Melatonin has demonstrated a potential protective effect in central nervous system. Thus, it is interesting to determine whether pre-ischemia melatonin administration could protect against cerebral ischemia/reperfusion (IR)-related injury and the underlying molecular mechanisms. In this study, we revealed that IR injury significantly activated endoplasmic reticulum (ER) stress and autophagy in a middle cerebral artery occlusion mouse model. Pre-ischemia melatonin treatment was able to attenuate IR-induced ER stress and autophagy. In addition, with tandem RFP-GFP-LC3 adeno-associated virus, we demonstrated pre-ischemic melatonin significantly alleviated IR-induced autophagic flux. Furthermore, we showed that IR induced neuronal apoptosis through ER stress related signalings. Moreover, IR-induced autophagy was significantly blocked by ER stress inhibitor (4-PBA), as well as ER-related signaling inhibitors (PERK inhibitor, GSK; IRE1 inhibitor, 3,5-dibromosalicylaldehyde). Finally, we revealed that melatonin significantly alleviated cerebral infarction, brain edema, neuronal apoptosis, and neurological deficiency, which were remarkably abolished by tunicamycin (ER stress activator) and rapamycin (autophagy activator), respectively. In summary, our study provides strong evidence that pre-ischemia melatonin administration significantly protects against cerebral IR injury through inhibiting ER stress-dependent autophagy. Our findings shed light on the novel preventive and therapeutic strategy of daily administration of melatonin, especially among the population with high risk of cerebral ischemic stroke.

Silent information regulator 1 (SIRT1), a type of histone deacetylase, is a highly effective therapeutic target for protection against ischemia reperfusion (IR) injury (IRI). Previous studies showed that melatonin preserves SIRT1 expression in neuronal cells of newborn rats after hypoxia-ischemia. However, the definite role of SIRT1 in the protective effect of melatonin against cerebral IRI in adult has not been explored. In this study, the brain of adult mice was subjected to IRI. Prior to this procedure, the mice were given intraperitoneal with or without the SIRT1 inhibitor, EX527. Melatonin conferred a cerebral-protective effect, as shown by reduced infarct volume, lowered brain edema, and increased neurological scores. The melatonin-induced upregulation of SIRT1 was also associated with an increase in the anti-apoptotic factor, Bcl2, and a reduction in the pro-apoptotic factor Bax. Moreover, melatonin resulted in a well-preserved mitochondrial membrane potential, mitochondrial Complex I activity, and mitochondrial cytochrome c level while it reduced cytosolic cytochrome c level. However, the melatonin-elevated mitochondrial function was reversed by EX527 treatment. In summary, our results demonstrate that melatonin treatment attenuates cerebral IRI by reducing IR-induced mitochondrial dysfunction through the activation of SIRT1 signaling.

Subarachnoid hemorrhage (SAH) is a devastating condition with high morbidity and mortality rates due to the lack of effective therapy. Nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation associated with the upregulation of apoptotic signaling pathway has been implicated in various inflammatory diseases including hemorrhagic insults. Melatonin is reported to possess substantial anti-inflammatory properties, which is beneficial for early brain injury (EBI) after SAH. However, the molecular mechanisms have not been clearly identified. This study was designed to investigate the protective effects of melatonin against EBI induced by SAH and to elucidate the potential mechanisms. The adult mice were subjected to SAH. Melatonin or vehicle was injected intraperitoneally 2 hr after SAH. Melatonin was neuroprotective, as shown by increased survival rate, as well as elevated neurological score, greater survival of neurons, preserved brain glutathione levels, and reduced brain edema, malondialdehyde concentrations, apoptotic ratio, and blood-brain barrier (BBB) disruption. Melatonin also attenuated the expressions of NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), cleaved caspase-1, interleukin-1β (IL-1β), and interleukin-6 (IL-6); these changes were also associated with an increase in the anti-apoptotic factor (Bcl2) and reduction in the pro-apoptotic factor (Bim). In summary, our results demonstrate that melatonin treatment attenuates the EBI following SAH by inhibiting NLRP3 inflammasome-associated apoptosis.

The genetic variability and population structure of a collection of 45 Grapevine leafroll-associated virus 3 (GLRaV-3) isolates were studied by single-stranded conformation polymorphism (SSCP) and sequence analysis of the RNA-dependent RNA polymerase (RdRp), heat-shock protein 70 homologue (HSP-70) and coat protein (CP) genes. The distribution of SSCP profiles was not correlated with the geographical origin of the isolates, indicating that GLRaV-3 is a single, undifferentiated population. The majority of the isolates showed an SSCP profile and a population structure that were composed of a single predominant variant. However, 10 % of the isolates for the RdRp and HSP-70 genes and 15 % for the CP gene were composed of a combination of two or more variants. Estimation of genetic diversity and phylogenetic analysis disclosed the possible existence of vines with mixed infections by diverging sequence variants, showing, in some cases, possible recombination events. Furthermore, differences in the genetic diversity and constraints existing in the three regions analysed indicated a higher variability in the CP gene. The epidemiological and biological implications of this finding are discussed.