Dietary Zinc Acts as a Sleep Modulator

While zinc is known to be important for many biological processes in animals at a molecular and physiological level, new evidence indicates that it may also be involved in the regulation of sleep. Recent research has concluded that zinc serum concentration varies with the amount of sleep, while orally administered zinc increases the amount and the quality of sleep in mice and humans. In this review, we provide an exhaustive study of the literature connecting zinc and sleep, and try to evaluate which molecular mechanism is likely to be involved in this phenomenon. A better understanding should provide critical information not only about the way zinc is related to sleep but also about how sleep itself works and what its real function is

Characterization and Distribution of Prostaglandin D Synthetase in Rat Skin

The biochemical properties and immunohistochemical localization of prostaglandin D synthetase were investigated in adult rat skin. The activity of prostaglandin D synthetase, which isomerizes prostaglandin H2 to prostaglandin D2, was detected in the 100,000 g supernatant of the homogenate of adult rat skin. Whole skin showed considerable activity (1.9 nmol/min/mg protein), and prostaglandin D2 was the major prostaglandin among those formed from prostaglandin H2 in the presence of glutathione. The epidermis, which was separated from whole skin by heating (55°C, 30 s), exhibited about three times higher activity (3.5) than the dermis (1.0). The enzymatic properties of both layers were similar; they were absolutely glutathione-dependent, were inhibited only a few percent by 1mM 1-chloro-2,4-dinitrobenzene, and were completely absorbed by anti-rat spleen prostaglandin D synthetase antibody. Immunohistochemical studies, using anti-rat spleen prostaglandin D synthetase antibody and the immunoperoxidase method, showed that prostaglandin D synthetase was localized in Langerhans cells (not in keratinocytes) in the epidermis, in macrophages or histiocytes, and also in mast cells in the dermis. Immunoelectron microscopy also supported these findings. These results suggest that prostaglandin D2 is one of the most important arachidonic acid metabolites and plays a significant role in immunological function in the skin via Langerhans cells and macrophages

The Role of Nucleus Accumbens Core/Shell in Sleep-Wake Regulation and their Involvement in Modafinil-Induced Arousal

Background: We have previously shown that modafinil promotes wakefulness via dopamine receptor D1 and D2 receptors; however, the locus where dopamine acts has not been identified. We proposed that the nucleus accumbens (NAc) that receives the ventral tegmental area dopamine inputs play an important role not only in reward and addiction but also in sleep-wake cycle and in mediating modafinil-induced arousal. Methodology/Principal Findings: In the present study, we further explored the role of NAc in sleep-wake cycle and sleep homeostasis by ablating the NAc core and shell, respectively, and examined arousal response following modafinil administration. We found that discrete NAc core and shell lesions produced 26.5% and 17.4% increase in total wakefulness per day, respectively, with sleep fragmentation and a reduced sleep rebound after a 6-hr sleep deprivation compared to control. Finally, NAc core but not shell lesions eliminated arousal effects of modafinil. Conclusions/Significance: These results indicate that the NAc regulates sleep-wake behavior and mediates arousal effects of the midbrain dopamine system and stimulant modafinil

Anti-inflammatory therapy by ibudilast, a phosphodiesterase inhibitor, in demyelination of twitcher, a genetic demyelination model

BACKGROUND: Twitcher mouse (twi/twi) is an authentic murine model of Krabbe's disease. Accumulation of psychosine, resulting in apoptosis of oligodendrocytes and subsequent demyelination, is a cardinal event to the pathogenesis of this disease. Moreover, recruitment of inflammatory cells plays a significant role in the pathological process in the twi/twi central and peripheral nervous systems. In this study, we investigated the 1) the relationship between tumor necrosis factor-α (TNFα), pro-inflammatory cytokine, and the progression of this disease and 2) effect of the anti-inflammatory therapy by ibudilast, a phosphodiesterase inhibitor. METHODS: We quantified the expression level of TNFα and TNF-receptor mRNA in twi/twi using semi-quantitative RT-PCR. The relationship between TNFα expression, apoptosis of oligodendrocytes and demyelination was studied with immunohistochemistry and TUNEL method. We then treated twi/twi with a daily intraperitoneal injection of ibudilast (10 mg/kg), which suppress TNFα production in the brain. RESULTS: We found that TNFα-immunoreactive microglia/macrophages appeared in the twi/twi brain and that the mRNA levels of TNFα and TNF-receptor 1 was increased with the progression of demyelination. The distribution profile of TNFα-immunoreactive microglia/macrophages overlapped that of TUNEL-positive oligodendrocytes in the twi/twi brain. When twi/twi was treated with ibudilast from PND30, the number of oligodendrocytes undergoing apoptosis was markedly reduced and demyelination was milder. Obvious improvement of clinical symptom was noted in two of five. The failure of constant clinical improvement by ibudilast may result from hepatotoxicity and/or the inhibition of proliferation of NG2-positive oligodendrocyte precursors. CONCLUSION: We conclude that anti-inflammatory therapy by a phosphodiesterase inhibitor can be considered as a novel alternative therapy for Krabbe's disease

Involvement of S-nitrosylation of actin in inhibition of neurotransmitter release by nitric oxide

<p>Abstract</p> <p>Background</p> <p>The role of the diffusible messenger nitric oxide (NO) in the regulation of pain transmission is still a debate of matter, pro-nociceptive and/or anti-nociceptive. <it>S</it>-Nitrosylation, the reversible post-translational modification of selective cysteine residues in proteins, has emerged as an important mechanism by which NO acts as a signaling molecule. The occurrence of <it>S</it>-nitrosylation in the spinal cord and its targets that may modulate pain transmission remain unclarified. The "biotin-switch" method and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry were employed for identifying <it>S</it>-nitrosylated proteins.</p> <p>Results</p> <p>Here we show that actin was a major protein <it>S</it>-nitrosylated in the spinal cord by the NO donor, <it>S</it>-nitroso-<it>N</it>-acetyl-DL-penicillamine (SNAP). Interestingly, actin was <it>S</it>-nitrosylated, more in the S2 fraction than in the P2 fraction of the spinal homogenate. Treatment of PC12 cells with SNAP caused rapid <it>S</it>-nitrosylation of actin and inhibited dopamine release from the cells. Just like cytochalasin B, which depolymerizes actin, SNAP decreased the amount of filamentous actin cytoskeleton just beneath the membrane. The inhibition of dopamine release was not attenuated by inhibitors of soluble guanylyl cyclase and cGMP-dependent protein kinase.</p> <p>Conclusion</p> <p>The present study demonstrates that actin is a major <it>S</it>-nitrosylated protein in the spinal cord and suggests that NO directly regulates neurotransmitter release by <it>S</it>-nitrosylation in addition to the well-known phosphorylation by cGMP-dependent protein kinase.</p

Structure of the inhibitor complex of old yellow enzyme from Trypanosoma cruzi

The structures of old yellow enzyme from Trypanosoma cruzi which produces prostaglandin F2α from PGH2 have been determined in the presence or absence of menadione

Perineuronal Oligodendrocytes Protect against Neuronal Apoptosis through the Production of Lipocalin-Type Prostaglandin D Synthase in a Genetic Demyelinating Model

The genetic demyelinating mouse "twitcher" is a model of the human globoid cell leukodystrophy, caused by galactosylceramidase (GALC) deficiency. Demyelination in the twitcher brain is secondary to apoptotic death of oligodendrocytes (OLs). Lipocalin-type prostaglandin (PG) D synthase (L-PGDS), a protein expressed in mature OLs, was progressively upregulated in twitcher OLs; whereas expression of OL-associated proteins such as carbonic anhydrase II, myelin basic protein, and myelin-associated glycoprotein was downregulated during demyelination in twitcher brains. The upregulation of L-PGDS was more remarkable in perineuronal OLs than in interfascicular OLs. A larger number of L-PGDS-positive OLs was found in selected fiber tracts of twitcher brains where fewer apoptotic cells were detected. The distribution of L-PGDS-positive OLs was inversely related to the severity of demyelination, as assessed by accumulation of scavenger macrophages. Mice doubly deficient for L-PGDS and GALC disclosed a large number of apoptotic neurons, which were never seen in twitcher brains, in addition to an increased number of apoptotic OLs. A linear positive correlation was observed between the population of L-PGDS-positive OLs in the twitcher brain and the ratio of apoptotic nuclei in the double mutant versus those in the twitcher, suggesting a dose-dependent effect of L-PGDS against apoptosis. These lines of evidence suggest that L-PGDS is an anti-apoptotic molecule protecting neurons and OLs from apoptosis in the twitcher mouse. This is a novel example of OL-neuronal interaction

The Leptomeninges Produce Prostaglandin D2 Involved in Sleep Regulation in Mice

Injection of nanomolar amounts of prostaglandin D2 (PGD2) into the rat brain has dose and time-dependent somnogenic effects, and the PGD2-induced sleep is indistinguishable from physiologic sleep. Sleep-inducing PGD2 is produced in the brain by lipocalin-type PGD2 synthase (LPGDS). Three potential intracranial sources of LPGDS have been identified: oligodendrocytes, choroid plexus, and leptomeninges. We aimed at the identification of the site of synthesis of somnogenic PGD2 and therefore, generated a transgenic mouse line with the LPGDS gene amenable to conditional deletion using Cre recombinase (flox-LPGDS mouse). To identify the cell type responsible for producing somnogenic PGD2, we engineered animals lacking LPGDS expression specifically in oligodendrocytes (OD-LPGDS KO), choroid plexus (CP-LPGDS KO), or leptomeninges (LM-LPGDS KO). We measured prostaglandins and LPGDS concentrations together with PGD synthase activity in the brain of these mice. While the LPGDS amount and PGD synthase activity were drastically reduced in the OD- and LM-LPGDS KO mice, they were unchanged in the CP-LPGDS KO mice compared with control animals. We then recorded electroencephalograms, electromyograms, and locomotor activity to measure sleep in 10-week-old mice with specific knockdown of LPGDS in each of the three targets. Using selenium tetrachloride, a specific PGDS inhibitor, we demonstrated that sleep is inhibited in OD-LPGDS and CP-LPGDS KO mice, but not in the LM-LPGDS KO mice. We concluded that somnogenic PGD2 is produced primarily by the leptomeninges, and not by oligodendrocytes or choroid plexus

A Key Role for Old Yellow Enzyme in the Metabolism of Drugs by Trypanosoma cruzi

Trypanosoma cruzi is the etiological agent of Chagas' disease. So far, first choice anti-chagasic drugs in use have been shown to have undesirable side effects in addition to the emergence of parasite resistance and the lack of prospect for vaccine against T. cruzi infection. Thus, the isolation and characterization of molecules essential in parasite metabolism of the anti-chagasic drugs are fundamental for the development of new strategies for rational drug design and/or the improvement of the current chemotherapy. While searching for a prostaglandin (PG) F2α synthase homologue, we have identified a novel “old yellow enzyme” from T. cruzi (TcOYE), cloned its cDNA, and overexpressed the recombinant enzyme. Here, we show that TcOYE reduced 9,11-endoperoxide PGH2 to PGF2α as well as a variety of trypanocidal drugs. By electron spin resonance experiments, we found that TcOYE specifically catalyzed one-electron reduction of menadione and β-lapachone to semiquinone-free radicals with concomitant generation of superoxide radical anions, while catalyzing solely the two-electron reduction of nifurtimox and 4-nitroquinoline-N-oxide drugs without free radical production. Interestingly, immunoprecipitation experiments revealed that anti-TcOYE polyclonal antibody abolished major reductase activities of the lysates toward these drugs, identifying TcOYE as a key drug-metabolizing enzyme by which quinone drugs have their mechanism of action