Johanna Gutierrez-Vargas

GluN2B N‐methyl‐D‐aspartic acid receptor subunit mediates atorvastatin‐Induced neuroprotection after focal cerebral ischemia

Statins are potent cholesterol biosynthesis inhibitors that exert protective effects in humans and in experimental models of stroke. The mechanisms involved in these protective actions are not completely understood. This study evaluates whether atorvastatin (ATV) treatment affects the GluN1 and GluN2B subunits of the N‐methyl‐D‐aspartic acid receptor in the somatosensory cerebral cortex at short and long periods following ischemia. Sham and ischemic male Wistar rats received 10 mg/kg of ATV or placebo by gavage every 24 hr for 3 consecutive days. The first dose was administered 6 hr after ischemia–reperfusion or the sham operation. ATV treatment resulted in faster recovery of neurological scores than placebo, prevented the appearance of pyknotic neurons, and restored microtubule‐associated protein 2 and neuronal nuclei staining to control values in the somatosensory cerebral cortex and the hippocampus at 72 hr and 15 days postischemia. Furthermore, ATV prevented spatial learning and memory deficits caused by cerebral ischemia. Cerebral ischemia reduced the number of GluN1/PSD‐95 and GluN2B/PSD‐95 colocalization clusters in cortical pyramidal neurons and reduced the levels of brain‐derived neurotrophic factor (BDNF) in the cerebral cortex. These effects of the ischemic insult were prevented by ATV, which also induced GluN2B/PSD‐95 colocalization in neuronal processes and an association of GluN2B with TrkB. The GluN2B pharmacological inhibitor ifenprodil prevented the increase in BDNF levels and the motor and cognitive function recovery caused by ATV in ischemic rats. These findings indicate that GluN2B is involved in the neuroprotective mechanism elicited by ATV to promote motor and cognitive recovery after focal cerebral ischemia.

Targeting CDK5 post-stroke provides long-term neuroprotection and rescues synaptic plasticity.

Post-stroke cognitive impairment is a major cause of long-term neurological disability. The prevalence of post-stroke cognitive deficits varies between 20% and 80% depending on brain region, country, and diagnostic criteria. The biochemical mechanisms underlying post-stroke cognitive impairment are not known in detail. Cyclin-dependent kinase 5 is involved in neurodegeneration, and its dysregulation contributes to cognitive disorders and dementia. Here, we administered cyclin-dependent kinase 5-targeting gene therapy to the right hippocampus of ischemic rats after transient right middle cerebral artery occlusion. Cyclin-dependent kinase 5 RNA interference prevented the impairment of reversal learning four months after ischemia as well as neuronal loss, tauopathy, and microglial hyperreactivity. Additionally, cyclin-dependent kinase 5 silencing increased the expression of brain-derived neurotrophic factor in the hippocampus. Furthermore, deficits in hippocampal long-term potentiation produced by excitotoxic stimulation were rescued by pharmacological blockade of cyclin-dependent kinase 5. This recovery was blocked by inhibition of the TRKB receptor. In summary, these findings demonstrate the beneficial impact of cyclin-dependent kinase 5 reduction in preventing long-term post-ischemic neurodegeneration and cognitive impairment as well as the role of brain-derived neurotrophic factor/TRKB in the maintenance of normal synaptic plasticity.

Erratum to: Atorvastatin Modulates Regulatory T Cells and Attenuates Cerebral Damage in a Model of Transient Middle Cerebral Artery Occlusion in Rats

1 Grupo Inmunovirología, Facultad de Medicina, Universidad de Antioquia UdeA, Calle 70 No, 52-21 Medellín, Colombia 2 Area de Neurobiología Celular y Molecualr, Grupo de Neurociencias de Antioquia, Facultad de Medicina, Universidad de Antioquia UdeA, Calle 70 No, 52-21 Medellín, Colombia 3 Grupo de Inmunología Celular e Inmunogenética (GICIG), Instituto de Investigaciones Médicas, Facultad de Medicina, Universidad de Antioquia UdeA, Calle 70 No, 52-21 Medellín, Colombia 4 Unidad de Citometría, Facultad de Medicina, Sede de Investigación Universitaria, Universidad de Antioquia UdeA, Calle, 70-52-21 Medellín, Colombia J Neuroimmune Pharmacol (2017) 12:210 DOI 10.1007/s11481-016-9714-5

Glycogen synthase kinase-3β/β-catenin signaling in the rat hypothalamus during the estrous cycle

During the estrous cycle, a remodeling of synapses on somas and dendritic spines occurs in the rat hypothalamic arcuate nucleus. The synaptic remodeling is known to be induced by estradiol, but the molecular mechanisms involved still have not been fully clarified. β‐Catenin is known to regulate synaptic plasticity, so we have assessed possible modifications of β‐catenin in the rat mediobasal hypothalamus during the estrous cycle. Our findings indicate that β‐catenin expression is increased during proestrus and estrus in comparison with diestrus day. This increase was accompanied by an enhanced phosphorylation of Akt in Ser473 and of glycogen synthase kinase‐3β (GSK3β) in Ser9. Also, the association of β‐catenin with the synaptic protein PSD95 was increased during these same stages of the estrous cycle, whereas the levels of synapsin I were significantly decreased in proestrus. These findings suggest that Akt/GSK3β/β‐catenin signaling is involved in the synaptic modifications that occur in the basal hypothalamus during the estrous cycle.

Gene Therapy for Cognitive Recovering After Ischemic Stroke

Cerebrovascular accident (CVA) is the second leading cause of death in the world and the first cause of disability in adults, being a 34% of affected people younger than 65 years old. Which is an important consequence by sedentary lifestyle and a high intake of fats and sugars. One of the major shortcomings of current therapeutical approach is the lack of comorbidity studies, intervention time (less than 4.5 h) and the short time of protection or follow-up study, which unprotect for long-term sequelae in the patients. Gene therapy has been shown to be a very useful tool for the treatment of neurodegenerative diseases; specifically in cerebral ischemia there are few experimental studies, which are mentioned in this chapter. The most of them have a pretreatment approach, which does not facilitate the clinical translation, therefore, a major challenge of gene therapy is that it to be implemented as post-injury therapy, which is supported by our results using shRNAmiR carried out in adeno associated viral vector, preventing and reversing neurodegeneration, neurovascular unit uncoupling and cognitive impairment, which could be relevant in the field of translational medicine.

Modulación de la neurogénesis y la gliogénesis en la isquemia cerebral mediante una terapia basada en la interferencia de CDK5

INTRODUCTION Cerebral ischemia is the third cause of death risk in Colombia and the first cause of physical disability worldwide. Different studies on the silencing of the cyclin-dependent kinase 5 (CDK5) have shown that reducing its activity is beneficial in ischemic contexts. However, its effect on neural cell production after cerebral ischemia has not been well studied yet. OBJECTIVE To evaluate CDK5 silencing on the production of neurons and astrocytes after a focal cerebral ischemia in rats. MATERIALS AND METHODS We used 40 eight-week-old male Wistar rats. Both sham and ischemia groups were transduced at CA1 hippocampal region with an adeno-associated viral vector using a noninterfering (shSCRmiR) and an interfering sequence for CDK5 (shCDK5miR). We injected 50 mg/kg of bromodeoxyuridine intraperitoneally from hour 24 to day 7 post-ischemia. We assessed the neurological abilities during the next 15 days and we measured the immunoreactivity of bromodeoxyuridine (BrdU), doublecortin (DCX), NeuN, and glial fibrillary acid protein (GFAP) from day 15 to day 30 post-ischemia. RESULTS Our findings showed that CDK5miR-treated ischemic animals improved their neurological score and presented increased BrdU+ cells 15 days after ischemia, which correlated with higher DCX and lower GFAP fluorescence intensities, and, although mature neurons populations did not change, GFAP immunoreactivity was still significantly reduced at 30 days post-ischemia in comparison with untreated ischemic groups. CONCLUSION CDK5miR therapy generated the neurological recovery of ischemic rats associated with the induction of immature neurons proliferation and the reduction of GFAP reactivity at short and longterm post-ischemia.

Modulación de la neurogénesis y gliogénesis en isquemia cerebral por terapia basada en la interferencia de CDK5

INTRODUCTION Cerebral ischemia is the third cause of death risk in Colombia and the first cause of physical disability worldwide. Different studies on the silencing of the cyclin-dependent kinase 5 (CDK5) have shown that reducing its activity is beneficial in ischemic contexts. However, its effect on neural cell production after cerebral ischemia has not been well studied yet. OBJECTIVE To evaluate CDK5 silencing on the production of neurons and astrocytes after a focal cerebral ischemia in rats. MATERIALS AND METHODS We used 40 eight-week-old male Wistar rats. Both sham and ischemia groups were transduced at CA1 hippocampal region with an adeno-associated viral vector using a noninterfering (shSCRmiR) and an interfering sequence for CDK5 (shCDK5miR). We injected 50 mg/kg of bromodeoxyuridine intraperitoneally from hour 24 to day 7 post-ischemia. We assessed the neurological abilities during the next 15 days and we measured the immunoreactivity of bromodeoxyuridine (BrdU), doublecortin (DCX), NeuN, and glial fibrillary acid protein (GFAP) from day 15 to day 30 post-ischemia. RESULTS Our findings showed that CDK5miR-treated ischemic animals improved their neurological score and presented increased BrdU+ cells 15 days after ischemia, which correlated with higher DCX and lower GFAP fluorescence intensities, and, although mature neurons populations did not change, GFAP immunoreactivity was still significantly reduced at 30 days post-ischemia in comparison with untreated ischemic groups. CONCLUSION CDK5miR therapy generated the neurological recovery of ischemic rats associated with the induction of immature neurons proliferation and the reduction of GFAP reactivity at short and longterm post-ischemia.