Perinatal bupivacaine and infant behavior in rhesus monkeys

Epidural analgesia in labour: separating fact from fiction for autism and neurodevelopment

Having epidural analgesia in labour has been associated with a later diagnosis of autism spectrum disorder in the offspring, resulting in concerns about childhood wellbeing. Neurodevelopmental changes are inconsistently reported in the literature, creating challenges in the interpretation of these findings. Here we explore the limitations of the current evidence base, and why findings differ between studies, concluding that the current body of evidence does not support a causal association between use of epidural analgesia in labour and autism spectrum disorder.

Behavioural and neuropsychological outcomes in children exposed in utero to maternal labour epidural analgesia

BACKGROUND

Recent studies report conflicting results regarding the relationship between labour epidural analgesia (LEA) in mothers and neurodevelopmental disorders in their offspring. We evaluated behavioural and neuropsychological test scores in children of mothers who used LEA.

METHODS

Children enrolled in the Raine Study from Western Australia and delivered vaginally from a singleton pregnancy between 1989 and 1992 were evaluated. Children exposed to LEA were compared with unexposed children. The primary outcome was the parent-reported Child Behaviour Checklist (CBCL) reporting total, internalising, and externalising behavioural problem scores at age 10 yr. Score differences, an increased risk of clinical deficit, and a dose-response based on the duration of LEA exposure were assessed. Secondary outcomes included language, motor function, cognition, and autistic traits.

RESULTS

Of 2180 children, 850 (39.0%) were exposed to LEA. After adjustment for covariates, exposed children had minimally increased CBCL total scores (+1.41 points; 95% confidence interval [CI] 0.09 to 2.73; P=0.037), but not internalising (+1.13 points; 95% CI -0.08 to 2.34; P=0.066) or externalising (+1.08 points; 95% CI -0.08 to 2.24; P=0.068) subscale subscores. Increased risk of clinical deficit was not observed for any CBCL score. For secondary outcomes, score differences were inconsistently observed in motor function and cognition. Increased exposure duration was not associated with worse scores in any outcomes.

CONCLUSIONS

Although LEA exposure was associated with slightly higher total behavioural scores, there was no difference in subscores, increased risk of clinical deficits, or dose-response relationship. These results argue against LEA exposure being associated with consistent, clinically significant neurodevelopmental deficits in children.

Association between combined spinal-epidural analgesia and neurodevelopment at 3 years old: The Japan Environment and Children's Study

AIM

To investigate the association between maternal combined spinal-epidural analgesia during vaginal delivery and neurodevelopment in 3-year-old children.

METHODS

Using data from the Japan Environment and Children's Study, a birth cohort study on pregnant women and their offspring, we described the background, perinatal outcomes, and neurodevelopmental outcomes of participants with a singleton pregnancy who received combined spinal-epidural analgesia during vaginal delivery and those who did not. The association between maternal combined spinal-epidural analgesia and abnormalities in five domains of the Ages and Stages Questionnaire, Third Edition, was analyzed using univariable and multivariable logistic regression analyses. Crude and adjusted odds ratios with 95% confidence intervals (95% CI) were calculated.

RESULTS

Among 59 379 participants, 82 (0.1%) children (exposed group) were born to mothers who received combined spinal-epidural analgesia during vaginal delivery. In the exposed versus control groups, 1.2% versus 3.7% had communication abnormalities (adjusted odds ratio [95% CI]: 0.30 [0.04-2.19]), 6.1% versus 4.1% exhibited gross-motor abnormalities (1.36 [95% CI: 0.55-3.36]), 10.9% vs. 7.1% had fine-motor abnormalities (1.46 [95% CI: 0.72-2.96]), 6.1% vs. 6.9% showed difficulties with problem-solving (0.81 [95% CI: 0.33-2.01]), and 2.4% vs. 3.0% had personal-social problems (0.70 [95% CI: 0.17-2.85]).

CONCLUSIONS

Exposure to combined spinal-epidural analgesia during vaginal delivery was not associated with the risk of neurodevelopmental abnormalities; however, the sample size of our study might not be appropriate for the study design.

Perinatal Anesthesia Exposure and Autism Spectrum Disorders

Epidural analgesia is frequently used during labor among pregnant people in the United States. Different factors have been associated with the development of autism spectrum disorder in the epidemiological literature: maternal health, infectious and pharmacological etiologies, social factors, and environmental exposures. Current data indicates no clear association between the use of epidural labor analgesia and the development of autism spectrum disorder in the offspring. This review presents the public health perspective on the postulated association between perinatal anesthesia exposure and autism spectrum disorders.

Association of epidural analgesia during labor with neurodevelopment of children during the first three years: the Japan Environment and Children's Study

BACKGROUND

Epidural analgesia relives pain during labor. However, the long-term effects on neurodevelopment in children remain unclear. We explored associations between exposure to epidural analgesia during labor and childhood neurodevelopment during the first 3 years of life, in the Japan Environment and Children's Study (JECS), a large-scale birth cohort study.

METHODS

Pregnant women were recruited between January 2011 and March 2014, and 100,304 live births of singleton children born at full-term by vaginal delivery, and without congenital diseases were analyzed. Data on mothers and children were collected using a self-administered questionnaires and medical record transcripts. The children's neurodevelopment was repeatedly assessed for five domains (communication, gross motor, fine motor, problem solving, and personal-social), using the Ages and Stages Questionnaires, Third Edition, at six time points from age 6 to 36 months. After adjusting for potential confounders, the associations between exposure to epidural analgesia during labor and children's neurodevelopment at each time point were assessed.

RESULTS

Of the 42,172 children with valid data at all six time points, 938 (2.4%) were born to mothers who received epidural analgesia during labor. Maternal exposure to epidural analgesia was associated with neurodevelopmental delays during the first 3 years after birth. Delay risks in gross and fine motor domains were the greatest at 18 months (adjusted odds ratio (aOR) [95% confidence interval (CI)]: 1.40 [1.06, 1.84] and 1.54 [1.17, 2.03], respectively), subsequently decreasing. Delay risks in communication and problem-solving domains were significantly high at 6 and 24 months, and remained significant at 36 months (aOR [95% CI]: 1.40 [1.04, 1.90] and 1.28 [1.01, 1.61], respectively). Exposure to epidural analgesia was also associated with the incidence of problem solving and personal-social delays from 18 to 24 months old. Neurodevelopmental delay risks, except for communication, were dominant in children born to mothers aged ≥30 years at delivery.

CONCLUSIONS

This study showed that maternal exposure to epidural analgesia during labor was associated with neurodevelopmental delays in children during the first 3 years after birth.

Impact of maternal neuraxial labor analgesia exposure on offspring's neurodevelopment: A longitudinal prospective cohort study with propensity score matching

Background

Neuraxial analgesia is widely used to relieve labor pain; its effects on long-term neurodevelopment of offspring remain unclear. This study was designed to investigate the influence of maternal neuraxial labor analgesia on offspring mental development.

Methods

This was a predefined secondary analysis of a 2-year prospective longitudinal study. Nulliparous women with single-term cephalic pregnancy preparing for vaginal delivery self-selected neuraxial analgesia or not during labor. Mothers and their offspring were followed up 2 years later. children's mental development was assessed with the bayley scales of infant development. A multivariable logistic model was used to identify factors associated with below-average mental development (Mental Development Index <90).

Results

A Total of 508 pairs of mothers and children completed a 2-year follow-up. after propensity score matching, 387 pairs were included in the analysis. In both cohorts, the proportions with below-average mental development were slightly lower in children whose mothers received neuraxial labor analgesia, although not statistically significant [in the full cohort: 9.8 % (36/368) vs. 15.7% (22/140), P = 0.060; In the matched cohort: 8.3% (21/254) vs. 14.3% (19/133), P = 0.065]. A higher 2-year depression score (in the full cohort: Odds Ratio 1.15, 95% CI 1.08–1.22, P < 0.001; In the matched cohort: Odds Ratio 1.09, 95% CI 1.01–1.18, P = 0.037), but not neuraxial analgesia exposure, was associated with an increased risk of below-average mental development.

Conclusions

Maternal depression at 2 years was associated with the risk of below-average mental development, whereas maternal exposure to neuraxial labor analgesia was not.

Clinical Trial Registration

The study was registered with www.chictr.org.cn (ChiCTR-OCH-14004888) and ClinicalTrials.gov (NCT02823418).

Epidural labour analgesia and autism spectrum disorder: is the current evidence sufficient to dismiss an association?

Findings from a population-based study using a sibling-matched analysis published in this issue of the British Journal of Anaesthesia indicate that epidural labour analgesia is not associated with an increased risk of autism spectrum disorder. These findings are consistent with those from three other population-based studies that used similar methodological approaches. Cumulatively, these robust, high-quality epidemiological data support the assertion that there is no meaningful association between epidural labour analgesia and autism spectrum disorder in offspring.

Labor epidural analgesia and risk of autism Spectrum disorders in offspring: A systematic review and meta-analysis

Background

The effect of labor epidural anesthesia (LEA) on the risk of autism spectrum disorder (ASD) in offspring has been investigated recently, and available results are inconsistent.

Methods

We searched the PubMed and EMBASE databases for relevant studies and performed a systematic review and meta-analysis of the literature. Subgroup analyses were conducted to assess the sources of heterogeneity. Both fixed and random effects models were used was used to estimate overall relative risk.

Results

Our results showed that LEA was associated with an increased risk of ASD in offspring [HR = 1.3, 95% confidence interval (CI): 1.25-1.35; P < 0.001] after combining crude estimates from the included studies. This association was gradually reduced, but still statistically significant, when potential confounding factors were considered (HR 1.13, 95% CI 1.03-1.25, P = 0.014). However, there was no significant association when we combined data of siblings from other pregnancies (HR = 1.07, 95% CI: 0.99-1.16, P = 0.076), implying that the association was due to confounding factors.

Conclusion

The statistically significant association between LEA and ASD in the offspring can be partially explained by unmeasured confounding.

Systematic Review Registration

Identifier CRD42022302892.

Association of Neuraxial Labor Analgesia for Vaginal Childbirth With Risk of Autism Spectrum Disorder

IMPORTANCE

Recent studies have reported conflicting findings regarding a potential association between analgesia used during labor and autism spectrum disorder in the offspring.

OBJECTIVE

To evaluate whether neuraxial labor analgesia increases the risk of autism spectrum disorder in the offspring.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study included mother-child dyads who underwent vaginal delivery and were exposed to neuraxial labor analgesia. Delivery data were collected from the Medicaid Analytic eXtract (2005-2014) for mothers with public insurance and the IBM Health MarketScan Research Database (2005-2015) for mothers with private insurance. Data analysis was conducted from January to October 2021.

EXPOSURES

Presence of a procedure code indicating neuraxial labor analgesia.

MAIN OUTCOMES AND MEASURES

Children with autism spectrum disorder, identified using a validated algorithm (positive predictive value: 94% [95% CI, 83%-99%]). Cumulative incidence curves stratified by exposure were assessed using Kaplan-Meier analyses. Hazard ratios were estimated through Cox proportional hazards regression, using propensity-score fine stratification for confounding control. Estimates from both insurance cohorts were combined through fixed-effects meta-analysis. Subsequently, results from these analyses were combined with existing published studies.

RESULTS

The cohort of mother-child dyads with public insurance consisted of 910 696 deliveries (mean [SD] maternal age, 24.3 [5.7] years; 286 025 [31.4%] Black mothers; 374 282 [41.1%] White mothers), with 484 752 (53.2%) being exposed to neuraxial labor analgesia. The cohort of mother-child dyads with private insurance included 696 883 deliveries (mean [SD] maternal age, 31.0 [4.5] years; race and ethnicity data not available), with 513 347 (73.7%) being exposed. Cumulative incidence of autism spectrum disorder by 10 years of age was 1.93% (95% CI, 1.73%-2.13%) among children in the exposed group vs 1.64% (95% CI, 1.51%-1.76%) among children in the unexposed group in the publicly insured cohort. Respective numbers were 1.33% (95% CI, 1.19%-1.46%) and 1.19% (95% CI, 0.99%-1.38%) in the privately insured cohort. Adjusting for potential confounders and pooling across both cohorts resulted in a hazard ratio of 1.08 (95% CI, 1.02-1.15). Results were consistent when additionally adjusting for empirically identified variables through high-dimensional propensity score analyses (pooled hazard ratio, 1.07; 95% CI, 1.00-1.14) or expanding the cohorts to include cesarean deliveries and assisted vaginal deliveries (pooled hazard ratio, 1.07; 95% CI, 1.03-1.12). Meta-analysis of this study and recently published observational studies yielded similar findings with a pooled hazard ratio of 1.10 (95% CI, 1.06-1.13).

CONCLUSIONS AND RELEVANCE

Although a small increase in risk cannot be ruled out, the combined evidence from observational studies does not support the notion that neuraxial labor analgesia is associated with an increased risk of autism spectrum disorder.

Association Between Epidural Analgesia During Labor and Risk of Autism Spectrum Disorders in Offspring

IMPORTANCE

Although the safety of labor epidural analgesia (LEA) for neonates has been well documented, the long-term health effects of LEA on offspring remain to be investigated.

OBJECTIVE

To assess the association between maternal LEA exposure and risk of autism spectrum disorders (ASDs) in offspring.

DESIGN, SETTING, AND PARTICIPANTS

Data for this retrospective longitudinal birth cohort study were derived from electronic medical records from a population-based clinical birth cohort. A total of 147 895 singleton children delivered vaginally between January 1, 2008, and December 31, 2015, in a single integrated health care system were included. Children were followed up from the age of 1 year until the first date of the following occurrences: clinical diagnosis of ASD, last date of health plan enrollment, death, or the study end date of December 31, 2018.

EXPOSURES

Use and duration of LEA.

MAIN OUTCOMES AND MEASURES

The main outcome was clinical diagnosis of ASD. Cox proportional hazards regression analysis was used to estimate the hazard ratio (HR) of ASD associated with LEA exposure.

RESULTS

Among the cohort of 147 895 singleton children (74 425 boys [50.3%]; mean [SD] gestational age at delivery, 38.9 [1.5] weeks), 109 719 (74.2%) were exposed to maternal LEA. Fever during labor was observed in 13 055 mothers (11.9%) in the LEA group and 510 of 38 176 mothers (1.3%) in the non-LEA group. Autism spectrum disorders were diagnosed in 2039 children (1.9%) in the LEA group and 485 children (1.3%) in the non-LEA group. After adjusting for potential confounders, including birth year, medical center, maternal age at delivery, parity, race/ethnicity, educational level, household income, history of comorbidity, diabetes during pregnancy, smoking during pregnancy, preeclampsia or eclampsia, prepregnancy body mass index, gestational weight gain, gestational age at delivery, and birth weight, the HR associated with LEA vs non-LEA exposure was 1.37 (95% CI, 1.23-1.53). Relative to the unexposed group, the adjusted HR associated with LEA exposure of less than 4 hours was 1.33 (95% CI, 1.17-1.53), with LEA exposure of 4 to 8 hours was 1.35 (95% CI, 1.20-1.53), and with LEA exposure of more than 8 hours was 1.46 (95% CI, 1.27-1.69). Within the LEA group, there was a significant trend of ASD risk associated with increasing duration of LEA exposure after adjusting for covariates (HR for linear trend, 1.05 [95% CI, 1.01-1.09] per 4 hours). Adding fever to the model did not change the HR estimate associated with LEA exposure (adjusted HR for LEA vs non-LEA, 1.37 [95% CI, 1.22-1.53]).

CONCLUSIONS AND RELEVANCE

This study suggests that maternal LEA may be associated with increased ASD risk in children. The risk appears to not be directly associated with epidural-related maternal fever.

Binge drinking prior to pregnancy detection in a nonhuman primate: behavioral evaluation of offspring

BACKGROUND

Minimal scientific information is available to inform public health policy on binge drinking prior to pregnancy detection. The nonhuman primate provides a valuable animal model for examining consequences to reproduction and offspring function that may result from this common pattern of alcohol abuse.

METHODS

Adult female rhesus monkeys were dosed with 1.5 g/kg per day ethanol (EtOH) by gavage 2 d/wk beginning 7 months prior to mating and continuing to pregnancy detection at 19 to 20 days gestation. Postnatal evaluation of control (n = 6) and EtOH-treated (n = 4) infants included a neonatal neurobehavioral assessment, a visual paired comparison (cognitive) test at 35 days of age, and mother-infant interaction at 100 to 112 days of age.

RESULTS

Alcohol-exposed neonates did not differ from controls in posture and reflex measures. Longer durations of visual fixation, suggesting slower visual processing, and greater novelty preference were seen in the alcohol group. At early weaning age, as infants spent more time away from their dams, more of the reunions between mother and infant were initiated by the mothers in the alcohol-exposed group, suggesting a more immature mother-infant interaction.

CONCLUSIONS

Intermittent high-dose alcohol exposure (binge drinking) discontinued at early pregnancy detection in rhesus monkey can result in altered behavioral function in the infant. Mediating effects on ovum, reproductive tract, and early embryo can be explored in this model. Studies of longer-term consequences in human populations and animal models are needed.

Object discrimination reversal as a method to assess cognitive impairment in nonhuman primate enhanced pre- and postnatal developmental (ePPND) studies: statistical power analysis

An important aspect of the enhanced pre- and postnatal developmental (ePPND) toxicity study in nonhuman primates (NHP) is that it combines in utero and postnatal assessments in a single study. However, it is unclear if NHP ePPND studies are suitable to perform all of the evaluations incorporated into rodent PPND studies. To understand the value of including cognitive assessment in a NHP ePPND toxicity study, we performed a power analysis of object discrimination reversal task data using a modified Wisconsin General Testing Apparatus (ODR-WGTA) from two NHP ePPND studies. ODR-WGTA endpoints evaluated were days to learning and to first reversal, and number of reversals. With α = 0.05 and a one-sided t-test, a sample of seven provided 80% power to predict a 100% increase in all three of the ODR-WGTA endpoints; a sample of 25 provided 80% power to predict a 50% increase. Similar power analyses were performed with data from the Cincinnati Water Maze (CWM) and passive avoidance tests from three rat PPND toxicity studies. Groups of 5 and 15 in the CWM and passive avoidance test, respectively, provided 80% power to detect a 100% change. While the power of the CWM is not far superior to the NHP ODR-WGTA, a clear advantage is the routine use of larger sample size, with a group of 20 rats the CWM provides ~90% power to detect a 50% change. Due to the limitations on the number of animals, the ODR-WGTA may not be suitable for assessing cognitive impairment in NHP ePPND studies.

Neuraxial labor analgesia for vaginal delivery and its effects on childhood learning disabilities

BACKGROUND

In prior work, children born to mothers who received neuraxial anesthesia for cesarean delivery had a lower incidence of subsequent learning disabilities compared with vaginal delivery. The authors speculated that neuraxial anesthesia may reduce stress responses to delivery, which could affect subsequent neurodevelopmental outcomes. To further explore this possibility, we examined the association between the use of neuraxial labor analgesia and development of childhood learning disabilities in a population-based birth cohort of children delivered vaginally.

METHODS

The educational and medical records of all children born to mothers residing in the area of 5 townships of Olmsted County, Minnesota from 1976 to 1982 and remaining in the community at age 5 years were reviewed to identify those with learning disabilities. Cox proportional hazards regression was used to compare the incidence of learning disabilities between children delivered vaginally with and without neuraxial labor analgesia, including analyses adjusted for factors of either potential clinical relevance or that differed between the 2 groups in univariate analysis.

RESULTS

Of the study cohort, 4684 mothers delivered children vaginally, with 1495 receiving neuraxial labor analgesia. The presence of childhood learning disabilities in the cohort was not associated with use of labor neuraxial analgesia (adjusted hazard ratio, 1.05; 95%confidence interval, 0.85-1.31; P = 0.63).

CONCLUSION

The use of neuraxial analgesia during labor and vaginal delivery was not independently associated with learning disabilities diagnosed before age 19 years. Future studies are needed to evaluate potential mechanisms of the previous finding indicating that the incidence of learning disabilities is lower in children born to mothers via cesarean delivery under neuraxial anesthesia compared with vaginal delivery.

Evidence of metacognitive control by humans and monkeys in a perceptual categorization task

Metacognition research has focused on the degree to which nonhuman primates share humans' capacity to monitor their cognitive processes. Convincing evidence now exists that monkeys can engage in metacognitive monitoring. By contrast, few studies have explored metacognitive control in monkeys, and the available evidence of metacognitive control supports multiple explanations. The current study addresses this situation by exploring the capacity of human participants and rhesus monkeys (Macaca mulatta) to adjust their study behavior in a perceptual categorization task. The study found that humans and monkeys increased their study for high-difficulty categories, suggesting that both share the capacity to exert metacognitive control. (PsycINFO Database Record (c) 2009 APA, all rights reserved).

Anesthesia for cesarean delivery and learning disabilities in a population-based birth cohort

BACKGROUND

Anesthetics administered to immature brains may cause histopathological changes and long-term behavioral abnormalities. The association between perinatal exposure to anesthetics during Cesarean delivery (CD) and development of learning disabilities (LD) was determined in a population-based birth cohort.

METHODS

The educational and medical records of all children born to mothers residing in five townships of Olmsted County, Minnesota from 1976-1982 and remaining in the community at age 5 were reviewed to identify those with LDs. Cox proportional hazards regression was used to compare rates of LD between children delivered vaginally and via CD (with general or regional anesthesia).

RESULTS

Of the 5,320 children in this cohort, 497 were delivered via CD (under general anesthesia n = 193, and regional anesthesia n = 304). The incidence of LD depended on mode of delivery (P = 0.050, adjusted for sex, birth weight, gestational age, exposure to anesthesia before age 4 yr, and maternal education). LD risk was similar in children delivered by vagina or CD with general anesthesia, but was reduced in children receiving CD with regional anesthesia (hazard ratio = 0.64, 95% confidence interval 0.44 to 0.92; P = 0.017 for comparison of CD under regional anesthesia compared to vaginal delivery).

CONCLUSION

Children exposed to general or regional anesthesia during CD are not more likely to develop LD compared to children delivered vaginally, suggesting that brief perinatal exposure to anesthetic drugs does not adversely affect long-term neurodevelopmental outcomes. The risk of LD may be lower in children delivered by CD whose mothers received regional anesthesia.

Visual recognition memory and auditory brainstem response in infant rhesus monkeys exposed perinatally to environmental tobacco smoke

The impact of perinatal exposure to environmental tobacco smoke (ETS) on cognitive development is controversial. We exposed rhesus monkeys to ETS or filtered air (5 animals per group) beginning in utero on day 50 of pregnancy and continuing throughout postnatal testing. In infancy, we evaluated both groups for visual recognition memory and auditory function (auditory brainstem response). The ETS group showed significantly less novelty preference in the visual recognition task whereas no effects on auditory function were detected. These preliminary results support the view that perinatal ETS exposure has adverse effects on cognitive function and indicate further that rhesus monkeys may provide a valuable nonhuman primate model for investigating this link.

Behavioral consequences of developmental iron deficiency in infant rhesus monkeys

Human studies have shown that iron deficiency and iron deficiency anemia in infants are associated with behavioral impairment, but the periods of brain development most susceptible to iron deficiency have not been established. In the present study, rhesus monkeys were deprived of iron by dietary iron restriction during prenatal (n=14, 10 microg Fe/g diet) or early postnatal (n=12, 1.5 mg Fe/L formula) brain development and compared to controls (n=12, 100 microg Fe/g diet, 12 mg Fe/L formula) in behavioral evaluations conducted during the first four months of life in the nonhuman primate nursery. Iron deficiency anemia was detected in the pregnant dams in the third trimester and compromised iron status was seen in the prenatally iron-deprived infants at birth, but no iron deficiency was seen in either the prenatally or postnatally iron-deprived infants during the period of behavioral evaluation. Neither prenatal nor postnatal iron deprivation led to significant delays in growth, or gross or fine motor development. Prenatally deprived infants demonstrated a 20% reduced spontaneous activity level, lower inhibitory response to novel environments, and more changes from one behavior to another in weekly observation sessions. Postnatally deprived infants demonstrated poorer performance of an object concept task, and greater emotionality relative to controls. This study indicates that different syndromes of behavioral effects are associated with prenatal and postnatal iron deprivation in rhesus monkey infants and that these effects can occur in the absence of concurrent iron deficiency as reflected in hematological measures.

Cellular actions of Al at low (1.25 microM) concentrations in primary oligodendrocyte culture

At a physiologically relevant concentration (1.25 microM), aluminum had an activating effect on oligodendrocyte cell cultures, similar to that previously reported for other cell types. G protein-linked signal transduction was stimulated as indicated by enhanced production of IP3, and protein synthesis was increased. At this concentration Al did not promote cell damage but did enhance oxidative effects initiated by reactive oxygen species. Both AlCl(3) and Al transferrin (AlTf) had similar actions at equimolar concentrations. In vivo, physiological Al ion may act by common cellular pathways in diverse cell types. These effects may be relevant to Al toxicological, pharmacological (immunoadjuvant), and physiological effects.

Long-term consequences of developmental exposure to aluminum in a suboptimal diet for growth and behavior of Swiss Webster mice

Swiss Webster mice received diets containing 7 (control), 100, 500, or 1000 microg aluminum (Al)/g throughout development (conception to 35 days of age) and were tested behaviorally as adults (>90 days of age). The basal diet contained the same percent of recommended dietary amounts of phosphate, calcium, iron, magnesium, and zinc as young women usually consume. These "realistic" dietary conditions led to 12--15% growth retardation in the Al1000 group at the time of testing. Females were evaluated in a cognitive task (Morris water maze) at 3 months of age and males were evaluated in a motor test battery at 5 months of age. Al1000 females (n=16) were slower than controls in learning the Morris maze, as suggested by fewer mice with low latencies during the first three sessions of the four-session learning series. Influences of Al on cue utilization were also found in probe sessions eliminating salient or nonsalient cues. With motor testing, the Al1000 males (n=20) had significantly lower hindlimb grip strength than controls, an effect that was eliminated by covariance analysis with body weight. Subtle influences of Al on rotarod and wire suspension tests were also noted. The data suggest that developmental Al exposure under normal, but less than optimal, dietary conditions can lead to subtle but long-term effects on growth and brain function in adulthood.

Lifelong feeding of a high aluminum diet to mice

In three experiments, high aluminum diets (1000 microg Al/g diet) were fed to mice throughout their life span to determine whether neurodegenerative changes were seen with aging. Brain Al concentrations were slightly lower in Al-treated mice than controls. Generally, no increased mortality or gross evidence of neurodegeneration was seen in Al-treated mice. Eighteen and 24 month old Swiss Webster mice fed the high aluminum diet differed from controls on some neurobehavioral tests, but differences were no greater than previously seen with shorter term exposure in younger mice. Both brain Al concentration and susceptibility to oxidative damage, as measured with TBARS, were lower in the Al-treated aged mice than in controls. In addition, Al-treated aged Swiss Webster and C57BL/6J mice showed somewhat enhanced performance in the Morris water maze. Finally, Al treatment did not exacerbate the effect of MPTP treatment on a grip strength measure in either 66 or 235 day old male mice. Swiss Webster and C57BL/6J mice do not appear to provide useful models for studying Al-induced neurodegenerative changes in aging.

Effects of dietary aluminum on pubertal mice

Puberty is a period of rapid growth and nervous system maturation, but it is little studied as a sensitive period for neurotoxicant effects. In this experiment, diets containing 7 (control), 100, 500, 750, or 1000-microg aluminum (Al.)/g diet as Al lactate and 3.2% citrate (to promote Al absorption) were fed to male mice beginning at puberty (45 days of age) for either 4 or 8 weeks. ANOVAs were conducted to identify group differences from control, and regression analysis with Al intake was used to evaluate dose-response trends. Dose-responsive effects of dietary Al on brain weight, Al, and Mn concentration, and on grip strength were seen at the end of the 4-week exposure. Although brain Al concentration was also elevated at the end of the 8-week exposure, no dose-responsive effects on other variables were noted. Neither exposure influenced auditory startle amplitude. The period after puberty was sensitive to dietary Al exposure, but affected variables apparently recovered when exposure continued into young adulthood.