Neurodegenerative disease is an umbrella term for different conditions which primarily affect the neurons in the human brain. In the last century, significant research has been focused on mechanisms and risk factors relevant to the multifaceted etiopathogenesis of neurodegenerative diseases. Currently, neurodegenerative diseases are incurable, and the treatments available only control the symptoms or delay the progression of the disease. This review is aimed at characterizing the complex network of molecular mechanisms underpinning acute and chronic neurodegeneration, focusing on the disturbance in redox homeostasis, as a common mechanism behind five pivotal risk factors: aging, oxidative stress, inflammation, glycation, and vascular injury. Considering the complex multifactorial nature of neurodegenerative diseases, a preventive strategy able to simultaneously target multiple risk factors and disease mechanisms at an early stage is most likely to be effective to slow/halt the progression of neurodegenerative diseases.
One of the most substantial and established environmental risk factors for neurological and psychiatric disorders is stress exposure, whose detrimental consequences hinge on several variables including time. In this regard the gestational period is known to present an intrinsic vulnerability to environmental insults and thus stressful events during pregnancy can lead to severe consequences on the offspring’s brain development with long-term repercussions throughout adulthood. On this basis, we investigated the long-lasting impact of prenatal stress exposure on the susceptibility to the experimental autoimmune encephalomyelitis (EAE), a well-established murine model of multiple sclerosis. Although stress is considered a triggering factor for this chronic, progressive, autoimmune disease, little is known about the underlying mechanisms. To this end, EAE was induced by immunization with MOG35-55/CFA and pertussis toxin administration in adult female C57BL/6 mice born from control or stressed dams exposed to restraint stress during the last days of gestation. Our results demonstrate that gestational stress induces a marked increase in the severity of EAE symptoms in adulthood. Further, we highlight an altered maturation of oligodendrocytes in the spinal cord of prenatally stressed EAE mice, as indicated by the higher levels of GPR17, a marker of immature oligodendrocyte precursor cells. These behavioral and molecular alterations are paralleled by changes in the expression and signaling of the neurotrophin BDNF, an important mediator of neural plasticity that may contribute to stress-induced impaired remyelination. Since several already marketed drugs are able to modulate BDNF levels, these results pave the way to the possibility of repositioning these drugs in multiple sclerosis.
Rationale
Although the occurrence of stressful events is very common during life, their impact may be different depending on the experience severity and duration. Specifically, acute challenges may trigger adaptive responses and even improve the individual’s performance. However, such a physiological positive coping can only take place if the underlying molecular mechanisms are properly functioning. Indeed, if these systems are compromised by genetic factors or previous adverse conditions, the response set in motion by an acute challenge may be maladaptive and even cause the insurgence or the relapse of stress-related psychiatric disorders.
Objectives
On these bases, we evaluated in the rat brain the role of the antioxidant component of the redox machinery on the acute stress responsiveness and its modulation by potential detrimental or beneficial events.
Methods
The expression of several antioxidant enzymes was assessed in different brain areas of adult male rats exposed to acute stress 3 weeks after a chronic immobilization paradigm with or without a concomitant treatment with the antipsychotic lurasidone.
Results
The acute challenge was able to trigger a marked antioxidant response that, despite the washout period, was impaired by the previous adverse experience and restored by lurasidone in an anatomical-specific manner.
Conclusions
We found that a working antioxidant machinery takes part in acute stress response and may be differentially affected by other experiences. Given the essential role of stress responsiveness in almost every life process, the identification of the underlying mechanisms and their potential pharmacological modulation add further translational value to our data.
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