RESUMO
OBJECTIVE: Suicide is an outcome arising from a combination of risk and protective factors. Examining psychological resilience traits associated with successful aging may help to better understand late-life suicide and depression. We examined self-reported protective factors including mindfulness, life satisfaction and engagement, flourishing, and subjective and objective social support in a high suicide-risk sample of depressed older adults. METHODS: Participants were 297 individuals aged 55+ (mean age: 64.2): 92 depressed suicide attempters, 138 depressed individuals who never attempted suicide, and 67 non-psychiatric comparisons. Using linear and binomial logistic regression, we examined the effects of a combined Protective Factor value on presence and severity of depression and suicidal ideation, and history of suicide attempt. RESULTS: Relative to the non-psychiatric comparison group, all depressed participants had significantly lower Protective Factor values. Higher Protective Factor value was associated with lower likelihood of depression, depression severity, and likelihood of ideation, but was not associated with ideation severity or history of suicide attempt. Participants with one standard deviation higher Protective Factor had lower odds of ideation incidence by a factor of OR=0.68 (95%CI=0.48-0.96). CONCLUSION: Resiliency characteristics relevant to psychological wellbeing and successful aging may mitigate the emergence of depression and suicidal ideation, as well as the severity of depression in late-life. The Resilience Factor used in this study can help clinicians nuance their appraisal of depression and suicide risk.
Assuntos
Atenção Plena , Tentativa de Suicídio , Humanos , Idoso , Tentativa de Suicídio/prevenção & controle , Tentativa de Suicídio/psicologia , Ideação Suicida , Depressão/epidemiologia , Depressão/psicologia , Satisfação Pessoal , Fatores de RiscoRESUMO
Animals with external fertilization, as amphibians, store their sperm in a quiescent state in the testis. When spermatozoa are released into natural fertilization media, the hypotonic shock triggers activation of sperm motility. Rhinella (Bufo) arenarum sperm are immotile in artificial seminal plasma (ASP, resembling testicular plasma tonicity) but acquire in situ flagellar beating upon dilution. However, if components from the egg shelly coat are added to this medium, motility shifts to a progressive pattern. Recently, we have shown that the signal transduction pathway required for in situ motility activation involves a rise in intracellular cAMP through a transmembrane adenylyl cyclase and activation of PKA, mostly in the midpiece and in the sperm head. In this report, we demonstrate that activation of calcineurin (aka PP2B and PPP3) is required for the shift from in situ to progressive sperm motility. The effect of calcineurin is manifested by dephosphorylation of PKC substrates, and can be promoted by intracellular calcium rise by Ca(2+) ionophore. Both phosphorylated PKC substrates and calcineurin localized to the flagella, indicating a clear differentiation between compartmentalization of PKA and calcineurin pathways. Moreover, no crosstalk is observed between these signaling events, even though both pathways are required for progressive motility acquisition as discussed.
Assuntos
Proteínas de Anfíbios/metabolismo , Bufo arenarum/metabolismo , Calcineurina/metabolismo , Proteína Quinase C/metabolismo , Transdução de Sinais , Motilidade dos Espermatozoides , Espermatozoides/enzimologia , Animais , Inibidores de Calcineurina , Ionóforos de Cálcio/farmacologia , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Inibidores Enzimáticos/farmacologia , Flagelos/enzimologia , Masculino , Pressão Osmótica , Fosforilação , Transdução de Sinais/efeitos dos fármacos , Peça Intermédia do Espermatozoide/enzimologia , Motilidade dos Espermatozoides/efeitos dos fármacos , Cauda do Espermatozoide/enzimologia , Espermatozoides/efeitos dos fármacos , Especificidade por SubstratoRESUMO
Sperm motility is essential for achieving fertilization. In animals with external fertilization as amphibians, spermatozoa are stored in a quiescent state in the testis. Spermiation to hypotonic fertilization media triggers activation of sperm motility. Bufo arenarum sperm are immotile in artificial seminal plasma (ASP) but acquire in situ flagellar beating upon dilution. In addition to the effect of low osmolarity on sperm motility activation, we report that diffusible factors of the egg jelly coat (EW) regulate motility patterns, switching from in situ to progressive movement. The signal transduction pathway involved in amphibian sperm motility activation is mostly unknown. In the present study, we show a correlation between motility activation triggered by low osmotic pressure and activation of protein kinase A (PKA). Moreover, this is the first study to present strong evidences that point toward a role of a transmembrane adenyl-cyclase (tmAC) in the regulation of amphibian sperm motility through PKA activation.
Assuntos
Adenilil Ciclases/metabolismo , Bufo arenarum/fisiologia , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Motilidade dos Espermatozoides , Espermatozoides/fisiologia , Inibidores de Adenilil Ciclases , Animais , Membrana Celular/enzimologia , AMP Cíclico/metabolismo , Ativação Enzimática , Soluções Hipotônicas/farmacologia , Masculino , Fosforilação , Espermatozoides/efeitos dos fármacos , Espermatozoides/enzimologiaRESUMO
Vitellogenin (Vtg), a large lipoglycophosphoprotein, is the most important precursor of the yolk proteins, and the major source of nutrients for the developing embryo in oviparous species. After its uptake by the oocytes, Vtg is converted into lipovitellins (high and light) and phosvitin, which are deposited into crystalline yolk platelets. We describe here the presence of two high molecular mass lipovitellin isoforms in Bufo arenarum mature oocytes with masses of 113 and 100 kDa, respectively. The amino acid sequence analysis of p113 and p100 peptides showed a high sequence homology between both polypeptides and the complete reported sequences of Xenopus laevis vitellogenin. Using specific antibodies, we determined that the Vtg uptake begins early during oogenesis, at the previtellogenic stage, and continues until oocytes have reached their mature status. In addition, we found that large endocytic vesicles mediate Vtg uptake in stage I oocytes, and that the size of the endocytic vesicles declines with oogenesis progression. In terms of the Vtg protein trafficking, we detected the Vtg precursor (190 kDa) in the liver of estradiol-injected females. Finally, we propose a subclassification of B. arenarum stage II oocytes into three physiologically and morphologically distinct periods (early, mid and late).
Assuntos
Bufo arenarum/metabolismo , Proteínas do Ovo/química , Proteínas do Ovo/metabolismo , Oócitos/crescimento & desenvolvimento , Oócitos/metabolismo , Vitelogênese , Sequência de Aminoácidos , Animais , Bufo arenarum/crescimento & desenvolvimento , Bufo arenarum/fisiologia , Proteínas do Ovo/isolamento & purificação , Feminino , Imuno-Histoquímica , Dados de Sequência Molecular , Peso Molecular , Oócitos/ultraestrutura , Transporte Proteico , Análise de Sequência de DNA , Fatores de TempoRESUMO
Sperm from the toad Bufo arenarum must penetrate the egg jelly before reaching the vitelline envelope (VE), where the acrosome reaction is triggered. When the jelly coat is removed, sperm still bind to the VE, but acrosomal exocytosis is not promoted. Our previous work demonstrated that diffusible substances of the jelly coat, termed "egg water" (EW), triggered capacitation-like changes in B. arenarum sperm, promoting the acquisition of a transient fertilizing capacity. In the present work, we correlated this fertilizing capacity with the ability of the sperm to undergo the acrosome reaction, further substantiating the role of the jelly coat in fertilization. When sperm were exposed to the VE, only those preincubated in EW for 5 or 8 min underwent an increase in the intracellular Ca(2+) concentration ([Ca(2+)](i)), which led to acrosomal exocytosis. Responsiveness to the VE was not acquired on preincubation in EW for 2 or 15 min or in Ringer solution regardless of the preincubation time. In contrast, depletion of intracellular Ca(2+) stores (induced by thapsigargin) promoted [Ca(2+)](i) rise and the acrosome reaction even in sperm that were not exposed to EW. Acrosomal exocytosis was blocked by the presence of Ca(2+) chelators independent of whether a physiological or pharmacological stimulus was used. However, Ni(2+) and mibefradil prevented [Ca(2+)](i) rise and the acrosome reaction of sperm exposed to the VE but not of sperm exposed to thapsigargin. These data suggest that the acrosomal responsiveness of B. arenarum sperm, present during a narrow period, is acquired during EW incubation and involves the modulation of a voltage-dependent Ca(2+) channel.