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The home environment is a critical modulator of behaviour. Environmental enrichment (EE) is a laboratory housing protocol that employs complex sensory and social stimulations to enrich the cage environment of laboratory rodents. Prior studies suggested that EE elicits improvements in rodents' metabolic profile in addition to profound cognitive and behavioural outcomes, among which is reduced inter-male aggression. However, the underlying mechanism mediating the positive outcomes of EE remains poorly characterised. EE has been associated with altered brain-derived neurotrophic factor (Bdnf) gene expression. The Bdnf gene consists of multiple transcript variants, all of which encode for an identical protein. Remarkably, different Bdnf transcripts expression in different tissues influences different metabolic and behavioural functions. Therefore, we hypothesised that EE modifies the feeding and aggressive behaviours in mice via altering Bdnf gene expression in a transcript variant-specific and brain region-specific manner. To test this hypothesis, we employed behavioural and gene expression analyses to examine the influence of EE on feeding and aggressive behaviours and the associated expression of genes encoding neurotrophins in male C57BL/6 mice. In the first study, we showed, for the first time, that EE potentiates the feeding-suppressing effect of glucose in 8-hr fasted mice. Furthermore, intraperitoneal glucose injection promoted hypothalamic activation, as assessed by increased Fos expression. Moreover, glucose treatment significantly upregulated hypothalamic glial cell line-derived neurotrophic factor (Gdnf) mRNA levels while selectively downregulating Bdnf transcript variants levels in the hypothalamus and amygdala of the EE mice. In the second study, we showed that EE significantly reduced inter-male aggression in group-housed mice. This effect was associated with reduced activity of the aggression-linked corticolimbic circuits. Importantly, EE significantly r

The home environment is a critical modulator of behaviour. Environmental enrichment (EE) is a laboratory housing protocol that employs complex sensory and social stimulations to enrich the cage environment of laboratory rodents. Prior studies suggested that EE elicits improvements in rodents' metabolic profile in addition to profound cognitive and behavioural outcomes, among which is reduced inter-male aggression. However, the underlying mechanism mediating the positive outcomes of EE remains poorly characterised. EE has been associated with altered brain-derived neurotrophic factor (Bdnf) gene expression. The Bdnf gene consists of multiple transcript variants, all of which encode for an identical protein. Remarkably, different Bdnf transcripts expression in different tissues influences different metabolic and behavioural functions. Therefore, we hypothesised that EE modifies the feeding and aggressive behaviours in mice via altering Bdnf gene expression in a transcript variant-specific and brain region-specific manner. To test this hypothesis, we employed behavioural and gene expression analyses to examine the influence of EE on feeding and aggressive behaviours and the associated expression of genes encoding neurotrophins in male C57BL/6 mice. In the first study, we showed, for the first time, that EE potentiates the feeding-suppressing effect of glucose in 8-hr fasted mice. Furthermore, intraperitoneal glucose injection promoted hypothalamic activation, as assessed by increased Fos expression. Moreover, glucose treatment significantly upregulated hypothalamic glial cell line-derived neurotrophic factor (Gdnf) mRNA levels while selectively downregulating Bdnf transcript variants levels in the hypothalamus and amygdala of the EE mice. In the second study, we showed that EE significantly reduced inter-male aggression in group-housed mice. This effect was associated with reduced activity of the aggression-linked corticolimbic circuits. Importantly, EE significantly r

Efforts to refine the care and use of animals in research have been ongoing for many years and have led to general standardization of rodent models, particularly with regard to animal housing, genetics, and health status. Concurrently, numerous informal practices and recommendations have been promulgated with the laudable intent of promoting general animal wellbeing through so-called enrichment of the cage environment. However, the variety of housing conditions fostered by efforts at environmental enrichment (EE) complicates the goal of establishing standardized or even defined environments for laboratory rodents. Many studies over the years have sought to determine whether or how various enrichment strategies affect the behavior and physiology of laboratory rodents. The findings, conclusions, and interpretations of these studies are mixed, particularly with regard to their application across rodent species, strains, genders, and ages; whether or how they affect the animals and the science; and, in some cases, whether the effects are positive, negative, or neutral in terms of animal wellbeing. Crucial issues related to the application of EE in research settings include its poorly defined effect on the animals, the potential for increased variability in the data, poor definition across labs and in publications, and potential for animal or scientific harm. The complexities, uncertainties, interpretational conundrums, varying conclusions, and lack of consensus in the EE literature warrant careful assessment of the benefits and liabilities associated with implementing such interventions. Reliance on evidence, professional judgment, and performance standards are crucial in the development of EE strategies., Pub. in Comparative Medicine, v61 n4 p314-321, 2011.