The impact of maternal separation on adult mouse behaviour and on the total neuron number in the mouse hippocampus

Abstract

The maternal separation paradigm has been applied to C57BL/6J mice as an animal developmental model for understanding structural deficits leading to abnormal behaviour. A maternal separation (MS) model was used on postnatal day (PND) 9, where the pups were removed from their mother for 24 h (MS24). When the pups were 10 weeks old, the level of anxiety and fear was measured with two behavioural tests; an open field test and an elevated plus maze test. The Barnes platform maze was used to test spatial learning, and memory by using acquisition trials followed by reverse trial sessions. The MS24 mice spent more time in the open arms of the elevated plus maze compared to controls, but no other treatment differences were found in the emotional behavioural tests. However, in the reverse trial for the Barnes maze test there was a significant difference in the frequency of visits to the old goal, the number of errors made by the MS24 mice compared to controls and in total distance moved. The mice were subsequently sacrificed and the total number of neurons estimated in the hippocampus using the optical fractionator. We found a significant loss of neurons in the dentate gyrus in MS mice compared to controls. Apparently a single maternal separation can impact the number of neurons in mouse hippocampus either by a decrease of neurogenesis or as an increase in neuron apoptosis. This study is the first to assess the result of maternal separation combining behaviour and stereology.

Minimizing fear and anxiety in working dogs: A review

“…Rodents studies show that early separation of pups from their mother can induce shortand long-term changes in the stress reactivity system, as indicated by the potentiated HPA axis response to subsequent stressors (e.g., Knuth and Etgen, 2007;Lippmann et al, 2007). Early and abrupt separation also enhances manifestations of anxiety and depression-like behaviors (Fabricius et al, 2008;Lambás-Señas et al, 2009) and impairs spatial learning and memory (Aisa et al, 2007;Tata et al, 2015) during adulthood. In contrast, repeated, short maternal separation increased resilience to stressful events later in life (Parker et al, 2006;Benetti et al, 2007) and reduced fearfulness (Macrì and Würbel, 2006).…”

Severe Early Life Stress Hampers Spatial Learning and Neurogenesis, but Improves Hippocampal Synaptic Plasticity and Emotional Learning under High-Stress Conditions in Adulthood

“…Emphasizing its persistent nature, MD in rodents was found to affect hippocampal structure in adulthood, resulting in lower hippocampal neuron and glia numbers (Leventopoulos et al, 2007;Fabricius et al, 2008) and reduced mossy fiber density (Huot et al, 2002). With respect to adult hippocampal neurogenesis, repeated maternal separation was shown to reduce only cell proliferation (Mirescu et al, 2004;Aisa et al, 2009) but not newborn cell survival in rats (Mirescu et al, 2004;Greisen et al, 2005;Petersen et al, 2008).…”

Morphometric Analysis of Infant and Adult Medullary Nuclei Through Optical Disector Method

“…The CE for the estimate of the volume, that is, CE(V), is function of the noise effect and systematic uniform random sampling (SURS) variance for the sums of areas: the noise effect represents the uncertainty deriving from point counting; SURS variance for the sum of areas is the uncertainty of sampling between sections, as estimates on different sections may vary. The CE(V) was calculated according to the following formulas (Gundersen et al, 1999;Christensen et al, 2007;Eriksen and Pakkenberg, 2007;Fabricius et al, 2008):…”