Fetal homologue of infant crying.

Four behavioural states are recognised in the human fetus and are comparable to those of the neonate: 1F (quiet sleep), 2F (active state), 3F (quiet awake), and 4F (active awake). State 5, or crying, is not considered to have a fetal correlate. In a study assessing the effects of exposure to tobacco and cocaine during pregnancy on fetal response and habituation to vibroacoustic stimulation, what appears to be the fetal homologue of crying was observed. These behaviours were seen on ultrasound, and have been captured on video recordings and include: an initial exhalation movement associated with mouth opening and tongue depression, followed by a series of three augmented breaths, the last breath ending in an inspiratory pause followed by an expiration and settling. This is the first report/video documenting these behaviours and suggests the possibility of a state 5F.

Effects of maternal cigarette smoking and cocaine use in pregnancy on fetal response to vibroacoustic stimulation and habituation.

BACKGROUND: Cigarette smoking and cocaine use in pregnancy are common in the US and both are risk factors for sudden infant death syndrome (SIDS). Although the cause of SIDS is not known, one postulated mechanism involves abnormalities of arousal and arousal regulation. Cigarette smoking and cocaine use may cause deficits of arousal. Many believe arousal deficits occur prenatally. AIMS: The aim of this study was to assess the effects of cigarette smoke and cocaine exposure during pregnancy on measures of fetal arousal and arousal competency: 1) the fetal response to vibroacoustic stimulation (VAS) and 2) habituation to VAS. HYPOTHESIS: Maternal cigarette smoking and cocaine use in pregnancy are associated with altered arousal and arousal regulation in the fetus. METHODS: Three groups of mother-fetal dyads were enrolled: 1) cigarette smokers (n = 54), 2) cocaine users (n = 30), and 3) controls (n = 60). One hundred eight fetuses were tested at 29-31 wk gestation, 119 at 32-35 wk, and 118 at 36+ wk. The fetal response to VAS was assessed using real-time ultrasound and a paradigm of arousal responsiveness. Responders were tested with repeated VAS to assess habituation. Also, the quality of fetal reactivity to repeated stimuli was assessed as a measure of arousal and arousal regulation competence (Behavioral Reactivity Scale). RESULTS: The control group had a larger proportion of fetuses who were too active to initiate testing ("too active to test") (p = 0.013); the proportion of fetuses too active to test decreased with increasing gestational age. The majority of the fetuses who could be tested responded to the initial VAS, and there were no group differences. The proportion of fetuses that habituated and the rate of habituation did not differ between the groups. Behavioral reactivity did not differ between groups. CONCLUSIONS: The original hypotheses were not confirmed. However, the chosen assessment paradigms may have lacked sensitivity. The proportion of fetuses that were "too active to test" decreased with gestational age. The control group had a larger proportion of fetuses that were "too active to test" compared with the exposure groups. We speculate that these findings indicate that prenatal exposure to these neuroteratogens may have produced an acceleration of the behavioral response to vibroacoustic stimulation.

State control in the substance-exposed fetus. I. The fetal neurobehavioral profile: an assessment of fetal state, arousal, and regulation competency.

Behavioral states are stable structures of behaviors that become more definable and coordinated with increasing age. With ultrasound we can see the fetus move, breathe, and react to changes in its environment. Ultrasound used in conjunction with Doppler fetal heart rate recording provides behavioral and neurophysiologic data useful in state determination. The Fetal Neurobehavioral Profile (FNP) was developed by our group as an assessment of fetal behaviors reflecting CNS integrity in the drug-exposed fetus. The FNP was designed to parallel methods of examining the newborn infant, especially in state-related behaviors. The FNP measures: fetal responsiveness and arousal after environmental perturbation with vibroacoustic stimulation (VAS); habituation to VAS; state recovery; and self-regulation post-VAS. From the behavioral and physiologic recordings, the constructs of state differentiation, organization, and regulation as well as fetal arousal and regulation competency can be measured. Previous work using the FNP showed that those fetuses with abnormal or suspect fetal state regulation demonstrated impaired performance on the NBAS (Am. J. Obstet. Gynecol. 161: 685, 1989). To expand these observations, three populations are currently being studied: prenatal nicotine-exposed, prenatal cocaine-exposed, and controls. Data are from 97 women/fetus dyads and a total of 236 FNP at ages 28-30 weeks gestational age, 31-34 weeks gestational age, and > 36 weeks gestational age. Although there are no group differences in the ability to achieve state by 36 weeks, interesting trends emerge: fetuses prenatally cocaine-exposed spend less time in 1F, more time in 4F and have fewer transitions. At FNP, fewer cocaine-exposed fetuses had an initial reaction to VAS, whereas fewer nicotine-exposed fetuses habituated. Although the ability to habituate to VAS did not discriminate the cocaine group from the control or nicotine groups, the number of stimuli required for habituation differed between groups: 7 for the cocaine-exposed, 3 for the nicotine, and 5 for the control groups. Thus latency, a measure of arousal, differs among the groups Preliminary data also suggest a correlation of prenatal data with postnatal outcome.

Prenatal cocaine and/or nicotine exposure in rats: preliminary findings on long-term cognitive outcome and genital development at birth.

Prenatal cocaine or nicotine exposure is associated with a variety of teratogenic effects. The current study was conducted to determine their effects alone and in combination on cognitive function and sexual differentiation. Pregnant Long-Evans rats (N = 19) were exposed to either cocaine (15 mg/kg/dose b.i.d. SC on GD 8-20); nicotine (4 mg/kg/day continuous SC infusion on GD 4-20); both nicotine + cocaine; or vehicle only. Birth weight and anogenital distance (AGD) were measured in all pups at birth. Learning and memory were tested in the Morris water maze (MWM) during prepubertal and pubertal ages in five daily consecutive sessions and a sixth session 1 week later and in the radial-arm maze (RAM) during adulthood. In the RAM, a drug challenge of the beta-noradrenergic antagonist propranolol (10-20 mg/kg) was given after acquisition training. Maternal weight gain was reduced 13-42% and offspring birth weight was reduced by 7-12% in all three exposure groups compared to controls. Cocaine decreased the AGD of males (2.68 mm) compared to 2.88 mm in noncocaine-exposed male pups (p < 0.025). A sex-selective cocaine effect was also seen after adjustment of AGD measurements for body weight. With this measure cocaine-treated females showed significantly (p < 0.05) greater AGD than those not exposed to cocaine. In the MWM, there were two types of trials: cued reference memory trials and uncued spatial working memory trials. On cued reference memory trials significant cocaine-induced latency deficits were seen on only the first session. On spatial working memory trials cocaine-induced latency deficits were seen throughout daily training on sessions 1-5, but not the retention session 6, 1 week later. During RAM acquisition, there were no significant differences in choice accuracy between exposure groups. Following propranolol challenge, deficits in choice accuracy were demonstrated in rats prenatally exposed to cocaine or nicotine. These rats did not show any response to propranolol, whereas the controls slightly improved their choice accuracy. The results of this study indicated that prenatal cocaine exposure altered long-term cognitive function under basal conditions in the MWM and drug challenge in the RAM, birth weight, and genital development. Cocaine-induced cognitive deficits were predominately in working memory rather than reference memory or long-term retention. Prenatal nicotine exposure was only observed to alter birth weight and cognitive function in response to propranolol challenge in the RAM.

Developmental characteristics in the daily rhythm of norepinephrine concentration within rabbit brainstem regions.

To examine the development of daily variations in norepinephrine levels, norepinephrine concentrations were measured within five distinct brainstem regions in 3-day-old, 21-day-old, and adult rabbits at 6-h intervals throughout the day. Norepinephrine was measured by radioenzymatic assay, and norepinephrine concentration was expressed relative to wet tissue weight. The data suggest that daily variations for norepinephrine concentrations are established by the third day of life. In the brainstem as a whole, there was an early nocturnal peak (2130 hours) for 3-day-old animals in contrast to a late nocturnal peak (0330 hours) for 21-day-old animals. Adult animals showed a late diurnal (1530 hours) peak. These gross daily variations constitute the sum of distinct region-specific patterns in the development of daily variations in norepinephrine concentration. Norepinephrine is involved in cardiorespiratory regulation and in the regulation of sleep/wake cycles. The observed developmental patterns may relate to the maturation and integration of these physiologic processes.

Maternal polydrug use including cocaine and postnatal infant sleep architecture: preliminary observations and implications for respiratory control and behavior.

Twelve-hour overnight pneumocardiograms were assessed for sleep architecture and sleep efficiency in two groups of healthy term newborn infants: a group exposed prenatally to cocaine alone or in combination with other drugs and a non-exposed group. Sleep was differentiated from wakefulness by an increase in heart rate, an increase in or variation in the duration and amplitude of the respiration and increased artifacts on the heart rate channel. Quiet and active sleep were determined by the regularity or irregularity of heart rate and respiration. In a sub-set of infants, the number of arousals during active sleep was calculated. Overall significance was confirmed by ANOVA followed by paired comparisons using the Student's-test. When compared to non-exposed infants within the first week of life, infants exposed prenatally to cocaine alone or in combination with other drugs demonstrated more wakefulness and less sleep (P < 0.05), more frequent arousals during active sleep (P < 0.01), and the tendency of a higher proportion of active sleep compared to quiet sleep. These findings may have implications to both behavioral and respiratory control findings associated with prenatal cocaine exposure.

Ontogeny of dopamine daily rhythms within rabbit brainstem regions.

To examine the development of daily variations in dopamine levels, we measured dopamine concentrations within five distinct brainstem regions in 3- and 21-day-old, and adult rabbits at 09.30, 15.30, 21.30 and 03.30 h. Dopamine was measured by radioenzymatic assay and the dopamine concentration was expressed relative to wet tissue weight. In addition to defining the presence of a daily variation in the dopamine concentration in the whole brainstem, we were interested in identifying brainstem region-specific differences in this daily variation. Our data suggest that daily variations in dopamine concentrations are established by 3 days of life. Analysis of gross brainstem daily variation data suggest a peak in the dopamine concentration during the early light phase (09.30 h) for 3-day-old animals in contrast to a late light phase peak (15.30 h) for 21-day-old animals. Adult animals showed a peak in the early dark phase (21.30 h). These gross daily variations reflect the net sum of distinct region-specific patterns in the dopamine concentration. Analysis by region reflects a region-specific ontogeny in the development of daily variations for dopamine. Dopamine is involved in cardiorespiratory regulation. The observed developmental patterns may relate to the maturation and integration of these physiologic processes.

Pre- and postnatal effects of chronic maternal hypoxia on substance-P immunoreactivity in rabbit brainstem regions.

The effect of chronic maternal hypoxia on substance-P immunoreactivity (SPI) was examined in brainstem regions of fetal (gestational day E-28), neonatal (postnatal days 3, 7, 14, 21), and adult rabbits. Time-dated pregnant rabbit does were housed in environmental chambers at gestational day E-10. Between E-14 and E-28, the pregnant does were separated into two groups. Group 1, the control group, breathed 21% O2/79% N2 and group 2 the hypoxia-exposed group, breathed 12-14% O2/86-88% N2. Sacrifice occurred at various days depending on the experimental paradigm. On gestational day E-28, 6 pregnant animals were delivered by hysterotomy and the pups were immediately sacrificed. On and after gestational day E-28, the remaining 12 pregnant animals breathed room air. These animals delivered spontaneously between E-30 and E-32 and the pups remained with their mothers until sacrifice. On postnatal days 3, 7, 14, and 21, SPI was measured by radioimmunoassay in the colliculi (fetal animals), superior and inferior colliculi (postnatal analysis), pons and medulla (both groups). In both prenatally normoxia- and hypoxia-exposed animals, SPI was highest in the medulla, intermediate in the pons and lowest in the colliculi. SPI increased with development. Chronic maternal hypoxia did not alter the caudal-rostral profile nor did it alter the maturational increase in SPI. However, chronic maternal hypoxia increased SPI in prenatal animals and decreased SPI in postnatal animals at 14 and 21 days of life but not in postnatal 3- and 7-day-old animals. These data support the concept that regional differences exist in basal SPI within the brainstem of fetal and neonatal animals, and that maternal hypoxia has both immediate and long-term effects on brainstem SPI.

Prenatal cocaine exposure alters postnatal hypoxic arousal responses and hypercarbic ventilatory responses but not pneumocardiograms in prenatally cocaine-exposed term infants.

To test the hypothesis that respiratory control is altered in cocaine-exposed infants, we evaluated the hypoxic arousal response and the ventilatory response to carbon dioxide (CO2) in 18 term newborn infants prenatally exposed to cocaine and in 10 healthy, term newborn infants within the first week of life. Three infants could not be tested for the hypoxic arousal response because of low baseline oxygen saturation, and data from these infants were excluded from analysis. Twelve hour overnight pneumocardiograms were performed on all infants. Results show that 60% (9/15) of the prenatally cocaine-exposed infants had an abnormal hypoxic arousal response and 87% (13/15) had abnormal hypercarbic ventilatory response. Only 6% (1/15) of the prenatally cocaine-exposed infants demonstrated any abnormality on pneumocardiogram. In contrast, all control infants (10/10) were aroused by the hypoxic challenge and 80% (8/10) had normal ventilatory response to CO2. No abnormalities were found in the assessment of the overnight pneumocardiogram in the control infants. For the cocaine-exposed infants, test abnormalities were not correlated with a concurrent positive urine toxicology for cocaine, suggesting that the injury occurs early in development. These findings support the hypothesis that infants prenatally exposed to cocaine demonstrate abnormalities of respiratory control.

Ultrasound diagnosis of fetal anomalies associated with in utero cocaine exposure: further support for cocaine-induced vascular disruption teratogenesis.

The dramatic increase in cocaine use over the past decade has led to a concern about its possible teratogenicity. We have identified 6 structural fetal anomalies which we postulate may have cocaine-induced vascular accidents as the teratogenic mechanism: 2 complex choroid plexus cysts, gastroschisis, meconium peritonitis, urethral stenosis, and radial hypoplasia. Two additional anomalous neonates were born to perinatal cocaine users. Eight of 51 (15.7%) cocaine-exposed perinates exhibited anomalies versus 120 of 2,194 (5.4%) perinates without known cocaine exposure during this time period. This represents a 3-fold relative risk (RR = 2.87, OR = 3.22, chi square = 9.68, p < 0.005) for the cocaine-exposed fetus. Subjects were all identified as cocaine users prior to ultrasound-detected anomaly and ultrasonologists were blinded to maternal drug history. The vascular disruption model as the plausible mechanism for cocaine-associated teratogenesis is supported by the type of anomalies reported. In addition, cocaine use was prospectively determined to have occurred at the critical developmental period in each case.

Prenatal cocaine exposure alters postnatal ornithine decarboxylase activity in rabbit brain.

Ornithine decarboxylase, a modulator of tissue growth during fetal and neonatal mammalian development, serves as a sensitive marker enzyme for perturbations in neural development. To test the hypothesis that cocaine is a central nervous system neurodevelopmental teratogen through mechanisms involving direct cellular injury, we measured ornithine decarboxylase activity in brain sections of 4- to 6-day-old rabbit pups which were prenatally cocaine exposed and in pair-fed and free-fed controls. Rabbit does were implanted with the osmotic minipump prior to Gestational Day 10 and cocaine and/or sterile water was delivered between Gestational Days 10 and 32. The flow rate in the cocaine group was calculated to provide a daily cocaine dose of 30 mg/kg/day. Pups were sacrificed, brains were dissected into the cortex, pons, and medulla, and ornithine decarboxylase activity was measured. When compared to the pair-fed group, prenatal cocaine exposure significantly decreased ornithine decarboxylase activity in the cortex (0.531 +/- 0.070 nmol/g/h SEM vs 0.913 +/- 0.201 nmol/g/h SEM; cocaine vs pair fed, respectively; P < or = 0.05) and in the pons (0.533 +/- 0.036 nmol/g/h SEM vs 0.728 +/- 0.075 nmol/g/h SEM, cocaine vs pair fed, respectively; P < or = 0.05) but not in the medulla (0.374 +/- 0.040 nmol/g/h SEM vs. 0.392 +/- 0.045 nmol/g/h SEM, cocaine vs pair fed, respectively; P > 0.05). Although there were no statistically significant differences in ornithine decarboxylase activity between the cocaine-exposed group and the free-fed group in any brain region, all regions showed a relative decrease in ornithine decarboxylase activity with prenatal cocaine exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Cocaine and development: mechanisms of fetal toxicity and neonatal consequences of prenatal cocaine exposure.

As cocaine use during pregnancy has become increasingly recognized, there also has been increased concern about the toxic and teratogenic properties of cocaine on the fetus. A significant literature exists describing the adverse fetal and neonatal outcomes associated with in utero cocaine exposure. However, specific causality by cocaine on outcome in the human is difficult to ascertain because of multiple confounding variables associated with substance abuse including social factors and polydrug use as well as difficulty in confirming timing, dose and frequency of cocaine exposure. Most literature suggests that prenatal cocaine exposure is associated with developmental risk to the fetus. What is currently unknown is the extent of risk, the additive and/or synergistic factors contributing to cocaine's toxicity and the reversibility of the injury. In this paper we review the pharmacologic properties of cocaine as related to a model of mechanisms for developmental injury secondary to cocaine exposure and the published literature on the adverse fetal and neonatal outcomes associated with cocaine use during pregnancy. Specific attention has been focused on the structural, neurobehavioral and respiratory control teratogenesis.

Effects of prenatal cocaine on the ventilatory response to hypoxia in newborn rabbits.

Recently, investigators have reported an alteration of postnatal respiratory pattern, deficient hypoxic arousal from sleep, and an increased incidence of sudden infant death syndrome (SIDS) among human infants exposed to cocaine prenatally, thus suggesting that prenatal cocaine exposure may perturb the maturation of respiratory control thereby increasing the risk for SIDS. To investigate the effects of prenatal cocaine on postnatal respiration, we evaluated the ventilatory response to 0.21 FIO2 (baseline) and at 0.15, 0.10, and 0.08 FIO2 by the barometric method on days 4-5 of life in 23 New Zealand White rabbit pups born to cocaine-exposed (30 mg/kg/day of cocaine HCl by continuous subcutaneous infusion), pair-fed and free-fed does. The chamber pressure deflection (proportional to VT after appropriate calculation) was computer-sampled at 200 Hz when the unanesthetized pups were resting quietly with no gross body movements. Recording was made after 10 min acclimatization to a specific FIO2. We found that baseline ventilation did not differ significantly among study groups. However, minute ventilation (VI), inspiratory flow (VT/TI), tidal volume (VT), increased significantly with hypoxia to peak values at 0.08 FIO2 in pair-fed and free-fed pups but these measurements did not increase significantly in cocaine-exposed pups. Our finding of a deficient second phase of the hypoxic ventilatory response among cocaine-exposed pups supports the hypothesis that prenatal cocaine perturbs the maturation of respiratory control.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of prenatal cocaine exposure on perinatal morbidity and postnatal growth in the rabbit.

Prenatal cocaine (CC) exposure may result in increased fetal loss, growth retardation, altered neurodevelopment, and sudden infant death syndrome (SIDS). We sought to establish an animal model for prenatal cocaine exposure which (1) would allow us to distinguish the direct effects from the indirect and nutritional effects of the drug, and (2) might be used to address questions of cocaine's toxicity, specifically to the developing respiratory control system. The study design included 38 New Zealand White rabbit does among CC, pair-fed (PF), and free-fed (FF) groups. Miniosmotic pumps were implanted in each doe on day 10 of timed gestation providing continuous subcutaneous administration of either 30 mg/kg/day of cocaine HCl in H2O (CC) or sterile H2O alone (PF and FF). Mean (SEM) plasma cocaine concentration was 1.71 +/- 0.21 mumol/l (519.4 +/- 64.4 ng/ml). Pregnancy outcome compared for incidence of stillbirth, maternal death, spontaneous abortion, and gross malformation among 211 pups was significant only for increased stillbirths among CC pups (18%, p less than 0.04) as compared to PF (6%) and FF pups (7%). External and renal malformation and postnatal weight, crown-rump length, and snout-occiput head circumference for pups aged 4 and 5 days of age did not differ among groups. The direct effects of prenatal cocaine evaluated in our model do not reproduce the altered perinatal outcome observed among humans. However, our results do not determine if physiologic function has been altered. Investigation of the physiologic and pathologic abnormalities that are relevant to this human condition, specifically to the developing respiratory control system, should add clarity to the mechanism of action of cocaine during pregnancy.

Maternal cocaine addiction. II: An animal model for the study of brainstem mechanisms operative in sudden infant death syndrome.

Respiratory control abnormalities are mechanistic in Sudden Infant Death Syndrome (SIDS). In particular, arousal form sleep is an important component of respiratory regulation. Cocaine alters central neurotransmitter metabolism, particularly the monoamines. The locus coeruleus, the major Norepinephrine (NE) neuronal system, is involved in arousal from sleep related apnea and has extensive forebrain and brainstem projections. Thus, it is plausible that in utero cocaine exposure disrupts the normal maturation of transmitters and/or brain structures essential to sleep related respiratory regulation. Infants exposed to cocaine in utero may have an increased incidence of SIDS. We propose that cocaine use in pregnancy alters the normal maturation of centers and/or neurotransmitters involved in respiratory regulation thereby altering postnatal respiratory control. We hypothesize that the increased incidence of SIDS in cocaine exposed infants may be secondary to deficits in arousal. The study of prenatal brain development and of postnatal respiratory control in rabbit pups exposed to cocaine in utero will provide a useful model for the study of mechanisms operative in SIDS.

Maternal cocaine addiction and fetal behavioral state. I: A human model for the study of sudden infant death syndrome.

Abnormalities of respiratory regulation, such as apnea and abnormal hypoxic arousal during sleep, are mechanistic in the pathophysiology of SIDS. In utero cocaine exposure is associated with poor head growth, abnormal neurodevelopment, and an increased incidence of sudden, unexplained death, suggesting that in utero cocaine exposure disrupts the central regulation of breathing. It is likely that this disruption is due to altered CNS maturation. Indeed, cocaine alters norepinephrine metabolism within the locus coeruleus, important in arousal from sleep, suggesting that the increased incidence of SIDS in cocaine exposed infants may be secondary to sleep-related deficits in arousal. Since components of fetal behavioural state organization reflect the successful integration of the Central Nervous System, have a specific developmental timetable, and can be studied by fetal ultrasound techniques, we developed a strategy for assessing the state organization of the fetus by ultrasound techniques. We hypothesize that fetal evaluation of state will be a marker of abnormal CNS maturation and a predictor of risk, i.e. abnormal neurodevelopment and/or state related arousal deficits predisposing the cocaine exposed neonate to SIDS. We propose that the study of in utero cocaine exposed fetuses will provide a human model for examining the pathophysiology of SIDS.

Systemic Torulopsis glabrata infection in a neonate.

We have reported a case of neonatal Torulopsis glabrata peritonitis and ventriculitis associated with a ventriculoperitoneal shunt. Treatment of fungemia and ventriculitis with amphotericin B and 5-fluorocytosine was successful.

Developmental characteristics in the daily rhythm of serotonin concentration within rabbit brainstem regions.

To examine the development of daily rhythms in serotonin levels, we measured serotonin concentration within five distinct brainstem regions in 3-day-old, 21-day-old and adult rabbits at 09.30, 15.30, 21.30 and 03.30. Serotonin was measured by radioenzymatic assay in the superior and inferior colliculi, rostral pons, caudal pons and medulla, and serotonin concentration was expressed relative to wet tissue weight. In addition to defining the presence of a daily rhythm in serotonin concentration in whole brainstem, we were interested in identifying brainstem region-specific differences in this rhythm. Our data suggest that daily rhythms for serotonin are established by 3 days of life. Analysis of gross brainstem rhythm data suggests a nocturnal peak in serotonin concentration in 3-day-old and adult animals in contrast to a diurnal peak for 21-day-old animals. These gross rhythms reflect the net sum of distinct region-specific patterns in serotonin concentration. Analysis by region reflects a region-specific ontogeny in the development of daily rhythms in serotonin concentration. Serotonin is involved in the initiation of sleep. The observed developmental patterns may relate to the maturation and integration of sleep/wake states.

In utero cocaine exposure: observations of fetal behavioral state may predict neonatal outcome.

Components of fetal behavioral state organization reflect the successful integration of the central nervous system, have a specific developmental timetable, and can be studied with fetal ultrasonographic techniques. To test the hypothesis that evaluation of state organization is a marker of abnormal central nervous system maturation and a predictor of risk, we studied 20 fetuses and newborns exposed to cocaine in utero. Fetal assessments were accomplished by serial ultrasonographic examination, videotaped, and scored by a scheme developed by the authors to assess organization and regulation of behavioral states. Newborn neurobehavioral assessments also emphasized organization and regulation of behavioral state. Abnormal or delayed state behavior was identified in 13 of 20 fetuses. State organization was evaluated as suspect or abnormal for 16 of the 20 exposed newborns. Disorganized behavioral state in the fetus successfully predicted abnormal newborn behavior. These findings support the concepts that cocaine exposure disrupts central nervous system development and that fetal assessment of state is predictive of neonatal outcome.

Development of daily variations in methionine enkephalin within rabbit brainstem regions.

To examine the development of daily variations in methionine enkephalin, we measured methionine enkephalin concentration within five distinct brainstem regions in 3-day-old, 21-day-old, and adult rabbits at 09.30, 15.30, 21.30 and 03.30 h. Methionine enkephalin was measured by radioimmunoassay and methionine enkephalin concentration was expressed relative to wet tissue weight. In addition to defining the presence of a daily variation in methionine enkephalin concentration in the whole brainstem, we were interested in identifying brainstem region specific differences in this daily variation. Our data suggest that daily variations for methionine enkephalin are established by three days of life. Analysis of gross brainstem daily variation data suggests a nocturnal peak in methionine enkephalin concentration for 3-day-old animals in contrast to a diurnal peak for 21-day-old animals. Adult animals, showed a biphasic pattern. These gross daily variations reflect the net sum of distinct region specific patterns in methionine enkephalin concentration. Analysis by region reflects a region specific ontogeny in the development of daily variations for methionine enkephalin. Our data also suggest a caudal-rostral progression in the establishment of daily rhythms. Methionine enkephalin is involved in nociception and cardiorespiratory regulation. The observed developmental patterns may relate to the maturation and integration of these physiologic processes.