Neuroprotective effects of ammonium tetrathiomolybdate, a slow-release sulfide donor, in a rodent model of regional stroke.

BACKGROUND: Several therapeutic strategies to rescue the brain from ischemic injury have improved outcomes after stroke; however, there is no treatment as yet for reperfusion injury, the secondary damage caused by necessary revascularization. Recently we characterized ammonium tetrathiomolybdate (ATTM), a drug used as a copper chelator over many decades in humans, as a new class of sulfide donor that shows efficacy in preclinical injury models. We hypothesized that ATTM could confer neuroprotection in a relevant rodent model of regional stroke. METHODS AND RESULTS: Brain ischemia was induced by transient (90-min) middle cerebral artery occlusion (tMCAO) in anesthetized Wistar rats. To mimic a clinical scenario, ATTM (or saline) was administered intravenously just prior to reperfusion. At 24 h or 7 days post-reperfusion, rats were assessed using functional (rotarod test, spontaneous locomotor activity), histological (infarct size), and molecular (anti-oxidant enzyme capacity, oxidative damage, and inflammation) outcome measurements. ATTM-treated animals showed improved functional activity at both 24 h and 7-days post-reperfusion, in parallel with a significant reduction in infarct size. These effects were additionally associated with increased brain antioxidant enzyme capacity, decreased oxidative damage, and a late (7-day) effect on pro-inflammatory cytokine levels and nitric oxide products. CONCLUSION: ATTM confers significant neuroprotection that, along with its known safety profile in humans, provides encouragement for its development as a novel adjunct therapy for revascularization following stroke.

Characterization and modulation of microglial phenotypes in an animal model of severe sepsis.

We aim to characterize the kinetics of early and late microglial phenotypes after systemic inflammation in an animal model of severe sepsis and the effects of minocycline on these phenotypes. Rats were subjected to CLP, and some animals were treated with minocycline (10 ug/kg) by i.c.v. administration. Animals were killed 24 hours, 5, 10 and 30 days after sepsis induction, and serum and hippocampus were collected for subsequent analyses. Real-time PCR was performed for M1 and M2 markers. TNF-α, IL-1ß, IL-6, IL-10, CCL-22 and nitrite/nitrate levels were measured. Immunofluorescence for IBA-1, CD11b and arginase was also performed. We demonstrated that early after sepsis, there was a preponderant up-regulation of M1 markers, and this was not switched to M2 phenotype markers later on. We found that up-regulation of both M1 and M2 markers co-existed up to 30 days after sepsis induction. In addition, minocycline induced a down-regulation, predominantly, of M1 markers. Our results suggest early activation of M1 microglia that is followed by an overlap of both M1 and M2 phenotypes and that the beneficial effects of minocycline on sepsis-associated brain dysfunction may be related to its effects predominantly on the M1 phenotype.

Early life experience contributes to the developmental programming of depressive-like behaviour, neuroinflammation and oxidative stress.

This study used an animal model of depression induced by maternal care deprivation (MCD) to investigate whether depressive behaviour, neuroinflammation and oxidative stress were underlying factors in developmental programming after early life stress. At postnatal days (PND) 20, 30, 40, and 60, individual subsets of animals were evaluated in behavioural tests and then euthanized to assess cytokine levels and oxidative stress parameters in the prefrontal cortex (PFC), hippocampus and serum. The results showed that MCD did not induce behavioural changes at PND 30 and 40. However, at PND 20 and 60, the rats displayed a depressive-like behaviour in the forced swimming test, without changes in locomotor spontaneous activity. In the brain and serum, the levels of pro-inflammatory cytokines (interleukin-1ß (IL-1ß), interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α)) were increased, and the anti-inflammatory cytokine (interleukin-10) level was reduced throughout developmental programming (PND 20, 30, 40 and 60). Protein carbonyl levels increased in the brain at PND 30, 40 and 60. Superoxide dismutase (SOD) activity was decreased during all developmental programming phases evaluated in the brain. Catalase (CAT) activity was decreased at PND 20, 40 and 60 in the brain. Our results revealed that "critical episodes" in early life stressful events are able to induce behavioural alterations that persist into adulthood and can stimulate inflammation and oxidative damage in both central and peripheral systems, which are required for distinct patterns of resilience against psychiatric disorders later in life.