Methamphetamine exposure during pregnancy at pharmacological doses produces neurodevelopmental and behavioural effects in rat offspring

Dexmedetomidine Improves Long-term Neurological Outcomes by Promoting Oligodendrocyte Genesis and Myelination in Neonatal Rats Following Hypoxic-ischemic Brain Injury

Neonatal hypoxic-ischemic brain injury (HIBI) can lead to white matter damage, which significantly contributes to cognitive dysfunction, emotional disorders, and sensorimotor impairments. Although dexmedetomidine enhances neurobehavioral outcomes, its impact on oligodendrocyte genesis and myelination following hypoxic-ischemic events, as well as the underlying mechanisms, remain poorly understood. Dexmedetomidine was administered 15 min post-HIBI. We assessed neurobehavioral deficits using various tests: surface righting, negative geotaxis, forelimb grip strength, cliff avoidance, sensory reflexes, novel object recognition, T-maze, and three-chamber social interaction. We also investigated the relationship between myelination and neurobehavioral outcomes. Measurements included oligodendrocyte precursor cell (OPC) proliferation and survival 24 h post-injury, early myelination, and oligodendrocyte differentiation by postnatal day 14. Furthermore, we evaluated microglial activation towards the M2 phenotype and the extent of neuroinflammation during the acute phase. Dexmedetomidine significantly ameliorated long-term neurological deficits caused by HIBI. Pearson linear regression analysis revealed a strong correlation between long-term neurological outcomes and myelin maturity. The treatment notably mitigated the long-term deterioration of myelin formation and maturation following HIBI. This protective effect was primarily due to enhanced OPC proliferation and survival post-HIBI during the acute phase and, to a lesser extent, to the modulation of microglial activity towards the M2 phenotype and a reduction in neuroinflammation. Dexmedetomidine offers substantial protection against long-term neurobehavioral disabilities induced by HIBI, primarily by revitalizing the impaired survival and maturation of oligodendrocyte progenitor cells and promoting myelination.

Linalool attenuates hypothalamus proteome disturbance facilitated by methamphetamine induced neurotoxicity in rats

BACKGROUND

One of the most powerful stimulants of the central nervous system is methamphetamine (METH). Linalool has a neuroprotective effect against ischemia injury by reducing oxidative stress and apoptosis. The present study investigated whether linalool can reverse the hypothalamus neurotoxicity and proteome disturbance in METH-treated rats.

BRIEF METHOD

A total of 36 male albino rats were split into two equal groups (normal and METH-treated). Three equal subgroups of normal rats were created; Control, Linalool (25 mg/kg), and Linalool (50 mg/kg); Normal rats were given daily oral doses of 1 ml of distilled water, 25 mg/kg linalool, and 50 mg/kg of linalool, respectively. METH groups were divided into 3 equal subgroups; METH-treated rats, Linalool (25 mg/kg)+METH-treated, and Linalool (50 mg/kg)+METH-treated subgroups; METH-treated rats received daily and oral doses of 1 ml distilled water, 25 mg/kg linalool, and 50 mg/kg of linalool, respectively.

RESULTS

According to the data obtained, METH caused a decrease of the sucrose preference test, travel distance test, and center square entries test, superoxide dismutase, glutathione peroxidase, catalase, NADPH oxidase, interleukin-10 but a rise in the center square duration test, tail suspension test, and forced swimming test, malondialdehyde, conjugated dienes, oxidative index, serotonin, dopamine, norepinephrine, γ-aminobutyric acid, tumour necrosis factor-α, interleukin-1β, interleukin-6 levels. When compared to the control group, rats treated with METH had lower sodium/potassium ATPase activity and missing of prothrombin, fibrinogen, and ceruloplasmin protein bands in the hypothalamus. In METH-treated rats, daily and oral co-administration with linalool brought all these parameters back to values that were close to control.

SIGNIFICANCE

According to obtained data, linalool could protect the hypothalamus against METH-induced neurotoxicity and proteome disturbance probably by modifying oxidative stress, neurotransmitters, inflammation, sodium/potassium-ATPase activity, proteome disturbance, and tissue histology in METH-treated rats where higher dose of linalool was more efficient than lower dose.

Maternal sevoflurane exposure induces neurotoxicity in offspring rats via the CB1R/CDK5/p-tau pathway

Sevoflurane is widely used for maternal anesthesia during pregnancy. Sevoflurane exposure of rats at mid-gestation can cause abnormal development of the central nervous system in their offspring. Sevoflurane is known to increase the expression of cannabinoid 1 receptor (CB1R) in the hippocampus. However, the effect of cannabinoid 1 receptor on fetal and offspring rats after maternal anesthesia is still unclear. At gestational day 14, pregnant rats were subjected to 2-h exposure to 3.5% sevoflurane or air. Rats underwent intraperitoneal injection with saline or rimonabant (1 mg/kg) 30 min prior to sevoflurane or air exposure. cannabinoid 1 receptor, cyclin-dependent kinase 5 (CDK5), p35, p25, tau, and p-tau expression in fetal brains was measured at 6, 12, and 24 h post-sevoflurane/air exposure. Neurobehavioral and Morris water maze tests were performed postnatal days 3-33. The expression of cannabinoid 1 receptor/cyclin-dependent kinase 5/p-tau and histopathological staining of brain tissues in offspring rats was observed. We found that a single exposure to sevoflurane upregulated the activity of cyclin-dependent kinase 5 and the level of p-tau via cannabinoid 1 receptor. This was accompanied by the diminished number of neurons and dendritic spines in hippocampal CA1 regions. Finally, these effects induced lower scores and platform crossing times in behavioral tests. The present study suggests that a single exposure to 3.5% sevoflurane of rats at mid-gestation impairs neurobehavioral abilities and cognitive memory in offspring. cannabinoid 1 receptor is a possible target for the amelioration of postnatal neurobehavioral ability and cognitive memory impairments induced by maternal anesthesia.

Daily, limited access to methamphetamine self-administration during pregnancy leads to increased methamphetamine sensitivity in adult offspring

Methamphetamine use by women, even throughout pregnancy, is common. But there is limited knowledge about the effects in prenatally methamphetamine-exposed children. This study investigated how prenatal methamphetamine exposure in rats, via maternal i.v. self-administration, affected the sensitivity of adult offspring to methamphetamine in comparison with controls. The offspring were generated from dams either self-administering methamphetamine daily under limited-access conditions prior to and throughout pregnancy, or their respective saline-yoked control dams. Spontaneous and methamphetamine-induced locomotor activity was assessed in male and female offspring of both exposure groups after a range of methamphetamine doses. In a separate group of offspring, acquisition of i.v. methamphetamine self-administration, responding under fixed and progressive ratio schedules of methamphetamine reinforcement, and reinstatement of extinguished drug-seeking behavior were assessed. Methamphetamine dose-dependently increased locomotor activity in both exposure groups. However, methamphetamine-exposed males showed significantly enhanced locomotor activity compared with controls at 1 mg/kg, and methamphetamine-exposed females showed significantly enhanced locomotor activity compared with controls at 3.2 mg/kg. Methamphetamine-exposed offspring of both sexes acquired methamphetamine self-administration faster and showed overall higher levels of methamphetamine-induced reinstatement compared with controls. Taken together, these results indicate that prenatal methamphetamine exposure to relatively low levels alters methamphetamine sensitivity in male and female adult offspring.

Methamphetamine: burden, mechanism and impact on pregnancy, the fetus, and newborn

While the opioid epidemic has garnered worldwide attention, increasing methamphetamine use has drawn less scrutiny. Methamphetamine is a highly addictive psychostimulant affecting people from all backgrounds and regions. It is a potent vasoconstrictor, is associated with arrhythmias and dilated cardiomyopathy. Cardiovascular disease-related mortality is a leading cause of death in methamphetamine users. Women of childbearing age increasingly use methamphetamine and continue during pregnancy. In the short term, prenatal methamphetamine use is associated with fetal growth restriction and low birth weight in the newborn. Animal studies show reduction in uterine and umbilical blood flow following maternal methamphetamine administration. Based on currently available evidence, prenatal methamphetamine exposure has transient effects on gross motor development, no effect on language and cognition, and modest effects on behavior and executive functioning with poor inhibitory control, which may be attributable to early adversity. Further research is needed to evaluate long-term effects of prenatal methamphetamine exposure.

Reduced fractional anisotropy in projection, association, and commissural fiber networks in neonates with prenatal methamphetamine exposure

Prenatal exposure to methamphetamine is associated with neurostructural changes, including alterations in white matter microstructure. This study investigated the effects of methamphetamine exposure on microstructure of global white matter networks in neonates. Pregnant women were interviewed beginning in mid-pregnancy regarding their methamphetamine use. Diffusion weighted imaging sets were acquired for 23 non-sedated neonates. White matter bundles associated with pairs of target regions within five networks (commissural fibers, left and right projection fibers, and left and right association fibers) were estimated using probabilistic tractography, and fractional anisotropy (FA) and diffusion measures determined within each connection. Multiple regression analyses showed that increasing methamphetamine exposure was significantly associated with reduced FA in all five networks, after control for potential confounders. Increased exposure was associated with lower axial diffusivity in the right association fiber network and with increased radial diffusivity in the right projection and left and right association fiber networks. Within the projection and association networks a subset of individual connections showed a negative correlation between FA and methamphetamine exposure. These findings are consistent with previous reports in older children and demonstrate that microstructural changes associated with methamphetamine exposure are already detectable in neonates.

Teratogen update: Amphetamines

Amphetamines are synthetic noncatecholamine sympathomimetic amines that act as psychostimulants. They have been prescribed for the treatment of attention-deficit/hyperactivity disorder (ADHD), narcolepsy, and additional health conditions. Amphetamines are also drugs of abuse. Some experimental animal studies suggested adverse developmental effects of amphetamines, including structural malformations. These effects were most often observed in experimental animals at higher dose levels than those used for treatment or abuse and at dose levels that produce maternal toxicity. Controlled studies of amphetamine use for the treatment of ADHD and other indications did not suggest that amphetamines are likely to cause structural malformations, although there are three studies associating medication for ADHD or methamphetamine abuse with gastroschisis. We did not locate studies on the neurobehavioral effects of prenatal exposures to therapeutic amphetamine use. Amphetamine abuse was associated with offspring neurobehavioral abnormalities, but lack of adequate adjustment for confounding interferes with interpretation of the associations. Adverse effects of methamphetamine abuse during pregnancy may be due to factors associated with drug abuse rather than methamphetamine itself. The adverse effects observed in methamphetamine abuse studies may not be extrapolatable to amphetamine medication use.

Toxicity assessment due to prenatal and lactational exposure to lead, cadmium and mercury mixtures

The heavy metals lead (Pb), cadmium (Cd) and mercury (Hg) are common environmental pollutants that can be detected simultaneously in blood, serum, and urine samples from the general human population. However, there is limited information regarding toxicity of low-level exposure to Pb, Cd, and Hg mixtures. Our previous research showed the interaction of these three elements at low concentrations in vitro. In this study, we further evaluate early effects of low dose exposure to Pb, Cd, and Hg mixtures on the brain, heart, liver, kidney, and testicle in rats. Pregnant rats were exposed to various concentrations of heavy metal mixtures (MM) in drinking water, during gestation and lactation, and the impacts on offspring were measured at postnatal day 23. Our results showed that the concentrations of Pb, Cd, and Hg in the blood of rat pups were similar to those in the blood of the general human population. Additionally, the MM concentrations in their blood and brain significantly increased in a dose-dependent manner. MM exposure caused histopathological changes in the brain, liver, kidney and testicle. Statistically significant increases in liver CYP450 and PON1, kidney KIM1, and decrease in testicle SDH were observed. In the brain, significant increases were detected in oxidative stress, intracellular free calcium, and cell apoptosis. Further neurobehavioral testing revealed that MM exposure caused dose-dependent impairments in learning and memory as well as sensory perception. MM exposure also disrupted synapse remodeling, which may be associated with pathways involved in dendritic spine growth, maintenance, and elimination. These results suggested that exposure to Pb, Cd, and Hg mixtures, at human environmental exposure related levels, caused damage to multiple organs as well as impairments in neurobehavioral functions of rats. Our findings emphasize the need to control and regulate potential sources of heavy metal contamination.

Maternal methamphetamine exposure causes cognitive impairment and alteration of neurodevelopment-related genes in adult offspring mice

Prenatal drug exposure altered cognitive function in individuals, and may also impact their offspring's susceptibility to cognitive impairment. The high incidence of methamphetamine (METH) abuse among adolescents and women of childbearing age elevates the importance to determine the influence of maternal METH exposure on cognitive functions in the descendants. We hypothesized that maternal METH exposure affects cognitive behavior in offspring mice by disrupting gene expression associated with neural development. Here, female C57BL/6 mice were exposed to intermittent escalating doses of METH or saline from adolescence to adulthood, and then continued through pregnancy. Interestingly, male but not female offspring exhibited impaired short-term recognition memory and long-term spatial memory retention in novel object recognition and Morris water maze test respectively. Additionally, maternal METH exposure altered neurodevelopmental genes in both male and female offspring, and 12 differentially expressed genes between male and female were observed in the HPC and NAc regions. These differentially expressed genes are involved in neurogenesis, axon guidance, neuron migration and synapse of neural development circuits. Our observations suggest that maternal METH exposure induced differential expression patterns of neurodevelopment-related genes in the HPC and NAc of male and female mice, which may underlie the different cognitive behavior phenotypes in both genders.

Prenatal methamphetamine exposure is associated with corticostriatal white matter changes in neonates

Diffusion tensor imaging (DTI) studies have shown that prenatal exposure to methamphetamine is associated with alterations in white matter microstructure, but to date no tractography studies have been performed in neonates. The striato-thalamo-orbitofrontal circuit and its associated limbic-striatal areas, the primary circuit responsible for reinforcement, has been postulated to be dysfunctional in drug addiction. This study investigated potential white matter changes in the striatal-orbitofrontal circuit in neonates with prenatal methamphetamine exposure. Mothers were recruited antenatally and interviewed regarding methamphetamine use during pregnancy, and DTI sequences were acquired in the first postnatal month. Target regions of interest were manually delineated, white matter bundles connecting pairs of targets were determined using probabilistic tractography in AFNI-FATCAT, and fractional anisotropy (FA) and diffusion measures were determined in white matter connections. Regression analysis showed that increasing methamphetamine exposure was associated with reduced FA in several connections between the striatum and midbrain, orbitofrontal cortex, and associated limbic structures, following adjustment for potential confounding variables. Our results are consistent with previous findings in older children and extend them to show that these changes are already evident in neonates. The observed alterations are likely to play a role in the deficits in attention and inhibitory control frequently seen in children with prenatal methamphetamine exposure.

Prenatal exposure to modafinil alters behavioural response to methamphetamine in adult male mice

Modafinil is a psychostimulant drug prescribed for treatment of narcolepsy. However, it is used as a "smart drug" especially by young adults to increase wakefulness, concentration and mental performance. Therefore, it can also be used by women with childbearing potential and its developmental effects can become a concern. The aim of this study was to assess behavioural and immune effects of prenatal modafinil exposure in mice and to evaluate the reaction to methamphetamine exposure on these animals in adult age. Pregnant female mice were given either saline or modafinil (50 mg/kg orally) from gestation day (GD) 3 to GD 10 and then a challenge dose on GD 17. The male offspring were treated analogously at the age of 10 weeks with methamphetamine (2.5 mg/kg orally). Changes in the spontaneous locomotor/exploratory behaviour and anxiogenic profile in the open field test were assessed in naïve animals, after an acute and 8th modafinil dose and the challenge dose following a 7-day wash-out period. One month after completion of the behavioural study, the leukocyte phagocytosis was examined by zymosan induced and luminol-aided chemiluminiscence assay in vitro. The modafinil prenatally exposed mice showed basal hypolocomotion, increased anxiety, lower locomotor effect of acute methamphetamine and increased vulnerability to behavioural sensitization. The leukocyte activity did not show significant differences. Prenatal modafinil exposure alters basal behavioural profile, decreases acute effect of methamphetamine and enhances vulnerability to development of behavioural sensitization at adulthood. This may lead to higher vulnerability to development of addiction.

Detrimental effects of self-administered methamphetamine during pregnancy on offspring development in the rat

BACKGROUND

Methamphetamine (METH) abuse by pregnant women is a commonly observed phenomenon. While the harmful effects of METH are well described for adults, there is only limited knowledge of the effects of METH use during pregnancy on the developing child. In the present study, we investigated how intraveneous (iv) METH self-administration throughout pregnancy affected rat dams and their offspring through weaning, compared to controls.

METHODS

Female rats (n=16) were trained to self-administer METH iv; every drug infusion by a dam also resulted in a saline injection to a yoked control (n=16). When stable levels of self-administration were reached, all females were mated. Daily, 2-h self-administration sessions continued until litters were born. General health and weight was assessed daily in dams and pups. In addition, pups were evaluated for achievement of age-appropriate developmental milestones (i.e., righting reflex, negative geotaxis, pinna detachment, fur appearance, incisor eruption and eye opening).

RESULTS

Dams self-administered 2-3mg/kg/day METH throughout gestation without consequence to dam health or weight gain during pregnancy. All females produced viable litters, and litter size and composition did not differ between saline and METH dams. Similarly, maternal pup-directed behavior was not affected by prior METH self-administration. However, despite a lack of weight difference in pups, METH-exposed pups were significantly delayed in reaching all assessed developmental milestones compared to controls.

CONCLUSION

These results indicate that in utero exposure to moderate METH doses can profoundly and adversely affect offspring development, suggesting that even recreational METH use during pregnancy has potential for harm.

Learning and memory effects of neonatal methamphetamine exposure in rats: Role of reactive oxygen species and age at assessment

In utero methamphetamine (MA) exposure leads to a range of adverse effects, such as decreased attention, reduced working-memory capability, behavioral dysregulation, and spatial memory impairments in exposed children. In the current experiment, preweaning Sprague-Dawley rats-as a model of third trimester human exposure-were administered the spin trapping agent, N-tert-butyl-α-phenylnitrone (PBN), daily prior to MA. Rats were given 0 (SAL) or 40 mg/kg PBN prior to each MA dose (10 mg/kg, 4× per day) from postnatal day (P) 6-15. Littermates underwent Cincinnati water maze, Morris water maze, and radial water maze assessment beginning on P30 (males) or P60 (females). Males were also tested for conditioned contextual and cued freezing, while females were trained in passive avoidance. Findings show that, regardless of age/sex, neonatal MA induced deficits in all tests, except passive avoidance. PBN did not ameliorate these effects, but had a few minor effects. Taken together, MA induced learning deficits emerge early and persist, but the mechanism remains unknown.

Does effect from developmental methamphetamine exposure on spatial learning and memory depend on stage of neuroontogeny?

Psychostimulants, including methamphetamine (MA), have neurotoxic effect, especially, if they are targeting CNS during its critical periods of development. The present study was aimed to examine cognitive changes after prenatal and neonatal MA treatment in combination with chronic MA exposure in adulthood of male rats. Eight groups of male rats were tested in adulthood: males whose mothers were exposed to MA (5 mg/kg) or saline (SA, 1 ml/kg) during the first half of gestation period (GD 1-11), the second half of gestation period (GD 12-22) and neonatal period (PD 1-11). In addition, we compared indirect neonatal application via the breast milk with the group of rat pups that received MA or SA directly by injection (PD 1-11). Males were tested in adulthood for cognitive changes in the Morris Water Maze (MWM). MWM experiment lasted for 12 days: Learning (Day 1-6), Probe test (Day 8) and Retrieval Memory test (Day 12). Each day of the MWM animals were injected with MA (1 mg/kg) or SA (1 ml/kg). Prenatal MA exposure did not induce changes in learning abilities of male rats, but neonatal exposure to MA leads to an increase search errors and latencies to find the hidden platform. Prenatal and also neonatal MA exposure impaired cognitive ability to remember the position of the platform in Retrieval Memory test in adulthood. Animals exposed to the prenatal treatment within the second half of gestation (ED 12-22) swam longer, slower and spent more time to find the hidden platform in Retrieval Memory test than animals exposed throughout other periods. The present study demonstrated that stage of development is crucial for determination the cognitive deficits induced by prenatal or neonatal MA exposure.

Substance Use in the Perinatal Period

Perinatal substance use remains a major public health problem and is associated with a number of deleterious maternal and fetal effects. Polysubstance use in pregnancy is common and can potentiate adverse maternal and fetal outcomes. Tobacco is the most commonly used substance in pregnancy, followed by alcohol and illicit substances. The treatments for perinatal substance use are limited and consist mostly of behavioral and psychosocial interventions. Of these, contingency management has shown the most efficacy. More recently, novel interventions such as progesterone for postpartum cocaine use have shown promise. The purpose of this review is to examine the recent literature on the use of tobacco, alcohol, cannabis, stimulants, and opioids in the perinatal period, their effects on maternal and fetal health, and current treatments.

Developmental and behavioral consequences of prenatal methamphetamine exposure: A review of the Infant Development, Environment, and Lifestyle (IDEAL) study

This study reviews the findings from the Infant Development, Environment, and Lifestyle (IDEAL) study, a multisite, longitudinal, prospective study designed to determine maternal outcome and child growth and developmental findings following prenatal methamphetamine exposure from birth up to age 7.5 years. These findings are presented in the context of the home environment and caregiver characteristics to determine how the drug and the environment interact to affect the outcome of these children. No neonatal abstinence syndrome requiring pharmacologic intervention was observed but heavy drug exposure was associated with increased stress responses in the neonatal period. Poorer inhibitory control was also observed in heavy methamphetamine exposed children placing them at high risk for impaired executive function. Independent of methamphetamine exposure, children with more responsive home environments to developmental and emotional needs demonstrated lower risks for internalizing and externalizing behavior.

Neurobehavioral Effects from Developmental Methamphetamine Exposure

Intrauterine methamphetamine exposure adversely affects the neurofunctional profile of exposed children, leading to a variety of higher order cognitive deficits, such as decreased attention, reduced working-memory capability, behavioral dysregulation, and spatial memory impairments (Kiblawi et al. in J Dev Behav Pediatr 34:31-37, 2013; Piper et al. in Pharmacol Biochem Behav 98:432-439 2011; Roussotte et al. in Neuroimage 54:3067-3075, 2011; Twomey et al. in Am J Orthopsychiatry 83:64-72, 2013). In animal models of developmental methamphetamine, both neuroanatomical and behavioral outcomes critically depend on the timing of methamphetamine administration. Methamphetamine exposure during the third trimester human equivalent period of brain development results in well-defined and persistent wayfinding and spatial navigation deficits in rodents (Vorhees et al. in Neurotoxicol Teratol 27:117-134, 2005, Vorhees et al. in Int J Dev Neurosci 26:599-610, 2008; Vorhees et al. in Int J Dev Neurosci 27:289-298, 2009; Williams et al. in Psychopharmacology (Berl) 168:329-338, 2003b), whereas drug delivery during the first and second trimester equivalents produces no such effect (Acuff-Smith et al. in Neurotoxicol Teratol 18:199-215, 1996; Schutova et al. in Physiol Res 58:741-750, 2009a; Slamberova et al. in Naunyn Schmiedebergs Arch Pharmacol 380:109-114, 2009, Slamberova et al. in Physiol Res 63:S547-S558, 2014b). In this review, we examine the impact of developmental methamphetamine on emerging neural circuitry, neurotransmission, receptor changes, and behavioral outcomes in animal models. The review is organized by type of effects and timing of drug exposure (prenatal only, pre- and neonatal, and neonatal only). The findings elucidate functional patterns of interconnected brain structures (e.g., frontal cortex and striatum) and neurotransmitters (e.g., dopamine and serotonin) involved in methamphetamine-induced developmental neurotoxicity.