Neuroprotective agents in the management of glaucoma.

Glaucoma is an optic neuropathy, specifically a neurodegenerative disease characterized by loss of retinal ganglion cells (RGCs) and their axons. The pathogenesis of RGC loss in glaucoma remains incompletely understood and a broad range of possible mechanisms have been implicated. Clinical evidence indicates that lowering intraocular pressure (IOP) does not prevent progression in all patients; therefore, risk factors other than those related to IOP are involved in the disease. The need for alternative, non-IOP-lowering treatments focused at preventing progression, that is, neuroprotectants, has become of interest to both the patient and the physician. Experimental evidence accumulated during the past two decades lend a great deal of support to molecules endowed with neuroprotective features. However, translation to the clinic of the latter drugs results unsuccessful mostly because of the lack of reliable in vivo measure of retinal damage, thus hampering the good therapeutic potential of neuroprotective agents given alone or as adjuvant therapy to IOP-lowering agents. Further research effort is needed to better understand the mechanisms involved in glaucoma and the means to translate into clinic neuroprotective drugs.

Rational Basis for the Use of Bergamot Essential Oil in Complementary Medicine to Treat Chronic Pain.

In complementary medicine, aromatherapy uses essential oils to improve agitation and aggression observed in dementia, mood, depression, anxiety and chronic pain. Preclinical research studies have reported that the essential oil obtained from bergamot (BEO) fruit (Citrus bergamia, Risso) modifies normal and pathological synaptic plasticity implicated, for instance, in nociceptive and neuropathic pain. Interestingly, recent results indicated that BEO modulates sensitive perception of pain in different models of nociceptive, inflammatory and neuropathic pain modulating endogenous systems. Thus, local administration of BEO inhibited the nociceptive behavioral effect induced by intraplantar injection of capsaicin or formalin in mice. Similar effects were observed with linalool and linalyl acetate, major volatile components of the phytocomplex, Pharmacological studies showed that the latter effects are reversed by local or systemic pretreatment with the opioid antagonist naloxone hydrochloride alike with naloxone methiodide, high affinity peripheral µ-opioid receptor antagonist. These results and the synergistic effect observed following systemic or intrathecal injection of an inactive dose of morphine with BEO or linalool indicated an activation of peripheral opioid system. Recently, in neuropathic pain models systemic or local administration of BEO or linalool induced antiallodynic effects. In particular, in partial sciatic nerve ligation (PSNL) model, intraplantar injection of the phytocomplex or linalool in the ipsilateral hindpaw, but not in the contralateral, reduced PSNL-induced extracellularsignal- regulated kinase (ERK) activation and mechanical allodynia. In neuropathic pain high doses of morphine are needed to reduce pain. Interestingly, combination of inactive doses of BEO or linalool with a low dose of morphine induced antiallodynic effects in mice. Peripheral cannabinoid and opioid systems appear to be involved in the antinociception produced by intraplantar injection of ß -caryophyllene, present in different essential oils including BEO. The data gathered so far indicate that the essential oil of bergamot is endowed with antinociceptive and antiallodynic effects and contribute to form the rational basis for rigorous testing of its efficacy in complementary medicine.

Neuroprotection by leptin in a rat model of permanent cerebral ischemia: effects on STAT3 phosphorylation in discrete cells of the brain.

In addition to its effects in the hypothalamus to control body weight, leptin is involved in the regulation of neuronal function, development and survival. Recent findings have highlighted the neuroprotective effects of leptin against ischemic brain injury; however, to date, little is known about the role performed by the signal transducer and activator of transcription (STAT)-3, a major mediator of leptin receptor transduction pathway in the brain, in the beneficial effects of the hormone. Our data demonstrate that systemic acute administration of leptin produces neuroprotection in rats subjected to permanent middle cerebral artery occlusion (MCAo), as revealed by a significant reduction of the brain infarct volume and neurological deficit up to 7 days after the induction of ischemia. By combining a subcellular fractionation approach with immunohistofluorescence, we observe that neuroprotection is associated with a cell type-specific modulation of STAT3 phosphorylation in the ischemic cortex. The early enhancement of nuclear phospho-STAT3 induced by leptin in the astrocytes of the ischemic penumbra may contribute to a beneficial effect of these cells on the evolution of tissue damage. In addition, the elevation of phospho-STAT3 induced by leptin in the neurons after 24 h MCAo is associated with an increased expression of tissue inhibitor of matrix metalloproteinases-1 in the cortex, suggesting its possible involvement to the neuroprotection produced by the adipokine.

Calpain-mediated cleavage of Beclin-1 and autophagy deregulation following retinal ischemic injury in vivo.

Autophagy is the major intracellular degradation pathway that regulates long-lived proteins and organelles turnover. This process occurs at basal levels in all cells but it is rapidly upregulated in response to starvation and cellular stress. Although being recently implicated in neurodegeneration, it remains still unclear whether autophagy has a detrimental or protective role. In this study, we investigated the dynamics of the autophagic process in retinal tissue that has undergone transient ischemia, an experimental model that recapitulates features of ocular pathologies, including glaucoma, anterior ischemic optic neuropathy and retinal vessels occlusion. Retinal ischemia, induced in adult rats by increasing the intraocular pressure, was characterized by a reduction in the phosphatidylethanolamine-modified form of LC3 (LC3II) and by a significant decrease in Beclin-1. The latter event was associated with a proteolytic cleavage of Beclin-1, leading to the accumulation of a 50-kDa fragment. This event was prevented by intravitreal treatment with the non-competitive N-methyl-D-aspartate antagonist MK801 and calpain inhibitors or by calpain knockdown. Blockade of autophagy by pharmacological inhibition or Beclin-1 silencing in RGC-5 increased cell death, suggesting a pro-survival role of the autophagic process in this neuronal cell type. Altogether, our results provide original evidence for calpain-mediated cleavage of Beclin-1 and deregulation of basal autophagy in the rat retina that has undergone ocular ischemia/reperfusion injury.

Modulation of pro-survival and death-associated pathways under retinal ischemia/reperfusion: effects of NMDA receptor blockade.

Loss of retinal ganglion cells occurs in a variety of pathological conditions, including central retinal artery occlusion, diabetes and glaucoma. Using an experimental model of retinal ischemia induced by transiently raise the intraocular pressure (IOP), In this study, we report the original observation that ischemic retinal ganglion cells death is associated with the transient deactivation of the pro-survival kinase Akt and activation of GSK-3beta followed, during reperfusion, by a longer lasting, PI3K-dependent, activation of Akt and phosphorylation of GSK-3beta. Under these experimental conditions, retinal ischemia induced the expression of Bad, a pro-apoptotic protein, member of the Bcl-2 family. The detrimental effects yielded by the ischemic stimulus were minimized by intravitreal administration of the NMDA receptor antagonist, MK801, that reduced the expression of Bad and significantly increased Akt phosphorylation. In conclusion, our present results contribute to unravel the mechanisms underlying retinal damage by high IOP-induced transient ischemia in rat. In addition, these data implicate the pro-survival PI3K/Akt pathway and the observed reduced expression of Bad in the neuroprotection afforded by MK801.

Cell signaling pathways in the mechanisms of neuroprotection afforded by bergamot essential oil against NMDA-induced cell death in vitro.

BACKGROUND AND PURPOSE: The effects of bergamot essential oil (BEO; Citrus bergamia, Risso) on excitotoxic neuronal damage was investigated in vitro. EXPERIMENTAL APPROACH: The study was performed in human SH-SY5Y neuroblastoma cells exposed to N-methyl-D-aspartate (NMDA). Cell viability was measured by dye exclusion. Reactive oxygen species (ROS) and caspase-3 activity were measured fluorimetrically. Calpain I activity and the activation (phosphorylation) of Akt and glycogen synthase kinase-3beta (GSK-3beta) were assayed by Western blotting. KEY RESULTS: NMDA induced concentration-dependent, receptor-mediated, death of SH-SY5Y cells, ranging from 11 to 25% (0.25-5 mM). Cell death induced by 1 mM NMDA (21%) was preceded by a significant accumulation of intracellular ROS and by a rapid activation of the calcium-activated protease calpain I. In addition, NMDA caused a rapid deactivation of Akt kinase and this preceded the detrimental activation of the downstream kinase, GSK-3beta. BEO (0.0005-0.01%) concentration dependently reduced death of SH-SY5Y cells caused by 1 mM NMDA. In addition to preventing ROS accumulation and activation of calpain, BEO (0.01%) counteracted the deactivation of Akt and the consequent activation of GSK-3beta, induced by NMDA. Results obtained by using specific fractions of BEO, suggested that monoterpene hydrocarbons were responsible for neuroprotection afforded by BEO against NMDA-induced cell death. CONCLUSIONS AND IMPLICATIONS: Our data demonstrate that BEO reduces neuronal damage caused in vitro by excitotoxic stimuli and that this neuroprotection was associated with prevention of injury-induced engagement of critical death pathways.

Outcomes of a pharmacoepidemiological survey on the antibiotic treatment of uncomplicated acute cystitis in community.

We carried out a community-based survey in order to emphasize the importance of therapeutic appropriateness of antibiotic prescription by local physicians and the close connection between pharmacotherapy and pharmacoeconomics. Twenty general practitioners belonging to the local sanitary firm of Paola (CS, Italy) provided information, including their prescription, regarding 64 patients, both male and female, presenting clinical symptoms of uncomplicated acute cystitis. The data collected were compared with those of a previous trial performed in the same setting and documenting the effectiveness and advantages associated with the use of amoxicillin against community-acquired uncomplicated urinary tract infections (UTI). By comparing the prescriptive behaviour of physicians between the first and the present survey, we detected a significant increase in the use of amoxicillin (from 0 to 26.56%), paralleled by a decrease in prescribing aminoglycosides (from 18.18 to 1.56%). In addition, this resulted in a significant reduction in the costs of treatment (from 23.06 to 12.75 euros). Therefore, given the vast consensus concerning the adoption of empirical treatment for the eradication of UTI, the present survey underlines the crucial role of local antibiotic resistance monitoring in order to optimize the use of these drugs. Moreover, we have also observed a significant reduction in treatment costs associated with an appropriate and effective treatment of UTI.

Rational use of antibiotics in acute uncomplicated cystitis: a pharmaco-epidemiological study.

Uncomplicated community-acquired urinary tract infections are among those most commonly found in clinical practice, resulting in significant morbidity and health care costs. Current management is usually empirical because of the narrow and predictable spectrum of etiologic agents that cause acute cystitis and their susceptibility patterns. However, since antimicrobial resistance is increasing, the use narrow-spectrum, inexpensive antimicrobial agents becomes less feasible. In our study we have evaluated the effectiveness of amoxicillin, a narrow-spectrum, inexpensive and non toxic drug, against non-complicated acute cystitis in 34 patients, and compared the results with the antibiotic therapy previously employed by the physicians of the Health Care Unit of Paola (CS), Italy. Amoxicillin was found to be effective for the treatment of community-acquired cystitis, thus suggesting that the development of bacterial resistance does not represent a limit to its use. Furthermore, our study demonstrates that besides providing an effective alternative to broad-spectrum antibiotics, the use of amoxicillin significantly reduced health care costs.

Inducible nitric oxide synthase is involved in the mechanisms of cocaine enhanced neuronal apoptosis induced by HIV-1 gp120 in the neocortex of rat.

Cocaine, often abused by human immunodeficiency virus (HIV) infected patients, has been suggested to worsen the HIV associated dementia via unknown mechanisms. Here we report that subchronic treatment with a dose of cocaine (30 mg/kg i.p.), unable per se to cause neuronal death, increases the number of apoptotic cells typically observed in the neocortex of rats treated with HIV-1 gp120 (100 ng given i.c.v.). A pre-treatment with MK801 (0.3 mg/kg i.p.), a NMDA receptor antagonist, L-NAME (10 mg/kg i.p.) and 7-nitroindazole (50 mg/kg i.p.), two specific inhibitors of NOS, or with 1400 W (1 mg/kg s.c.), a selective inhibitor of inducible NOS (iNOS), minimized neurotoxicity by combined administration of cocaine and gp120 thus implicating iNOS. This conclusion is supported by the evidence that cocaine increases brain neocortical citrulline, the co-product of NO synthesis.

Apoptosis in the mechanisms of neuronal plasticity in the developing visual system.

Visual experience during early postnatal life is essential for normal development of synaptic connections in the visual system. In fact, altered visual experiences such as monocular deprivation (MD) or abnormal visual stimulation (e.g. strabismus, anisometropia) during this period disrupt the physiologic organization of the visual pathway, leading to loss of visual responses in cortical neurons and reduction in visual acuity of the affected eye, so that it becomes amblyopic. The authors review the main functional and morphologic changes induced by altered visual experiences in the developing visual system and focus on the recent discovery that MD induces apoptotic cell death in the lateral geniculate nucleus of newborn rats. Particular attention is given to the authors' studies documenting that, during development, MD leads retinal terminals to release excessive glutamate in the lateral geniculate nucleus where it elevates nitric oxide and causes DNA fragmentation. The latter event is known to activate poly-(ADP-ribose) polymerase, which in turn may trigger apoptosis. Better understanding of the mechanisms underlying the morphologic changes induced by altered visual experiences during development may open new venues for studying novel neuroprotective strategies for amblyopia and, more generally, for the treatment of ophthalmic diseases associated with neuronal apoptosis.