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- Daoura, Loudin
(author)
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Early Environment and Adolescent Ethanol Consumption : Effects on Endogenous Opioids and Behaviour in Rats
- 2013
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Doctoral thesis (other academic/artistic)abstract
- Excessive and compulsive ethanol drinking is one of the most serious public health issues. Therefore, it is vital to increase the knowledge about risks and protection for alcohol use disorders (AUD) to optimize prevention and treatment strategies. Ethanol consumption commonly initiates during adolescence when extensive neuronal maturation and development also occurs. Early exposure to ethanol is a risk factor for AUD, but the effects of adolescent drinking and the basis for the individual susceptibility to AUD are not fully understood. The interactions between genotype and environmental factors determine the individual risk for AUD and this thesis aimed to examine the environmental impact. The specific aims were to investigate 1) how early-life conditions affect adolescent voluntary ethanol drinking, behavioural profiles, endogenous opioids and response to treatment with an opioid antagonist (naltrexone), and 2) whether alterations detected in the offspring may be mediated by variations in maternal behaviour. A rodent maternal separation (MS) model was used to mimic a protective and risk-inducing early-life environment, respectively, with the use of 15 min (MS15) or 360 min (MS360) of daily MS. The main findings were 1) the MS360, but not the MS15 rats, responded to naltrexone following adolescent ethanol drinking; all adolescent rats had a high voluntary ethanol intake independent of early environmental conditions whereas in the adult groups the MS360, but not the MS15 rats, increased their ethanol intake and preference over time; adolescent ethanol exposure resulted in higher dynorphin levels in hippocampus and higher Met-enkephalin-Arg6Phe7 in the amygdala, independently of rearing conditions, 2) behavioural profiling using the multivariate concentric square field™ test showed: the young MS360 rats had increased risk assessment and risk taking behaviour compared to the young MS15 rats; the young MS15 rats increased, whereas the young MS360 rats decreased, their risk assessment and risk taking behaviour over time; differences in pup-retrieval strategies where the MS360 dams retrieved some pups into a safe area but as compared to MS15 rats they left more pups in a risk area; increased risk assessment behaviour in the MS360 dams immediately after weaning. Taken together, early-life environmental conditions alter adult but not adolescent drinking, the response to naltrexone, and behaviour in dams and offspring. Adolescent rats consumed more ethanol independent of rearing conditions and displayed increased opioid levels in brain areas related to cognition and addiction.
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- Daoura, Loudin, et al.
(author)
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Early Environmental Factors Differentially Affect Voluntary Ethanol Consumption in Adolescent and Adult Male Rats
- 2011
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In: Alcoholism. - : Wiley. - 0145-6008 .- 1530-0277. ; 35:3, s. 506-515
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Journal article (peer-reviewed)abstract
- Background: Previous studies using the maternal separation (MS) model have shown that environmental factors early in life affect adult ethanol consumption. Prolonged MS is related to enhanced propensity for high adult ethanol intake when compared to short MS. Less is known about the environmental impact on adolescent ethanol intake. In this study, the aim was to compare establishment of voluntary ethanol consumption in adolescent and adult rats subjected to different rearing conditions. Methods: Wistar rat pups were separated from their mother 0 minutes (MS0), 15 minutes (MS15), or 360 minutes (MS360) daily during postnatal days (PNDs) 1 to 20. After weaning, the male rats were divided into two groups; rats were given free access to water, 5 and 20% ethanol at either PND 26 or 68. Ethanol was provided in 24-hour sessions three times per week for 5 weeks. Results: MS resulted in altered ethanol consumption patterns around the pubertal period but otherwise the rearing conditions had little impact on ethanol consumption in adolescents. In adults, the establishment of ethanol consumption was dependent on the rearing condition. The adult MS0 and MS15 rats had a stable ethanol intake, whereas the MS360 rats increased both their ethanol intake and preference over time. Conclusions: With the use of intermittent access to ethanol, new data were provided, which confirm the notion that MS360 represents a risk environment related to higher ethanol intake compared to MS15. The adolescent rats had higher ethanol intake than adult rats but the consumption was independent of rearing condition. Experiences during the first three postnatal weeks thus affect the establishment of voluntary ethanol consumption differently in adolescent and adult rats. Further studies are now warranted to examine the consequences of a combination of early environmental influence and high adolescent ethanol intake.
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- Daoura, Loudin, et al.
(author)
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Postpartum Behavioral Profiles in Wistar Rats Following Maternal Separation : Altered Exploration and Risk-Assessment Behavior in MS15 Dams
- 2010
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In: Frontiers in Behavioral Neuroscience. - : Frontiers Media SA. - 1662-5153. ; 4
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Journal article (peer-reviewed)abstract
- The rodent maternal separation (MS) model is frequently used to investigate the impact of early environmental factors on adult neurobiology and behavior. The majority of MS studies assess effects in the offspring and few address the consequences of repeated pup removal in the dam. Such studies are of interest since alterations detected in offspring subjected to MS may, at least in part, be mediated by variations in maternal behavior and the amount of maternal care provided by the dam. The aim of this study was to investigate how daily short (15 min; MS15) and prolonged (360 min; MS360) periods of MS affects the dam by examining postpartum behavioral profiles using the multivariate concentric square field (MCSF) test. The dams were tested on postpartum days 24-25, i.e., just after the end of the separation period and weaning. The results reveal a lower exploratory drive and lower risk-assessment behavior in MS15 dams relative to MS360 or animal facility reared dams. The present results contrast some of the previously reported findings and provide new information about early post-weaning behavioral characteristics in a multivariate setting. Plausible explanations for the results are provided including a discussion how the present results fit into the maternal mediation hypothesis.
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- Daoura, Loudin, et al.
(author)
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Qualitative differences in pup-retrieval strategies in a maternal separation paradigm
- 2013
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In: Journal of Behavioral and Brain Science. - : Scientific Research Publishing, Inc.. - 2160-5866 .- 2160-5874. ; 3, s. 603-616
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Journal article (peer-reviewed)abstract
- The rodent maternal separation (MS) paradigm is frequently used to investigate the impact of early-life conditions in the offspring. One critical issue is whether the effects seen in the offspring are a result of maternal contact deprivation and/or altered pup-directed maternal behavior. To address this question we used an innovative approach with a qualita-tive analysis of pup-retrieval strategies in a test situation related to risk for the pups. The dams were separated from their litters for 0 (MS0) or 360 (MS360) min, respectively. The pups were placed in a risk area in the multivariate con-centric square field™ test at two test occasions and the pup-retrieval strategies were recorded. No significant evident differences between MS0 and MS360 dams were found. However, there were clearly two different strategies, either removing the pups out of potential danger or into safety, and these strategies were represented in both MS groups. As compared to the MS0 dams, the MS360 dams did not change their strategies and left more pups in the risk area in both pup-retrieval tests. This implies different pup-retrieval strategies depending on early-life conditions.
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