A dose-response study of chronic cocaine on maternal behavior in rats

Coordination of social behaviors by the bed nucleus of the stria terminalis

The bed nucleus of the stria terminalis (BNST) is a sexually dimorphic, neuropeptide-rich node of the extended amygdala that has been implicated in responses to stress, drugs of abuse, and natural rewards. Its function is dysregulated in neuropsychiatric disorders that are characterized by stress- or drug-induced alterations in mood, arousal, motivation, and social behavior. However, compared to the BNST's role in mood, arousal, and motivation, its role in social behavior has remained relatively understudied. Moreover, the precise cell types and circuits underlying the BNST's role in social behavior have only recently begun to be explored using modern neuroscience techniques. Here, we systematically review the existing literature investigating the neurobiological substrates within the BNST that contribute to the coordination of various sex-dependent and sex-independent social behavioral repertoires, focusing largely on pharmacological and circuit-based behavioral studies in rodents. We suggest that the BNST coordinates social behavior by promoting appropriate assessment of social contexts to select relevant behavioral outputs and that disruption of socially relevant BNST systems by stress and drugs of abuse may be an important factor in the development of social dysfunction in neuropsychiatric disorders.

Mothering under the influence: how perinatal drugs of abuse alter the mother-infant interaction

Although drug-abusing women try to moderate their drug and alcohol use during pregnancy, they often relapse at a time when childcare needs are high and maternal bonding is critical to an infant's development. In the clinical setting, the search for the neural basis of drug-induced caregiving deficits is complex due to several intervening variables. Rather, the preclinical studies that control for drug dose and regimen, as well as for gestational and postpartum environment, allow a precise determination of the effects of drugs on maternal behaviour. Given the relevance of the issue, this review will gather reports on the phenotypic correlates of maternal behaviour in preclinical studies, and focus on the detrimental consequences on the mother-infant interaction exerted by the perinatal use of alcohol, nicotine, cannabis, cocaine and stimulants and opiates. The drug-induced disruptions of this maternal repertoire are associated with adverse maternal and infant outcomes. A comprehensive overview will help promote the refinement of the treatment approaches toward maternal drug use disorders and maternal misbehaviour, in favour of augmented parenting resiliency.

Cocaína durante la gestación y conducta materna postparto en ratones

El abuso materno de cocaína durante la gestación se relaciona con negligencia, maltrato y perturbación del vínculo madre- hijo, lo que incide directamente en el desarrollo de los infantes; por esto, las diversas problemáticas neuroconductuales de los hijos de padres drogodependientes podrían atribuirse a la inadecuada conducta materna o a la exposición prenatal a la droga. El objetivo de esta investigación fue analizar los efectos de la administración crónica de cocaína durante la gestación en la conducta materna postparto de ratones. Para esto se asignaron aleatoriamente 21 ratones CD1 hembras gestantes para la administración de solución salina y cocaína (25 mg/kg/día y 50 mg/kg/día), desde el octavo hasta el día veintiuno de gestación. Después del parto, durante 20 días (15 minutos diarios), se registró individualmente la frecuencia de presentación de 16 índices de conducta materna mediante un etograma. Se encontró que la cocaína afectó levemente la frecuencia de la conducta materna, aunque posiblemente afecte otros parámetros como la latencia, duración y secuencia de esta conducta.  

Prenatal substance exposure and child self-regulation: Pathways to risk and protection

A conceptual model of the association between prenatal cocaine exposure (PCE) and child self-regulation via maternal harshness and language development was examined. Specifically, the model tested whether PCE was associated with self-regulation either directly or indirectly via high maternal harshness and poor language development. The role of child sex, autonomic reactivity, and cumulative environmental risk as potential moderators was also explored. The sample was 216 mother-child dyads recruited at birth and assessed at 2, 7, 13, 24, 36, and 48 months of child ages. Participating mothers were primarily African American (72%). Results indicated a significant indirect association between PCE and child effortful control at 36 months via higher maternal harshness. Autonomic reactivity moderated the association between maternal harshness and self-regulation such that among children with poor autonomic reactivity, high maternal harshness was associated with lower conscience at 3 years. Child sex and environmental risk did not moderate the association between PCE and self-regulation. Thus, the quality of caregiving experience played a significant role in the development of self-regulation among PCE children, especially those at higher autonomic risk. In particular, PCE children who also exhibit poor autonomic reactivity may be particularly susceptible to environmental influences such as parenting.

Effects of prenatal cocaine exposure on early postnatal rodent brain structure and diffusion properties

Prenatal cocaine exposure has been associated with numerous behavioral phenotypes in clinical populations, including impulsivity, reduced attention, alterations in social behaviors, and delayed language and sensory-motor development. Detecting associated changes in brain structure in these populations has proven difficult, and results have been inconclusive and inconsistent. Due to their more controlled designs, animal models may shed light on the neuroanatomical changes caused by prenatal cocaine; however, to maximize clinical relevance, data must be carefully collected using translational methods. The goal of this study was two-fold: (1) to determine if prenatal cocaine alters developmental neuroanatomy using methods that are available to human researchers, specifically structural MRI and diffusion tensor imaging, and (2) to determine the feasibility of rodent in vivo neuroimaging for usage in longitudinal studies of developmental disorders. Cocaine-exposed (prenatal days 1-20, 30mg/kg/day) rat pups were sedated and imaged live using diffusion tensor imaging and postmortem (fixed) using magnetic resonance histology on postnatal day 14. Volume and diffusion properties in whole brain as well as specific regions of interest were then assessed from the resulting images. Whole brain analyses revealed that cocaine-exposed animals showed no change in whole brain volume. Additionally, we found alterations in fractional anisotropy across regions associated with reward processing and emotional regulation, especially in the thalamus and globus pallidus, as well as sex-dependent effects of cocaine in the right cortex. Reductions in fractional anisotropy were paired with reductions only in axial diffusivity, which preliminarily suggests that the changes observed here may be due to axonal damage, as opposed to reductions in myelination of the affected regions/pathways. Our data indicate that prenatal cocaine may target a number of developing brain structures but does not result in overt changes to brain volumes. These results highlight not only the brain alterations that result from prenatal cocaine but also the advancements in live imaging that allow longitudinal study designs in other models.

Prenatal cocaine exposure and trajectories of externalizing behavior problems in early childhood: examining the role of maternal negative affect

This study examined the association between prenatal cocaine exposure (PCE) and developmental trajectories of externalizing behavior problems from 18 to 54 months of child age. A hypothesized indirect association between PCE and externalizing trajectories via maternal negative affect was also examined. Caregiving environmental risk and child sex were evaluated as moderators. This study consisted of 196 mother-child dyads recruited at delivery from local area hospitals (107 PCE, 89 non-PCE) and assessed at seven time points across the toddler to preschool periods. Results revealed no direct associations between PCE and externalizing behavior problem trajectories. However, results did indicate that PCE shared a significant indirect relationship with externalizing behavior problem trajectories via higher levels of maternal negative affect. The association between PCE and externalizing problem trajectories was also moderated by caregiving environmental risk such that PCE children in high-risk caregiving environments did not experience the well-documented normative decline in externalizing behavior problems beginning at around 3 years of age. This study suggests potential pathways to externalizing behavior problems among high-risk children.

Cocaine withdrawal influences paternal behavior and associated central expression of vasopressin, oxytocin and tyrosine hydroxylase in mandarin voles

Although the disruptive effects of cocaine on the maternal care are well known, little is known about paternal care in the context of cocaine abuse. Vasopressin (AVP), oxytocin (OT) and dopamine (DA) have been found to regulate paternal behavior and are also involved in cocaine abuse. Mandarin voles (Microtus mandarinus) are socially monogamous and display high levels of paternal care. Here, we investigated whether paternal behavior and associated central levels of AVP, OT and DA were altered following 24 h of withdrawal from 4 day administration of 20 mg/kg/day cocaine. Our data shows that vole fathers did not experience altered levels of locomotion during an open field test. However, compared to controls, cocaine attenuated licking/grooming and contact behavior and shortened the latency to crouching, contact and pup retrieval. Last, fewer AVP and OT immunoreactive neurons in the paraventricular nucleus and more tyrosine hydroxylase immunoreactive neurons in the ventral tegmental area were observed in cocaine-treated fathers. These results indicate that cocaine withdrawal disturbs the expression of partial paternal behavior by altering central levels of AVP, OT and DA.

Effect of prenatal cocaine on early postnatal thermoregulation and ultrasonic vocalization production

Prenatal cocaine exposure can alter the postnatal care received by rat pups. Such effects could be caused in part by alterations in pup-produced stimuli that elicit early postnatal maternal care. Pup ultrasonic vocalizations are thought to be a particularly salient stimulus, and when paired with other cues, may elicit maternal attention. Cocaine is known to acutely alter thermoregulatory and cardiac function, thus prenatal cocaine may affect vocalizations through altering these functions. The data presented here determine the impact of full term prenatal cocaine exposure, saline exposure, or no exposure on thermogenic capacity, cardiac function, and the resulting ultrasonic vocalizations across the early postnatal period (days 1–5). Results indicated that while sharing many similar characteristics with saline-exposed and untreated animals, prenatal cocaine exposure was associated with specific alterations in vocalization characteristics on postnatal day 1 (PND 1), including call amplitude. Furthermore, numerous spectral parameters of their vocalizations were found altered on PND 3, including rate, call duration, and frequency, while no alterations were found on PND 5. Additionally, cocaine-exposed pups also showed a reduced thermoregulatory capacity compared to saline animals and reduced cardiac mass compared to untreated animals on PND 5. Together, these findings indicate that prenatal cocaine may be altering the elicitation of maternal care through its impact on vocalizations and thermoregulation, and suggests a potential mechanism for these effects through cocaine's impact on developing stress systems.

Prenatal and gestational cocaine exposure: Effects on the oxytocin system and social behavior with implications for addiction

Drug abuse during pregnancy is a major public health concern, with negative consequences throughout development. Prenatal cocaine exposure (PCE) in rats produces social behavior deficits with corresponding changes in neuroendocrine and monoaminergic signaling. The relevance of parental care in social behavior maturity cannot be ignored, and gestational exposure to cocaine severely disrupts parental care, thus impacting the early environment of the offspring. Oxytocin (Oxt) is critical in regulating social behaviors and central levels are disrupted following acute and chronic cocaine (CC) treatment in postpartum rat dams, coincident with deficits in maternal care. We will discuss studies aimed to determine the relative contribution of PCE and CC-induced deficits in maternal care to social behaviors and Oxt signaling across development. PCE results in decreased social (including parental) behaviors in adolescence and adulthood. PCE is also associated with increased aggression in adults. Rearing by CC-exposed mothers synergistically increases the behavioral effects of PCE. Rearing by CC-exposed mothers, but not PCE, disrupts Oxt levels and mRNA in regions relevant to social behavior, but does not affect receptors in postpartum adult offspring. Preliminary work indicates that PCE/CC rearing has dynamic effects on Oxt levels and receptors in neonatal rat pups, suggesting very early regulation of Oxt signaling. This work highlights how the interactive role of Oxt signaling and behavioral context throughout development can be derailed by drug abuse during pregnancy. The relevance of disrupted Oxt to intergenerational transmission of addiction is briefly discussed.

Effects of cocaine on maternal behavior and neurochemistry

Drug addiction is a chronic relapsing disorder that involves drug seeking and abuse despite the negative social and health consequences. While the potential effects of cocaine on child development have been extensively studied over the last 30 years, few researchers have focused on the effects of cocaine on maternal behavior, which includes offspring care and maternal aggression towards an unfamiliar individual. In humans, maternal cocaine use can lead to child neglect, abuse, and disrupt the mother-child bond. While it has been argued the developmental effects of maternal cocaine use on children were initially overstated, it is clear that disruptions of typical maternal behavior (i.e. postpartum depression, anxiety disorders) are detrimental to the physical and emotional health of offspring. Cocaine use in mothers is commonly associated with psychological disorders, including depression and anxiety, and it is postulated that many of the negative effects of maternal cocaine use on offspring are mediated through changes in maternal behavior. This review will summarize research on cocaine and maternal behavior in animal and human studies, discuss potential mechanisms, and suggest therapeutic strategies for treating cocaine-affected maternal behavior which may improve the physical and behavioral health of both mother and child. The primary objective is to stimulate future communication, cooperation, and collaboration between researchers who use animals and humans to study cocaine and maternal behavior.

Delayed developmental changes in neonatal vocalizations correlates with variations in ventral medial hypothalamus and central amygdala development in the rodent infant: effects of prenatal cocaine

While variations in neonatal distress vocalizations have long been shown to reflect the integrity of nervous system development following a wide range of prenatal and perinatal insults, a paucity of research has explored the neurobiological basis of these variations. To address this, virgin Sprague-Dawley rats were bred and divided into three groups: [1] untreated, [2] chronic-cocaine treated (30 mg/kg/day, gestation days (GDs) 1-20); or [3] chronic saline treated (2 mg/kg/day, GDs 1-20). Pregnant dams were injected with Bromodeoxyuridine (10 mg/kg) on GDs 13-15 to label proliferating cells in limbic regions of interest. Ultrasonic vocalizations (USVs) were recorded on postnatal days (PNDs) 1, 14, and 21, from one male and female pup per litter. Variations in acoustic properties of USVs following cocaine-exposure were age and sex-dependent including measures of total number, total duration and amplitude of USVs, and percent of USVs with at least one harmonic. Following USV testing brains were stained with standard fluorescent immunohistochemistry protocols and examined for variations in neuronal development and if variations were associated with acoustic characteristics. Limbic region developmental differences following cocaine-exposure were sex- and age-dependent with variations in the ventral medial hypothalamus and central amygdala correlating with variations in vocalizations on PND 14 and 21. Results suggest maturation of the ventral medial hypothalamus and central amygdala may provide the basis for variations in the sound and production of USVs. As vocalizations may serve as a neurobehavioral marker for nervous system integrity, understanding the neurobiological basis of neonatal vocalizations may provide the basis for early intervention strategies in high-risk infant populations.

Chronic cocaine exposure during pregnancy increases postpartum neuroendocrine stress responses

The cycle of chronic cocaine (CC) use and withdrawal results in increased anxiety, depression and disrupted stress-responsiveness. Oxytocin and corticosterone (CORT) interact to mediate hormonal stress responses and can be altered by cocaine use. These neuroendocrine signals play important regulatory roles in a variety of social behaviours, specifically during the postpartum period, and are sensitive to disruption by CC exposure in both clinical settings and preclinical models. To determine whether CC exposure during pregnancy affected behavioural and hormonal stress response in the early postpartum period in a rodent model, Sprague-Dawley rats were administered cocaine daily (30 mg/kg) throughout gestation (days 1-20). Open field test (OFT) and forced swim test (FST) behaviours were measured on postpartum day 5. Plasma CORT concentrations were measured before and after testing throughout the test day, whereas plasma and brain oxytocin concentrations were measured post-testing only. The results obtained indicated increased CORT response after the OFT in CC-treated dams (P ≤ 0.05). CC-treated dams also exhibited altered FST behaviour (P ≤ 0.05), suggesting abnormal stress responsiveness. Peripheral, but not central, oxytocin levels were increased by cocaine treatment (P ≤ 0.05). Peripheral oxytocin and CORT increased after the FST, regardless of treatment condition (P ≤ 0.05). Changes in stress-responsiveness, both behaviourally and hormonally, may underlie some deficits in maternal behaviour; thus, a clearer understanding of the effect of CC on the stress response system may potentially lead to treatment interventions that could be relevant to clinical populations. Additionally, these results indicate that CC treatment can have long-lasting effects on peripheral oxytocin regulation in rats, similar to changes observed in persistent social behaviour and stress-response deficits in clinical populations.

Disruption of maternal parenting circuitry by addictive process: rewiring of reward and stress systems

Addiction represents a complex interaction between the reward and stress neural circuits, with increasing drug use reflecting a shift from positive reinforcement to negative reinforcement mechanisms in sustaining drug dependence. Preclinical studies have indicated the involvement of regions within the extended amygdala as subserving this transition, especially under stressful conditions. In the addictive situation, the reward system serves to maintain habitual behaviors that are associated with the relief of negative affect, at the cost of attenuating the salience of other rewards. Therefore, addiction reflects the dysregulation between core reward systems, including the prefrontal cortex (PFC), ventral tegmental area (VTA), and nucleus accumbens (NAc), as well as the hypothalamic-pituitary-adrenal axis and extended amygdala of the stress system. Here, we consider the consequences of changes in neural function during or following addiction on parenting, an inherently rewarding process that may be disrupted by addiction. Specifically, we outline the preclinical and human studies that support the dysregulation of reward and stress systems by addiction and the contribution of these systems to parenting. Increasing evidence suggests an important role for the hypothalamus, PFC, VTA, and NAc in parenting, with these same regions being those dysregulated in addiction. Moreover, in addicted adults, we propose that parenting cues trigger stress reactivity rather than reward salience, and this may heighten negative affect states, eliciting both addictive behaviors and the potential for child neglect and abuse.

Cocaine Exposure and Children's Self-Regulation: Indirect Association via Maternal Harshness

OBJECTIVES

This study examined the association between prenatal cocaine exposure and children's self-regulation at 3 years of child age. In addition to direct effects of prenatal cocaine exposure on children's self-regulation, we hypothesized there would be indirect associations between cocaine exposure and self-regulation via higher maternal harshness and poor autonomic regulation in infancy.

METHODS

The sample consisted of 216 mother-infant dyads recruited at delivery from local area hospitals (116 cocaine-exposed, 100 non-exposed). Infant autonomic regulation was measured at 7 months of age during an anger/frustration task, maternal harshness was coded from observations of mother-toddler interactions at 2 years of age, and children's self-regulation was measured at 3 years of age using several laboratory paradigms.

RESULTS

Contrary to hypotheses, there were no direct associations between maternal cocaine use during pregnancy and children's self-regulation. However, results from testing our conceptual model including the indirect effects via maternal harshness or infant parasympathetic regulation indicated that this model fit the data well, χ(2) (23) = 34.36, p > 0.05, Comparative Fit Index = 0.95, RMSEA = 0.05. Cocaine using mothers displayed higher intensity of harshness toward their toddlers during lab interactions across a variety of tasks at 2 years of age (β = 0.23, p < 0.05), and higher intensity of harshness at 2 years was predictive of lower self-regulation at 3 years (β = -0.36, p < 0.01). Maternal cocaine use was also predictive of a non-adaptive increase in respiratory sinus arrhythmia (RSA) from baseline to the negative affect task, but RSA change in infancy was not predictive of self-regulation at 3 years.

CONCLUSION

RESULTS are supportive of animal models indicating higher aggression among cocaine treated dams, and indicate that higher maternal harshness among cocaine using mothers is predictive of child self-regulatory outcomes in the preschool period.

Maternal cocaine use and mother-infant interactions: Direct and moderated associations

This study examined the associations between prenatal cocaine exposure and quality of mother-infant play interactions at 13 months of infant ages. We investigated whether maternal psychological distress and infant reactivity mediated or moderated this association. Participants consisted of 220 (119 cocaine exposed and 101 non-cocaine exposed) mother-infant dyads participating in an ongoing longitudinal study of prenatal cocaine exposure. Results indicated that mothers who used cocaine during pregnancy displayed higher negative affect and lower sensitivity toward their infant during play interactions at 13 months, and that their infants were less responsive toward them. Contrary to hypothesis, this association was not mediated by maternal psychological distress or by infant reactivity. However, results for both the cocaine and non-cocaine exposed infants were supportive of a transactional model where lower maternal sensitivity at 1 month was predictive of higher infant reactivity at 7 months, which in turn was predictive of lower maternal warmth/sensitivity at 13 months, controlling for potential stability in maternal behavior. Results also indicated that as hypothesized, infant reactivity moderated the association between maternal cocaine use during pregnancy and maternal warmth/sensitivity at 13 months of age. Cocaine-using mothers who experienced their infants as being more reactive in early infancy were less warm/sensitive toward them in later infancy. Results have implications for parenting interventions that may be targeted toward improving maternal sensitivity among cocaine-using mothers with more reactive infants.

Social behavior of offspring following prenatal cocaine exposure in rodents: a comparison with prenatal alcohol

Clinical and experimental reports suggest that prenatal cocaine exposure (PCE) alters the offsprings' social interactions with caregivers and conspecifics. Children exposed to prenatal cocaine show deficits in caregiver attachment and play behavior. In animal models, a developmental pattern of effects that range from deficits in play and social interaction during adolescence, to aggressive reactions during competition in adulthood is seen. This review will focus primarily on the effects of PCE on social behaviors involving conspecifics in animal models. Social relationships are critical to the developing organism; maternally directed interactions are necessary for initial survival. Juvenile rats deprived of play behavior, one of the earliest forms of non-mother directed social behaviors in rodents, show deficits in learning tasks and sexual competence. Social behavior is inherently complex. Because the emergence of appropriate social skills involves the interplay between various conceptual and biological facets of behavior and social information, it may be a particularly sensitive measure of prenatal insult. The social behavior surveyed include social interactions, play behavior/fighting, scent marking, and aggressive behavior in the offspring, as well as aspects of maternal behavior. The goal is to determine if there is a consensus of results in the literature with respect to PCE and social behaviors, and to discuss discrepant findings in terms of exposure models, the paradigms, and dependent variables, as well as housing conditions, and the sex and age of the offspring at testing. As there is increasing evidence that deficits in social behavior may be sequelae of developmental exposure alcohol, we compare changes in social behaviors reported for prenatal alcohol with those reported for prenatal cocaine. Shortcomings in the both literatures are identified and addressed in an effort to improve the translational value of future experimentation.

Cocaine addiction in mothers: potential effects on maternal care and infant development

Maternal cocaine addiction is a significant public health issue particularly affecting children, with high rates of reported abuse, neglect, and foster care placement. This review examines both preclinical and clinical evidence for how cocaine abuse may affect maternal care and infant development, exploring brain, behavioral, and neuroendocrine mechanisms. There is evidence that cocaine affects infant development both directly, via in utero exposure, and indirectly via alterations in maternal care. Two neural systems known to play an important role in both maternal care and cocaine addiction are the oxytocin and dopamine systems, mediating social and reward-related behaviors and stress reactivity. These same neural mechanisms may also be involved in the infant's development of vulnerability to addiction. Understanding the neuroendocrine pathways involved in maternal behavior and addiction may help facilitate earlier, more effective interventions to help substance-abusing mothers provide adequate care for their infant and perhaps prevent the intergenerational transmission of risk.

Impact of gestational cocaine treatment or prenatal cocaine exposure on early postpartum oxytocin mRNA levels and receptor binding in the rat

Prior research reported decreased oxytocin levels in specific brain regions correlated with disruptions in maternal care following gestational cocaine treatment in rats. Similarly, prenatal exposure to cocaine impaired subsequent maternal behavior in adulthood, but behavioral alterations were not associated with decreases in oxytocin levels in the same brain regions as were found in their cocaine-treated rat dams. To determine if other aspects of the oxytocin system are disrupted by cocaine treatment or prenatal exposure to cocaine during critical time points associated with maternal care, oxytocin mRNA transcription and receptor binding were examined on postpartum day two in relevant brain regions following gestational treatment with, or prenatal exposure to, either cocaine or saline. We hypothesized that oxytocin mRNA levels and receptor binding would be differentially affected by cocaine in the early postpartum period of dams and their offspring. Our findings indicate that gestational cocaine treatment resulted in significant increases in oxytocin mRNA levels in only the paraventricular nucleus of cocaine-treated dams, with almost significant increases in both generations in the supraoptic nucleus, but no significant effects of cocaine on receptor binding in either generation of dams. These findings indicate that in addition to oxytocin levels, cocaine treatment or prenatal exposure primarily affects oxytocin mRNA synthesis, with little effect on receptor binding in specific brain regions associated with maternal behavior in the early postpartum period of the rat.

Methamphetamine administration during gestation impairs maternal behavior

Previous studies demonstrated that repeated drug exposure, such as opiates or cocaine, during the gestation period attenuates maternal behavior of rats; however, it is not known whether methamphetamine (MA), a drug whose usage has increased recently, negatively affects maternal behavior as well. Therefore, the present study tested the hypothesis that repeated subcutaneous administration of MA (5 mg/kg daily) throughout the entire gestation period alters maternal behavior. Dams (control, saline-, and MA-treated) were observed with their pups in two types of tests. In the observation test, 11 types of activities and three types of nursing positions of mothers were recorded 10 times during each 50-min session for the 22-day lactation period. A decrease in nursing and active maternal behavior was found in MA-treated mothers relative to control rats. In addition, stereotypic behavior such as rearing and sniffing was increased in MA- as well as in saline-treated mothers relative to controls. All mothers, regardless of the treatment, displayed significantly less maternal behavior and more nonmaternal activities as postpartum time progressed. In the retrieval test, mothers also were tested for pup retrieval from postpartum Days 1 through 12. MA-treated mothers were slower in retrieving the first pup, returning the first pup into the nest, and returning all pups into the nest relative to controls or saline-treated mothers. Interestingly, the latency to return all pups to the nest was longer in saline-treated mothers relative to controls. In conclusion, the present study demonstrates a novel finding that MA administered during the gestation period has a negative effect on maternal behavior.

Maternal behavior is impaired by methamphetamine administered during pre-mating, gestation and lactation

Previous studies demonstrated that stimulant drugs, such as cocaine or amphetamine, administered during gestation or lactation may attenuate maternal behavior in rats. The effect of methamphetamine (MA), a drug whose usage has increased lately, on maternal behavior has not yet been investigated. The present study tested the effect of MA (5 mg/kg daily) administered prior to, during and after gestation on maternal behavior. Regularity of the estrous cycle, the incidence of impregnation, and the weight gain was compared between groups (control, saline- and MA-treated). Maternal behavior was examined using two tests: Observation test (without disturbance of the mother and pups) and Retrieval test (with short separation of pups from the mother). All tests were conducted prior to dosing each day. In the Observation test, MA decreased the blanket position of active nursing, while increasing passive nursing. There were no MA-induced changes in other maternal activities such as mother being in the nest, in contact with pups, or grooming pups. MA increased some non-maternal activities, such as drinking, eating, and sleeping, while decreasing stereotypic behavior (sniffing and rearing) when compared to controls. In the Retrieval test, MA-treated mothers were slower in retrieving the first pup, returning the first pup into the nest, and returning all pups into the nest. Interestingly, there were differences in maternal behavior also in saline-treated mothers relative to controls. Saline-treated mothers spent more time in the nest and groomed pups more than controls or MA-treated mothers. In conclusion, the present study demonstrates a novel finding that MA administered during pre-mating, gestational and lactational periods has a negative effect on maternal behavior toward pups.

Deficits in plasma oxytocin responses and increased negative affect, stress, and blood pressure in mothers with cocaine exposure during pregnancy

In animals, oxytocin enhances maternal behavior and lowers blood pressure (BP) and negative affect, while parturitional cocaine disrupts oxytocin activity and increases maternal neglect and aggression. Thus, we compared oxytocin, BP, maternal behavior, and affect in mothers of infants who used cocaine (cocaine, n = 10) or did not (no drug, n = 25) during pregnancy. Laboratory BP and circulating oxytocin, catecholamines, and cortisol were examined before and during a speech stressor on 2 days, with vs. without prestress baby holding. Ambulatory monitoring assessed BP, urinary norepinephrine, and cortisol for 24 h at home. The cocaine group had lower oxytocin levels, greater hostility and depressed mood, less support from others and mastery over life events, higher BP during all events of testing without the baby, and higher ambulatory BP and urinary norepinephrine at home, while cortisol and epinephrine responses were blunted. Although they tended to hold their babies less often at home, baby holding in the laboratory led to decreased BP in cocaine mothers who then did not differ from no-drug mothers in BP or observed affect.

Effects of sodium arsenite exposure on development and behavior in the rat

Arsenic is an environmental contaminant found in soil, water and air in some zones of the world. It has been widely studied for its effects as a human carcinogenic agent, but few studies have dealt with neurobehavioral effects. In addition, studies of arsenic effects on development have only addressed its effects on embryotoxicity and teratogenicity after a single oral, gavage or intraperitoneal exposure. Among the behavioral alterations reported after intoxication with arsenic are both increased and decreased locomotor activity and learning deficits in a delayed alternation task [Toxicol. Lett. 54 (1990) 345; Bull. Environ. Contam. Toxicol. 50 (1993) 100; Brain Res. Bull. 55 (2001) 301]. To further characterize developmental and behavioral alterations induced by arsenic exposure, Sprague-Dawley rats were exposed to arsenite (36.70 mg arsenic/l in drinking water) from gestation day 15 (GD 15) or postnatal day 1 (PND 1), until approximately 4 months old. The pregnant or lactating dams received either the arsenic solution or regular drinking water and once pups were weaned, they continued receiving the same solution as drinking water. Animals exposed from GD 15 showed increased spontaneous locomotor activity and both exposed groups showed increased number of errors in a delayed alternation task in comparison to the control group. Total arsenic (TA) content in brain was similar for both exposed groups and significantly different from the control group. These results indicate that rats exposed to arsenic during development present deficits in spontaneous locomotor activity and alterations in a spatial learning task.

Dose-related effects of chronic gestational cocaine treatment on maternal aggression in rats on postpartum days 2, 3, and 5

Gravid Sprague-Dawley rats received subcutaneous injections of saline, 3.5, 7.5 or 15 mg/kg of cocaine, twice daily, throughout gestation. On postpartum days 2, 3, and 5, dams and their litters (surrogate or natural) were videotaped for 10 minutes in the presence of a male rat for assessment of aggression towards the intruder. Oxytocin levels in discrete brain areas were assayed on postpartum day 5. The 30 mg/kg dose group had a significantly greater increase in the frequency of threats from postpartum day2 through postpartum day 5 than the 7.5 mg/kg cocaine and the non-yoke-fed saline control groups. Dams with natural litters exhibited a significantly greater frequency of receptive behavior compared to dams with surrogate litters. There were no significant differences in oxytocin levels between the 30 mg/kg cocaine-treated group and the other treatment or control groups on postpartum day 5. There are very few statistically significant cocaine-induced increases in maternal aggressive behavior and no dose-dependent decreases in amygdaloid OT levels in the early postpartum period.

Acute cocaine alters oxytocin levels in the medial preoptic area and amygdala in lactating rat dams: implications for cocaine-induced changes in maternal behavior and maternal aggression

Acute cocaine administration has been correlated with disruptions in the onset and maintenance of maternal behavior as well as decreases in maternal aggressive behavior in rat dams. A growing body of evidence suggests that cocaine may alter oxytocin levels leading to impairments in maternal behavior and aggression. The current study assessed whether acute cocaine injections alter oxytocin (OT) levels in the medial preoptic area (MPOA), ventral tegmental area (VTA), amygdala (AMY), and hippocampus (HIP) on postpartum day (PPD) 1 or PPD 6. On PPD 1, 30 mg/kg cocaine reduced OT levels by approximately 26.9% (picograms/milligram) in the MPOA (t (18) = 3.44, P<.01) compared to saline. On PPD 6, 30 mg/kg cocaine significantly increased OT levels by approximately 20.9% (picograms/brain area) in the AMY (F (2,25) = 3.44, P=.05) relative to saline. These findings suggest that acute cocaine may disrupt maternal behavior and maternal aggression at least in part through its action on the oxytocinergic system.