Michelangelo Iannone

NGF RESTORES DECREASE IN CATALASE ACTIVITY AND INCREASES SUPEROXIDE DISMUTASE AND GLUTATHIONE PEROXIDASE ACTIVITY IN THE BRAIN OF AGED RATS

The effects of ageing on the activity of copper-zinc superoxide dismutase (SOD), selenium-dependent and independent glutathione peroxidase (GSH-Px) and catalase in several areas of the brain in 3-, 12-, and 24-month-old rats were studied. In addition, the effects of a subacute intracerebroventricular treatment of NGF (1 microgram daily for 28 consecutive days) on SOD, GSH-Px, and catalase activity in the same areas of the brain were assessed. The effects of ageing on the activities of antioxidant enzymes varied considerably in the different brain areas studied. Copper-zinc SOD was alone in being unaffected by ageing. Intraventricular infusion of NGF significantly increased SOD activity in the prefrontal cortex, hypothalamus, caudate nucleus, and mesencephalon of 24-month-old rats. Selenium-dependent GSH-Px activity did not significantly change in 12-month-old rats but it increased in the lower brain stem of 24-month-old animals. In comparison to vehicle-treated rats, NGF significantly increased selenium-dependent GSH-Px activity in all brain areas studied in 12- and 24-month-old rats. Catalase activity decreased significantly in the majority of the brain areas studied in 12- and 24-month-old rats. NGF completely restored the fall in catalase activity in 12- and 24-month-old animals to levels similar to those occurring in young rats. In conclusion, the present experiments show, for the first time, that long-term intraventricular administration of NGF significantly increases in old animals the activity of key enzymes involved in the metabolic degradation of superoxide radicals and hydrogen peroxide.

Effects of Lipid Composition and Preparation Conditions on Physical-Chemical Properties, Technological Parameters and In Vitro Biological Activity of Gemcitabine-Loaded Liposomes

The effects of lipid composition and preparation conditions on the physicochemical and technological properties of gemcitabine-loaded liposomes, as well as the in vitro anti-tumoral activity of various liposome formulations were investigated. Three liposome formulations were investigated: DPPC/Chol/Oleic acid (8:3:1 molar ratio, liposomes A), DPPC/Chol/DPPS (6:3:1 molar ratio, liposomes B) and DPPC/Chol/DSPE-MPEG (6:3:1 molar ratio, liposomes C). Multilamellar liposomes were prepared by using the TLE, FAT and DRV methods, while small unilamellar liposomes were obtained by extrusion through polycarbonate filters. Light scattering techniques were used to characterize liposome formulations. Loading capacity and release profiles of gemcitabine from various liposome formulations were also investigated. Caco-2 cells were used to evaluate in vitro the antitumoral activity of gemcitabine-loaded liposomes with respect to the free drug and also the intracellular drug uptake. Preparation methods and liposome lipid composition influenced both physicochemical parameters and drug delivery features. Liposomes with a size ranging from 200 nm to 7 microm were obtained. The gemcitabine entrapment was higher than that expected probably due to an interaction with the liposome lipid components. The following decreasing loading capacity order was observed: liposome B>liposome C>liposome A. Gemcitabine release from various liposome formulations is modulated by two different processes, i.e. desorption from and permeation through liposomal bilayers. MTT assay showed a greater cytotoxic effect of gemcitabine-loaded liposomes with respect to the free drug. The following decreasing anticancer activity order was observed between the various liposome formulations: liposome C>liposome A>liposome B. The increased anticancer activity is correlated to the ability of the colloidal carrier to increase the intracellular drug uptake. Due to the encouraging results and to the high liposome modularity various applications of potential therapeutic relevance can be envisaged for liposomes.

Tacrine-induced seizures and brain damage in LiCl-treated rats can be prevented by Nω-nitro-L-arginine methyl ester

The effects of tacrine (5 mg/kg i.p.), a potent acetylcholinesterase inhibitor, were studied in rats pretreated (24 h beforehand) with a single dose (12 mEq/kg i.p.) of LiCl. Tacrine and LiCl were ineffective when given individually. Tacrine elicited seizures and brain damage in 90% of the rats treated. The intracerebroventricular microinfusion of N omega-nitro-L-arginine methyl ester (300 micrograms given 24 h after LiCl administration) significantly reduced the seizures and brain damage produced by tacrine (given 15 min later). These experiments suggest that the seizures and brain damage elicited by tacrine may be due, in part, to increased nitric oxide production in the brain.

The effect of nitric oxide on cytokine-induced release of PGE2 by human cultured astroglial cells

The role of the L‐arginine‐nitric oxide (NO) pathway on the formation of prostaglandin E2 (PGE2) by human cultured astroglial cells incubated with interleukin‐1β (IL‐1β) and tumour necrosis factor‐α (TNF‐α) was investigated. Incubation of T 67 astroglial cell line with IL‐β (10 ng ml−1) and TNF‐α (500 u ml−1) produced a significant (P<0.05) increase of both nitrite (the breakdown product of NO), cyclic GMP and PGE2 levels in cell supernatants. Nω‐nitro‐L‐arginine methyl ester (L‐NAME; 20–300 μM), an inhibitor of NO synthase (NOS), inhibited the increase of cyclic GMP and nitrite levels found in supernatants of cytokine‐treated astroglial cells and reduced the release of PGE2. The latter effect showed that the enhanced arachidonic acid (AA) metabolism subsequent to stimulation of astroglial cells with IL‐1β and TNF‐α was, at least in part, induced by NO. This occurred also when sodium nitroprusside (SNP; 120 μM), an NO donor, was incubated with astroglial cells, an effect antagonized by oxyhaemoglobin (OxyHb; 10 μM). The inhibition elicited by L‐NAME on PGE2‐release by cytokine‐treated astroglial cells was reversed by adding AA (40 μM), showing that the effect of NO on cytokine‐dependent PGE2 release occurred at the cyclo‐oxygenase (COX) level. Furthermore, the release of PGE2 in cytokine‐treated astroglial cells was inhibited by indomethacin (10 μM), a COX inhibitor as well as by preincubating cells with dexamethasone (20 μM), an inhibitor of inducible enzymes, showing that the inducible isoform of COX (COX‐2) was involved. On the other hand, pretreating astroglial cells with methylene blue (MB; 10 μM), an inhibitor of NO biological activity acting at the guanylate cyclase level, failed to affect PGE2 release in cytokine‐treated astroglial cells, leading to the conclusion that cyclic GMP changes related to NO formation are not involved in the generation of AA metabolites. The present experiments demonstrated that the release of PGE2 by astroglial cells pretreated with IL‐1β and TNF‐α is due to enhanced COX‐2 activity via activation of the L‐arginine‐NO pathway, and this may be relevant to the understanding of the pathophysiological mechanisms underlying neuroimmune disorders.

Estradiol reduces cytochrome c translocation and minimizes hippocampal damage caused by transient global ischemia in rat

It is well-established that 17beta-estradiol (17beta-E(2)) confers neuroprotection to male and female rats exposed to focal cerebral ischemia, while less is known about the effects of the hormone under conditions of transient global ischemia. Since translocation of cytochrome c from the mitochondria to the cytosol is a critical step in apoptotic cell death after cerebral ischemia, we have investigated whether 17beta-E(2) interferes with such mechanism to exert neuroprotection. Global ischemia, induced in male Wistar rats by 5-min 4 vessel occlusion (4VO), resulted in a significant increase of cytosolic cytochrome c (cyt-c) levels as detected by Western blotting at 6h after reperfusion. 17beta-E(2) (0.2mg/kg, i.p.) given 1h before ischemia minimized cytochrome c translocation and the latter effect was partially reversed by tamoxifen (0.25mg/kg, i.p.). Bilateral cell counting revealed that delayed hippocampal damage typically caused by 4VO was abolished by 17beta-E(2) and this was partially reversed by tamoxifen in the CA3 subregion, but not in CA1/CA2 or CA4. These findings provide the original observation that 17beta-E(2) reduces delayed hippocampal damage caused by 4VO in male rats and blocks cytochrome c translocation during the early stages of neuronal death, thus providing an important mechanism involved in estrogen-mediated neuroprotection.

The contribution of oxidative stress in apoptosis of human-cultured astroglial cells induced by supernatants of HIV-1-infected macrophages

Apoptosis of neurons and astrocytes has been found in patientsundergoing AIDS dementia complex. We demonstrated that supernatantsfrom human primary macrophages (M/M) infected by HIV‐1 lead humanastroglial cells to oxidative stress, as shown by elevated levels ofmalondialdehyde, and then to apoptosis. Electron microscopy ofastrocytes shortly incubated with HIV‐1‐infected M/M supernatantsshowed apoptotic blebbing, cytoplasmic loss, and chromatincondensation. Apoptosis was antagonized by pretreating astrocytes withthe nonpeptidic superoxide dismutase (SOD) mimetic M40401 but notwith anti‐HIV‐1 compounds, thus showing that apoptosis of astrocytesdriven by HIV‐1‐infected M/M supernatants is mainly mediated byabnormal production of superoxide anions without relationship to HIV‐1replication in such cells. Overall results support the role ofoxidative stress mediated by HIV‐1‐infected M/M as one of the leadingcauses of neurodegeneration in patients with HIV‐1 and suggest the useof nonpeptidic SOD mimetics to counteract HIV‐1‐related neurologicaldisorders.

Bartonella quintana lipopolysaccharide effects on leukocytes, CXC chemokines and apoptosis: a study on the human whole blood and a rat model

Bartonella quintana, an emerging gram-negative pathogen, may cause trench fever, endocarditis, cerebral abscess and bacillary angiomatosis usually with the absence of septic shock in humans. B. quintana lipopolysaccharide (LPS), a deep rough endotoxin with strong reactivity in the limulus amebocyte lysate (LAL)-assay, was studied in human whole blood and in a rat model. A significant (P<0.05) increase of interleukin-8 (IL-8) concentration, comparable to the level induced by enterobacterial LPS, was stimulated in the human whole blood by B. quintana LPS. Isolated human neutrophils delayed their apoptotic behavior in the presence of B. quintana LPS. In the rat, B. quintana LPS induced a significant (P<0.001) increase in white blood cell count, both 30 and 60 min after intravenous injection. Such leukocytosis was inhibited by pretreatment with prazosin, an alpha-adrenergic antagonist. B. quintana LPS did not significantly change heart rate (HR), hematocrit (HCT) and platelet count in the above reported in vivo model, and regarding mean blood pressure (MAP) only a very early (5 min after LPS) and mild (yet significant) hypotension was observed. In contrast, a long-lasting decrease of MAP was found in Salmonella minnesota R595 LPS-treated animals. Blood TNFalpha levels did not change significantly from the baseline in rats injected with either saline or with B. quintana LPS, on the contrary S. minnesota R595 LPS-injected animals showed substantial increase of TNFalpha levels up to 2924 pg/ml at 60 min after LPS injection. B. quintana LPS as well as Salmonella LPS-injected rats exhibited an increase of the blood levels of GRO/CINC-1, particularly at 240 min after LPS administration. Apical part of rat gut villi showed several TUNEL-positive cells in tissue sections from B. quintana LPS-treated animals. Taken together, our data demonstrates that B. quintana LPS is able to selectively stimulate some inflammatory mediators. B. quintana LPS-induced leukocytosis appears mediated by an alpha-adrenergic receptor. The delayed apoptotic process of leukocytes and the chemokine increase may explain the apoptotic cells found in the rat gut and the inflammatory reactions in some human Bartonella diseases. This peculiar inflammatory pattern induced by B. quintana LPS, may partially account for the lack of severe septic shock, observed in human B. quintana infections.

Inhibition by Nω‐nitro‐L‐arginine methyl ester of the electrocortical arousal response in rats

In rats chronically implanted with cannulae into one lateral cerebral ventricle and recording electrodes onto the fronto‐parietal cortex, the effects of systemic or intraventricular administration of the nitric oxide (NO) synthesis inhibitor, Nω‐nitro‐l‐arginine methyl ester (l‐NAME), on electrocortical (ECoG) arousal response evoked by sound stimulation were studied. In control animals, a single acoustic stimulation (80 dB for 15 s) produced a significant decrease in ECoG total voltage power lasting approximately 25 s. No tolerance developed after repeating the same sound stimulation at 15, 30, 60 min and 24 h intervals. Under these experimental conditions, pretreatment with l‐NAME, given systemically (10 mg kg−1, i.p.) or intracerebroventricularly (300 μg), significantly reduced the sound‐evoked arousal response 1 h and 15 min later, respectively. In conclusion, the present data are in favour of a physiological role of NO in the control of arousal mechanisms.

NGF restores decrease in catalase and increases glutathione peroxidase activity in the brain of aged rats

The effects of subchronic administration of nerve growth factor (NGF) into the lateral ventricle on catalase and selenium-dependent glutathione-peroxidase (GSH-Px) activity in several areas of the brain in 3-, 12- and 24-month-old rats were studied. NGF given daily (1 microgram for 28 consecutive days) produced in all brain areas studied a significant increase in catalase activity in 12- and 24-month-old rats. The most important finding was a complete restoration in 12- and 24-month-old rats of catalase activity to levels similar to those occurring in young (3-month-old) rats. In addition, NGF produced in comparison to 3-month-old rats and to same age vehicle-treated rats a significant increase in selenium-dependent GSH-Px in all the brain areas studied in 12- and 24-month-old animals, whereas selenium-independent GSH-Px was unaffected. In conclusion, the present results show that long-term administration of NGF into the lateral ventricle significantly increases in old animals the activity of key enzymes involved in the metabolic degradation of hydrogen peroxide.

The protective effect of tianeptine on Gp120-induced apoptosis in astroglial cells: Role of GS and NOS, and NF-κB suppression

BACKGROUND AND PURPOSE Tianeptine is an antidepressant affecting the glutamatergic system. In spite of its proven clinical efficacy, molecular effects of tianeptine are not entirely clear. Tianeptine modulates cytokine expression in the CNS and protects the hippocampus from chronic stress effects. HIV infection is associated with inflammation and neuronal loss, causing HIV‐associated dementia (HAD). The human immunodeficiency virus type‐1 glycoprotein gp120 has been proposed as a likely aetiological agent of HAD. In this study, we determined whether tianeptine protects astroglial cells from the neurodegenerative effects of gp120.