Effects of adiponectin on the renal sympathetic nerve activity and blood pressure in rats

Adiponectin is an adipocytokine that modulates energy homeostasis and glucose metabolism. Here, we examined the effects of acute intravenous (iv) and lateral cerebral ventricular (LCV) injections of adiponectin on the renal sympathetic nerve activity (RSNA) and blood pressure (b/p) in urethane-anesthetized rats. Both iv and LCV injections of adiponectin induced dose-dependent suppressions of RSNA and b/p. Moreover, we found that bilateral lesions of the hypothalamic suprachiasmatic nucleus (SCN) abolished the effects of iv injection of adiponectin on RSNA and b/p. These findings suggest that adiponectin decreases the RSNA and b/p in a dose-dependent manner and that the SCN is implicated in mechanism of adiponectin actions on RSNA and b/p. These findings also suggest that the hypotensive-action activity of adiponectin is realized, at least partially, via changes in activities of autonomic nerves activity.     

Structural characterization of the proximal and distal histidine environment of cytoglobin and neuroglobin

Cytoglobin (Cgb) and neuroglobin (Ngb) are the first examples of hexacoordinated globins from humans and other vertebrates in which a histidine (His) residue at the sixth position of the heme iron is an endogenous ligand in both the ferric and ferrous forms. Static and time-resolved resonance Raman and FT-IR spectroscopic techniques were applied in examining the structures in the heme environment of these globins. Picosecond time-resolved resonance Raman (ps-TR3) spectroscopy of transient five-coordinate heme species produced by the photolysis of carbon monoxide (CO) adducts of Cgb and Ngb showed Fe-His stretching (nu(Fe-His)) bands at 229 and 221 cm(-1), respectively. No time-dependent shift in the nu(Fe-His) band of Cgb and Ngb was detected in the 20-1000 ps time domain, in contrast to the case of myoglobin (Mb). These spectroscopic data, combined with previously reported crystallographic data, suggest that the structure of the heme pocket in Cgb and Ngb is altered upon CO binding in a manner different from that of Mb and that the scales of the structural alteration are different for Cgb and Ngb. The structural property of the heme distal side of the ligand-bound forms was investigated by observing the sets of (nu(Fe-CO), nu(C-O), delta(Fe-C-O)) and (nu(Fe-NO), nu(N-O), delta(Fe-N-O)) for the CO and nitric oxide (NO) complexes of Cgb and Ngb. A comparison of the spectra of some distal mutants of Cgb (H81A, H81V, R84A, R84K, and R84T) and Ngb (H64A, H64V, K67A, K67R, and K67T) showed that the CO adducts of Cgb and Ngb contained three conformers and that the distal His (His81 in Cgb and His64 in Ngb) mainly contributes to the interconversion of the conformers. These structural characteristics of Cgb and Ngb are discussed in relation to their ligand binding and physiological properties.     

Clostridium perfringens alpha-toxin induces the release of IL-8 through a dual pathway via TrkA in A549 cells

A characteristic feature of gas gangrene with Clostridium perfringens (C. perfringens) is the absence of neutrophils within the infected area and the massive accumulation of neutrophils at the vascular endothelium around the margins of the necrotic region. Intravenous injection of C. perfringens alpha-toxin into mice resulted in the accumulation of neutrophils at the vascular endothelium in lung and liver, and release of GRO/KC, a member of the CXC chemokine family with homology to human interleukin-8 (IL-8). Alpha-toxin triggered activation of signal transduction pathways causing mRNA expression and production of IL-8, which activates migration and binding of neutrophils, in A549 cells. K252a, a tyrosine kinase A (TrkA) inhibitor, and siRNA for TrkA inhibited the toxin-induced phosphorylation of TrkA and production of IL-8. In addition, K252a inhibited the toxin-induced phosphorylation of extracellular regulated kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (MAPK). PD98059, an ERK1/2 inhibitor, depressed phosphorylation of ERK1/2 and nuclear translocation of nuclear factor kappa B (NF-κB) p65, but SB203580, a p38 MAPK inhibitor, did not. On the other hand, PD98059 and SB203580 suppressed the toxin-induced production of IL-8. Treatment of the cells with PD98059 resulted in inhibition of IL-8 mRNA expression induced by the toxin and that with SB203580 led to a decrease in the stabilization of IL-8 mRNA. These results suggest that alpha-toxin induces production of IL-8 through the activation of two separate pathways, the ERK1/2/NF-κB and p38 MAPK pathways.     

Dose-different effects of orexin-A on the renal sympathetic nerve and blood pressure in urethane-anesthetized rats

Previous studies have demonstrated that central injection of orexin-A affects renal sympathetic nerve activity (RSNA) and blood pressure (BP) in both anesthetized and unanesthetized rats. In the present study, we examined, using urethane-anesthetized rats, the dose-dependent effects of intravenous (iv) or intralateral cerebral ventricular (LCV) injection of various doses of orexin-A on RSNA and BP. We found that injection of a low dose of orexin-A (10 ng iv or 0.01 ng LCV) suppressed RSNA and BP significantly. Conversely, a high dose (1000 ng iv or 10 ng LCV) of orexin-A elevated both RSNA and BP significantly. Pretreatment with either iv or LCV injection of thioperamide, a histaminergic H(3)-receptor antagonist, eliminated the effects of a low dose of orexin-A on both RSNA and BP. Both iv and LCV injection of diphenhydramine, a histaminergic H(1)-receptor antagonist, abolished the effects of a high dose of orexin-A on RSNA and BP. Furthermore, bilateral lesions of the hypothalamic suprachiasmatic nucleus (SCN) abolished the effects of both low and high doses of orexin-A on RSNA and BP. These findings suggest that orexin-A affects RSNA and BP in a dose-dependent manner and that the SCN and histaminergic nerve may be involved in the dose-different effects of orexin-A in rats.     

Analysis of urinary prostacyclin and thromboxane/prostacyclin ratio in patients with rheumatoid arthritis using gas chromatography/selected ion monitoring.

We investigated production of prostacyclin and the urinary ratio of thromboxane and prostacyclin in patients with rheumatoid arthritis. The prostacyclin production level was assessed according to the level of urinary 2,3-dinor-6-keto-prostaglandin F(1 alpha)measuring by gas chromatography/selected ion monitoring. In patients receiving medication, the prostacyclin level was lower and the thromboxane/prostacyclin ratio was greater compare with that of healthy volunteers. The prostacyclin level in patients without medication was approximately 4-fold higher than that of healthy volunteers and 8-fold higher than those of medicated groups. Although the ratio of the group without medication was similar to that of healthy volunteers, the urinary levels of each prostanoid were higher than those of other groups. Then, the ratios of groups receiving steroids were higher than that of other groups owing to high TX level. The present findings demonstrated that endogenous prostacyclin and thromboxane production increased in patients without medication, and prostacyclin production decreased with medication.     

Site-specific protein dynamics in communication pathway from sensor to signaling domain of oxygen sensor protein, HemAT-Bs: Time-resolved Ultraviolet Resonance Raman Study

HemAT-Bs is a heme-based signal transducer protein responsible for aerotaxis. Time-resolved ultraviolet resonance Raman (UVRR) studies of wild-type and Y70F mutant of the full-length HemAT-Bs and the truncated sensor domain were performed to determine the site-specific protein dynamics following carbon monoxide (CO) photodissociation. The UVRR spectra indicated two phases of intensity changes for Trp, Tyr, and Phe bands of both full-length and sensor domain proteins. The W16 and W3 Raman bands of Trp, the F8a band of Phe, and the Y8a band of Tyr increased in intensity at hundreds of nanoseconds after CO photodissociation, and this was followed by recovery in ～50 μs. These changes were assigned to Trp-132 (G-helix), Tyr-70 (B-helix), and Phe-69 (B-helix) and/or Phe-137 (G-helix), suggesting that the change in the heme structure drives the displacement of B- and G-helices. The UVRR difference spectra of the sensor domain displayed a positive peak for amide I in hundreds of nanoseconds after photolysis, which was followed by recovery in ～50 μs. This difference band was absent in the spectra of the full-length protein, suggesting that the isolated sensor domain undergoes conformational changes of the protein backbone upon CO photolysis and that the changes are restrained by the signaling domain. The time-resolved difference spectrum at 200 μs exhibited a pattern similar to that of the static (reduced - CO) difference spectrum, although the peak intensities were much weaker. Thus, the rearrangements of the protein moiety toward the equilibrium ligand-free structure occur in a time range of hundreds of microseconds.     

Synthesis of modified siRNA bearing C-5 polyamine-substituted pyrimidine nucleoside in their 3'-overhang regions and its RNAi activity

Short interfering RNA (siRNA) induces specific gene silencing by the RNA interference (RNAi) pathway. Nucleosides in the 3′-overhang regions of siRNAs were replaced with 5-bis(aminoethyl)aminoethylcarbamoylmethyl-2′-deoxyuridine or thymidine. siRNA bearing modified nucleoside was more active in silencing the gene expression of hepatocyte nuclear factor 4α (HNF4α) compared with siRNA bearing thymidine.     

Induction of a neutral protease from rat intestine by a dietary manipulation

The activity of a neutral protease is increased in soluble fractions from the intestine of rats after a shift from a protein-free to a casein mash and an injection of triiodothyronine. The increased activity is prevented by the administration of cycloheximide. The time curve of the response of the protease activity in intestine is similar to that of liver DNA synthesis after a shift to 50% casein and triiodothyronine.