Psychological stress,but not physical stress,causes increase in diazepam binding inhibitor (DBI) mRNA expression in mouse brains

Effects of conditioned emotional stimuli (CES), which induce psychological stress, on the expression of cerebral diazepam binding inhibitor (DBI) mRNA in mouse were examined using a communication box. Cerebral DBI mRNA expression significantly increased in a time-dependent manner after the application of CES. The maximal enhancement of DBI mRNA expression was observed 2 days after the application of CES, and this increase faded out over 7 days after the treatment. Flunitrazepam (1 mg/kg), an agonist for central benzodiazepine (BZD) receptors, completely abolished the CES-induced elevation of cerebral DBI contents and its mRNA expressions. These results indicate that cerebral DBI is enhanced by psychological stress, which is regulated by central BZD receptors.     

Diphenidol has no actual broad antiemetic activity in dogs and ferrets

Previous studies showed that diphenidol was effective on emetogens-induced pica, eating of non-nutritive substances, in rats, a model analogous to emesis in other species. We evaluated the actual antiemetic activity of diphenidol against four emetic stimuli in the dog and ferret, animals that possess an emetic reflex. In dogs, emetic responses to apomorphine were significantly prevented by diphenidol (3.2 mg/kg, i.v.), whereas diphenidol (3.2 mg/kg, i.v. x 2) showed a weak inhibition to the vomiting evoked by cisplatin. In ferrets, diphenidol (10 mg/kg, i.p.) exhibited a weak antiemetic activity on the emesis induced by copper sulfate and had no activity on emesis by loperamide. On the other hand, CP-122,721, a NK1-receptor antagonist, significantly reduced the emetic episodes to all four stimuli. These results suggest that the prediction of antiemetic activity of compounds in animals lacking an emetic reflex does not always correspond with actual antiemetic activity.     

Chemotherapeutic Targeting of Etoposide to Regions of the Brain on the Basis of Polyamine Level

The effects of etoposide on body weight, regional weights, and the concentrations of putrescine, spermidine and spermine in the cerebellum, hippocampus, corpus striatum, cortex, the combined regions of the thalamus and hypothalamus and the diencephalon of the brain were examined in rats. Etoposide seems to be a better choice for management of cortical and hippocampal tumors because it reduces polyamines, which are associated with tumor cell growth, but not for the management of tumors of the diencephalon and corpus striatum because it increases polyamines.     

First phase of glucose-stimulated insulin secretion from MIN 6 cells does not always require extracellular calcium influx

To demonstrate an involvement of ATP-sensitive potassium (K(ATP)) channel-independent pathways in the first phase of glucose-stimulated insulin secretion (GSIS) from pancreatic beta cells, the time course of GSIS from MIN6 cells was analyzed at 30-s sample intervals. GSIS was biphasic with the first phase being observed 120 to 390 s after glucose addition, peaking at 180 s, and with a shoulder at 240 to 330 s. Both 10 microM diazoxide and 3 microM verapamil completely inhibited tolbutamide- or glibenclamide-induced insulin secretion and suppressed the peak of the first phase of GSIS, but did not result in complete suppression. The shoulder following the peak was suppressed by 1 muM dantrolene. The peak, but not shoulder, disappeared under the extracellular Ca2+-free condition. A significant amount of insulin secretion remained even in the combined presence of verapamil and dantrolene. The Na+ channel blocker tetrodotoxin (30 nM) nearly completely inhibited the first phase release. These results suggest that the first phase of GSIS from MIN6 cells depends on both Ca2+-dependent and -independent mechanisms. The former mechanism includes the extracellular Ca2+ influx via L-type voltage-dependent calcium channel and intracellular Ca2+ release from endoplasmic reticulum via ryanodine receptors, and the latter mechanism involves the pathways associated with Na+ channels.     

FK1706, a novel non-immunosuppressive immunophilin ligand, modifies the course of painful diabetic neuropathy

FK1706, a derivative of FK506, is a non-immunosuppressive immunophilin ligand with significant neurotrophic activity mediated via FKBP-52 and the RAS/RAF/MAPK signaling pathway. Here, we tested the effect of FK1706 on painful diabetic neuropathy in rat model of diabetes induced by streptozotocin (STZ). FK1706 ameliorated mechanical allodynia in this model at doses over 0.32 mg/kg, p.o., even if treatment was initiated after neuropathy was established, and did not affect plasma glucose levels. Furthermore, this improvement continued at least 4 weeks after the last administration. In morphological analysis, FK1706 treatment also restored intraepidermal nerve fiber density in footpad skin to almost normal levels. Gabapentin also improved mechanical allodynia in the same model, but efficacy disappeared the day after administration stopped. Allodynia responses were potentiated by co-administration of both compounds. Thus, FK1706 ameliorated painful diabetic neuropathy via a different mechanism from gabapentin and improved morphological outcomes, indicating that FK1706 improves painful diabetic neuropathy by modifying the underlying disease pathology.     

Pharmacological profile of FR260330, a novel orally active inducible nitric oxide synthase inhibitor

In this study, we examined effects of a newly synthesized chemical compound, FR260330, (2E)-3-(4-chlorophenyl)-N-[(1S)-2-oxo-2-{[2-oxo-2-(4-{[6-(trifluoromethyl)-4-pyrimidinyl]oxy}-1-piperidinyl)ethyl]amino}-1-(2-pyridinylmethyl)ethyl]acrylamide on nitric oxide (NO) production in rat splenocytes and human colon cancer cell line, DLD-1 cells. FR260330 inhibited NOx production dose dependently in both cells. In lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma) treated murine macrophage cell line, RAW264.7, Western blot analysis with gel filtration chromatography revealed FR260330 might prevent dimerization of inducible nitric oxide synthase (iNOS), but had no effect on the expression of iNOS protein. Furthermore, oral administration of FR260330 reduced NOx production dose dependently in plasma from rats exposed to LPS (IC50=1.6 mg/kg). Meanwhile, higher dose (100 mg/kg) of oral administration of FR260330 did not change mean arterial blood pressure in rats. These results suggest that FR260330 might be a useful therapeutical approach to various inflammatory diseases, in which superoxide or peroxynitrite formed from iNOS-derived NO are involved.     

Contribution of Lysosomes to the Subcellular Distribution of Basic Drugs in the Rat Liver

Purpose. We examined the subcellular distribution of the basic drugs, chlorpromazine (CPZ), imipramine (IMP) and biperiden (BP), in rat liver, and evaluated the contribution of lysosome (Lys) to their intracellular distribution in comparison with that of mitochondria (Mit). Methods. In an in vivo distribution, the concentrations of CPZ, IMP and BP in the liver subcellular fractions were determined. In an in vitro study, uptake of [³H]IMP into Lys and Mit fractions was determined in the presence or absence of several agents. Results. The distribution of these drugs 10 min after administration was quite similar. However, the relative specific contents (the drug concentration per protein of each fraction divided by that of the total homogenate) in Lys were 7.3, 9.6 and 4.2, respectively for CPZ, IMP and BP, whereas those in the other organella were only 0.4 ~ 1.7. In an in vitro uptake study, the dose response of IMP uptake into Lys was biphasic, while that into Mit fractions was monophasic. The binding of IMP to the high affinity sites of Lys was pH dependent and disappeared in 50 mM NH₄C1 or 50 µM CPZ, both of which increased the intralysosomal pH. the low affinity sites were not affected by these drugs. Conclusions. The results indicated that Lys has the highest affinity for the basic drugs in the liver and that its contribution to their subcellular distribution depends on the intralysosomal pH, which is also affected by these drugs. The importance of these effects may become significant in combination therapy using various basic drugs.     

Insulin-like growth factor-I prevents lethal acute liver failure induced by D-galactosamine and lipopolysaccharide in rats

The aim of this study was to evaluate the effect of insulin-like growth factor-I (IGF-I) on lethality and liver function in experimental acute liver failure. Intravenous co-administration of D-galactosamine (GalN) and lipopolysaccharide (LPS) to rats induced high mortality and marked increases in aspartate aminotransferase, alanine aminotransferase and total bilirubin, associated with hypoglycemia. One-hour pre-treatment with IGF-I significantly prevented lethality and blood parameter changes in rats. Histological examination also showed that massive hepatocellular hemorrhagic necrosis and inflammatory cell infiltration around peri-central veins in the liver, as well as shrinkage of cytoplasm and nuclear condensation, were induced by GalN plus LPS injection, but these all were improved by pre-treatment with IGF-I. Overall, this study showed that IGF-I treatment resulted in effective prevention of lethal acute liver failure in rats induced by GalN plus LPS, suggesting a therapeutic potential for IGF-I in the prevention of acute liver failure.     

Phase 1 clinical tests of influenza MDP-virosome vaccine (KD-5382).

MDP-virosome vaccine, which contains haemagglutinin (HA) and neuraminidase (NA) antigens isolated from influenza virus combined with 6-O-(2-tetradecylhexadecanoyl)-N-acetylmuramoyl-L-alanyl-D-isoglutamine) (B30-MDP) and cholesterol was tested, in comparison with a currently used HA vaccine, for immunogenicity and adverse reactions on 77 adult male volunteers. The volunteers were divided into eight groups, and each individual was injected subcutaneously once, or twice at a 4 week interval, in their upper arm with one of seven different MDP-virosome vaccine preparations or with HA vaccine as control. Of the three virus strains used as vaccine antigens, MDP-virosome vaccines induced higher haemagglutination inhibiting (HI) antibody to A/Yamagata/120/86 (H1N1) and A/Fukuoka/C29/86 (H3N2) than did HA vaccine, whereas it induced lower HI antibody to B/Nagasaki/1/87, comparable with that induced by HA vaccine. Regarding local adverse reactions, MDP-virosome vaccinees frequently developed mild local pain, reddening and swelling, which disappeared within 5 days; as regards systemic no adverse reactions, leucocytosis developed among the MDP-virosome vaccines, but no other reactions were observed. The leucocytosis may have been caused by the pharmacoimmunological activity of B30-MDP derivatives.