Autophagy protects against neural cell death induced by piperidine alkaloids present in Prosopis juliflora (Mesquite)

ABSTRACT Prosopis juliflora is a shrub that has been used to feed animals and humans. However, a synergistic action of piperidine alkaloids has been suggested to be responsible for neurotoxic damage observed in animals. We investigated the involvement of programmed cell death (PCD) and autophagy on the mechanism of cell death induced by a total extract (TAE) of alkaloids and fraction (F32) from P. juliflora leaves composed majoritary of juliprosopine in a model of neuron/glial cell co-culture. We saw that TAE (30 µg/mL) and F32 (7.5 µg/mL) induced reduction in ATP levels and changes in mitochondrial membrane potential at 12 h exposure. Moreover, TAE and F32 induced caspase-9 activation, nuclear condensation and neuronal death at 16 h exposure. After 4 h, they induced autophagy characterized by decreases of P62 protein level, increase of LC3II expression and increase in number of GFP-LC3 cells. Interestingly, we demonstrated that inhibition of autophagy by bafilomycin and vinblastine increased the cell death induced by TAE and autophagy induced by serum deprivation and rapamycin reduced cell death induced by F32 at 24 h. These results indicate that the mechanism neural cell death induced by these alkaloids involves PCD via caspase-9 activation and autophagy, which seems to be an important protective mechanism.

Selección espermática en semen congelado/descongelado de equino: evaluación de las membranas plasmática, acrosomal y potencial de membrana mitocondrial / Sperm selection in frozen/thawed semen of equine: evaluation of plasma, acrosome membranes and mitochondrial membrane potential

Los procedimientos de criopreservación inducen cambios morfofuncionales en los espermatozoides. Es importante post descongelación espermática utilizar procedimientos de selección que permitan recuperar espermatozoides altamente funcionales. El objetivo del presente estudio fue comparar la eficiencia del Swim-up y Equipure® en la selección de espermatozoides funcionales en semen descongelado de equino. Semen de 4 potros reproductores Criollos Chilenos (A, B, C y D), fueron descongelados separadamente y procesados (n=15) por: I.- Swim-up (SU) y II.- Equipure® (EQ). Post descongelación se determinó por citometría de flujo la viabilidad e integridad de membrana plasmática (SYBR-14/PI), potencial de membrana mitocondrial (YDm; JC-1), integridad de la membrana acrosomal (FITC-PSA/PI). La motilidad progresiva (%) en dos animales fue más alta (P<0,05) por SU comparado con EQ: A (55,7±5,8% v/s 38,17±3,7%) y C (37,5±7% vs. 32±2,1%, respectivamente). La integridad de la membrana plasmática (%), tres animales presentaron diferencias (P<0,05), siendo más alta por SU en dos animales comparado con EQ (A: 54,3±1,7 vs. 36,7±1,9, C: 36,1±5,7 vs. 29,4±4,8 y D: 34,4±9,4 vs. 52,7±5,2; respectivamente), solamente un animal fue superior EQ. En el YDm (%), diferencias significativas (P<0,05) fueron detectadas en los cuatro animales, siendo más altos en SU comparado con EQ (A: 69,1±8,6% vs. 47,4±3,3%, B: 59,34±12,3% vs. 24,8±1,5%, C: 54,9±12,3% vs. 43,2±3,1% y D: 53,1±17,6% vs. 37,5±5,7%; respectivamente). Los resultados obtenidos en el presente estudio demostraron que los métodos de selección espermática Swim-up y Equipure® permiten recuperar espermatozoides de diferente calidad funcional en semen congelado-descongelado de equino, presentándose diferencias individuales entre los animales con respecto a los métodos. Se observó una tendencia del método Swim-up en seleccionar espermatozoides de equino descongelados con mayor calidad funcional comparado con Equipure®.

Freeze-thaw procedures induce structural and functional changes in sperm. It is important to use post thaw sperm selection procedures that can retrieve highly functional sperm. The aim of this study was to compare the efficiency of the Swim-up and Equipure® in the selection of functional sperm of thawed equine semen. Semen of four Chilean Criollo reproductive stallions (A, B , C and D) were frozen and thawed using a standard protocol and processed separately (n = 15) : I. Swim-up (SU) and II. Equipure® (EQ). Post sperm selection,was determined by flow cytometry. Viability and plasma membrane integrity (SYRB-14/PI), mitochondrial membrane potential (YDm, JC -1), acrosome membrane integrity (FITC-PSA/PI). Progressive motility (%) was higher (P<0.05) in two animals per SU compared with EQ, A (55.7±5.8% vs. 38.17±3.7%) and C (37.5±7.0% vs. 32±2.1%, respectively). The viability and integrity of the plasma membrane (%), three animals showed differences (P<0.05), being higher for SU in two animals compared with EQ (A: 54.3±1.7 vs. 36.7±1.9, C: 36.1±5.7 vs. 29.4±4.8 and D: 34.4±9.4 vs. 52.7±5.2, respectively), only one animal was higher EQ. In YDm (%), significant differences were detected (P<0.05) in all four animals, being higher in SU compared with EQ (A: 69.1±8.6% vs. 47.4±3.3% B: 59.34±12.3% vs. 24.8±1.5%, C: 54.9±12.3% vs. 43.2±3.1% and D: 53.1±17.6% vs. 37.5±5.7%, respectively). The results obtained in this study showed that sperm selection methods Swim-up and Equipure® can retrieve different functional sperm quality in frozen-thawed equine semen, and that individual differences were registered among animals with respect to methods. In the Swim-up method a tendency for selecting higher functional quality in thawed equine sperm was observed when compared to Equipure®.

Normal skin and hypertrophic scar fibroblasts differentially regulate collagen and fibronectin expression as well as mitochondrial membrane potential in response to basic fibroblast growth factor

Basic fibroblast growth factor (bFGF) regulates skin wound healing; however, the underlying mechanism remains to be defined. In the present study, we determined the effects of bFGF on the regulation of cell growth as well as collagen and fibronectin expression in fibroblasts from normal human skin and from hypertrophic scars. We then explored the involvement of mitochondria in mediating bFGF-inducedeffects on the fibroblasts. We isolated and cultivated normal and hypertrophic scar fibroblasts from tissue biopsies of patients who underwent plastic surgery for repairing hypertrophic scars. The fibroblasts were then treated with different concentrations of bFGF (ranging from 0.1 to 1000 ng/mL). The growth of hypertrophic scar fibroblasts became slower with selective inhibition of type I collagen production after exposure to bFGF. However, type III collagen expression was affected in both normal and hypertrophic scar fibroblasts. Moreover, fibronectin expression in the normal fibroblasts was up-regulated after bFGF treatment. bFGF (1000 ng/mL) also induced mitochondrial depolarization in hypertrophic scar fibroblasts (P < 0.01). The cellular ATP level decreased in hypertrophic scar fibroblasts (P < 0.05), while it increased in the normal fibroblasts following treatment with bFGF (P < 0.01). These data suggest that bFGF has differential effects and mechanisms on fibroblasts of the normal skin and hypertrophic scars, indicating that bFGF may play a role in the early phase of skin wound healing and post-burn scar formation.

Effect of liver ischemic preconditioning in cirrhotic rats submitted to hepatic ischemia/reperfusion injury / Efeito do pré-condicionamento isquêmico hepático submetidos a lesão de isquemia/reperfusão do fígado

PURPOSE: The main aim of this study was to determine the influence of ischemic preconditioning (IPC) on rat liver cirrhosis. METHODS: Cirrhosis was induced in Wistar rats by occlusion of the hepatic duct. The animals were divided into four groups of six animals each: non-cirrhotic group (simulated operation only), cirrhotic control group (simulated operation in cirrhotic rats), I/R group (40-minute ischemia without IPC), and IPC group (cirrhotic rats with ischemia, previously submitted to IPC). The IPC procedure consisted of partial hepatic ischemia for five minutes, followed by 10 minutes of reperfusion. In the case of the IPC group, the animals were submitted to liver ischemia for 40 minutes after the preconditioning procedure, followed by 2 hours of reperfusion. Blood samples were collected for measurement of serum aminotransferases (ALT and AST). The respiratory control ratio (RCR), the mitochondrial membrane potential (MMP), and malondialdehyde (MDA) values in the hepatic tissue were analyzed. Nonparametric statistical analysis was used and a value of p<0.05 was considered statistically significant. RESULTS: Ischemia did not induce significant increase in ALT and AST levels. MDA values were significantly higher in cirrhotic animals. MMP did not significantly change in cirrhosis and liver ischemia. Mitochondrial RCR decreased in liver cirrhosis, accentuated upon liver ischemia, and did not significantly change with IPC. CONCLUSION: Ischemic preconditioning does not protect the liver from hepatic injury induced by the ischemia/ reperfusion process.

OBJETIVO: O objetivo deste estudo foi determinar a influência do pré-condicionamento isquêmico (IPC) em fígados de ratos cirróticos. MÉTODOS: A cirrose hepática foi induzida em ratos Wistar machos (250 a 300g) por oclusão, durante 30 dias, do ducto hepático comum.A seguir, os animais cirróticos foram divididos em três grupos de seis; Grupo controle cirrótico (operação simulada para isquemia/reperfusão/pré-condicionamento), Grupo I/R, isquemia de 40 minutos sem pré-condicionamento (IPC) e grupo IPC com isquemia precedida por IPC. O IPC consistiu de uma isquemia parcial por cinco minutos, seguida por 10 minutos de reperfusão. No grupo IPC, após o pré-condicionamento, os animais foram submetidos à isquemia hepática de 40 minutos seguida de 2 horas de reperfusão. Foram colhidas amostras de sangue para dosagem sérica de aminotransferases (ALT e AST). Razão de controle respiratório (RCR), potencial de membrana das mitocôndrias (PMM) e dosagem de malondialdeído (MDA) foram analisadas no tecido hepático. Analise estatística não paramétrica foi utilizada com nível de significância de 5 por cento para as comparações entre grupos. RESULTADOS: A isquemia não induziu aumento significativo das aminotransferases. Houve aumento significativo de MDA nos animais cirróticos.O PMM não se alterou significativamente na cirrose e na isquemia hepática. A RCR mitocondrial diminuiu na cirrose hepática e acentuou-se com a isquemia do fígado e não se alterou significativamente com o IPC. CONCLUSÃO: O pré-condicionamento isquêmico não protegeu o fígado das lesões hepáticas induzidas pelo processo de isquemia/reperfusão.