Fetal associative learning mediated through maternal alcohol intoxication.

BACKGROUND: The aim of the present study was to analyze whether alcohol as an unconditioned stimulus is capable of supporting associative learning in near-term fetuses. METHODS: In experiment 1, we determined pharmacokinetic profiles of alcohol and of an aromatic substance (cineole) in amniotic fluid and maternal blood during late gestation. The results obtained through gas chromatographic analysis allowed a second experiment in which we explicitly paired peak levels of cineole with peak levels of alcohol in amniotic fluid and blood, by intragastrically administering cineole and ethanol to the dams during gestational days 17 through 20 (paired condition). Control groups were dams given cineole 4 hr before commencement of an acute state of alcohol intoxication (long-delay group) or were only exposed to water administrations (water control group). The progeny were evaluated during postnatal day 16 in terms of behavioral responsiveness to intraorally infused solutions (cineole or alcohol presented in milk vehicle, or milk alone). RESULTS: Mouthing responsiveness to cineole was strongly affected by the nature of prenatal treatments. Pups in the paired prenatal condition mouthed significantly less than did long-delay and water controls. Physical and behavioral measures allowed us to reject the possibility that these effects were due to teratogenic effects of alcohol during late gestation. CONCLUSIONS: These results indicate that before birth, rat fetuses are capable of acquiring associative memories supported by the unconditioned properties of alcohol. This associative memory can be expressed during infancy through a significant reduction in mouth movements in the presence of the specific orosensory cue explicitly paired with alcohol interoceptive effects in utero.

Interactions between perinatal and neonatal associative learning defined by contiguous olfactory and tactile stimulation.

Tactile stimulation of the neonate, as performed by the mother during and after delivery, has been described as an effective unconditioned stimulus during early ontogeny (Leon, 1987; Ronca & Alberts, 1994). The present experiments examined the interaction between perinatal and neonatal learning determined by the explicit association between alcohol odor and vigorous body stimulation of the perinatal organism. In Experiment 1, rat fetuses were exposed to either alcohol or saline 10 min prior to cesarean delivery. The alcohol administration procedure here employed was sufficient to provide sensory contamination of the amniotic fluid but avoid fetal alcohol intoxication. Pups in the two prenatal treatments later experienced the smell of alcohol, tactile stimulation, or both stimuli explicitly paired or unpaired. Other postnatal groups were composed of pups that had no explicit experience with either experimental stimulus. Pups subjected to alcohol odor in utero displayed more overall motor activity in response to that odor than saline controls. The increased motor responses were further potentiated in pups that experienced additional postnatal alcohol odor paired with tactile stimulation. In Experiment 2, pups were exposed to alcohol in the amniotic fluid 10 or 30 min prior to birth. As previously demonstrated the memory acquired in utero appears highly dependent upon contingency between exposure to this particular scent and delivery procedures. Pups in both prenatal treatment groups were then exposed to alcohol odor paired or unpaired with tactile stimulation. Some control animals received no further experience with either stimuli. Those pups exposed to alcohol odor paired with tactile stimulation both pre- and postnatally later showed maximum motor activity elicited by the odor of alcohol. The results support the notion of fetal associative learning comprising alcohol's chemosensory cues and behaviorally activating stimuli. Furthermore, the conditioned response under analysis is potentiated whenever neonates are reexposed to contingent presentations of the elements that defined the original associative memory.

Neonatal responsiveness to alcohol odor and infant alcohol intake as a function of alcohol experience during late gestation.

It has been previously suggested that maternal alcohol intoxication during the last days of pregnancy promotes fetal experiences that include chemosensory processing of the drug. In this study pregnant Wistar-derived rats were administered saline or one of two alcohol doses (1 or 2 g/kg) during gestational days 17-20. Immediately after birth, pups were tested in regard to motor-eliciting properties of the odor of amniotic fluid or alcohol, or of these stimuli presented as a configuration. Saline controls showed significantly shorter duration of overall motor activity and head movements when stimulated with the biological cue (amniotic fluid) than when exposed to a novel stimulus (ethanol alone or configured with the amniotic fluid). The opposite pattern was found in pups with prenatal experience with the higher alcohol dose. In a second experiment, the impact of similar alcohol treatments on infant consumption of different tastants, including alcohol and a configuration of sucrose and quinine, was tested. This configuration appears to mimic psychophysical properties of ethanol. Consumption of water, sucrose, or quinine was unaffected by the prenatal status of the subjects. Antenatal alcohol experience with the lower alcohol dose (1 g/kg) increased both alcohol and sucrose-quinine consumption. The 2 g/kg alcohol animals also ingested more sucrose-quinine relative to saline controls. As a whole, the results confirm the hypothesis that an intrauterine alcohol sensory memory selectively affects neonatal recognition of the alcohol's olfactory attributes and infant intake of either alcohol or solutions that share certain sensory equivalence with this psychopharmacological agent.

Perinatal responsiveness to alcohol's chemosensory cues as a function of prenatal alcohol administration during gestational days 17-20 in the rat.

Rat fetuses proximal to birth process alcohol-derived cues when the drug is directly delivered into the amniotic fluid. Prior evidence indicates that chemosensory sensation is detected during gestational Day 17 (GD17). In the present study Wistar-derived pregnant females received 0, 1, or 2 g/kg/day of alcohol (intragastric intubation) during GDs 17-20. Prenatal treatment failed to affect different maternal-fetal and perinatal physical parameters, e.g., placenta weight, umbilical cord length, offspring's body weights, weights and/or size of the olfactory bulbs, cerebral hemispheres, and cerebellum. Alcohol chemosensory responsiveness assessed in a perinatal motor activity test, indicated that pups pretreated with the 1 and 2 g/kg alcohol dose exhibit significant decrements in their activity rate when alcohol odor is presented in the test chamber. Alcohol concentrations in maternal and fetal blood and in the amniotic fluid were also recorded through head-space chromatography 1 h after females received the last intubation procedure (GD20) with the 1 or 2 g/kg alcohol doses. Dose-dependent alcohol concentrations across the different sites of assessment were recorded. As indicated by previous studies, even the alcohol level in the amniotic fluid attained with the 1 g/kg alcohol dose is above threshold values in terms of allowing fetal chemosensory stimulation with alcohol-derived cues. The results suggest that maternal ethanol intoxication during the last days of pregnancy leads to fetal exposure to alcohol's sensory attributes and that this experience subsequently modifies responsiveness to these cues.

Aversions to alcohol's orosensory cues in infant rats: generalization to compounds of alcohol with sucrose or sodium chloride.

Prior research has demonstrated that rat pups perceive alcohol's orosensory consequences during an acute state of intoxication with the drug and are able to associate these orosensory stimuli with aversive reinforcement. The present two experiments tested whether the resulting conditioned aversion to ethanol orosensory consequences generalized to two basic tastants (sucrose or sodium chloride) and if ethanol's orosensory consequences were detected when this agent was configured with these tastants. Conditioned aversions to alcohol were expressed only in rejection of an intraoral infusion of an ethanol solution alone or ethanol in compound with sucrose (experiment 1). A sucrose aversion was recorded in pups that had been subjected to infusions of a sucrose-ethanol compound paired with aversive reinforcement. An aversion to sodium chloride was not induced, however, by analogous procedures (experiment 2). The results indicate that, as in adults, ethanol aversions do not generalize directly to sucrose alone or sodium chloride alone. The infant is, however, capable of detecting the drug in compound with sucrose, and an acquired aversion to ethanol can be transferred to sucrose through ingestion of a sucrose-alcohol compound.

[Properties of white sorghum diastatic malt]. / Propiedades de malta diastásica de sorgo blanco.

Diastatic malt enzymes have potential to hydrolize pregelatinized starches releasing soluble sugars, lowering viscosity of slurries and allowing the use of high nutrient densities for preparation of cereal-based creams, baby food and drinks. Determination of the extent in which sorghum malt is able to develop desirable functional properties such as viscoty, water solubility and nutritional quality is fundamental. In this work the characteristics of a white sorghum during germination and the resulting malt were evaluated. "Dorado" white sorghum was germinated at 28 degrees C and 95% RH during 6 days in complete darkness, dried at 55 degrees C and ground to produce diastatic malt flour. Physicochemical, chemical, diastatic and nutritional characteristics of malt and its ability to liquify precooked flour slurries were determined. Maximum diastatic activity occurred at 3-4 days germination. Dry matter loss increased during germination at a rate of 2.7 percent units per day. Longer germination resulted in increased dry matter loss and decreased diastatic activity. Water solubility index of sorghum increased linearly during the first 5 days of germination probably caused by the production of soluble sugars and free amino acids. In vitro protein digestibility, lysine content and C-PER increased during germination. Sorghum malt was able to liquify precooked rice, wheat, oats or millet pastes (20% solids) in 5 min mixing at 30 degrees C. Utilization of malts with maximum diastatic activity are useful to liquify precooked cereal pastes or drinks and to increase the total solid contents and nutrient density while keeping the liquid properties of the product.(ABSTRACT TRUNCATED AT 250 WORDS)

Alcohol in the amniotic fluid prior to cesarean delivery: effects of subsequent exposure to the drug's odor upon alcohol responsiveness.

Rat fetuses during the last day of gestation have the capacity to process ethanol and non-ethanol-related chemosensory cues present in the amniotic fluid. Recent studies suggest that the consequences related to cesarean delivery act as an unconditioned stimulus that is associated with these cues. In the first experiment, ethanol neonatal responsiveness assessed through a motor activity test was analyzed in pups that received ethanol or saline in utero proximal to cesarean delivery. Different factors and the interaction among them, were analyzed in this experiment: (i) ethanol concentration administered into the amniotic sac (0, 6, or 18% v/v), (ii) delay between administration and cesarean section (3, 10, or 30 min), and (iii) postnatal exposure to ethanol odor prior to test (0, 7.5, or 15 min). Only animals exposed to ethanol 10 min prior to delivery differed from vehicle-exposed subjects. Subsequent postnatal exposure to ethanol odor attenuated the magnitude of prenatally established effects. In the second experiment it was observed that prenatal ethanol exposure was sufficient to increase ethanol intake during Postnatal Day 11. Again, this effect was strongly attenuated when pups were exposed to the odor of the drug prior to assessment procedures. These results suggest that (i) associations between chemosensory cues in the amniotic fluid and consequences related with perinatal manipulations are likely to occur and (ii) postnatal reexposure to similar cues exerts an effect comparable to an extinction phenomenon.

Operant responding controlled by milk or milk contaminated with alcohol as positive reinforcers in infant rats.

Infant rats during the first, second, or third week of life were tested in operant conditioning with uncontaminated milk or milk supplemented with 6.0% v/v absolute ethanol (EtOH) as the reinforcer. Relative to yoked controls, pups of each age group reinforced on a response-contingent basis exhibited a significantly higher rate of responding with either reinforcer. In terms of amount of reinforcement, milk induced a higher rate of lever pressing than did the EtOH-contaminated compound. Age-related differences in the onset of differential responding for plain milk and EtOH-contaminated milk suggested developmental changes in the effects of alcohol. In a second experiment, forced drinking of milk and EtOH-contaminated milk was compared in similar age groups. Patterns of intake resembled the patterns of operant responding controlled by the same substance in the first experiment. These experiments indicate that the presence of alcohol in milk partially inhibits the reinforcing capacity of uncontaminated milk. Nevertheless, the former compound is still effective as a positive reinforcer during the first weeks of life.