Potential biomarkers for neuroinflammation and neurodegeneration at short and long term after neonatal hypoxic-ischemic insult in rat.

Background: Hypoxic-ischemic (HI) encephalopathy causes life-long morbidity and premature mortality in term neonates. Therapies in addition to whole-body cooling are under development to treat the neonate at risk for HI encephalopathy, but are not a quickly measured serum inflammatory or neuronal biomarkers to rapidly and accurately identify brain injury in order to follow the efficacy of therapies. Methods: In order to identify potential biomarkers for early inflammatory and neurodegenerative events after neonatal hypoxia-ischemia, both male and female Wistar rat pups at postnatal day 7 (P7) were used and had their right carotid artery permanently doubly occluded and exposed to 8% oxygen for 90 min. Sensory and cognitive parameters were assessed by open field, rotarod, CatWalk, and Morris water maze (MWM) test. Plasma and CSF biomarkers were investigated on the acute (24 h and 72 h) and chronic phase (4 weeks). Brains were assessed for gene expression analysis by quantitative RT-PCR Array. Results: We found a delay of neurological reflex maturation in HI rats. We observed anxiolytic-like baseline behavior in males more than females following HI injury. HI rats held on the rotarod for a shorter time comparing to sham. HI injury impaired spatial learning ability on MWM test. The CatWalk assessment demonstrated a long-term deficit in gait parameters related to the hind paw. Proinflammatory biomarkers such as IL-6 in plasma and CCL2 and TNF-\u3b1 in CSF showed an upregulation at 24 h after HI while other cytokines, such as IL-17A and CCL5, were upregulated after 72 h in CSF. At 24 h post-injury, we observed an increase of Edn1, Hif1-\u3b1, and Mmp9 mRNA levels in the ipsilateral vs the contralateral hemisphere of HI rats. An upregulation of genes involved with clotting and hematopoietic processes was observed 72 h post-injury. Conclusions: Our work showed that, in the immature brain, the HI injury induced an early increased production of several proinflammatory mediators detectable in plasma and CSF, followed by tissue damage in the hypoxic hemisphere and short-term as well as long-lasting neurobehavioral deficits

Intravitreal NGF administration counteracts retina degeneration after permanent carotid artery occlusion in rat

<p>Abstract</p> <p>Background</p> <p>The neurotrophin nerve growth factor (NGF) is produced by different cell types in the anterior and posterior eye, exerting a neuroprotective role in the adult life. The visual system is highly sensitive to NGF and the retina and optic nerve provides suitable subjects for the study of central nervous system degeneration. The model of bilateral carotid occlusion (two-vessel occlusion, 2VO) is a well-established model for chronic brain hypoperfusion leading to brain capillary pathology, to retina and optic nerve degeneration. In order to study if a single intravitreal injection of NGF protects the retina and the optic nerve from degeneration during systemic circulatory diseases, we investigated morphological and molecular changes occurring in the retina and optic nerve of adult rats at different time-points (8, 30 and 75 days) after bilateral carotid occlusion.</p> <p>Results</p> <p>We demonstrated that a single intravitreal injection of NGF (5 μg/3 μl performed 24 hours after 2VO ligation) has a long-lasting protective effect on retina and optic nerve degeneration. NGF counteracts retinal ganglion cells degeneration by early affecting Bax/Bcl-2 balance- and <it>c-jun- </it>expression (at 8 days after 2VO). A single intravitreal NGF injection regulates the demyelination/remyelination balance after ischemic injury in the optic nerve toward remyelination (at 75 days after 2VO), as indicated by the MBP expression regulation, thus preventing optic nerve atrophy and ganglion cells degeneration. At 8 days, NGF does not modify 2VO-induced alteration in VEFG and related receptors mRNA expression.</p> <p>Conclusion</p> <p>The protective effect of exogenous NGF during this systemic circulatory disease seems to occur also by strengthening the effect of endogenous NGF, the synthesis of which is increased by vascular defect and also by the mechanical lesion associated with NGF or even vehicle intraocular delivery.</p

d aspartate exerts an opposing role upon age dependent nmdar related synaptic plasticity and memory decay

In the present study, we demonstrated that D-aspartate acts as an _in vitro_ and _in vivo_ neuromodulatory molecule upon hippocampal NMDAR transmission. Accordingly, we showed that this D-amino acid, widely expressed during embryonic phase, was able to strongly influence hippocampus-related functions at adulthood. Thus, while up-regulated levels of D-aspartate increased LTP and spatial memory in four-month old adult mice, the prolonged deregulation of this molecule in thirteen-month old animals induced a substantial acceleration of age-dependent decay of synaptic plasticity and cognitive functions. Moreover, we highlighted a role for D-aspartate in enhancing NMDAR-dependent synaptic plasticity through an inducible "turn-on/turn-off-like mechanism". Strikingly, we also showed that D-aspartate, when administered to aged mice, strongly rescued their physiological synaptic decay and attenuated their cognitive deterioration. In conclusion, our data suggest a tantalizing hypothesis for which this in-embryo-occurring D-amino acid, might disclose plasticity windows in the aging brain

Gender effect on neurodegeneration and myelin markers in an animal model for multiple sclerosis

Multiple sclerosis (MS) varies considerably in its incidence and progression in females and males. In spite of clinical evidence, relatively few studies have explored molecular mechanisms possibly involved in gender-related differences. The present study describes possible cellular- and molecular-involved markers which are differentially regulated in male and female rats and result in gender-dependent EAE evolution and progression. Attention was focused on markers of myelination (MBP and PDGF\u3b1R) and neuronal distress and/or damage (GABA synthesis enzymes, GAD65 and GAD67, NGF, BDNF and related receptors), in two CNS areas, i.e. spinal cord and cerebellum, which are respectively severely and mildly affected by inflammation and demyelination. Tissues were sampled during acute, relapse/remission and chronic phases and results were analysed by two-way ANOVA

Long-Term Effects of Experimental Carotid Stenosis on Hippocampal Infarct Pathology, Neurons and Glia and Amelioration by Environmental Enrichment

Hippocampal atrophy and pathology are common in ageing-related disorders and associated with cognitive impairment and dementia. We explored whether environmental enrichment (EE) ameliorated the pathological sequelae in the hippocampus subsequent to chronic cerebral hypoperfusion induced by bilateral common carotid artery stenosis (BCAS). Seventy-four male C57BL/6 J mice underwent BCAS or sham surgery. One-week after surgery, mice were exposed to three different degrees of EE; either standard housing conditions (std), limited 3-hour exposure to EE per day (3h) or full-time exposure to EE (full) for 3 months. Four months after surgery, the hippocampus was examined for the extent of vascular brain injury and neuronal and glial changes. Results showed that long-term BCAS induced strokes, most often in CA1 subfield, reduced 40-50% CA1 neurons (P<0.01) and increased microglia/macrophage in CA1-CA3 subfields (P<0.02). Remarkably, both 3h and full-time EE regimes attenuated hippocampal neuronal death and repressed recurrent strokes with complete prevention of larger infarcts in mice on full-time EE (P<0.01). Full-time EE also reduced astrocytic clasmatodendrosis and microglial/macrophage activation in all CA subfields. Our results suggest that exposure to EE differentially reduces long-term hypoperfusive hippocampal damage. The implementation of even limited EE may be beneficial for patients diagnosed with vascular cognitive impairment

Neurosteroid Dehydroepiandrosterone Interacts with Nerve Growth Factor (NGF) Receptors, Preventing Neuronal Apoptosis

The neurosteroid dehydroepiandrosterone (DHEA), produced by neurons and glia, affects multiple processes in the brain, including neuronal survival and neurogenesis during development and in aging. We provide evidence that DHEA interacts with pro-survival TrkA and pro-death p75NTR membrane receptors of neurotrophin nerve growth factor (NGF), acting as a neurotrophic factor: (1) the anti-apoptotic effects of DHEA were reversed by siRNA against TrkA or by a specific TrkA inhibitor; (2) [3H]-DHEA binding assays showed that it bound to membranes isolated from HEK293 cells transfected with the cDNAs of TrkA and p75NTR receptors (KD: 7.4±1.75 nM and 5.6±0.55 nM, respectively); (3) immobilized DHEA pulled down recombinant and naturally expressed TrkA and p75NTR receptors; (4) DHEA induced TrkA phosphorylation and NGF receptor-mediated signaling; Shc, Akt, and ERK1/2 kinases down-stream to TrkA receptors and TRAF6, RIP2, and RhoGDI interactors of p75NTR receptors; and (5) DHEA rescued from apoptosis TrkA receptor positive sensory neurons of dorsal root ganglia in NGF null embryos and compensated NGF in rescuing from apoptosis NGF receptor positive sympathetic neurons of embryonic superior cervical ganglia. Phylogenetic findings on the evolution of neurotrophins, their receptors, and CYP17, the enzyme responsible for DHEA biosynthesis, combined with our data support the hypothesis that DHEA served as a phylogenetically ancient neurotrophic factor

Novel Neuroprotective Strategies in Ischemic Retinal Lesions

Retinal ischemia can be effectively modeled by permanent bilateral common carotid artery occlusion, which leads to chronic hypoperfusion-induced degeneration in the entire rat retina. The complex pathways leading to retinal cell death offer a complex approach of neuroprotective strategies. In the present review we summarize recent findings with different neuroprotective candidate molecules. We describe the protective effects of intravitreal treatment with: (i) urocortin 2; (ii) a mitochondrial ATP-sensitive K+ channel opener, diazoxide; (iii) a neurotrophic factor, pituitary adenylate cyclase activating polypeptide; and (iv) a novel poly(ADP-ribose) polymerase inhibitor (HO3089). The retinoprotective effects are demonstrated with morphological description and effects on apoptotic pathways using molecular biological techniques