain to its current state of functioning. Like other bodily organs, the human brain has been subject to the forces of biological adaptation. The structure and function of the brain, is very complex and only now we are beginning to understand some of the basic concepts of cognition. Therefore, this article proposes that brain-machine interfacing and nootropics are not going to produce “augmented” brains because we do not understand enough about how evolutionary pressures have informed the neural networks which support human cognitive faculties.

Long-lasting recognition memory impairment and alterations in brain levels of cytokines and BDNF induced by maternal deprivation: effects of valproic acid and topiramate

Exposure to stressful events early in life may have permanent deleterious consequences on nervous system function and increase the susceptibility to psychiatric conditions later in life. Maternal deprivation, commonly used as a source of neonatal stress, impairs memory in adult rats and reduces hippocampal brain-derived neurotrophic factor (BDNF) levels. Inflammatory cytokines, such as interleukins (IL) and tumor necrosis factor-α (TNF-α) have been shown to be increased in the peripheral blood of patients with psychiatric disorders. The aim of the present study was to investigate the effects of maternal separation on the levels of IL-10 and TNF-α, and BDNF in the hippocampus and prefrontal cortex of adult rats. We also evaluated the potential ameliorating properties of topiramate and valproic acid on memory deficits and cytokine and BDNF changes associated with maternal deprivation. The results indicated that, in addition to inducing memory deficits, maternal deprivation increased the levels of IL-10 in the hippocampus, and TNF-α in the hippocampus and in the cortex, and decreased hippocampal levels of BDNF, in adult life. Neither valproic acid nor topiramate were able to ameliorate memory deficits or the reduction in BDNF induced by maternal separation. The highest dose of topiramate was able to reduce IL-10 in the hippocampus and TNF-α in the prefrontal cortex, while valproate only reduced IL-10 levels in the hippocampus. These findings may have implications for a better understanding of the mechanisms associated with alterations observed in adult life induced by early stressful events, and for the proposal of novel therapeutic strategies.

Sex-dependent effects of an early life treatment in rats that increases maternal care: vulnerability or resilience?

Early life stress (ELS) in rodents has profound long-term effects that are partially mediated by changes in maternal care. ELS not only induces “detrimental” effects in adulthood, increasing psychopathology, but also promotes resilience to further stressors. In Long-Evans rats, we evaluated a combination of two procedures as a model of ELS: restriction of bedding during the first post-natal days and exposure to a “substitute” mother. The maternal care of biological and “substitute” mothers was measured. The male and female offspring were evaluated during adulthood in several contexts. Anxiety was measured by the elevated plus-maze (EPM), acoustic startle response (ASR) and forced swim test (FST). In other group of animals, novelty-seeking was measured (activity in an inescapable novel environment, preference for novel environments and exploration of novel objects). Plasmatic ACTH and corticosterone in basal conditions and in response to stress were also measured. Cognitive impulsivity was assessed by a delay-discounting paradigm, and impulsive action, attention and compulsive-like behavior by a five choice serial reaction time task (5CSRTT). ELS decreased pup body weight and increased the care of the biological mother; however, the “substitute” mother did not exhibit overt maltreatment. A mixture of “detrimental” and “beneficial” effects was shown. In the 5CSRTT, attention was impaired in both genders, and in females, ELS increased compulsive-like behavior. Novel object exploration was only increased by ELS in males, but the preference for novel spaces decreased in both genders. Baseline anxiety (EPM and ASR) and recognition memory were not affected. Unexpectedly, ELS decreased the ACTH response to novelty and swim stress and increased active coping in the FST in both genders. Cognitive impulsivity was decreased only in females, but impulsive action was not affected. The enhancement in maternal care may “buffer” the effects of ELS in a context-dependent manner.

Sleep and protein synthesis-dependent synaptic plasticity: impacts of sleep loss and stress

Sleep has been ascribed a critical role in cognitive functioning. Several lines of evidence implicate sleep in the consolidation of synaptic plasticity and long-term memory. Stress disrupts sleep while impairing synaptic plasticity and cognitive performance. Here, we discuss evidence linking sleep to mechanisms of protein synthesis-dependent synaptic plasticity and synaptic scaling. We then consider how disruption of sleep by acute and chronic stress may impair these mechanisms and degrade sleep function.