Effect of methamphetamine exposure during prenatal and preweaning periods lasts for generations in rats

Does paternal methamphetamine exposure affect the behavior of rat offspring during development and in adulthood?

Methamphetamine (MA) is one of the most abused psychostimulants in the Czech Republic and worldwide. Previous studies have demonstrated the adverse effects of maternal drug abuse. However, the father's contribution as a parent and donor of the half genetic information is unclear. The present study aimed to examine the effect of paternal MA exposure on behavioral development and locomotor activity in rat offspring. MA was administrated subcutaneously for 30 days at a dose of 5 mg/kg to adult male rats. The impact of paternal MA exposure on rat pups was investigated using behavioral tests during development and locomotor activity tests in adulthood. Prior to testing, adult offspring were exposed to an acute challenge dose of MA (1 mg/kg) to examine the possible sensitizing effect of the paternal treatment. Our results found no significant differences in behavioral development or locomotor activity in adulthood of offspring linked to paternal MA application. These results differ from the effects induced by maternal MA application. Further, our results demonstrated a significant increase in locomotor activity on the Laboras test after acute MA application. When comparing sex differences, females showed more activity than males in adulthood, whereas males were more active during development.

Methamphetamine-induced changes in myocardial gene transcription are sex-dependent

BACKGROUND

Prior work demonstrated that female rats (but not their male littermates) exposed to methamphetamine become hypersensitive to myocardial ischemic injury. Importantly, this sex-dependent effect persists following 30 days of subsequent abstinence from the drug, suggesting that it may be mediated by long term changes in gene expression that are not rapidly reversed following discontinuation of methamphetamine use. The goal of the present study was to determine whether methamphetamine induces sex-dependent changes in myocardial gene expression and whether these changes persist following subsequent abstinence from methamphetamine.

RESULTS

Methamphetamine induced changes in the myocardial transcriptome were significantly greater in female hearts than male hearts both in terms of the number of genes affected and the magnitude of the changes. The largest changes in female hearts involved genes that regulate the circadian clock (Dbp, Per3, Per2, BMal1, and Npas2) which are known to impact myocardial ischemic injury. These genes were unaffected by methamphetamine in male hearts. All changes in gene expression identified at day 11 returned to baseline by day 30.

CONCLUSIONS

These data demonstrate that female rats are more sensitive than males to methamphetamine-induced changes in the myocardial transcriptome and that methamphetamine does not induce changes in myocardial transcription that persist long term after exposure to the drug has been discontinued.

Influence of Prenatal Methamphetamine Abuse on the Brain

Methamphetamine (MA), a psychostimulant, has become a serious problem in recent years. It is one of the most widely abused psychostimulants in the world. In the Czech Republic, ecstasy is the most commonly used non-cannabis drug, followed by hallucinogenic fungi, LSD, MA, cocaine, and finally heroin. The prevalence of the usage of all addictive substances is highest in the age category of 15-34. Approximately 17.2% of registered drug addicts, both male and female, in the Czech Republic use MA as their first-choice drug. This group consists mostly of women who are unemployed and addicted to MA (85%). Almost half of the addicted women switched to MA from other drugs in the course of pregnancy. Psychostimulants such as amphetamine and its synthetic derivate MA induce feelings of calm and happiness by suppressing anxiety and depression. When MA is abused for longer periods, it mimics symptoms of mania and can lead to the development of psychosis. MA is often abused for its anorectic effect, its simple preparation, and compared to heroin and cocaine, its low price. There are significant differences in the susceptibility of users to the stimulant, with reactions to MA fluctuating from person to person. Molecular mechanisms related to the variable response among users might represent an explanation for increased addiction-associated bipolar disorder and psychosis. Currently, there is limited information regarding genetic mechanisms linked to these disorders and the transmission of drug addiction. As such, animal models of drug addiction represent significant sources of information and assets in the research of these issues. The aim of this review is to summarize the mechanism of action of methamphetamine and its effect on pregnant addicted women and their children, including a detailed description of the anatomical structures involved.

Review of long-term consequences of maternal methamphetamine exposure

Methamphetamine is one of the most abused hard drugs in the Czech Republic. Its popularity is high not only in Eastern Bloc of Europe but is growing in other countries around the world, including the United States. In addition, methamphetamine abuse increases in drug addicts during pregnancy. Although research into the long-term effects of prenatal methamphetamine exposure has been ongoing for many years, the exact mechanism of action and factors that may influence the effect of this drug are still not fully understood. There have been many studies that investigated the effects of addictive substances on the behavior and cognitive function of individuals during adolescence. Some studies have shown prenatal or perinatal influences, e.g. drugs, stress, hypoxia, and malnutrition, can affect drug sensitivity or drug-seeking behavior in adulthood. However, when these factors are most impactful, i.e. prenatal vs. perinatal, and which stages of the prenatal and perinatal periods are the most sensitive to these factors is not yet clear. Our laboratory specializes in research on the effects of drugs (especially methamphetamine) on rat mothers and their offspring during postnatal development, adolescence, and adulthood. This review summarizes our past results on the long-term effects of methamphetamine on the mother and her offspring, its mechanism of action, the role of maternal care, the possible emergence of long-term sensitization, and the critical neurodevelopmental periods for methamphetamine exposure.

Methamphetamine exposure during the first, but not the second half of prenatal development, affects social play behavior

Methamphetamine (MA), as a psychostimulant drug that crosses the placental barrier, may disrupt the development of social play. The present study aims to examine the effect of prenatal MA (5 mg/kg) exposure during the first (gestational day (GD) 1-11) or second (GD 12-22) halves of prenatal development of rats on social play behavior. To investigate an acute effect of MA on social play in adulthood, juvenile rats were exposed to a dose of 1 mg/kg MA or saline on the test day and tested for social play for 15 min. Prenatal exposure to MA during GD 1-11 increased social play behavior during 5-10 min interval of the test in males but not females. Prenatal MA during GD 12-22 did not influence social play in males nor females. However, social play occurred to a greater extent in GD 12-22 groups compared with GD 1-11. Acute exposure to MA eliminated playful behavior in all groups and decreased social exploration in GD 1-11. Our results suggest that manipulation of prenatal development during the first half of the gestational period has a greater impact on social play behavior than during the second half.

Prenatal Exposure to Methamphetamine: Up-Regulation of Brain Receptor Genes

Methamphetamine (METH) is a widespread illicit drug. If it is taken by pregnant women, it passes through the placenta and just as it affects the mother, it can impair the development of the offspring. The aim of our study was to identify candidates to investigate for changes in the gene expression in the specific regions of the brain associated with addiction to METH in rats. We examined the various areas of the central nervous system (striatum, hippocampus, prefrontal cortex) for signs of impairment in postnatal day 80 in experimental rats, whose mothers had been administered METH (5 mg/kg/day) during the entire gestation period. Changes in the gene expression at the mRNA level were determined by two techniques, microarray and real-time PCR. Results of two microarray trials were evaluated by LIMMA analysis. The first microarray trial detected either up-regulated or down-regulated expression of 2189 genes in the striatum; the second microarray trial detected either up-regulated or down-regulated expression of 1344 genes in the hippocampus of prenatally METH-exposed rats. We examined the expression of 10 genes using the real-time PCR technique. Differences in the gene expression were counted by the Mann–Whitney U-test. Significant changes were observed in the cocaine- and amphetamine-regulated transcript prepropeptide, tachykinin receptor 3, dopamine receptor D3 gene expression in the striatum regions, in the glucocorticoid nuclear receptor Nr3c1 gene expression in the prefrontal cortex and in the carboxylesterase 2 gene expression in the hippocampus of prenatally METH-exposed rats. The microarray technique also detected up-regulated expression of trace amine-associated receptor 7 h gene in the hippocampus of prenatally METH-exposed rats. We have identified susceptible genes; candidates for the study of an impairment related to methamphetamine addiction in the specific regions of the brain.

DARK Classics in Chemical Neuroscience: Methamphetamine

Methamphetamine has the second highest prevalence of drug abuse after cannabis, with estimates of 35 million users worldwide. The ( S)-(+)-enantiomer is the illicit drug, active neurostimulant, and eutomer, while the ( R)-(-)-enantiomer is contained in over the counter decongestants. While designated a schedule II drug in 1970, ( S)-(+)-methamphetamine is available by prescription for the treatment of attention-deficit disorder and obesity. The illicit use of ( S)-(+)-methamphetamine results in the sudden "rush" of stimulation to the motivation, movement, pleasure, and reward centers in the brain, caused by rapid release of dopamine. In this review, we will provide an overview of the synthesis, pharmacology, adverse effects, and drug metabolism of this widely abused psychostimulant that distinguish it as a DARK classic in Chemical Neuroscience.

Does Prenatal Methamphetamine Exposure Induce Sensitization to Drugs in Adulthood?

Behavioral sensitization is defined as augmented psychomotor activity, which can be observed after drug re-administration following withdrawal of repeated drug exposure. It has been shown that abuse of one drug can lead to increased sensitivity to certain other drugs. This effect of developed general drug sensitivity is called cross-sensitization and has been reported between drugs with similar as well as different mechanisms of action. There is growing evidence that exposure to drugs in utero not only causes birth defects and delays in infant development, but also impairs the neural reward pathways, in the brains of developing offspring, in such a way that it can increase the tendency for drug addiction later in life. This review summarizes the results of preclinical studies that focused on testing behavioral cross-sensitization, after prenatal methamphetamine exposure, to drugs administered in adulthood, with both similar and different mechanisms of action. Traditionally, behavioral sensitization has been examined using the Open field or the Laboras Test to record locomotor activity, and the Conditioned Place Preference and Self-administration test to examine drug-seeking behavior. However, it seems that prenatal drug exposure can sensitize animals not only to the locomotor-stimulating and conditioning effects of drugs, but may also be responsible for modified responses to various drug effects.

Repeated exposure to methamphetamine induces sex-dependent hypersensitivity to ischemic injury in the adult rat heart

Background

We previously reported that adult female, but not male rats that were prenatally exposed to methamphetamine exhibit myocardial hypersensitivity to ischemic injury. However, it is unknown whether hypersensitivity to ischemic injury develops when rats are exposed to methamphetamine during adulthood. The goal of this study was to determine whether methamphetamine exposure during adulthood sensitizes the heart to ischemic injury.

Methods

Adult male and female rats received daily injections of methamphetamine (5 mg/kg) or saline for 10 days. Their hearts were isolated on day 11 and subjected to a 20 min ischemic insult on a Langendorff isolated heart apparatus. Cardiac contractile function was measured by an intraventricular balloon, and infarct size was measured by triphenyltetrazolium chloride staining.

Results

Hearts from methamphetamine-treated females exhibited significantly larger infarcts and suppressed postischemic recovery of contractile function compared to hearts from saline-treated females. In contrast, methamphetamine had no effect on infarct size or contractile recovery in male hearts. Subsequent experiments demonstrated that hypersensitivity to ischemic injury persisted in female hearts following a 1 month period of abstinence from methamphetamine. Myocardial protein kinase C-ε expression, Akt phosphorylation, and ERK phosphorylation were unaffected by adult exposure to methamphetamine.

Conclusions

Exposure of adult rats to methamphetamine sex-dependently increases the extent of myocardial injury following an ischemic insult. These data suggest that women who have a heart attack might be at risk of more extensive myocardial injury if they have a recent history of methamphetamine abuse.

The influence of methamphetamine on maternal behavior and development of the pups during the neonatal period

Since it enters breast milk, methamphetamine (MA) abuse during lactation can not only affect the quality of maternal behavior but also postnatal development of pups. The aim of the present study was to examine the effect of injected MA (5mg/kg) on maternal behavior of rats and the differences in postnatal development, during postnatal days (PD) 1-11, of pups when the pups were directly exposed (i.e., injected) to MA or received MA indirectly via breast milk. Maternal behavior was examined using observation test (PD 1-22) and pup retrieval test (PD 1-12). The following developmental tests were also used: surface righting reflex (PD 1-12), negative geotaxis (PD 9), mid-air righting reflex (PD 17), and the rotarod and beam-balance test (PD 23). The weight of the pups was recorded during the entire testing period and the day of eye opening was also recorded. MA-treated mothers groomed their pups less and returned the pups to the nest slower than control dams. The weight gain of pups indirectly exposed to MA was significantly slower. In addition, pups indirectly exposed to MA were slower on the surface righting reflex (on PD 1 and PD 2) and the negative geotaxis test. In females, indirect exposure to MA led to earlier eye opening compared to controls. At the end of lactation, males who received MA indirectly via breast milk performed worse on the balance beam test compared to males who received MA directly. However, direct exposure to MA improved performance on rotarod relative to controls. Our results suggest that indirect MA exposure, via breast milk, has a greater impact than direct MA exposure.

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.

Differences in Maternal Behavior and Development of Their Pups Depend on the Time of Methamphetamine Exposure During Gestation Period

The present study examined the hypothesis that the extension of noxious effect of methamphetamine (MA) on maternal behavior and postnatal development on the pups may differ in dependence with time of application. Female rats were injected with MA (5 mg/kg) or saline during first (embryonic day (ED) 1-11) or second (ED 12-22) half of gestation. Our results demonstrated that MA exposure on ED 12-22 led to decreased birth weight and weight gained during lactation period relative to rats treated on ED 1-11. Both sexes treated prenatally with MA on ED 1-11 opened eyes earlier compared to animals treated on ED 12-22. As a matter of sensorimotor development application of MA on ED 1-11 impaired the righting reflex, while MA exposure on ED 12-22 impaired the performance of beam balance test in male rats. There were no differences in maternal behavior. Therefore, it seems that MA exposure in the first half of the gestation impaired the early sensorimotor development that is under control of the brain stem, while the MA exposure in the second half of gestation affected the beam balance performance that is dependent on the function of the cerebellum.

Drugs in pregnancy: the effects on mother and her progeny

Drug abuse during pregnancy is a growing problem in all developed countries all over the world. The drugs easily cross the placental barrier into the fetal body and are present also in the maternal milk. Therefore, it may affect the development of the child pre- as well as postnatally. The effects of prenatal drug exposure are long-lasting and persist until adulthood. The present review summarizes the clinical and experimental evidence showing how opioids and psychostimulants can affect maternal behavior of drug-abusing mother and the development of their offspring.

Motor and cognitive outcomes through three years of age in children exposed to prenatal methamphetamine

BACKGROUND

Methamphetamine (MA) use among pregnant women is an increasing problem in the United States. The impact of prenatal MA exposure on development in childhood is unknown.

OBJECTIVE

To examine the effects of prenatal MA exposure on motor and cognitive development in children at 1, 2, and 3 years of age.

DESIGN/METHODS

IDEAL enrolled 412 mother-infant pairs at four sites (Tulsa OK, Des Moines IA, Los Angeles CA, and Honolulu HI). MA subjects (n=204) were identified by self report or GC/MS confirmation of amphetamine and metabolites in infant meconium. Comparison subjects (n=208) were matched (race, birth weight, maternal education, and type of insurance), denied amphetamine use, and had a negative meconium screen. Both groups included prenatal alcohol, tobacco and marijuana use, but excluded use of opiates, lysergic acid diethylamide, phencyclidine or cocaine only. The Peabody Developmental Motor Scales (PDMS-2) were administered to the infants at the 1 and 3 year visits. This analysis includes a subsample (n=350) of the IDEAL study with completed 1 and/or 3 year visits (n=330 and 281, respectively). At each annual visit we also conducted the Bayley Scales of Infant Development (BSID-II) as a general evaluation of mental and motor development. The BSID-II analysis includes a subsample (n=356) of the IDEAL study with completed 1, 2, and/or 3 year visits (n=331, 288, and 278 respectively). GLM analysis conducted on the PDMS-2 and BSID-II examined the effects of MA exposure and heavy MA exposure (≥3 days of use/week), with and without covariates. Longitudinal analyses were used to examine the effects of MA exposure on changes in motor and cognitive performance over time.

RESULTS

Heavy MA exposure was associated with significantly lower grasping scores than some and no use at 1 year (P=0.018). In longitudinal analysis, lower grasping scores associated with any MA exposure and heavy exposure persisted to 3 years. There were no effects of MA exposure, including heavy exposure, on the Bayley Mental Development Index (MDI) or Psychomotor Development Index (PDI) at any or across age.

CONCLUSIONS

There were no differences in cognition as assessed by the BSID-II between the groups. There was a subtle MA exposure effect on fine motor performance at 1 year with the poorest performance observed in the most heavily exposed children. By 3 years, no differences in fine motor performance were observed. These findings suggest MA exposure has modest motor effects at 1 year that are mostly resolved by 3 years.

Perinatal effect of methamphetamine on nociception in adult Wistar rats

Methamphetamine is a psychostimulant drug which causes the release of monoamine neurotransmitters. Although drugs of abuse are known to have analgesic effects, there is a lack of evidence regarding the effect of prenatal exposure to methamphetamine on nociception in adulthood. Adult Wistar rats whose mothers had received daily exposure to methamphetamine (5 mg/kg; s.c.) or saline, during gestation or gestation and lactation periods, were examined for: (1) gender differences in nociception; (2) an association between nociception and gross-motor behavior in the plantar test; (3) effects of cross-fostering on nociception; and (4) analgesic effects of an acute injection of methamphetamine (1 mg/kg s.c.). Nociception was tested using the plantar test on postnatal days 85-90. Prenatal methamphetamine increased sensitivity to pain on forelimbs (p<0.0001) and hind limbs (p<0.05) in females only. Prenatal methamphetamine treated male rats fostered by adoptive injection stressed mothers had higher sensitivity to pain than prenatally injection stressed rats fostered by methamphetamine treated mothers (p<0.05). Acute methamphetamine induced analgesia faster in prenatally methamphetamine exposed rats than in controls. In all groups, analgesia increased in the cranio-caudal direction (p<0.0001). From our behavioral data it can be concluded that exposure to methamphetamine during the prenatal period completely dissociates the relationship between nociception and intensity of overall behavior observed in intact animals in adulthood. Thus, our results indicate that perinatal exposure to psychostimulants may have long-term impact on several functions related to dopaminergic system.

Prenatal exposure to drugs: effects on brain development and implications for policy and education

The effects of prenatal exposure to drugs on brain development are complex and are modulated by the timing, dose and route of drug exposure. It is difficult to assess these effects in clinical cohorts as these are beset with problems such as multiple exposures and difficulties in documenting use patterns. This can lead to misinterpretation of research findings by the general public, the media and policy makers, who may mistakenly assume that the legal status of a drug correlates with its biological impact on fetal brain development and long-term clinical outcomes. It is important to close the gap between what science tells us about the impact of prenatal drug exposure on the fetus and the mother and what we do programmatically with regard to at-risk populations.

Cross-fostering effect on postnatal development of rat pups exposed to methamphetamine during gestation and preweaning periods

There are studies showing that drug abuse during pregnancy may have a long-term effect on progeny of drug-abusing mothers. Our previous work demonstrated that prenatal and/or postnatal methamphetamine injections impair maternal behavior. The purpose of the present study was to assess the effect of prenatal methamphetamine or stress exposure and postnatal breeding on postnatal development of rat pups. Female rats were injected with methamphetamine (5 mg/kg daily) or physiological saline prior, during and after gestation. Absolute controls did not receive any injections. On postnatal day 1, pups were cross-fostered so that each mother received some of her own and some of the pups from the mothers with the other two treatments. Pups were weighted daily for the entire lactation period. Postural motor reaction development was examined daily by righting reflex between postnatal day 1 and 12. On postnatal day 15 homing test examining pups' nest-seeking behavior was performed. On postnatal day 23 rotarod and bar-holding tests were used to investigate sensorimotor coordination of pups. We demonstrated that prenatal methamphetamine exposure impairs performance of sensorimotor tests (righting reflex on surface and rotarod test). Moreover, the effect of methamphetamine as well as the effect of prenatal stress induced by saline injections was affected by postnatal breeding conditions in sensorimotor tests as well as in the test of homing. Our results support the hypothesis that the variation in rat maternal care could serve as a mechanism for a nongenomic behavioral mode of transmission of traits.