Superoxide imbalance triggered by Val16Ala-SOD2 polymorphism increases the risk of depression and self-reported psychological stress in free-living elderly people.

BACKGROUND: Oxidative stress and chronic inflammatory states triggered by a single-nucleotide polymorphism (SNP) in superoxide dismutase manganese-dependent gene (Val16Ala-SOD2) have been associated with the risk of developing several chronic, nontransmissible diseases. However, it is still not clear whether the VV-SOD2 genotype that causes higher basal superoxide anion levels has any impact on the risk for depression and self-reported psychological stress in elderly people. METHODS: In the present study, we tested this hypothesis using a case-control study where depression was detected using the Geriatric Depression Scale-15 (GDS-15). A total of 612 Brazilian free-living elderly subjects with a mean age of 67.1 ± 7.1 years old (number of controls, C = 497, and depressive individuals, D = 115) were included in this study. All participants had similar social, health, and lifestyle variables, with the exception of polypharmacy (≥5 medicines daily intake), which was higher in the D group, compared to C subjects. RESULTS: Our results showed that the VV-SOD2 genotype significantly increased the risk for depression and psychological stress in the elderly subjects, independently of sex/gender, age, and other prior diseases and health indicators (depression risk = 1.842, 1.109-3.061 95% CI, p = .018). VV-subjects also had a higher daily intake of antidepressants, anxiolytics, and anti-inflammatory drugs than A-allele subjects. CONCLUSION: Our findings support the hypothesis that genetically induced oxidative superoxide-hydrogen peroxide imbalance may be involved in an increased risk for developing depression and psychological stress in free-living elderly people without other chronic nontransmissible diseases.

Association between T102C 5-HT2A receptor gene polymorphism and 5-year mortality risk among Brazilian Amazon riparian elderly population.

OBJECTIVE: Serotonin (5-HT) is a pleiotropic molecule that exerts several functions on brain and peripheral tissues via different receptors. The gene for the 5-HT2A receptor shows some variations, including a T102C polymorphism, that have been associated with increased risk of neuropsychiatric and vascular disorders. However, the potential impact of 5-HT2A imbalance caused by genetic variations on the human lifespan has not yet been established. METHODS: We performed a prospective study involving an Amazon riparian elderly free-living population in Maués City, Brazil, with a 5-year follow-up. Out of a cohort of 637 subjects selected in July, 2009, we genotyped 471 individuals, including 209 males (44.4%) and 262 females (55.6%), all averaging 72.3 ± 7.8 years of age (ranging from 60 to 100 years). RESULTS: The T102C-SNP genotypic frequencies were 14.0% TT, 28.0% CC, and 58.0% CT. From 80 elderly individuals who died during the period investigated, we observed significantly (P = .005) higher numbers of TT carriers (27.3%) and CC carriers (21.2%), compared to heterozygous CT carriers (12.5%). Cox-regression analysis showed that association between the T102C-SNP and elderly survival was independent of age, sex, and other health variables. CONCLUSIONS: Our findings strongly suggest that imbalance in 5-HT2A may cause significant disturbances that lead to an increased susceptibility to death for individuals who are over 60 years of age.

Association between Machado-Joseph disease and oxidative stress biomarkers.

Spinocerebellar ataxia type 3, also called Machado-Joseph disease (MJD), is an hereditary autosomal dominant neurodegenerative disease that affects the cerebellum and its afferent and efferent connections. Since the mechanism by which mutant ataxin-3 eventually leads to neuronal death is poorly understood, additional investigations to clarify the biological alterations related to Machado-Joseph disease are necessary. Recent investigations suggest that oxidative stress may contribute significantly to Machado-Joseph disease. We compared markers of oxidative stress between Machado-Joseph disease and healthy control subjects. The results showed that Machado-Joseph patients have higher catalase levels and lower thiol protein levels compared to control subjects. The peripheral blood lymphocyes of MJD patients also showed higher levels of DNA damage by the comet assay than control subjects. Our results corroborate the hypothesis that the oxidative stress is associated with MJD patients. However, whether strategies to increase cellular antioxidative capacity may be effective therapies for the treatment of Machado-Joseph disease is an open question.

Mini-review: spinocerebellar ataxias: an update of SCA genes.

Autosomal dominant spinocerebellar ataxias (SCAs) are a complex group of debilitating and neurodegenerative diseases that affect the cerebellum and its main connections and characterized by a generalized incoordination of gait, speech, and limb movements. In general, the onset of SCAs occurs during adult life and shows great clinical heterogeneity. Currently, the mutations responsible for different types of SCAs have been localized in different regions of the genome, and most of them were already mapped and cloned. Several pieces of evidence suggest that all these diseases share the same molecular mechanism and physiopathological processes. CAG trinucleotide expansion is a common mutational basis of several of these disorders. An expanded polyglutamine tract may become a toxic product when located within the coding region of the gene. The SCA genes, recent patents and the molecular aspects of these disorders are presented in this review. Our knowledge of the molecular mechanisms of SCAs is rapidly expanding, and the development of important studies is bringing hope for effective therapies.

Administration of Hsp70 in vivo inhibits motor and sensory neuron degeneration.

The induction of heat shock proteins (Hsps) serves not only as a marker for cellular stress but also as a promoter of cell survival, which is especially important in the nervous system. We examined the regulation of the constitutive and stress-induced 70-kD Hsps (Hsc70 and Hsp70, respectively) after sciatic nerve (SN) axotomy in the neonatal mouse. Additionally, the prevention of axotomy-induced SN cell death by administration of several preparations of exogenous Hsc70 and Hsp70 was tested. Immunohistochemistry and Western blot analyses showed that endogenous levels of Hsc70 and Hsp70 did not increase significantly in lumbar motor neurons or dorsal root ganglion sensory neurons up to 24 hours after axotomy. When a variety of Hsc70 and Hsp70 preparations at doses ranging from 5 to 75 microg were applied to the SN stump after axotomy, the survival of both motor and sensory neurons was significantly improved. Thus, it appears that motor and sensory neurons in the neonatal mouse do not initiate a typical Hsp70 response after traumatic injury and that administration of exogenous Hsc/Hsp70 can remedy that deficit and reduce the subsequent loss of neurons by apoptosis.