Joy Simpson

National University of Ireland, Galway, Galway, C, Ireland

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Publications (5)16.76 Total impact

  • Joy Simpson, John P Kelly
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    ABSTRACT: Environmental enrichment (EE) involves enhancing an animal's environment, with the goal of improving animal welfare. Though a well-established discipline, the consequences of EE on behavioural pharmacological tests have not been extensively examined. The purpose of this study was to examine the consequences of EE (or isolation) housing on a range of behavioural pharmacological tests in the rat. Male Sprague-Dawley rats were randomly assigned to the 3 housing conditions; IC (isolation) and SC (standard group-housed, 4/cage) were housed in standard cages (42 cm×25.5 cm×20 cm), while the EE group was housed in groups of 4 in larger cages (54 cm×38 cm×19 cm) enriched with a variety of wooden, cardboard and plastic toys/objects. After 4 weeks, housing effects were examined in the following pharmacological tests: diazepam (DZP) effects on anxiolytic behaviour in the elevated plus maze (EPM); desipramine (DMI) effects on immobility time in the forced swim test (FST) and amphetamine (AMP) effects on homecage activity. Dose-response assessments demonstrated that rats housed in EE showed reduced sensitivity to the behavioural effects of DZP and DMI but increased sensitivity to the locomotor-enhancing effects of AMP compared to SC and IC; while IC animals exhibited the clearest dose-response effects to increasing doses of DMI. It may be concluded that environmental manipulation can vary along a continuum and its intensity may be crucial to observable effects. Nonetheless, environmental factors can influence sensitivity to psychotropic drugs and should be considered when implementing EE protocols in such evaluations.
    Behavioural brain research 06/2012; 234(2):175-83. · 3.22 Impact Factor
  • Joy Simpson, John P Kelly
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    ABSTRACT: In clinical populations, sex differences in disease prevalence, symptoms and outcome have been established. Despite this, female rats are frequently omitted from preclinical research; growing preclinical evidence, however, illustrates meaningful sex differences in behavioural, neurochemical and neuroanatomical endpoints. This review outlines the effects of sex on tests of depression- and anxiety-like symptoms, learning and memory, and responses to stress in rats. In addition, sexual dimorphisms in monoamine neurotransmitter and neurotrophic factor levels, neurogenesis and plasticity, and responsiveness to drugs of abuse are reviewed. Female rats display greater baseline activity levels compared to males, test-specific sex differences also exist in learning and memory protocols as females respond more actively in conditioning paradigms and are somewhat impaired in tests of spatial memory compared to males. Differential baseline and stress-induced hypothalamic-pituitary-adrenal axis responses between male and female rats depend on the nature of the stressor. Females are more responsive to the effects of psychomotor stimulant drugs; sexual dimorphisms in response to psychotropic drugs are likely mediated by neurochemical differences between male and female rats. Differences exist in neurotransmitter activity, transporter and receptor expression between the sexes. Studies of ovariectomised and intact female rats demonstrate a potent impact of elevated estrogen during the estrous cycle on behaviour, neurochemistry, dendritic growth and drug response. Sex differences in baseline behaviours and the methodological procedures employed can influence behavioural pharmacology result interpretation. In addition, the inclusion of both male and female rats in studies investigating neurochemistry and neuromorphology may enhance the validity of drug or rehabilitative treatments.
    Behavioural brain research 04/2012; 229(1):289-300. · 3.22 Impact Factor
  • Joy Simpson, Dara Bree, John P Kelly
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    ABSTRACT: Employing environmental enrichment (EE) provides continual sources of dynamic interaction for animals. Though an established discipline in behavioural science, the consequences of EE on behavioural pharmacological tests have not been extensively examined. The purpose of this study was to examine the consequences of EE (or isolation housing) on a range of behavioural pharmacological tests and brain monoamine and brain-derived neurotrophic factor (BDNF) expression in the rat. Male rats were randomly assigned to IC (isolation), SC (standard group-housed) or EE conditions. IC and SC animals were housed singly or in groups of four in standard cages, whilst the EE group were housed in groups of four in larger cages enriched with a variety of wooden, cardboard and plastic objects. After 5weeks of housing, its impact on the effects of diazepam (DZP) in the elevated plus maze (EPM); desipramine (DMI) in the forced swim test (FST) and amphetamine (AMP) effects on homecage activity were assessed. Post-mortem monoamine and BDNF levels were analysed using HPLC and ELISA. EE rats displayed reduced activity in the OFT, however no other differences were found in baseline behaviours. DMI reduced immobility time in the FST, but only for rats housed in IC, while AMP effects were somewhat greater for socially-housed animals than those in IC. There were no housing effects on monoamine or BDNF levels in discreet brain regions. The results suggest that post-weaning enrichment had no significant effect on baseline behaviours or monoamine and BDNF levels, thus it is suitable to implement as a commonplace husbandry practice, however, caution must be taken when investigating responsiveness to psychotropic drugs.
    Progress in Neuro-Psychopharmacology and Biological Psychiatry 02/2012; 37(2):252-63. · 3.55 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Behavioural pharmacology relies on animal models which are primarily validated using the male laboratory rat. Many researchers solely employ male animals in studies; this is primarily due to concerns about the impact of variations in the female estrous cycle on behavioural responses. The objective of the present study therefore was to examine whether sex has any effect in some commonly employed behavioural pharmacology tests. Male and female Sprague Dawley rats were examined in the following behavioural pharmacology tests: diazepam (DZP) effects on anxiolytic behaviour in the elevated plus maze (EPM); desipramine (DMI) effects on immobility time in the forced swim test (FST); amphetamine (AMP) and apomorphine (APO) effects on locomotor activity in the homecage monitoring apparatus (HCMA). Baseline investigations revealed that females were more active than males in all three tests. DZP increased open arm time and entries for males but not for females. Similarly, significant reduction in immobility time with DMI was found for males in the FST, with no effect observed in females. There was a significant effect of AMP dose on distance moved for both sexes; the peak locomotor stimulating effects were seen following 1-2 mg kg⁻¹ AMP doses for males, while 0.5 mg kg⁻¹ produced the greatest effect in females. APO impaired locomotor activity in both sexes. These results demonstrate that male and female rats respond differently to psychotropic drugs. The absence of female responses to the effects of DZP and DMI in the EPM and FST respectively was due to the high baseline activity levels seen with females; thus behavioural tests must be designed to account for sex differences in baseline behaviours to allow for unambiguous extrapolation of the results.
    Progress in Neuro-Psychopharmacology and Biological Psychiatry 02/2012; 37(2):227-36. · 3.55 Impact Factor
  • Joy Simpson, John P Kelly
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    ABSTRACT: The provision of environmental enrichment (EE) for laboratory rats is recommended in European guidelines governing laboratory animal welfare. It is believed the EE implementation can improve animals' well-being and EE has been used to demonstrate learning and plasticity of the brain in response to the environment. This review suggests that the definition and duration of EE varies considerably across laboratories. Notwithstanding this, some EE protocols have revealed profound effects on brain neurochemistry and resulting behaviour, suggesting that EE can have the potential to significantly modify these parameters in rats. For this review, a literature search was conducted using PubMed and the search terms "Environmental Enrichment" and "rats". From the results of this search the most important variables for consideration in the implementation of EE are identified and summarised, and include cage size and housing density; rat age, sex and strain; duration of EE; the EE protocol and enrichment items employed; and the use of appropriate controls. The effects of EE in a number of behavioural tests and its effects on neurotransmitters, neurotrophic factors, stress hormones and neurogenesis and proliferation are outlined. The findings summarised in the present review show the range of EE protocols employed and their effects in tests of activity, learning and affect, as well neurochemical effects which mediate enhanced plasticity in the brain. EE, as is provided in many laboratories, may be of benefit to the animals, however it is important that future work aims to provide a better understanding of EE effects on research outcomes.
    Behavioural brain research 09/2011; 222(1):246-64. · 3.22 Impact Factor

Publication Stats

61 Citations
312 Views
16.76 Total Impact Points

Institutions

  • 2011–2012
    • National University of Ireland, Galway
      • Department of Pharmacology and Therapeutics
      Galway, C, Ireland