Essential Roles of Natural Products and Gaseous Mediators on Neuronal Cell Death or Survival

Although precise cellular and molecular mechanisms underlying neurodegeneration still remain enigmatic, key factors associated with degenerative disorders, such as glutamate toxicity and oxidative stress, have been recently identified. Accordingly, there has been growing interest in examining the effects of exogenous and endogenous molecules on neuroprotection and neurodegeneration. In this paper, we review recent studies on neuroprotective and/or neurodegenerative effects of natural products, such as caffeic acid and chlorogenic acid, and gaseous mediators, including hydrogen sulfide and nitric oxide. Furthermore, possible molecular mechanisms of these molecules in relation to glutamate signals are discussed. Insight into the pathophysiological role of these molecules will make progress in our understanding of molecular mechanisms underlying neurodegenerative diseases, and is expected to lead to potential therapeutic approaches

Familial Occurrence of a Congenital Portosystemic Shunt of the Portal Vein

A congenital portosystemic shunt of the portal vein is a very rare vascular anomaly associated with the liver. We report the case of a 5-year-old girl with a patent ductus venosus and her 31-year-old mother with a congenital portosystemic shunt. The child presented with a history of an extremely low birth weight in addition to an atrial septal defect and a patent ductus venosus. At the age of 2, she underwent ligation of the ductus venosus. Her mother was also diagnosed with a congenital vascular anomaly at the age of 16. We have followed up and evaluated her asymptomatic mother for 15 years. To our knowledge, this is the first report describing the occurrence of a congenital portosystemic shunt in both a mother and her child

Protein oxidation inhibits NO-mediated signaling pathway for synaptic plasticity.

Oxidative stress is a primary factor inducing brain dysfunction in aged animals. However, how oxidation affects brain function is not fully understood. Here we show that oxidation inhibits signaling pathways essential for synaptic plasticities in the cerebellum. We first revealed that nitric oxide (NO)-dependent plasticities at the parallel fiber-Purkinje cell synapse (PF synapse) were impaired in the cerebellar slices from aged mice, suggesting a possible inhibitory action of protein oxidation by endogenous reactive oxygen species. PF-synaptic plasticities were also blocked in the cerebellar slices from young mice preincubated with oxidizing agents or thiol blocker. Because the treatment of the slices with the oxidizing agent did not affect basic electrophysiological properties of excitatory postsynaptic current of PF (PF-EPSC) and did not occlude the synaptic plasticities, oxidation was revealed to specifically inhibit signaling pathways essential for PF-synaptic plasticities. Finally, biochemical analysis confirmed the idea that inhibitory action of protein oxidation on the PF-synaptic plasticities was mediated by impairment of nitric oxide-induced protein S-nitrosylation. Therefore, oxidation was revealed to inhibit the S-nitrosylation-dependent signaling pathway essential for synaptic plasticity in a "competitive" manner

Nitric oxide-induced calcium release: activation of type 1 ryanodine receptor by endogenous nitric oxide.

Ryanodine receptors (RyRs), located in the sarcoplasmic/endoplasmic reticulum (SR/ER) membrane, are required for intracellular Ca2+ release that is involved in a wide range of cellular functions. In addition to Ca2+-induced Ca2+ release in cardiac cells and voltage-induced Ca2+ release in skeletal muscle cells, we recently identified another mode of intracellular Ca2+ mobilization mediated by RyR, i.e., nitric oxide-induced Ca2+ release (NICR), in cerebellar Purkinje cells. NICR is evoked by neuronal activity, is dependent on S-nitrosylation of type 1 RyR (RyR1) and is involved in the induction of long-term potentiation (LTP) of cerebellar synapses. In this addendum, we examined whether peroxynitrite, which is produced by the reaction of nitric oxide with superoxide, may also have an effect on the Ca2+ release via RyR1 and the cerebellar LTP. We found that scavengers of peroxynitrite have no significant effect either on the Ca2+ release via RyR1 or on the cerebellar LTP. We also found that an application of a high concentration of peroxynitrite does not reproduce neuronal activity-dependent Ca2+ release in Purkinje cells. These results support that NICR is induced by endogenous nitric oxide produced by neuronal activity through S-nitrosylation of RyR1