Guanosine protects human neuroblastoma SH-SY5Y cells against mitochondrial oxidative stress by inducing heme oxigenase-1 via PI3K/Akt/GSK-3β pathway

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Guanosine, the endogenous guanine nucleoside, prevents cellular death induced by ischemic events and is a promising neuroprotective agent. During an ischemic event, nitric oxide has been reported to either cause or prevent cell death. Our aim was to evaluate the neuroprotective effects of guanosine against oxidative damage in hippocampal slices subjected to an in vitro ischemia model, the oxygen/glucose deprivation (OGD) protocol. We also assessed the participation of nitric oxide synthase (NOS) enzymes activity on the neuroprotection promoted by guanosine. Here, we showed that guanosine prevented the increase in ROS, nitric oxide, and peroxynitrite production induced by OGD. Moreover, guanosine prevented the loss of mitochondrial membrane potential in hippocampal slices subjected to OGD. Guanosine did not present an antioxidant effect per se. The protective effects of guanosine were mimicked by inhibition of neuronal NOS, but not of inducible NOS. The neuroprotective effect of guanosine may involve activation of cellular mechanisms that prevent the increase in nitric oxide production, possibly via neuronal NOS.

Section: Discussionmentioning

confidence: 99%

Guanosine prevents nitroxidative stress and recovers mitochondrial membrane potential disruption in hippocampal slices subjected to oxygen/glucose deprivation

Thomaz

Dal-Cim

Martins

et al. 2016

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“…An experimentally based hypothesis is that GUO caused an increase in extracellular ADO levels by competing with nucleoside transporter [19,20]. In fact, some of GUO's neuroprotective effects, but not all, are ADO receptor dependent [18][19][20][21][22]39].…”

Section: Discussionmentioning

confidence: 99%

“…A putative binding site for GUO was already described in rat brain membranes [17], but in opposite, several evidences point to an adenosine (ADO) receptors contribution for GUO effects. Indeed, some, but not all of the observed neuroprotective effects of GUO, were blocked by ADO receptor antagonists, suggesting multiple mechanisms of action for GUO [18][19][20][21][22]. Certainly, GUO effects seem to be directly mediated by action on the brain, as intracerebroventricular or intracortical GUO infusion in experimental models of excitotoxicity have demonstrated neuroprotection [8,13].…”

Section: Introductionmentioning

confidence: 99%

Intranasal guanosine administration presents a wide therapeutic time window to reduce brain damage induced by permanent ischemia in rats

Ramos

Müller

Rocha

et al. 2015

In addition to its intracellular roles, the nucleoside guanosine (GUO) also has extracellular effects that identify it as a putative neuromodulator signaling molecule in the central nervous system. Indeed, GUO can modulate glutamatergic neurotransmission, and it can promote neuroprotective effects in animal models involving glutamate neurotoxicity, which is the case in brain ischemia. In the present study, we aimed to investigate a new in vivo GUO administration route (intranasal, IN) to determine putative improvement of GUO neuroprotective effects against an experimental model of permanent focal cerebral ischemia. Initially, we demonstrated that IN [ 3 H] GUO administration reached the brain in a dose-dependent and saturable pattern in as few as 5 min, presenting a higher cerebrospinal GUO level compared with systemic administration. IN GUO treatment started immediately or even 3 h after ischemia onset prevented behavior impairment. The behavior recovery was not correlated to decreased brain infarct volume, but it was correlated to reduced mitochondrial dysfunction in the penumbra area. Therefore, we showed that the IN route is an efficient way to promptly deliver GUO to the CNS and that IN GUO Purinergic Signalling (2016) 12:149-159 DOI 10.1007 Denise Barbosa Ramos and Gabriel Cardozo Muller contributed equally as first authors.Electronic supplementary material The online version of this article (doi:10.1007/s11302-015-9489-9) contains supplementary material, which is available to authorized users.

“…Guanosine induces the expression of heme oxygenase 1 (HO1) via the PI3K pathway, thus protecting neural cells [90,91]. This protein acts as a scavenger of NO and has been associated with adaptive cytoprotection against a wide array of toxic insults by modulating antioxidant defenses, such as GSH system and thioredoxin [92,93].…”

Section: Discussionmentioning

confidence: 99%

Gliopreventive effects of guanosine against glucose deprivation in vitro

Quincozes‐Santos

Bobermin

Souza

et al. 2013

Guanosine, a guanine-based purine, is recognized as an extracellular signaling molecule that is released from astrocytes and confers neuroprotective effects in several in vivo and in vitro studies. Astrocytes regulate glucose metabolism, glutamate transport, and defense mechanism against oxidative stress. C6 astroglial cells are widely used as an astrocyte-like cell line to study the astrocytic function and signaling pathways. Our previous studies showed that guanosine modulates the glutamate uptake activity, thus avoiding glutamatergic excitotoxicity and protecting neural cells. The goal of this study was to determine the gliopreventive effects of guanosine against glucose deprivation in vitro in cultured C6 cells. Glucose deprivation induced cytotoxicity, an increase in reactive oxygen and nitrogen species (ROS/RNS) levels and lipid peroxidation as well as affected the metabolism of glutamate, which may impair important astrocytic functions. Guanosine prevented glucose deprivation-induced toxicity in C6 cells by modulating oxidative and nitrosative stress and glial responses, such as the glutamate uptake, the glutamine synthetase activity, and the glutathione levels. Glucose deprivation decreased the level of EAAC1, the main glutamate transporter present in C6 cells. Guanosine also prevented this effect, most likely through PKC, PI3K, p38 MAPK, and ERK signaling pathways. Taken together, these results show that guanosine may represent an important mechanism for protection of glial cells against glucose deprivation. Additionally, this study contributes to a more thorough understanding of the glial-and redox-related protective properties of guanosine in astroglial cells.