Effects of cell concentration during cryopreservation on the post-thaw quality of Santa ines ram sperm.

BACKGROUND: Non-surgical artificial insemination techniques for sheep may benefit from larger numbers of sperm in the insemination dose because the ewe cervix is convoluted and often cannot be traversed with an insemination gun resulting in deposition of the sperm at the os cervix. OBJECTIVE: To compare a range of sperm concentrations when cryopreserving semen from Santa Ines rams and determine the effects of this on post-thaw quality. MATERIALS AND METHODS: One ejaculate from each ram (n = 10) was diluted to four sperm concentrations to obtain the following groups: G-400, G-800, G-1200, and G-1600 x 106 sperm/mL. The semen samples were packaged in 0.25 mL straws, cooled to 5 degree C, cryopreserved in liquid nitrogen vapor, thawed in a water bath (40 degree C per 20 s), and were analyzed for computerized kinetics, capacitation and acrosome integrity, and plasma membrane integrity of sperm. RESULTS: The G-400 treatment resulted in samples with the highest linearity and progressive motion (P < 0.05) and had significantly greater plasma membrane integrity, and lower capacitation and acrosome reaction rates compared to G-1600 (P < 0.05). Overall, use of the G-400 treatment resulted in better kinetics, less plasma membrane damage and less early capacitation. However, despite reducing the ejaculate yield and increasing the costs of the semen freezing process, the G-800 and G-1200 treatments make a greater absolute number of sperm with good kinetics, plasma membrane integrity and capacitation status available. CONCLUSION: Ram sperm concentration impacts cryopreservation, and higher concentrations may be advantageous if a single artificial insemination protocol is desirable. doi.org/10.54680/fr22610110812.

Co-existence of ethanol-related respiratory and motivational learning processes based on a tactile discrimination procedure in neonatal rats.

In rats, high ethanol doses during early postnatal life exert deleterious effects upon brain development that impact diverse social and cognitive abilities. This stage in development partially overlaps with the third human gestational trimester, commonly referred to as the brain growth spurt period. At this stage in development, human fetuses and rat neonates (postnatal days [PD] 3-9) exhibit relatively high respiratory rates that are affected by subteratogenic ethanol doses. Recent studies suggest conditioned breathing responses in the developing organism, given that there are explicit associations between exteroceptive stimuli and the state of ethanol intoxication. Furthermore, studies performed with near-term rat fetuses suggest heightened sensitivity to ethanol's motivational effects. The present study was meant to analyze the unconditioned effects of ethanol intoxication and the possible co-occurrence of learning mechanisms that can impact respiratory plasticity, and to analyze the preference for cues that signal the state of intoxication as well as the effects of the drug, related with motor stimulation. Neonatal rats were subjected to differential experiences with salient tactile cues explicitly paired or not paired with the effects of vehicle or ethanol (2.0 g/kg). A tactile discrimination procedure applied during PDs 3, 5, 7, and 9 allowed the identification of the emergence of ethanol-derived non-associative and associative learning processes that affect breathing plasticity, particularly when considering apneic disruptions. Ethanol was found to partially inhibit the disruptions that appeared to be intimately related with stressful circumstances defined by the experimental procedure. Tactile cues paired with the drug's effects were also observed to exert an inhibitory effect upon these breathing disruptions. The level of contingency between a given tactile cue and ethanol intoxication also resulted in significant changes in the probability of seeking this cue in a tactile preference test. In addition, the state of intoxication exerted motor-stimulating effects. When contrasting the data obtained via the analysis of the different dependent variables, it appears that most ethanol-derived changes are modulated by positive and/or negative (anti-anxiety) reinforcing effects of the drug. As a whole, the study indicates co-existence of ethanol-related functional changes in the developing organism that simultaneously affect respiratory plasticity and preference patterns elicited by stimuli that signal ethanol's motivational effects. These results emphasize the need to consider significant alterations due to minimal ethanol experiences that argue against "safe" levels of exposure in a critical stage in brain development.

Brief ethanol exposure and stress-related factors disorganize neonatal breathing plasticity during the brain growth spurt period in the rat.

RATIONALE: The effects of early ethanol exposure upon neonatal respiratory plasticity have received progressive attention given a multifactorial perspective related with sudden infant death syndrome or hypoxia-associated syndromes. The present preclinical study was performed in 3-9-day-old pups, a stage in development characterized by a brain growth spurt that partially overlaps with the 3rd human gestational trimester. METHODS: Breathing frequencies and apneas were examined in pups receiving vehicle or a relatively moderate ethanol dose (2.0 g/kg) utilizing a whole body plethysmograph. The experimental design also considered possible associations between drug administration stress and exteroceptive cues (plethysmographic context or an artificial odor). Ethanol exposure progressively exerted a detrimental effect upon breathing frequencies. A test conducted at PD9 when pups were under the state of sobriety confirmed ethanol's detrimental effects upon respiratory plasticity (breathing depression). RESULTS: Pre-exposure to the drug also resulted in a highly disorganized respiratory response following a hypoxic event, i.e., heightened apneic episodes. Associative processes involving drug administration procedures and placement in the plethysmographic context also affected respiratory plasticity. Pups that experienced intragastric administrations in close temporal contiguity with such a context showed diminished hyperventilation during hypoxia. In a 2nd test conducted at PD9 while pups were intoxicated and undergoing hypoxia, an attenuated hyperventilatory response was observed. In this test, there were also indications that prior ethanol exposure depressed breathing frequencies during hypoxia and a recovery normoxia phase. CONCLUSION: As a whole, the results demonstrated that brief ethanol experience and stress-related factors significantly disorganize respiratory patterns as well as arousal responses linked to hypoxia in neonatal rats.

Conditioned breathing depression during neonatal life as a function of associating ethanol odor and the drug's intoxicating effects.

Fetal and neonatal ethanol-related alterations upon the respiratory system have been described in different mammals. Studies also indicate that perinates learn about the sensory attributes of ethanol and associate them with diverse physiological effects of the state of intoxication. The present study was conducted in rat neonates during a developmental stage equivalent to the third human gestational trimester. The major goal was to analyze the consequences of ethanol odor exposure, the state of intoxication, or the temporal contiguity between these factors upon breathing patterns. The main findings were as follows: (a) a conditioned breathing depression was observed following few trials defined by the association between ethanol odor and the state of intoxication and (b) sequential exposure to ethanol sensitizes the organism to the drug's respiratory depressant effects without affecting ethanol metabolism. These results indicate that early breathing disruptions caused by ethanol can be determined or modulated via learning processes. © 2016 Wiley Periodicals, Inc. Dev Psychobiol 58:670-686, 2016.

Ethanol-induced tolerance and sex-dependent sensitization in preweanling rats.

According to genetic studies, the acute stimulating effect of ethanol seems to be associated with an increased predisposition to consume large quantities of ethanol. Ethanol-induced stimulation has been rarely reported in adult rats. However, infant rats, particularly during the second postnatal week of life, are highly sensitive to ethanol-induced behavioral activation. They also consume more ethanol than in later ontogenetic stages. In adult mice repeated ethanol experience usually results in sensitization to the stimulating effect of ethanol, while tolerance is the predominant result in rats. The present study was designed to explore in rats whether repeated exposure to ethanol during infancy modifies subjects' sensitivity to the stimulating effect of the drug, either increasing or decreasing its magnitude (i.e. sensitization or tolerance, respectively). Furthermore, we also explored the possible context-modulation of these effects. In two experiments, subjects were trained with water or ethanol (2.5 g/kg) between postnatal days (PDs) 8 and 12 (Experiment 1) or between PDs 14 and 18 (Experiment 2), and tested in response to water or ethanol two days later. In these experiments we identified three variables that critically modulate the effect of the repeated ethanol exposure: sex, context and age. Ethanol exclusively and consistently induced locomotor sensitization in males trained outside of the testing context (Experiments 1a and 1b), while tolerance to the stimulating effect of ethanol was observed in males and females trained in the testing context (Experiment 1a). In Experiment 2 tolerance was detected in females trained outside of the testing context. Finally, experience with the testing context during training strongly attenuated the stimulating effect of ethanol in the older subjects (Experiment 2). These results show that the same ethanol treatment can produce opposite effects (tolerance or sensitization) and demonstrate the involvement of Pavlovian conditioning in the development of tolerance. Furthermore, sex was revealed as an important factor to take into consideration in the analysis of chronic experience with ethanol during infancy. We can conclude that specific ontogenetic stages can be used to study the biological determinants underlying both ethanol-induced tolerance and sensitization, and the environmental modulators of these effects.

A sensory-enhanced context allows renewal of an extinguished fear response in the infant rat.

Studies of extinction in preweanling rats have failed to find ABA-renewal in a fear conditioning paradigm. This result supports the hypothesis postulating ontogenetic qualitative differences in experimental extinction. A similar result in adult rats led to the conclusion that ABA-renewal requires contexts A and B to differ in several types of features, including odor cues. Recently we reported experimental evidence of the renewal of an extinguished taste aversion response in infant rats employing contexts which differ in their odor content. The present study examines the possibility of renewing an extinguished fear response in infant rats when contexts A and B do not include (Experiment 1) or include (Experiment 2) an explicit odor. Results showed absence of renewal when using standard contexts (without explicit odors, Experiment 1). However, when contexts A and B varied also in their odor content, the ABA-renewal procedure was effective in reinstating the extinguished CR (Experiment 2). Thus, it can be concluded that the sensory content of the context determines the observation of renewal in the infant rat, a result that is coherent with previous observations in the adult rat. As a whole, these results challenge our understanding of extinction as a learning process that is qualitatively different in preweanling rats than in later stages of ontogeny.

[Mechanism of acute urinary retention in patients with giant bladder diverticulum. Report of 4 cases]. / Mecanismo de la retención urinaria aguda en pacientes con divertículo vesical gigante. A propósito de 4 casos.

Urinary retention due to bladder diverticulum is a rare clinical entity. We report Three males that were subjected to transurethral resection of prostate due benign hyperplasia with urinary retention, after removal of the catheter during postoperative period, requiring a new catheterization, and an adolescent woman with history of urinary infection that presented urinary retention four previous months to her first interview in the service. The later investigation demonstrated in all patients a big bladder diverticulum. The diverticulectomy reestablished the satisfactory bladder emptying in all patients. The origin of the bladder diverticula, the mechanism of the urinary retention without obstruction and its treatment is discussed.

Fetal and infantile alcohol-mediated associative learning in the rat.

BACKGROUND: Infant rats express conditioned responses to an odor experienced prenatally as a chemosensory cue associated with moderate alcohol intoxication. This study examined postnatal intake of a chemosensory cue (cineole) that had been paired with alcohol's unconditioned effects. It also tested the interaction between prenatal association and postnatal conditioning with cineole and alcohol. METHODS: Pregnant female rats intubated with cineole were given ethanol (EtOH).25 or 4.0 hr later. Other groups received only water or water paired with ethanol. During postnatal day 15 (PD15), infant consumption of cineole solution was assessed. After the cineole drinking test, pups were intubated with EtOH or water to assess infant conditioning. On PD16, all pups were tested for mouthing to milk alone or to a milk-cineole solution. RESULTS: Statistical analysis confirmed fetal associative conditioning attributable to the unconditioned effects of prenatal alcohol. Fetuses given explicit pairings of cineole and alcohol ingested less cineole on PD15 than control fetuses given a 4-hr interval between cineole and alcohol. On PD16, consumption of cineole was significantly increased by prenatal exposure to cineole. Teratogenic effects of this dose of prenatal alcohol did not affect postnatal associative or nonassociative behavior. CONCLUSIONS: Prenatal associative learning can be established through temporal contiguity between fetal chemosensory stimulation and alcohol's unconditioned properties. This associative memory survives to infancy and modulates intake patterns and behavioral reactivity to substances that were prenatally paired with alcohol intoxication.

Nursing experiences with an alcohol-intoxicated rat dam counteract appetitive conditioned responses toward alcohol.

BACKGROUND: Infant rats detect small amounts of alcohol (175 mg%) that are present in maternal milk whenever the dam is moderately intoxicated with alcohol. Interaction with an alcohol-intoxicated mother during the first 2 weeks of life facilitates the preweanling's subsequent discrimination of alcohol's orosensory attributes and produces conditioned aversion to alcohol. The present study further analyzed the hedonic content of infantile alcohol memories established in the nursing context by testing the interaction between experiences with an alcohol-intoxicated dam and learning procedures aimed at establishing an appetitive conditioned response toward alcohol. METHODS: Experiment 1 was to determine appropriate parameters to establish a reliable conditioned preference for alcohol in 16-day-old infants. For conditioning, intraorally infused sucrose solution (appetitive reinforcer) was paired with alcohol's orosensory cues derived from an acute state of alcohol intoxication (3 g/kg). Two control groups included an unpaired condition and a group given sucrose after water intubation. Infants then were evaluated in an alcohol intake test. Relative to control animals, a reliable conditioned preference for alcohol was registered in paired pups. In experiment 2, these conditioning procedures were applied to infant rats which, before conditioning, suckled from dams subjected to a 2.5 g/kg alcohol dose (intragastric) or from water-treated females during postpartum days 3, 5, 7, 9, 11, and 13. RESULTS: Experiment 2 showed that maternal treatment significantly affected the establishment of conditioned preferences for alcohol. Whereas pups reared by control dams exhibited reliable appetitive conditioning to alcohol, infants raised by alcohol dams completely failed to develop appetitive conditioning. CONCLUSIONS: The present results suggest that alcohol-related memories generated via infantile interactions with an intoxicated dam counteract subsequent conditioning of alcohol ingestion. In conjunction with prior studies, it is concluded that alcohol-related nursing experiences are capable of promoting alcohol memories with a negative hedonic content.

Differential responsiveness to alcohol odor in human neonates: effects of maternal consumption during gestation.

Previous human and animal studies have shown that specific memories arise during prenatal life as a function of fetal processing of chemosensory stimuli present in the amniotic fluid. Furthermore, the animal literature indicates that fetal exposure to alcohol modifies subsequent neonatal and infantile responsiveness toward the sensory attributes of the drug. The main goal of the present study was to analyze whether differential maternal alcohol consumption during pregnancy affects neonatal reactivity to ethanol odor. To achieve this goal, an initial experiment examined how healthy human neonates respond to olfactory stimuli. In this first experiment, newborns (postpartum age: 24-48 h) were evaluated in terms of motor responsiveness elicited by repetitive stimulation with either alcohol or lemon odors. Infants exhibited a marked increase in duration of overall body and head and facial activity when the odorants were first presented. In four successive trials, behavioral responsiveness progressively declined until reaching baseline values. The introduction of a novel odorant served to dishabituate the motor responses under analysis. In the second experiment newborn's reactivity to the mentioned odorants was evaluated as a function of maternal self-reported patterns of consumption of alcohol during gestation. Mothers were classified as frequent or infrequent drinkers. Babies born to frequent drinkers exhibited heightened reactivity toward ethanol odor when compared to newborns delivered by infrequent drinkers. No differences emerged when comparing the responses of both groups of infants elicited by a non-ethanol stimulus such as lemon. The results coupled with prior human and animal research suggest the possibility of intrauterine experience with alcohol odor that yields a sensory memory likely to be retrieved immediately after birth.

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.

Infant rats respond differently to alcohol after nursing from an alcohol-intoxicated dam.

Our previous studies indicate that rat pups are able to detect the low levels of ethanol (175 mg %) found in the milk of a moderately intoxicated dam. The present study tested the effect of infantile interactions (including suckling) with ethanol-treated mothers on later behavioral responsiveness to ethanol's sensory properties. In Experiment 1, pups suckled from dams subjected to a 2.5 g/kg ethanol dose (i.g.) or water-treated females during postnatal days (PDs) 3, 5, 7, 9, 11, and 13. During PD 15, these pups were exposed to procedures to induce a conditioned aversion to the low level of ethanol (175 mg % in water), with lithium chloride as the unconditioned stimulus. Conditioning was more effective for pups with the prior ethanol experience within the nursing context. Greater responsiveness to ethanol in milk also was found for conditioning control pups that had interacted with intoxicated dams than for those that had interacted with water-treated dams. Experiment 2 determined that interaction with an intoxicated dam was sufficient for altered responsiveness to ethanol, in that the additional conditioning procedures of Experiment 1 were not needed for the effect. Generally, a relatively brief history of infantile interaction with ethanol-intoxicated dams increased later responsiveness to ethanol's orosensory properties. The results suggest that moderately intoxicated dams within the nursing context provide information to the progeny that may lead to the establishment of ethanol-related memories.

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.

Chronic alcohol administration in the rat pup: effects upon later consumption of alcohol and other palatable solutions.

Previous studies indicate that in rats, chronic alcohol exposure during the first weeks of life markedly affect subsequent ethanol consumption patterns. The present study examined the impact of different alcohol doses (0.5-3.0 g/kg), administered between postnatal days 6-12, upon subsequent infantile consumption of an ethanol solution as well as upon intake of various non-ethanol solutions (water, sucrose, quinine or sucrose mixed with quinine). Alcohol administration did not strongly affect consumption scores of water, sucrose or quinine. In contrast, 15-day-old pups pretreated with 2.0 and 3.0 g/kg alcohol doses showed significant increases in terms of alcohol consumption when compared to saline controls. Furthermore, a positive significant correlation was observed between alcohol intake patterns and alcohol dose administered during early ontogeny. Intake of sucrose mixed with quinine was also significantly and positively correlated with pretreatment ethanol dosage. Interestingly, this taste configuration has been shown to mimic psychophysical properties of ethanol in the rat. The results appear not to be explained by teratological effects of the drug upon sensory processing of distinctive tastants. It appears that chronic alcohol exposure during early ontogeny provides specific sensory-related alcohol information that later modulates alcohol intake patterns.

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.

Behavioral detection of low concentrations of ethanol in milk in the preweanling rat.

Previous animal models testing infantile reactivity to ethanol (EtOH) in maternal milk used EtOH doses that vastly exceeded levels actually encountered in a mildly or moderately intoxicated dam. The present study assessed whether 12- and 16-day-old rats are capable of detecting EtOH in milk at levels actually recorded in an intoxicated dam. Experiment 1 determined representative levels of EtOH in maternal milk as a function of maternal intragastric administration of EtOH (0.5-3.0 g/kg). Experiment 2A assessed generalization of conditioned taste aversions accrued with a high level of EtOH (6%) in either water or milk vehicles towards lower, more representative EtOH levels obtained from Experiment 1. With body weight gain as the dependent measure, conditioned aversions to milk were evident with the milk vehicle, but there was no detection of EtOH at any level at either age. Detection of the high level of EtOH (6%) in milk, however, was observed by 16 day olds within an habituation paradigm (Exp. 2b) via cardiac and behavioral (locomotion, mouthing) indexes. In Experiment 3 application of Experiment 2's more sensitive, behavioral index to assess generalization of the conditioned taste aversions revealed detection of a lower, more representative concentration of EtOH (175 mg%) in milk in 16-day-old rats. Overall the results show that the unweaned rat is capable of detecting very low concentrations of EtOH in milk and can modify their behavior accordingly. The expression of this capability is not, however, homogeneous across different response indexes. In conjunction with prior research it is clear that the infant rat's perception of EtOH in milk, including the very low levels of EtOH found in maternal milk during mild or moderate intoxication, is a relevant experience for generating new responses towards EtOH.

Ontogenetic differences in the expression of olfactory-conditioned aversions resulting from a state of acute alcohol intoxication in the rat.

Three experiments examined the effects of acute alcohol intoxication on olfactory conditioning in infant (16 days old) and adult rats (60-65 days old). In both age groups, alcohol administration (2 g/kg, IG) prior to conditioning procedures failed to affect subsequent expression of methyl-conditioned aversions in a two-way odor locational test. Nevertheless, whenever this same alcohol dose was administered prior to testing procedures, the expression of the olfactory conditioning was substantially impaired in infants but unaffected in adults. The factorial design allowed rejection of the possibility that ontogenetic differences in alcohol-induced state-dependent retention might explain this developmental difference (Experiment 1). A subsequent experiment (Exp. 2a) revealed major age related differences in terms of peak blood alcohol levels (BALs) that resulted from the 2 g/kg alcohol dose previously employed. As revealed by gas chromatography, infants exhibited significantly higher BALs than adults at time of conditioning and/or testing. Therefore in Experiment 2b, the alcohol dose administered in adults was increased until BALs were comparable to those attained in infants given 2 g/kg. This was accomplished with a 2.5 g/kg alcohol dose, employed in Experiment 2c to evaluate responsiveness of adults in conditioning circumstances identical to those of Experiment 1. Yet even with this dose the adults' expression of the conditioned olfactory aversion was unaffected by the alcohol at the time of testing. Experiment 3 analyzed the effects of alcohol intoxication on infantile and adult motor responses elicited by methyl and a novel odor (lemon), which might conceivably have affected performance in the two-way odor locational tests used to assess olfactory conditioning. The results failed to support the possibility that the previously observed ontogenetic differences in the expression of olfactory-conditioned aversions were due to alcohol's effect on sensorimotor responsiveness. In accordance with prior studies, the present results seem to indicate age-related sensitivity to alcohol's effects on cognitive processes.

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.

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.