Stress Resilience is Associated with Hippocampal Synaptoprotection in the Female Rat Learned Helplessness Paradigm

Chronic stress leads to persistent and contrasting stellate neuron dendritic hypertrophy in the amygdala of male and female rats, an effect not found in the hippocampus

In males, chronic stress enhances dendritic complexity in the amygdala, a region important in emotion regulation. An amygdalar subregion, the basolateral amygdala (BLA), is influenced by the hippocampus and prefrontal cortex to coordinate emotional learning and memory. This study quantified changes in dendritic complexity of BLA stellate neurons ten days after an unpredictable chronic stressor ended in both male and female rats. In addition, dendritic complexity of hippocampal neurons in male rats was assessed at a similar timepoint. Following Golgi processing, stressed male and female rats showed enhanced BLA dendritic complexity; increased arborization occurred near the soma in males and distally in females. As the brain was sampled ten days after chronic stress ended, BLA dendritic hypertrophy persisted in both sexes after the stressor had ended. For the hippocampus, CA3 dendritic complexity was similar for control and stressed males when assessed eight days after stress ended, suggesting that any stress-induced changes had resolved. These results show persistent enhancement of BLA dendritic arborization in both sexes following chronic stress, reveal sex differences in how BLA hypertrophy manifests, and suggest a putative neurobiological substrate by which chronic stress may create a vulnerable phenotype for emotional dysfunction.

A Preliminary Quantitative Electron Microscopic Analysis Reveals Reduced Number of Mitochondria in the Infralimbic Cortex of Rats Exposed to Chronic Mild Stress

Exposure to severe, uncontrollable and long-lasting stress is a strong risk factor for the development of numerous mental and somatic disorders. Animal studies document that chronic stress can alter neuronal morphology and functioning in limbic brain structures such as the prefrontal cortex. Mitochondria are intracellular powerhouses generating chemical energy for biochemical reactions of the cell. Recent findings document that chronic stress can lead to changes in mitochondrial function and metabolism. Here, we studied putative mitochondrial damage in response to chronic stress in neurons of the medial prefrontal cortex. We performed a systematic quantitative ultrastructural analysis to examine the consequences of 9-weeks of chronic mild stress on mitochondria number and morphology in the infralimbic cortex of adult male rats. In this preliminary study, we analyzed 4,250 electron microscopic images and 67000 mitochondria were counted and examined in the brains of 4 control and 4 stressed rats. We found significantly reduced number of mitochondria in the infralimbic cortex of the stressed animals, but we could not detect any significant alteration in mitochondrial morphology. These data support the concept that prolonged stress can lead to mitochondrial loss. This in turn may result in impaired energy production. Reduced cellular energy may sensitize the neurons to additional injuries and may eventually trigger the development of psychopathologies.

Prophylactic efficacy of ketamine, but not the low-trapping NMDA receptor antagonist AZD6765, against stress-induced maladaptive behavior and 4E-BP1-related synaptic protein synthesis impairment

Ketamine enhances the resilience against stress-induced depressive-like behavior, but its prophylactic efficacy in anxiety-related behaviors remains to be elucidated. Moreover, there is a need for developing novel preventive strategies against depressive- and anxiety-like behavior. AZD6765, a low-trapping NMDA receptor antagonist, shares with ketamine common molecular targets and produces rapid-onset antidepressant effects, suggesting that it could be a prophylactic agent. Therefore, this study investigated the prophylactic effect of ketamine against the depressive- and anxiety-like behavior induced by chronic restraint stress (2 h/day, for 10 days) in mice. We also investigated if AZD6765 exerts a resilience-enhancing response against these maladaptive behaviors. The contribution of 4E-BP1-related synaptic proteins synthesis (PSD-95/GluA1) in the possible pro-resilience efficacy of ketamine and AZD6765 was investigated. A single administration of ketamine (5 mg/kg, i.p.), but not AZD6765 (1 or 5 mg/kg, i.p.), given 1 week before the stress protocol, was effective in preventing stress-induced depressive-like behavior in the tail suspension test and splash test. Ketamine administered at 1 and 5 mg/kg (i.p.), but not AZD6765 (1 or 5 mg/kg, i.p.), prevented stress-induced anxiety-related self-grooming alterations. Stress-induced reduction on 4E-BP1 phosphorylation and PSD-95 and GluA1 immunocontent in the prefrontal cortex was prevented by ketamine (5 mg/kg, i.p.), but not AZD6765 (1 or 5 mg/kg, i.p.). The results indicate that ketamine, but not AZD6765, exerts a pro-resilience response against stress-induced maladaptive behavior, reinforcing that it could be a prophylactic agent to manage individuals at-risk to develop MDD and anxiety.

Learned Helplessness in Renal Dialysis Patients: Concept Analysis with an Evolutionary Approach

BACKGROUND

Learned helplessness is an early psychological concept, but in the field of nursing, the concept of learned helplessness in renal dialysis patients and its unique challenges are not well understood.

OBJECTIVE

This article provides a conceptual analysis of learned helplessness in renal dialysis patients to increase knowledge of this psychological phenomenon in the setting of renal nursing.

DESIGN

Rodgers' evolutionary concept analysis.

METHODS

The literature published in five databases (PubMed, CINAHL, Embase, PsycINFO, CNKI) was searched using specific terms. In the first stage, search terms and strategies were used to narrow the relevant articles. In the second stage, the data were extracted from the included articles. In the third stage, the data were analyzed using thematic analysis, and the results were presented in the form of attributes, antecedents, consequences, surrogate terms, and related terms. We found additional instruments and interventions and presented a model case to emphasize the practicality of the concept. In the fourth phase, experts contributed to the discussion and interpretation of the findings.

RESULTS

A total of 22 articles were included. Four attributes of learned helplessness in renal dialysis patients were identified: low self-concept, perceived loss, negative cognitive set, and abandonment of action. The antecedents were sociodemographic characteristics, disease and treatment, and psychological factors. Consequences were separated into four themes: psychological problems, physiological problems, quality of life, and health-related behavior. Surrogate terms are hopelessness and powerlessness, and the related term is depression.

CONCLUSION

The process of conceptual analysis in this study provides a means of identifying awareness gaps and practice challenges of learned helplessness in renal dialysis patients and other concepts. The findings can be used to guide the design of tools and interventions to expand the use of learned helplessness theory in nursing.