BackgroundInterleukin (IL)-6 plays a pivotal role in a variety of CNS functions such as the induction and modulation of reactive astrogliosis, pathological inflammatory responses and neuroprotection. Tumor necrosis factor (TNF)-α induces IL-6 release from rat C6 glioma cells through the inhibitory kappa B (IκB)-nuclear factor kappa B (NFκB) pathway, p38 mitogen-activated protein (MAP) kinase and stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK). The present study investigated the mechanism of TNF-α-induced IL-6 release in more detail than has previously been reported.MethodsCultured C6 cells were stimulated by TNF-α. IL-6 release from the cells was measured by an enzyme-linked immunosorbent assay, and the phosphorylation of IκB, NFκB, the MAP kinase superfamily, and signal transducer and activator of transcription (STAT)3 was analyzed by Western blotting. Levels of IL-6 mRNA in cells were evaluated by real-time reverse transcription-polymerase chain reaction.ResultsTNF-α significantly induced phosphorylation of NFκB at Ser 536 and Ser 468, but not at Ser 529 or Ser 276. Wedelolactone, an inhibitor of IκB kinase, suppressed both TNF-α-induced IκB phosphorylation and NFκB phosphorylation at Ser 536 and Ser 468. TNF-α-stimulated increases in IL-6 levels were suppressed by wedelolactone. TNF-α induced phosphorylation of STAT3. The Janus family of tyrosine kinase (JAK) inhibitor I, an inhibitor of JAK 1, 2 and 3, attenuated TNF-α-induced phosphorylation of STAT3 and significantly reduced TNF-α-stimulated IL-6 release. Apocynin, an inhibitor of NADPH oxidase that suppresses intracellular reactive oxygen species, significantly suppressed TNF-α-induced IL-6 release and mRNA expression. However, apocynin failed to affect the phosphorylation of IκB, NFκB, p38 MAP kinase, SAPK/JNK or STAT3.ConclusionThese results strongly suggest that TNF-α induces IL-6 synthesis through the JAK/STAT3 pathway in addition to p38 MAP kinase and SAPK/JNK in C6 glioma cells, and that phosphorylation of NFκB at Ser 536 and Ser 468, and NADPH oxidase are involved in TNF-α-stimulated IL-6 synthesis.

No abstract

The vasodilation of cerebral pial vessels induced by isoflurane and sevoflurane appears to be mediated, at least in part, via activation of adenosine triphosphate-sensitive K+ channels.

Background and Purpose-The effects of acute smoking on cerebral circulation are controversial. This study was designed(1) to clarify any differences between the effects of cigarette smoking and nicotine infusion and between the effects of single-and multiple-cigarette smoking on cerebral vessels and (2) to probe the mechanism(s) underlying the vascular responses. Methods-In pentobarbital-anesthetized, mechanically ventilated Sprague-Dawley rats, pial vessel diameters were measured with the use of a cranial window preparation. We studied the effects of (1) 60 puffs per minute of mainstream cigarette smoke from cigarettes having 2 nicotine levels (0.1 and 1 mg per cigarette), (2) administration of nicotine (0.05 mg per body IV), and (3) repeated smoking (four 1 mg nicotine-containing cigarettes at 30-minute intervals) (nϭ6 each). Results-Inhalation of smoke from a 0.1 or 1 mg nicotine-containing cigarette for 1 minute caused pial arterioles to constrict at 30 seconds (7.2% and 7.3%, respectively) and then to dilate (peak at 5 to 10 minutes; 4.6% and 17.9%, respectively). Nicotine infusion caused pial vasodilation (35.7%) without an initial vasoconstriction. Repeated smoking suppressed the pial vasodilation but not the initial vasoconstriction. The vasodilation induced by a single cigarette was greatly inhibited by pretreatment with mecamylamine or glibenclamide and attenuated by propranolol or N -nitro-Larginine methyl ester; the initial vasoconstriction was inhibited by seratrodast, a thromboxane A 2 receptor antagonist (nϭ6 in each case). Conclusions-Single-cigarette smoking had a significant biphasic effect on cerebral arteriolar tone. The vasodilation was attenuated by repeated smoking. The vasodilation is most likely an effect of nicotine, at least in part mediated via sympathetic activation, NO production, and K ϩ channel activation. The vasoconstriction is partially due to thromboxane A 2 induced by cigarette smoke. (Stroke. 1998;29:1656-1665.)

No abstract

No abstract

The results suggest that a direct inhibition of tetrodotoxin-resistant Na+ channels may contribute to the antinociceptive effects of clonidine and dexmedetomidine when used as additives to regional anaesthesia.

We investigated the relationship between HSP27 phosphorylation and collagen-stimulated activation of platelets in patients with diabetes mellitus (DM). Platelet-rich plasma was prepared from blood of type 2 DM patients. The platelet aggregation was analyzed in size of aggregates by an aggregometer using a laser scattering method. The protein phosphorylation was analyzed by Western blotting. Phosphorylated-HSP27 and PDGF-AB released from platelets were measured by ELISA. The phosphorylated-HSP27 levels at Ser-78 and Ser-82 induced by collagen were directly proportional to the platelet aggregation. Total HSP27 levels in platelets were decreased concomitantly with the phosphorylation. The released HSP27 levels were significantly correlated with the phosphorylated levels of HSP27 in the platelets stimulated by 0.3 μg/ml collagen. The low dose collagen-stimulated release of HSP27 was detected but relatively small in healthy donors. The released levels of PDGF-AB were in parallel with the levels of released HSP27. Area under the curve (AUC) of small aggregation (9-25 μm) induced by 0.3 μg/ml collagen was inversely proportional to the levels of released HSP27. AUC of large aggregation (50-70 μm) was directly proportional to the levels of released HSP27. Exogenous recombinant phosphorylated- HSP27 hardly affected the aggregation or the released levels of PDGF-AB induced by collagen. These results strongly suggest that HSP27 is released from human platelets accompanied with its phosphorylation induced by collagen, which is correlated with the acceleration of platelet aggregation in type 2 DM patients.