Evaluation of the effects of alpha-phenyl-N-tert-butyl nitrone pretreatment on the neurobehavioral effects of methamphetamine.

A relationship between formation of reactive oxygen species (ROS) and energy depletion has been proposed to play an important role in mediating methamphetamine (METH)-induced neurotoxicity. To evaluate this relationship, we examined the effect of the spin-trap agent, alpha-phenyl-N-tert-butyl nitrone (PBN) on hyperthermia and self-injurious behavior (SIB) and striatal dopamine (DA) depletion produced by METH (4 injections of 4 mg/kg, 2 hr intervals, s.c.) in BALB/c mice. Repeated administration of METH induced hyperthermia, incidence of SIB and striatal DA depletion (84% after 3 days). Pretreatment with PBN (4 injections of 60 or 120 mg/kg, i.p.) reduced METH-induced hyperthermia, but did not significantly attenuate METH-induced SIB or the striatal DA depletion. On the other hand, pretreatment with high doses of PBN (4 injections of 180 or 240 mg/kg, i.p.) protected against METH-induced hyperthermia and SIB, and PBN (180 mg/kg) also completely protected against the acute striatal DA depletion 60 min after the last injection of the drug. However, the long-lasting striatal DA depletion was only attenuated by 52 or 56%, respectively. These results indicate that METH-induced hyperthermia contributes to, but is not solely responsible for METH-induced neurotoxicity, and supports a role for formation of ROS and other mechanisms in the generation of METH-induced striatal dopaminergic neurotoxicity. In addition, the difference in the efficacy of PBN to protect against the acute or long-lasting striatal DA depletion induced by METH may indicate that both ROS formation and other mechanisms are required for METH-induced neurotoxicity to develop.

Methamphetamine-induced striatal dopamine release, behavior changes and neurotoxicity in BALB/c mice.

The behaviors associated with the neurotoxic effects of methamphetamine were evaluated in BALB/c mice. Hyperthermia and behavioral observations were measured 60 min after each subcutaneous injection of methamphetamine (4x4 or 8 mg/kg) or saline, each given 2 h apart. The behavioral observations included stereotyped behaviors, incidence of hemorrhage in breast, salivation and self-injurious behavior (SIB). Repeated administration of methamphetamine produced these behavioral changes and hyperthermia, but resulted in hypothermia by the final injection (8 mg/kg). In addition, the methamphetamine treatment induced a long-lasting dopamine depletion of similar magnitude in the 4 and 8 mg/kg-treated animals. In a time course study striatal monoamine levels were measured 60 min after each injection of these doses. The first and second injections of methamphetamine (8 mg/kg) produced a drastic increase in striatal 3-methoxytyramine; this failed to occur after the third or fourth injection of the same dose. In contrast, 4 mg/kg of methamphetamine also produced an increase in 3-methoxytyramine after the second and third injections of the drug and, in this case, these were maintained for the duration of the treatment. Striatal 3, 4-dihydroxyphenylacetic acid levels also drastically decreased following both doses of methamphetamine, suggesting inhibition of monoamine oxidase in striatum. Moreover, a single injection of methamphetamine increased striatal 2,3-dihydroxybenzoic acid formation. These results suggest that the incidence of hyperthermia, SIB and striatal dopamine neurotoxicity are closely linked to striatal dopamine release and inhibition of monoamine oxidase produced by methamphetamine in BALB/c mice.

Lipopolysaccharide increases cyclo-oxygenase-2 expression in a colon carcinoma cell line through nuclear factor-kappa B activation.

Both nonneoplastic colon epithelium and colon carcinoma cells in situ are continuously exposed to lipopolysaccharide (LPS). Few reports have addressed possible direct effects of LPS in promotion of colon carcinoma and underlying mechanisms. We found evidence that LPS directly stimulated growth of the human colon carcinoma cell line CE-1 through an increase in the production of prostaglandin E2 (PGE2) as a result of cyclo-oxygenase-2 (COX-2) expression. LPS induced significant increases in PGE2 production in CE-1 cells, which were found to express a high-affinity LPS receptor, CD14. Positive correlations were found between PGE2 production and activation of nuclear factor (NF)-kappa B as well as expression of both COX-2 mRNA and protein in LPS-stimulated CE-1 cells. When CE-1 cells were exposed to exogenous PGE2, DNA synthesis increased. These results indicate that LPS may stimulate DNA synthesis in certain colon carcinoma cells as a result of PGE2 production involving increased COX-2 expression that might result in turn from activation of NF-kappa B by LPS. Further investigation of the pathways mediating LPS-induced stimulation of colon carcinoma cells may provide insights into LPS effects in in vivo tumor biology.

Hepatocyte growth factor and invasion-stimulatory activity are induced in pleural fluid by surgery in lung cancer patients.

Hepatocyte growth factor (HGF) is a stromal cell-derived cytokine that can stimulate matrix invasion by carcinoma cells. We analysed the concentrations of HGF and invasion-stimulatory activity in pleural fluid after lung surgery. The concentration of HGF in pleural fluids was measured by enzyme-linked immunosorbent assay in seven patients who underwent pulmonary resection for primary or metastatic lung cancer. The effect of the pleural fluid on cancer cell invasion across reconstituted basement membrane (Matrigel) was assessed with a Boyden chamber assay using a lung adenocarcinoma cell line, A549. HGF levels in the pleural fluid after lung surgery ranged from 6.0 to 23.0 ng ml(-1) (average: 10.2 +/- 4.3 ng ml(-1)). The matrix invasion of lung carcinoma cells in the presence of the pleural fluid was significantly higher than that in the presence of culture medium alone or sera from normal subjects (P < 0.01). The invasion-stimulatory activity of the pleural fluid was strongly inhibited by HGF-neutralizing antibody. Positive correlation was found between the HGF level and invasion-stimulatory activity in the pleural fluids and normal sera (P = 0.0073). This is the first report demonstrating that the lung surgery induces a considerable amount of HGF, which is closely correlated with the invasion-stimulatory activity of the pleural fluid.

Nitric oxide synthase expression and nitric oxide production in human colon carcinoma tissue.

BACKGROUND AND OBJECTIVES: Nitric oxide (NO), the production of which is dependent on NO synthase (NOS), has been shown to contribute to various pathogeneses in cancer. The aim of this study was to determine whether inducible NO synthase (iNOS) is overexpressed in human colon carcinoma tissue, and whether NO is produced in tumor tissue. METHODS: We investigated iNOS mRNA expression in 24 human colon carcinoma tissue specimens by reverse transcription-polymerase chain reaction (RT-PCR). We then examined the expression of iNOS protein and nitrotyrosine, which indicates NO production in tissue, by immunohistochemistry. The possible immunosuppressive role of NO produced by colon carcinoma cells was analyzed in vitro. RESULTS: Semiquantitative RT-PCR analysis showed that iNOS mRNA expression in carcinoma tissues is elevated significantly compared to that in noncarcinoma tissue. Immunohistochemistry revealed that iNOS and nitrotyrosine are expressed strongly in carcinoma tissues. In vitro experiments showed that the supernatant from a culture of cytokine-treated colon carcinoma cells, which contained high levels of NO, significantly reduced the phytohemagglutinin (PHA)-stimulated, human lymphocyte proliferative response (60% of the control value). CONCLUSIONS: In human colon carcinoma tissue, iNOS mRNA, protein, and NO products are overexpressed and may contribute to tumor-related immunosuppression.

Effects of oral administration of trypsin inhibitor and repeated injections of pancreozymin on the insulin and glucagon contents of rat pancreas.

Rats were given soybean trypsin inhibitor or repeatedly injected with pancreozymin (daily 40 I.D.U./kg) for 7 days, and the insulin and glucagon contents of the pancreas were measured. The insulin and glucagon contents were markedly increased after these treatments and this effect was especially conspicuous after injections of large doses (daily 120 I.D.U.) of depot-type pancreozymin. Insulin content thus reached 1.9 times, and glucagon content 2.4 times as much in control values. This result is compatible with our previous histological finding that not only the exocrine pancreas but also islet cells undergo the trophic effect of endogenous and exogenous pancreozymin.