Early Stage Alterations in CA1 Extracellular Region Proteins Indicate Dysregulation of IL6 and Iron Homeostasis in the 5XFAD Alzheimer's Disease Mouse Model.

In recent years, an increasing number of research papers revealed that the compositional and volumetric alterations in the extracellular matrix are the consequences of aging and may be related to Alzheimer's disease (AD). In this study, we aimed to demonstrate the alterations in hippocampal extracellular fluid proteins in vivo using the 5XFAD mouse model. Samples were obtained from hippocampi of 5XFAD mice (n = 6) and their non-transgenic littermates by intracerebral push-pull perfusion technique at 3 months of age, representing the pre-pathological stage of the AD. Proteins in the hippocampal perfusates were analyzed by Ultra Performance Liquid Chromatography-Electrospray Ionization Quadrupole Time-of-Flight Mass Spectrometry (UPLC-ESI-qTOF-MS/MS). 178 proteins were identified and 19 proteins of them were found to be statistically significantly altered (p≤0.05, fold change ≥40%, unique peptide count ≥3) in the hippocampal CA1 extracellular fluid of the 5XFAD mouse model. Ingenuity pathway analysis of the protein expression results identified IL6 as an upstream regulator. The upregulation of IL6 was validated by immunohistochemical staining of the hippocampus and cortex of the 5XFAD mice prior to Aß plaque formation. Furthermore, the iron level in the hippocampus was measured by inductively coupled plasma-mass spectrometry as IL6 is mentioned in several studies to take part in iron homeostasis and inflammation and found to be increased in 5XFAD mice hippocampus. Alterations in extracellular matrix proteins in addition to increasing amount of hippocampal IL6 and iron in the early stages of AD may reveal inflammation-mediated iron dyshomeostasis in the early stages of neurodegeneration.

Uridine treatment protects against neonatal brain damage and long-term cognitive deficits caused by hyperoxia.

Exposure to excessive oxygen in survivors of preterm birth is one of the factors that underlie the adverse neurological outcome in later life. Various pathological changes including enhanced apoptotic activity, oxidative stress and inflammation as well as decreased neuronal survival has been demonstrated in animal models of neonatal hyperoxia. The aim of the present study was to investigate the effect of administering uridine, an anti-apoptotic agent, on cellular, molecular and behavioral consequences of hyperoxia-induced brain damage in a neonatal rat model. For five days from birth, rat pups were either subjected continuously to room air (21% oxygen) or hyperoxia (80% oxygen) and received daily intraperitoneal (i.p.) injections of saline (0.9% NaCl) or uridine (500mg/kg). Two-thirds of all pups were sacrificed on postnatal day 5 (P5) in order to investigate apoptotic cell death, myelination and number of surviving neurons. One-thirds of pups were raised through P40 in order to evaluate early reflexes, sensorimotor coordination and cognitive functions followed by investigation of neuron count and myelination. We show that uridine treatment reduces apoptotic cell death and hypomyelination while increasing the number of surviving neurons in hyperoxic pups on P5. In addition, uridine enhances learning and memory performances in periadolescent rats on P40. These data suggest that uridine administered during the course of hyperoxic insult enhances cognitive functions at periadolescent period probably by reducing apoptotic cell death and preventing hypomyelination during the neonatal period in a rat model of hyperoxia-induced brain injury.

Synaptic Membrane Synthesis in Rats Depends on Dietary Sufficiency of Vitamin C, Vitamin E, and Selenium: Relevance for Alzheimer's Disease.

Chronic consumption of a diet enriched with nutritional precursors of phospholipids, including uridine and the polyunsaturated fatty acids, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), was shown previously to enhance levels of brain phospholipids and synaptic proteins in rodents. Vitamin C, vitamin E, and selenium may directly affect the breakdown or synthesis of membrane phospholipids. The present study investigated the necessity of antioxidants for the effectiveness of supplementation with uridine plus DHA and EPA (as fish oil) in rats. Rats were randomized to four treatment groups and received, for 6 weeks, one of four experimental diets, i.e., a diet low in antioxidants, a diet high in antioxidants, a diet low in antioxidants supplemented with DHA+EPA+uridine, or a diet high in antioxidants supplemented with DHA+EPA+uridine. On completion of dietary treatment, rats were sacrificed, and brain levels of phospholipids, synaptic proteins, and two enzymes involved in phospholipid synthesis (choline-phosphate cytidylyltransferase, PCYT1A, and choline/ethanolamine phosphotransferase, CEPT1) were analyzed. Levels of phospholipids, the pre- and post-synaptic proteins Synapsin-1 and PSD95, and the enzymes PCYT1A and CEPT1 were significantly enhanced by combined supplementation of DHA+EPA+uridine and antioxidants and not enhanced by supplementation of DHA+EPA+uridine with insufficient antioxidant levels. Our data suggest that dietary vitamin C, vitamin E, and selenium are essential for the phospholipid precursors' effects on increasing levels of membrane phospholipids and synaptic proteins, the indirect indicators of synaptogenesis. Their concomitant supply may be relevant in Alzheimer's disease patients, because the disease is characterized by synapse loss and lower plasma and brain levels of phospholipid precursors and antioxidants.

Regenerative effects of peptide nanofibers in an experimental model of Parkinson's disease.

Parkinson's disease (PD) is characterized by progressive degeneration of dopaminergic nigrostriatal neurons and reduction in striatal dopamine levels. Although there are few treatment options for PD such as Levodopa, they are used just to relieve and modify the symptoms. There are no therapies available for PD to slow down the degeneration process in the brain and recover the lost function. In this study, we used extracellular matrix (ECM) mimetic peptide amphiphile (PA) nanofibers as a potential therapeutic approach in a PD rat model. We demonstrated the effect of heparan sulfate mimetic and laminin mimetic PA nanofibers on reducing striatal injury and enhancing functional recovery after unilateral striatal injection of 6-hydroxydopamine (6-OHDA). The bioactive self-assembled PA nanofibers significantly reduced forelimb asymmetry, contralateral forelimb akinesia and d-amphetamine-induced rotational behavior in cylinder, stepping and rotation tests, respectively, in 6-OHDA-lesioned rats after 6 weeks. The behavioral improvement with PA nanofiber administration was associated with enhanced striatal dopamine and tyrosine hydroxylase content as well as reduced cleaved-Caspase-3 levels. Histological assessment also showed that PA nanofiber injection to the striatum resulted in better tissue integrity compared to control groups. In addition, PA nanofibers reduced the progressive cell loss in SH-SY5Y cells caused by 6-OHDA treatment. These data showed that the bioactive peptide nanofibers improve neurochemical and behavioral consequences of Parkinsonism in rats and provide a promising new strategy for treatment of PD. STATEMENT OF SIGNIFICANCE: Biomimetic nanomaterials bearing natural bioactive signals which are derived from extracellular matrix components like laminin and heparan sulfates provide promising therapeutic strategies for regeneration of the nervous system. However, no research has been reported exploring the use of biomimetic materials against degeneration in Parkinson's disease. In this work, we investigated potential therapeutic effects of heparan sulfate and laminin mimetic PA nanofibers on reduction of striatal injury in experimental Parkinson's disease model. PA nanofibers enhanced functional recovery associated with enhanced striatal dopamine and tyrosine hydroxylase content as well as reduced cleaved-Caspase-3 levels. Overall, this study shows the improvement in consequences of Parkinsonism in rats and provides a new platform for treatment of Parkinson's disease.

Evidence for the existence of pyrimidinergic transmission in rat brain.

The uridine nucleotides uridine-5'-triphosphate (UTP) and uridine-5'-diphosphate (UDP) have previously been identified in media from cultured cells. However, no study to date has demonstrated their presence in brain extracellular fluid (ECF) obtained in vivo. Using a novel method, we now show that UTP and UDP, as well as uridine, are detectable in dialysates of striatal ECF obtained from freely-moving rats. Intraperitoneal (i.p.) administration of uridine or exposure of striatum to depolarizing concentrations of potassium chloride increases extracellular uridine, UTP and UDP, while tetrodotoxin (TTX) decreases their ECF levels. Uridine administration also enhances cholinergic neurotransmission which is accompanied by enhanced brain levels of diacylglycerol (DAG) and inositol trisphosphate (IP3) and blocked by suramin, but not by PPADS (pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid) or MRS2578 suggesting a possible mediation of P2Y2 receptors activated by UTP. These observations suggest that uridine, UTP and UDP may function as pyrimidinergic neurotransmitters, and that enhancement of such neurotransmission underlies pharmacologic effects of exogenous uridine on the brain.