Effects of climate change on water use efficiency (WUE) and its components, measured at different temporal and spatial scales in Fagus sylvatica

[EN] Effects of climate change on water use efficiency (WUE) and its components, measured at different temporal and spatial scales in Fagus sylvatica

Prenatal Alcohol Exposure as a Case of Involuntary Early Onset of Alcohol Use: Consequences and Proposed Mechanisms From Animal Studies

Prenatal alcohol exposure has been found to be an important factor determining later consumption of this drug. In humans, despite the considerable diversity of variables that might influence alcohol consumption, longitudinal studies show that maternal alcohol intake during gestation is one of the best predictors of later alcohol use from adolescence to young adulthood. Experimental studies with animals also provide abundant evidence of the effects of prenatal alcohol exposure on later alcohol intake. In addition to increased consumption, other effects include enhanced palatability and attractiveness of alcohol flavor as well as sensitization to its sensory and reinforcing effects. Most of these outcomes have been obtained after exposing rats to binge-like administrations of moderate alcohol doses during the last gestational period when the fetus is already capable of detecting flavors in the amniotic fluid and learning associations with aversive or appetitive consequences. On this basis, it has been proposed that one of the mechanisms underlying the increased acceptance of alcohol after its prenatal exposure is the acquisition (by the fetus) of appetitive learning via an association between the sensory properties of alcohol and its reinforcing pharmacological effects. It also appears that this prenatal appetitive learning is mediated by the activation of the opioid system, with fetal brain acetaldehyde playing an important role, possibly as the main chemical responsible for its activation. Here, we review and analyze together the results of all animal studies testing these hypotheses through experimental manipulation of the behavioral and neurochemical elements of the assumed prenatal association. Understanding the mechanisms by which prenatal alcohol exposure favors the early initiation of alcohol consumption, along with its role in the causal pathway to alcohol disorders, may allow us to find strategies to mitigate the behavioral effects of this early experience with the drug. We propose that prenatal alcohol exposure is regarded as a case of involuntary early onset of alcohol use when designing prevention policies. This is particularly important, given the notion that the sooner alcohol intake begins, the greater the possibility of a continued history of alcohol consumption that may lead to the development of alcohol use disorders.The research has been funded by the Basque Government (IT1341-19) to the research group (PI: Gabriel Rodriguez San Juan)

The role of acetaldehyde in the increased acceptance of ethanol after prenatal ethanol exposure

Recent studies show that acetaldehyde, the first metabolite in the oxidation of ethanol, can be responsible for both, the appetitive and the aversive effects produced by ethanol intoxication. More specifically, it has been hypothesized that acetaldehyde produced in the periphery by the liver is responsible for the aversive effects of ethanol, while the appetitive effects relate to the acetaldehyde produced centrally through the catalase system. On the other hand, from studies in our and other laboratories, it is known that ethanol exposure during the last gestational days (GD) consistently enhances the postnatal acceptance of ethanol when measured during early ontogeny in the rat. This increased liking of ethanol is a conditioned appetitive response acquired by the fetus by the association of ethanol’s flavor and an appetitive reinforcer. Although this reinforcer has not yet been fully identified, one possibility points to acetaldehyde produced centrally in the fetus as a likely candidate. This hypothesis is supported by data showing that very early in the rat’s ontogeny brain catalases are functional, while the liver’s enzymatic system is still immature. In this study, rat dams were administered on GD 17–20 with water or ethanol, together with an acetaldehyde-sequestering agent (D-penicillamine). The offspring’s responses to ethanol was then assessed at different postnatal stages with procedures adequate for each developmental stage: on day 1, using the “odor crawling locomotion test” to measure ethanol’s odor attractiveness; on day 5, in an operant conditioning procedure with ethanol as the reinforcer; and on day 14 in an ethanol intake test. Results show that the absence of acetaldehyde during prenatal ethanol exposure impeded the observation of the increased acceptance of ethanol at any age. This seems to confirm the crucial role of acetaldehyde as a reinforcer in the appetitive learning occurring during prenatal ethanol exposure

Participation of the endogenous opioid system in the acquisition of a prenatal ethanol-related memory: Effects on neonatal and preweanling responsiveness to ethanol

The present study tested the involvement of the opioid system in the acquisition and expression of prenatal ethanol-related memories. We evaluated how this prenatal experience modulates ethanol self-administration in newborn rats, and preweanling's ingestion of the drug.During Gestational Days (GDs) 17-20, four groups of dams were treated with ethanol (2. g/kg) or water, followed immediately by naloxone (10. mg/kg) or saline administration. A fifth group received a similar dose of naloxone 20. min before ethanol administration. On PD 1, pups were tested on an operant learning procedure to obtain milk or 3% ethanol. One hour later, an extinction session was performed. At Postnatal Days (PDs) 14 and 15, preweanlings representing each prenatal treatment were evaluated in an intake test with infusions of 5% ethanol or water. Prior to the intake test on PD14, preweanlings were administered naloxone (1. mg/kg), saline or remained untreated. In both tests, animals representative of both genders were utilized.One-day-old pups rapidly learned the operant behavior to gain access to milk. In contrast, only pups prenatally treated with ethanol (administered immediately before naloxone or saline injection) increased operant responding to gain access to ethanol. On an intake test at PDs 14 and 15, those animals prenatally exposed to naloxone 20. min before ethanol administration consumed significantly lower ethanol levels than the remaining prenatal ethanol groups. Postnatal treatment with naloxone diminished intake of all solutions at PD14.These results suggest that prenatal ethanol exposure facilitates neonatal operant learning reinforced by intraoral administration of ethanol and increases ethanol consumption during PDs 14-15. The endogenous opioid system apparently is involved in the acquisition of prenatal ethanol memories, which can modulate the reinforcing attributes of the drug in neonatal and preweanling rats.Fil: Miranda Morales, Roberto Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; ArgentinaFil: Molina, Juan Carlos. Universidad Nacional de Córdoba. Facultad de Psicología; Argentina. University of Binghamton; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; ArgentinaFil: Spear, Norman E.. University of Binghamton; Estados UnidosFil: Abate, Paula. Universidad Nacional de Córdoba. Facultad de Psicología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; Argentin

MC4-R signaling within the nucleus accumbens shell, but not the lateral hypothalamus, modulates ethanol palatability in rats

The Melanocortin (MC) system is one of the crucial neuropeptidergic systems that modulate energy balance. The roles of endogenous MC and MC-4 receptor (MC4-R) signaling within the hypothalamus in the control of homeostatic aspects of feeding are well established. Additional evidence points to a key role for the central MC system in ethanol consumption. Recently, we have shown that nucleus accumbens (NAc), but not lateral hypothalamic (LH), infusion of a selective MC4-R agonist decreases ethanol consumption. Given that MC signaling might contribute to non-homeostatic aspects of feeding within limbic circuits, we assessed here whether MC4-R signaling within the NAc and the lateral hypothalamus (LH) alters normal ingestive hedonic and/or aversive responses to ethanol in rats as measured by a taste reactivity test. Adult male Sprague-Dawley rats were given NAc- or LH- bilateral infusion of the selective MC4-R agonist cyclo (NH-CH2-CH2-CO-His-D-Phe-Arg-Trp-Glu)-NH2 (0, 0.75 or 1.5 µg/0.5µl/site) and following 30 min, the animals received 1 ml of ethanol solution (6% w/v) intraoral for 1 minute and aversive and hedonic behaviors were recorded. We found that NAc-, but not LH-administration, of a selective MC4-R agonist decreased total duration of hedonic reactions and significantly increased aversive reactions relative to saline-infused animals which support the hypothesis that MC signaling within the NAc may contribute to ethanol consumption by modulating non-homeostatic aspects (palatability) of intake

The developmental origin of adolescent alcohol use: Findings from the Mater University Study of Pregnancy and its outcomes

Background It is unclear whether fetal alcohol exposure contributes to alcohol use in adolescence. In this study, we examine the association between maternal alcohol use in pregnancy and adolescents’ drinking patterns at age 14. Methods The association of maternal alcohol exposure with early drinking was examined in 4363 adolescents taking part to the Mater University Study of Pregnancy (MUSP) and its outcomes, a population based birth cohort study commenced in Brisbane (Australia) in 1981. Mothers and children were followed up at birth, 5 and 14 years after the initial interview. Maternal alcohol use was assessed before and during pregnancy and at the 5 years follow-up. Adolescents’ alcohol use was assessed at child age 14. Results In multivariable analysis those born of mothers who consumed 3+ glasses during pregnancy were at increased risk to report drinking 3+ glasses compared with those whose mothers reported no drinking or drinking up to 2 glasses. Comparisons controlling for drinking before pregnancy and at age 5 found the averaged odds ratio of maternal drinking in pregnancy on risk of reporting alcohol consumption of 3 and more glasses at age 14 was 2.74 (CI 1.70, 4.22). Conclusion Our study suggests that they maybe a biological origin of early drinking. Further studies are needed to better disentangle the nature of the association and the role of other possible confounding factors

Some Parameters of Stimulus Preexposure that Affect Conditioning and Generalization of Taste Aversions in Infant Rats

The effects of stimulus preexposure on conditioning and generalization of a taste aversion were evaluated in infant rats, manipulating stimulus similarity and duration, and the length and procedure (intermixed vs. blocked) of preexposure. Preexposure to simple tastes retarded conditioning and reduced generalization (Experiment 1a), whereas preexposure to compound tastes facilitated conditioning and increased generalization (Experiment 1b). Increasing the number of preexposure trials retarded conditioning and decreased generalization with compound tastes (Experiment 1c). These experiments failed to find a differential effect of intermixed vs. blocked stimulus preexposure. In Experiment 2, a 15 min exposure to the conditioned stimulus during conditioning resulted in a weak aversion, whereas a 60-min exposure resulted in a strong aversion. In Experiment 3, the strength of the aversion and the duration of the conditioned stimulus were directly related in nonpreexposed pups, but inversely related in preexposed pups. In infant rats, the level of generalization between stimuli is determined by how preexposure affects acquisition rate

Mother’s scent for motherless neonates: Responses of artificially reared lambs to ewe’s inguinal wax odor

International audienceMammalian newborns depend on their mother’s milk to satisfy their initial needs of protection and nutrition. They reach the source of milk in following visual, tactile and olfactory cues. In particular, parturient ewes produce an odorous wax in the inguinal glands close to the teats. When presented separately to newly born lambs, this inguinal wax (IW) elicits arousal, head orientation, licking and increased respiratory rate indicative of their avidity for it. The present study assessed whether transferring IW into the environment of artificially fed lambs would improve their responses to the novelty of the situation. We first assessed whether suckled lambs preferred an IW-scented teat to a scentless control teat. Then, we assessed whether a teat odorized with IW was more easily learned as suckable relative to a control teat. Finally, the lambs’ growth performance from postnatal days (PND) 0 and 20 was compared in groups reared with or without IW spread on the milk-feeder in their home pen. The behavioral assays did not evidence any significant effect of IW odor on previously suckled lambs’ attraction and appetence responses. However, relative to the scentless control condition, being exposed to an IW-smeared milk-feeder led to a higher body weight at 20 days after birth. In the conditions of the present study, namely after suckling initiation, IW odor appeared not to be a strong determinant of short-term attraction or appetitive behavior in neonate lambs. The continued presence of IW, a familiar odor, in the artificial suckling context may improve artificially-reared lambs’ emotional state that may affect their weight gain