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Abstract: PC12 cell line has been widely used in a diverse array of neurophysiological studies including in exploration of oxygen-sensing mechanism. In present study, we first identified with immunocytochemistry and Western blot methods that interleukin-1 receptor type I was expressed in the PC12 cells. We then demonstrated with patch clamping technique that extracellular application of IL-1β dose-dependently inhibited the outward voltage-dependent and TEA-sensitive potassium currents (I K) in the PC12 cells, and pre-incubation with the interleukin-1 receptor antagonist almost completely abolished this inhibitory effect. In addition, application of IL-1β shifted steady-state inactivation of I K in hyperpolarizing direction, but did not alter its steady-state activation. Furthermore, IL-1β-induced inhibition of I K led to a membrane depolarization and a transient increase of [Ca2+]i in PC12 cells. Taking together, the present study elucidates that PC12 cells bear interleukin-1 receptor and response to IL-1β stimulation. [Copyright &y& Elsevier]

Increasing evidence indicates that there exists a reciprocal communication between the immune system and the brain. Interleukin 1β (IL-1β), a proinflammatory cytokine produced during immune challenge, is believed to be one of the mediators of immune-to-brain communication, but how it gets into the brain is unknown because of its large molecular weight and difficulty in crossing the blood–brain barrier. Our previous work has demonstrated that IL-1 receptor type I is strongly expressed in the glomus cells of rat carotid body (CB), a well characterized polymodal chemoreceptive organ which serves not only for the detection of hypoxia, hypercapnia and acidity, but also for low temperature and blood glucose. The present study was designed to test whether IL-1β could stimulate the CB glomus cells and alter the discharge properties in the carotid sinus nerve, the afferent nerve innervating the organ. The results from whole-cell patch-clamp recordings and calcium imaging showed that extracellular application of IL-1β significantly decreased the outward potassium current and triggered a transient rise in [Ca2+]i in the cultured glomus cells of rat CB. Furthermore, by using extracellular recordings and pharmacological intervention, it was found that IL-1β stimulation of the CB in the anaesthetized rat in vivo significantly increased the discharge rate in the carotid sinus nerve, most probably mediated by ATP release. This experiment provides evidence that the CB responds to cytokine stimulation and proposes the possibility that the CB might play a role in immune-to-brain communication. [ABSTRACT FROM AUTHOR]

Abstract: The enhanced production of nitric oxide (NO) via inducible nitric oxide synthase (iNOS) has been implicated in the pathogenesis of neuronal apoptosis after acute traumatic spinal cord injury (SCI). In the present study, to further characterize the pathways mediating the synthesis and release of NO, we examined activation of extracellular signal regulated kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinases (p38 MAPK) in microglia/macrophages in the injured area of adult rats subjected to a complete transection at the T10 vertebrae level and assessed their role in NO production and survival of neurons by using immunohistochemistry, Western blot, RT-PCR and pharmacological interventions. Results showed activation of microglia/macrophages featured by morphological changes, as visualized immunohistochemically with the marker OX-42, in the areas adjacent to the lesion epicenter 1 h after surgery. Concomitantly, iNOS mRNA and its protein in the activated microglia/macrophages were also significantly upregulated at early hours after surgery. Their levels were maximal at 6 h, persisted for at least 24 h, and returned to basal level 72 h after SCI. Furthermore, phosphorylated ERK1/2 and p38 MAPK were activated as well in microglia/macrophages in injured area with a similar time course as iNOS. With administration of l-NAME, a NOS inhibitor, the number of apoptotic neurons was clearly decreased, as assessed with TUNEL method at 24 h after SCI. In parallel, loss of neurons induced by SCI, assessed with NeuN immunohistochemistry, was also diminished. Moreover, the effect of inhibition of phosphorylation ERK1/2 and p38 MAPK by corresponding inhibitors PD98059 and SB203580 administered before and after SCI was also investigated. Inhibition of p38 effectively reduced iNOS mRNA expression and rescued neurons from apoptosis and death in the area adjacent to the lesion epicenter; whereas the inhibition of ERK1/2 had a smaller effect on decrease of iNOS mRNA and no long-term protective effect on cell loss. These results indicate the ERK1/2 and p38 MAPK signaling pathway, especially the latter, play an important role in NO-mediated degeneration of neuron in the spinal cord following SCI. Strategies directed to blocking the initiation of this cascade prove to be beneficial for the treatment of acute SCI. [Copyright &y& Elsevier]

Phosphorylated extracellular signal-regulated kinases1/2 (pERK1/2) -like immunoreactivity (LI) was enhanced in the neurons of the nucleus of the solitary tract (NTS) and dorsal motor nucleus of the vagus nerve (DMV) 8 min after an intraperitoneal injection of acetic acid in the mouse; the enhancement in pERK1/2-LI was suppressed after vagotomy. With immunofluorescent double labeling technique, the co-localization of acetic acid-induced pERK1/2 and tyrosine hydroxylase-LIs was observed in some of the NTS and DMV neurons. These results suggest that ERK1/2 signal-transducting pathway is involved in neuronal activities in NTS and DMV which are induced by vagus-conveyed nociceptive visceral information, and that some of these pERK1/2- immunoreactive neurons in NTS and DMV are catecholaminergic. [Copyright &y& Elsevier]

Purpose: To investigate the involvement of the extracellular signal-regulated kinase (ERK) signaling pathway after intravitrevous injection of glutamate in rat retina. Methods: Three groups of five Sprague-Dawley rats each were studied. Group I was a normal control group, intravitreal saline injections. In Group II, one eye received an intravitreal glutamate injection (375 nmol, dissolved in saline) while the contralateral eye served as control. In Group III, intravitreal PD98059 (100 μ mol, an inhibitor of ERK) injections were administered 1 hr before glutamate injections. Seven days after injections, phosphorylated (activated) ERK in retina was localized by immunohistochemistry and fluorescent double labeling of retinal cryosections. Specific ERK blockade was documented to assess the functional significance of activated ERK. TUNEL staining was performed to assess apoptotic cell death. Results: Expression of phosphorylated ERK in rat retina was observed in the inner nuclear layer, the outer nuclear layer, and the nerve fiber layer after 3 days intravitreous injection of glutamate, increasing significantly after 7 days. Double immunofluorescence labling demonstrated that the increased retinal immunostaining for phospho-ERK was predominantly localized to the retinal Müller cells after 7 days intravitreous injection of glutamate. Moreover, blocking activation of ERK significantly improved the number of TUNEL-positive cells in the eyes receiving intravitreal PD98059 injections compared with the eyes receiving glutamate injections. Conclusions: The ERK pathway is involved in signal transduction in the retina after excessive stimulation by glutamate, which may contribute to the antiapoptotic role in retinal ganglion cell death induced by glutamate. [ABSTRACT FROM AUTHOR]

The carotid body (CB) is a complex sensory organ that functions to sense homeostatic O 2 in the blood. Previous studies have shown that CBs express interleukin (IL)-1 receptor type I and that the chemosensitivity of CBs is increased following stimulation with pro-inflammatory cytokines. However, the effects of pro-inflammatory cytokines, such as IL-1β, on the neurogenesis of CB are unclear. Thus, in this study, we aimed to assess the effects of IL-1β and intermittent hypobaric hypoxia (IHH) plus IL-1β on the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2, tyrosine hydroxylase (TH) and the expression of nestin, a well-established stem cell marker in the nervous system. The results showed that TH, nestin expression and ERK1/2 phosphorylation were increased in the rat CB following intraperitoneal injection of IL-1β. Moreover, IL-1β had additive effects on IHH. These results suggested that the plasticity of CB was increased following treatment with IL-1β and that ERK1/2 may be involved in neurogenic signaling in CBs. [ABSTRACT FROM AUTHOR]

Abstract: Sertraline is one of the most commonly used antidepressants in clinic. Although it is well accepted that sertraline exerts its action through inhibition of the reuptake of serotonin at presynaptic site in the brain, its effect on the neural stem cells (NSCs) has not been well elucidated. In this study, we utilized NSCs separated from the hippocampus of fetal rat to investigate the effect of sertraline on the proliferation and differentiation of NSCs. The study demonstrated that sertraline had no effect on NSCs proliferation but it significantly promoted NSCs to differentiate into serotoninergic neurons other than glia cells. Furthermore, we found that sertraline protected NSCs against the lipopolysaccharide-induced cellular damage. These data indicate that sertraline can promote neurogenesis and protect the viability of neural stem cells. [Copyright &y& Elsevier]

Abstract: Nicotine can increase size and severity of experimental choroidal neovascularization (CNV); however, the mechanism is uncertain. Recent studies demonstrated that the development of CNV involves the contribution of bone marrow-derived cells (BMCs). This study aims to investigate the effects and the potential mechanism of nicotine on BMCs'' contribution to CNV. Green fluorescent protein (GFP) chimeric mice were developed by transplanting bone marrow cells from GFP transgenic mice to C57BL/6J mice. CNV was induced by lasering. Nicotine was administered orally in drinking water. Histopathologic study and choroidal flatmount were performed to measure the CNV severity and BMCs recruitment. BMCs expressing different cell markers in CNV and local expressions of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF) and vascular cell adhesion molecule-1 (VCAM-1) were detected by immunofluorescence. Nicotine administration resulted in larger diameter and surface area of CNV (P <0.05). Nicotine-exposed mice demonstrated increased area and density of GFP+ cells, increased GFP+ vascular cells area, and decreased ratio of BMCs expressing F4/80 in CNV (P <0.05). Furthermore, the expression of VEGF and bFGF within CNV and VCAM-1 in choroid beneath CNV was up-regulated in nicotine-exposed mice. Our results suggest that nicotine promotes recruitment and incorporation of BMCs into CNV and affects differentiation of BMCs in CNV. These effects may be partly due to indirect actions of nicotine on BMCs via other factors (e.g. VEGF or VCAM-1). It is helpful to understand the mechanism of the effect of nicotine in CNV development. [Copyright &y& Elsevier]

Abstract: Green tea, owing to its beneficial effect on health, is becoming more and more popular worldwide. (−)-Epigallocatechin-3-gallate (EGCG), the main ingredient of green tea polyphenols, is a known protective effect on injured neurons in neurodegenerative disease, such as Alzheimer''s disease and Parkinson''s disease. Paraquat (PQ) is a widely used herbicide that possesses a similar structure to MPP+ and is toxic to mesencephalic dopaminergic neurons. In the present study, PQ-injured PC12 cells were chosen as an in vitro cell model of Parkinson''s disease and the neuroprotective effects of EGCG were investigated. The results showed that EGCG attenuated apoptosis of PC12 cells induced by PQ. The possible mechanism may be associated with maintaining mitochondrial membrane potential, inhibiting caspase-3 activity and downregulating the expression of pro-apoptotic protein Smac in cytosol. The present study supports the notion that EGCG could be used as a neuroprotective agent for treatment of neurodegenerative diseases. [Copyright &y& Elsevier]

Abstract: It has been well known that oxytocin (OT)-ergic and arginine vasopressin (AVP)-ergic neurons located in the hypothalamic paraventricular nucleus (PVN) and superoptic nucleus (SON) are two kinds of neuroendocrine cells with diverse functions. It has also been demonstrated that immune stimuli can activate these neurons to secret OT and AVP. However, the intracellular signal transduction molecules responsible for the activation of these OT-ergic and AVP-ergic neurons in PVN by immune stimuli are still unclear. In this experiment, the roles of Fos, a protein product of immediate early gene c-fos, and extracellular signal-regulated protein kinase (ERK) 1/2, a signal transduction molecule of mitogen-activated protein kinase (MAPK) family, in these processes were studied in the PVN of the rat following IL-1β stimulation. The Sprague–Dawley rats were received either 750ng/kg IL-1β or equal volume normal saline (NS) injection intravenously (i.v.), and perfused transcardially by 4% paraformaldehyde 3h later. Fos and phosphorylated ERK1/2 (pERK1/2)-immunoreactivity (-ir) was observed in PVN by ABC immunohistochemical staining. Meanwhile, the double staining for OT/Fos, AVP/Fos, OT/pERK1/2 and AVP/pERK1/2 were also processed. The ABC immunohistochemical staining results showed that after an i.v. injection of IL-1β, the expressions of Fos and pERK1/2 increased evidently in the PVN. Double-staining results showed that a large number of OT-ir cells contained strong Fos-ir products in their nuclei, while only a few of OT cells were double labeled with pERK1/2. As to AVP neurons, great quantities of AVP cells were strongly double labeled with pERK1/2 while there were nearly no Fos-ir nuclei in AVP-ir cells. We conclude from these results that the intracellular IL-1β-induced events in OT and AVP neurons in PVN are quite different. The OT neurons are mainly activated via Fos without involvement of ERK1/2 pathway, while the latter, but not Fos, involves the intracellular event in AVP neurons activated by IL-1β. [Copyright &y& Elsevier]