Overexpression of mineralocorticoid receptors does not affect memory and anxiety-like behavior in female mice

Mineralocorticoid receptors (MRs) have been implicated in behavioral adaptation and learning and memory. Since – at least in humans - MR function seems to be sex-dependent, we examined the behavioral relevance of MR in female mice exhibiting transgenic MR overexpression in the forebrain. Transgenic MR overexpression did not affect contextual fear memory or cued fear learning and memory. Moreover, MR overexpressing and control mice discriminated equally well between fear responses in a combined cue and context fear conditioning paradigm. Also context-memory in an object recognition task was unaffected in MR overexpressing mice. We conclude that MR overexpression in female animals does not affect fear conditioned responses and object recognition memory

Early life adversity:Lasting consequences for emotional learning

The early postnatal period is a highly sensitive time period for the developing brain, both in humans and rodents. During this time window, exposure to adverse experiences can lastingly impact cognitive and emotional development. In this review, we briefly discuss human and rodent studies investigating how exposure to adverse early life conditions - mainly related to quality of parental care - affects brain activity, brain structure, cognition and emotional responses later in life. We discuss the evidence that early life adversity hampers later hippocampal and prefrontal cortex functions, while increasing amygdala activity, and the sensitivity to stressors and emotional behavior later in life. Exposure to early life stress may thus on the one hand promote behavioral adaptation to potentially threatening conditions later in life -at the cost of contextual memory formation in less threatening situations- but may on the other hand also increase the sensitivity to develop stress-related and anxiety disorders in vulnerable individuals

Effects of Mineralocorticoid Receptor Overexpression on Anxiety and Memory after Early Life Stress in Female Mice

Early-life stress (ELS) is a risk factor for the development of psychopathology, particularly in women. Human studies have shown that certain haplotypes of NR3C2, encoding the mineralocorticoid receptor (MR), that result in gain of function, may protect against the consequences of stress exposure, including childhood trauma. Here, we tested the hypothesis that forebrain-specific overexpression of MR in female mice would ameliorate the effects of ELS on anxiety and memory in adulthood. We found that ELS increased anxiety, did not alter spatial discrimination and reduced contextual fear memory in adult female mice. Transgenic overexpression of MR did not alter anxiety but affected spatial memory performance and enhanced contextual fear memory formation. The effects of ELS on anxiety and contextual fear were not affected by transgenic overexpression of MR. Thus, MR overexpression in the forebrain does not represent a major resilience factor to early life adversity in female mice

Overexpression of Mineralocorticoid Receptors in the Mouse Forebrain Partly Alleviates the Effects of Chronic Early Life Stress on Spatial Memory, Neurogenesis and Synaptic Function in the Dentate Gyrus

Evidence from human studies suggests that high expression of brain mineralocorticoid receptors (MR) may promote resilience against negative consequences of stress exposure, including childhood trauma. We examined, in mice, whether brain MR overexpression can alleviate the effects of chronic early life stress (ELS) on contextual memory formation under low and high stress conditions, and neurogenesis and synaptic function of dentate gyrus granular cells. Male mice were exposed to ELS by housing the dam with limited nesting and bedding material from postnatal day (PND) 2 to 9. We investigated the moderating role of MRs by using forebrain-specific transgenic MR overexpression (MR-tg) mice. Low-stress contextual (i.e., object relocation) memory formation was hampered by ELS in wildtype but not MR-tg mice. Anxiety like behavior and high-stress contextual (i.e., fear) memory formation were unaffected by ELS and/or MR expression level. At the cellular level, an interaction effect was observed between ELS and MR overexpression on the number of doublecortin-positive cells, with a significant difference between the wildtype ELS and MR-tg ELS groups. No interaction was found regarding Ki-67 and BrdU staining. A significant interaction between ELS and MR expression was further observed with regard to mEPSCs and mIPSC frequency. The ratio of evoked EPSC/IPSC or NMDA/AMPA responses was unaffected. Overall, these results suggest that ELS affects contextual memory formation under low stress conditions as well as neurogenesis and synaptic transmission in dentate granule cells, an effect that can be alleviated by MR-overexpression

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

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

Brain Mineralocorticoid Receptors and Resilience to Stress

Exposure to stressful experiences triggers the release of-among others-glucocorticoids from the adrenal glands. These hormones, cortisol and corticosterone in humans and rodents respectively, activate mineralocorticoid receptors (MRs) and glucocorticoid receptors (GRs) that regulate neuronal activity and behavioral adaptation to stressful experiences. This review discusses molecular properties of MRs, the role of MRs in regulating neuronal function and behavior and, ultimately, evidence that enhanced MR function may confer resilience to stressful experiences

Metsonsoitimen riistapainoitteinen metsänhoito : Case: A. Ahlström Kiinteistöt Oy, Pöytyä

Metsänhoito käsitteenä on lähes jokaiselle metsänomistajille tuttu termi, mutta riistataloudellinen metsänhoito on osalle tuntematon. Metson soidinalueet saavat jo normaalissa metsänhoidossa erityiskohtelun, koska nämä ovat merkittäviä alueita riistan kannalta. Omassa työssäni perehdyn enemmän riistametsänhoitoon metson soidinalueella. Opinnäytetyöni tavoite on turvata metson soitimen säilyminen hakkuusuunnitelmalla. Soidinalueen turvaaminen tapahtuu hakkuuajankohtien pitkittämisellä ja säästämällä metsolle suojapaikkoja lähellä soidinaluetta. Alueen metsien riistan-hoidollinen suunnittelu ei vain anna suojaa metsolle, vaan toimenpiteistä hyötyvät myös useammat riistalajit. Etukäteen minulla oli tiedossa, että alue on yksi Etelä-Suomen merkittävimpiä metson soidinalueita. Näiden paikkojen säästämisellä ja riistanhoidollisella suunnittelulla on erittäin suuri merkitys metsokannan säilymiselle elinvoimaisena. Metso on suurten metsien lintuna kärsinyt metsätaloudesta. Jäljellä olevista suurista soidinpaikoista on syytä huolehtia.Forestry as a term is usually known by forest owners, but wild game favouring is not known that much. Capercaillie is a largest grouse in Finland. Capercaillie courting areas already have a special treatment in forestry, because they have a huge effect on capercaillie populations. This thesis became familiar more with game favouring forestry in capercaillie courting areas. The purpose of the thesis was to secure capercaillie courting area using a logging plan. Capercaillie courting area securing happens by changing the timing of the logging and by saving protected areas near the courting area. Game favouring forestry does not just give shelter to capercaillie, but also other wild game benefits. It is known that this area is one of the most significant capercaillie courting areas in Southern Finland. Protecting these places and having game favouring plans have a huge effect on capercaillie survivability. Capercaillie, a bird living in large forests, has suffered from modern forestry. There are few known large capercaillie courting areas left, and they must have taken care of

Behavioral parameters (averaged over the day) recorded during the spatial training trials in MR-Tg and MR^CaMKCre mice and their control littermates.

<p>The spatial task consisted of six trials. Data represent mean ± SEM of all trials. For statistics a repeated measures ANOVA was used over the trials. Behavioral parameters that differ significantly; p<0.05: *vs same sex control littermates; ^#female MR^CaMKCre vs MR-Tg; ^$male vs female control littermates of MR^CaMKCre mice.</p

Percentage of serial hole visits averaged over the trials of the two days of the stimulus-response task.

<p>Both days of the stimulus-response task consisted of six trials. Data represent mean ± SEM of all trials of one day. For statistics a repeated measures ANOVA was used over the trials of one day.</p>*<p>Significantly different between genotypes of the same group over the day; p<0.05.</p