Dendritic Morphology of Hippocampal and Amygdalar Neurons in Adolescent Mice Is Resilient to Genetic Differences in Stress Reactivity

Abstract

Many studies have shown that chronic stress or corticosterone over-exposure in rodents leads to extensive dendritic remodeling, particularly of principal neurons in the CA3 hippocampal area and the basolateral amygdala. We here investigated to what extent genetic predisposition of mice to high versus low stress reactivity, achieved through selective breeding of CD-1 mice, is also associated with structural plasticity in Golgi-stained neurons. Earlier, it was shown that the highly stress reactive (HR) compared to the intermediate (IR) and low (LR) stress reactive mice line presents a phenotype, with respect to neuroendocrine parameters, sleep architecture, emotional behavior and cognition, that recapitulates some of the features observed in patients suffering from major depression. In late adolescent males of the HR, IR, and LR mouse lines, we observed no significant differences in total dendritic length, number of branch points and branch tips, summated tip order, number of primary dendrites or dendritic complexity of either CA3 pyramidal neurons (apical as well as basal dendrites) or principal neurons in the basolateral amygdala. Apical dendrites of CA1 pyramidal neurons were also unaffected by the differences in stress reactivity of the animals; marginally higher length and complexity of the basal dendrites were found in LR compared to IR but not HR mice. In the same CA1 pyramidal neurons, spine density of distal apical tertiary dendrites was significantly higher in LR compared to IR or HR animals. We tentatively conclude that the dendritic complexity of principal hippocampal and amygdala neurons is remarkably stable in the light of a genetic predisposition to high versus low stress reactivity, while spine density seems more plastic. The latter possibly contributes to the behavioral phenotype of LR versus HR animals.

Mutations in Vps15 perturb neuronal migration in mice and are associated with neurodevelopmental disease in humans

“…For Golgi staining, mice aged 4 months were perfused with 0.9% NaCl and their brains treated with the Rapid GolgiStain Kit according to the manufacturer’s instructions (FD Neurotechnologies, Inc., PK401). Dendritic spines were quantified as described 69 . In short, images of pyramidal neurons of the CA1 region of the hippocampus were captured using a Axioplan bright-field microscope.…”

Distinct Effects of Repeated Restraint Stress on Basolateral Amygdala Neuronal Membrane Properties in Resilient Adolescent and Adult Rats

“…Alternatively, it is possible that the differences in neuronal physiology between resilient and vulnerable rat existed before stress. However, a previous study that examined the morphology of BA neurons in high and low stress-responsive rodents did not find any difference (Pillai et al, 2012), whereas Adamec et al (2012) found significant dendritic hypertrophy in anxious control rats, but no further effect of stress. Furthermore, neuronal excitability of control rats was significantly less than stressed rats, before subdivision into resilient and vulnerable, indicating that stress had an overall impact on membrane properties.…”

Repeated restraint stress-induced atrophy of glutamatergic pyramidal neurons and decreases in glutamatergic efflux in the rat amygdala are prevented by the antidepressant agomelatine

“…Additionally, the dendritic complexity index (DCI) was calculated using the Neurolucida software as follows: DCI = (R branch tip orders + number branch tips) Â (total dendritic length/total number of primary dendrites). Branch tip order is determined by the number of bifurcations in a particular dendritic segment between a particular terminal tip and the cell body (Pillai et al, 2012). Dendritic arborization was analyzed using a Sholl analysis.…”