Biomedical subjects

Paola Tirassa

Publications and source records attributed to Paola Tirassa.

12 recordsLinked to original sources

PubMed2006

CCK-8 induces NGF and BDNF synthesis and modulates TrkA and TrkB expression in the rat hippocampus and septum: Effects on kindling development.

In our previous studies, we demonstrated that intraperitoneal (i.p.) injections with the neurotransmitter/neuromodulatory peptide Cholecystokinin-8 (CCK-8) stimulate the synthesis of the neurotrophin nerve growth factor (NGF) resulting in the structural and functional recovery of neuronal damage. This neurotrophin-mediated neuroprotective action of CCK-8 has opened a new perspective for a better understanding of the CCK neurobiological and pharmacological properties. To explore the possible beneficial effects of the CCK-induced increase of neurotrophin availability in brain, we compared the effects of i.p. CCK-8 in healthy rats and in a chemical kindling model using a subconvulsive dose of pentylenetetrazol (PTZ). Behavioural changes were monitored during treatment and classified according to a six-point scale. After 3 weeks of treatment (12 trials), the PTZ group of rats manifested generalized clonic-tonic seizures (Class 5 behaviour). For this reason, this time point was chosen to compare the effects of CCK-8 treatment on the expression of NGF, the brain derived neurotrophin factor (BDNF) and their receptors in the septum and hippocampus. We found that repeated i.p. injections with CCK-8 in adult rats result in: (1) an increase of NGF and BDNF protein and mRNA levels in the septum and hippocampus; (2) a down-regulation of TrkA and p75NTR and an up-regulation of TrkB; (3) reduced susceptibility to develop chemical kindling; (4) recovery of the PTZ-induced changes in the expression of neurotrophin receptors in the septal and hippocampal tissues. This data clearly indicates that CCK-induced variation of neurotrophin synthesis in brain is able to influence the susceptibility to develop seizures in adult rats most probably by counteracting the progressive neuronal dysfunction and/or damage.

Animals↗

PubMed2005

Nerve growth factor modulates in vitro the expression and release of TGF-beta1 by amniotic membrane.

PURPOSE: To determinate the basal production of NGF and TGF-beta1 by amniotic membrane (AM) and to verify the presence of NGF receptors (trkA(NGFR) and p75(NTR)) in AM. Thereafter, to evaluate in an in vitro model if increasing concentrations of NGF are able to stimulate AM to produce and release TGF-beta1. METHODS: Immunohistochemistry, ELISA, in situ hybridization and PCR analysis for NGF, TGF-beta1, trkA(NGFR) and p75(NTR) were performed to study their presence in AM. Amniotic membranes were stimulated in vitro with increasing concentrations of NGF. After 24 h, the amount of TGF- beta1 in the AM tissue and in the culture medium was investigate. RESULTS: AM expressed TGF-beta1, NGF, trkA(NGFR) and p75(NTR) mRNAs and proteins and released basal amounts of NGF and TGF-beta1 in the medium. Stimulation of AM by addition of NGF induced a significant (P<0.05) increase of TGF-beta1 mRNA/protein in AM tissue as well as a release of TGF-beta1 protein into the culture medium, in a dose-dependent fashion. CONCLUSIONS: This study demonstrates that amniotic membrane releases basal amounts of NGF and TGF-beta1 and expresses NGF receptors . Moreover, the addition of NGF to the culture medium stimulates the amniotic membrane to significantly increase the production and release of TGF-beta1.

Amnion↗

PubMed2005

Presence of nerve growth factor and TrkA expression in the SVZ of EAE rats: evidence for a possible functional significance.

Nerve growth factor (NGF) is a well-characterized neurotrophic factor that plays a crucial role during development in the growth, differentiation, and maintenance of brain neurons as well as in the reparative response of the adult brain to neuronal damage. Recent studies have shown that acute axonal loss occurs in multiple sclerosis (MS) and its animal model, experimental allergic encephalomyelitis (EAE), and that NGF suppresses clinical symptoms of EAE in nonhuman primates. Aim of the present study was to investigate the role of NGF in the regenerative response of the adult brain to neuronal damage occurring in EAE. Using EAE rats, we have found that exogenous NGF injection and NGF deprivation (NGF autoimmunization) can act on growth and differentiation of brain precursor cells in the subventricular zone (SVZ) of EAE rats. Moreover, NGF administration in brain of EAE rats stimulates the expression of early neuronal markers on proliferating precursor cells of the SVZ. The data obtained demonstrated that NGF and its antibody affect bromodeoxyuridine (BrdU) incorporation and NGF receptor expression by SVZ progenitor cells in the brain of EAE rats.

Animals↗

PubMed2005

CCK-8 prevents the development of kindling and regulates the GABA and NPY expression in the hippocampus of pentylenetetrazole (PTZ)-treated adult rats.

Neuronal loss and irreversible brain damage often cause the worsening of symptoms and the decreased efficacy of pharmacological treatment occurring in epileptic patients and animal models of kindling. Recently we reported that the neurotransmitter/neuromodulatory peptide Cholecystokinin-8 (CCK-8) is able to induce the structural and functional neuronal recovery of chemical- and surgical-induced lesions when i.p. injected in rodents. The present study therefore, was aimed at verifying the hypothesis that treatment with a CCK-8 dose having a neuroprotective action might affect brain alterations and the development of kindling in adult rats receiving the convulsant agent pentylenetetrazole (PTZ). Compared to rats receiving Saline prior to PTZ, which manifested clonic-tonic seizures (Class 5 behavioural change scale) after three weeks of treatment, rats pre-treated with CCK-8 showed an improvement of behavioural score exhibiting myoclonus and occasionally tonic seizures (Class 3/4). This decreased susceptibility to develop convulsions was associated with the recovery of PTZ-induced reduction of ChAT levels in forebrain and GABA/GAD expression in the hippocampus. Furthermore, NPY immunoreactivity distribution and NPY mRNA levels were also increased in the hippocampus of rats receiving CCK-8 injection before each PTZ treatment. These data indicate that CCK-8 possesses the ability to prevent and/or suppress the convulsant effects of PTZ by stimulating the synthesis of neurotransmitters/peptides involved in the inhibition of hippocampal hyper-excitability. Our findings suggest that CCK-8 may have anticonvulsant and neuroprotective properties that merit further investigation.

Analysis of Variance↗

PubMed2005

Pharmacokinetics of conjunctivally applied nerve growth factor in the retina and optic nerve of adult rats.

PURPOSE: Nerve growth factor (NGF) has been shown to inhibit retinal ganglion cell (RGC) degeneration when injected intraocularly in animal models of ocular hypertension, optic nerve transaction, and ischemia. The present study sought to establish the bioavailability of topical NGF to the retina and optic nerve in rats. METHODS: Autoradiography was performed to evaluate whether exogenous (125)I-labeled NGF reaches the retina and optic nerve when applied topically to the rat conjunctiva. To quantify NGF levels, a highly specific immunoenzymatic test (ELISA) was performed on the retina, optic nerve, lens, sclera and serum of rats at different time points after administration of NGF (1-500 microg/mL). The physiological activity of topically applied NGF was evaluated by determining retinal brain-derived neurotrophic factor (BDNF) protein and mRNA levels by ELISA and RT-PCR, respectively. RESULTS: After topical conjunctival administration of NGF, high levels were detected in ocular tissues, including the retina and optic nerve, showing a peak increase 6 hours after administration at a concentration of 200 mug/mL. NGF treatment was associated with an increase in BDNF protein and mRNA levels in rat retina. CONCLUSIONS: These data demonstrate the bioavailability of NGF to the retina and optic nerve in rats when administered topically. These findings justify investigating the clinical effects of topical NGF therapy for treatment of posterior segment diseases.

Administration, Topical↗

PubMed2003

EGF and NGF injected into the brain of old mice enhance BDNF and ChAT in proliferating subventricular zone.

The response of cells localized in the brain subventricular zone (SVZ) to growth factor stimulation has been largely described for development and adult life, whereas no information on their behavior during aging is available. To address the question of whether the cells in the SVZ of old mice respond to the intracerebroventricular administration of epidermal growth factor (EGF) and nerve growth factor (NGF), we studied the distribution of proliferating cells and the effects on ChAT and brain-derived neurotrophic factor (BDNF) synthesis in forebrain and SVZ. It was found that the conjoint administration of EGF + NGF produced a major increase in ChAT expression in both forebrain and SVZ. The ChAT mRNA levels and the number of ChAT positive cells localized in the ventricular border and in the parenchyma of SVZ area were also increased significantly in the mice receiving EGF + NGF. Enhanced numbers of SVZ cells expressing proliferative markers were also discovered in EGF + NGF treated mice and some of these cells expressed cholinergic markers, as demonstrated by double immunostaining. In addition, EGF and NGF treatments significantly upregulate BDNF protein and mRNA levels in this brain region. The present study demonstrates that cells localized in SVZ of aged mouse brain retain the capacity to respond to EGF and NGF and that after stimulation with these two growth factors, the synthesis of ChAT and BDNF also increases. The implication that cells of the SVZ remain a reservoir of cholinergic and BDNF-positive neurons in aged brain opens a new perspective for understanding the role of growth factors during neurodegenerative disorders associated with aging.

Acetylcholine↗

PubMed2003

Agonistic encounters in aged male mouse potentiate the expression of endogenous brain NGF and BDNF: possible implication for brain progenitor cells' activation.

The condition of dominance or submission following agonistic encounters in the adult male mouse is known to differentially affect brain nerve growth factor, a neurotrophin playing a role in brain remodeling, in the fine tuning of behaviour and in the regulation of the basal forebrain cholinergic neurons. During development and adult life nerve growth factor regulates brain expression of neurotransmitters and the stimulation of progenitor cells (stem cells) which, under different external stimuli, may differentiate into neuronal and/or glial cells promoting the recovery of the injured brain. However, little information is available for the aged brain. Thus in the present study we investigated the effect of the social status ('dominance' vs. 'submission') in the aged mouse on the presence of nerve growth factor, brain-derived neurotrophic factor, choline acetyltransferase, neuropeptide Y and progenitor cells of selected brain regions. We found that aged dominant mice showed increased brain-derived neurotrophic factor in the subventricular zone and hippocampus and increased choline acetyltransferase in the septum and basal nuclei, which were associated with increased presence of progenitor cells in the subventricular zone. Conversely, in aged subordinate mice the data showed a marked brain increase in nerve growth factor in the subventricular zone and hippocampus, choline acetyltransferase in the septum and basal nuclei and neuropeptide Y in the hippocampus and parietal cortex. The possible functional implications of these findings are discussed.

Aging↗

PubMed2003

Apoptotic PC12 cells exposing phosphatidylserine promote the production of anti-inflammatory and neuroprotective molecules by microglial cells.

The interaction of phosphatidylserine (PS), exposed on the surface of apoptotic cells and with its specific receptor (PtdSerR) expressed by microglia, is a crucial event in the recognition and clearance of apoptotic neurons. Here, we extend our previous studies in which PS-liposomes mimicking apoptotic cells were used to investigate the functional role of PS-PtdSerR interactions on microglial functional state. Purified rat microglial cells were either incubated with PC12 cells maintained in complete medium (healthy), exposed to staurosporine or serum deprivation (apoptotic), or treated with hydrogen peroxide (necrotic). After 24 hours, supernatants from co-cultures and single cell type cultures were analyzed for nitric oxide (NO), tumor necrosis factor-alpha (TNF-alpha), interleukin-10 (IL-10), prostaglandin E2 (PGE2), transforming growth factor-beta1 (TGF-beta1), and nerve growth factor (NGF). When lipopolysaccharide (LPS)-activated microglia was cultured with apoptotic PC12 cells, NO and TNF-alpha levels significantly decreased, IL-10 was not affected, and PGE2 levels were substantially increased. In addition, TGF-beta and NGF syntheses increased when resting microglia was cultured with apoptotic but not healthy or necrotic PC12 cells. We proposed that upon interaction with PS-expressing apoptotic neurons, microglia no longer act as a promoter of the inflammatory cascade and that the specific microglial functional state induced by PS-PtdSerR may be relevant for the final outcome of neurodegenerative diseases.

Animals↗

PubMed2002

Brain NGF and EGF administration improves passive avoidance response and stimulates brain precursor cells in aged male mice.

Nerve growth factor (NGF) has been shown to improve damage in spatial cognition following aging, whereas epidermal growth factor (EGF) is important in brain cell proliferation. It is also known that the adult mammalian central nervous system contains persistent progenitor cells with characteristics of stem cells. These studies suggest that under appropriate external stimuli progenitor cells may generate neuronal and glial cells promoting recovery of the injured nervous system. However, little is known about the presence and responsiveness of progenitor cells in the aged brain. In the present investigation, we studied the effect of brain intracerebroventricular injections of EGF and/or NGF on progenitor cells of the subventricular area (SVZ) in aged male mice to test learning performances in the passive avoidance apparatus. We found that neither NGF nor EGF improved learning responses. However, combined NGF and EGF administration in the brain improved learning responses of aged mice in the passive avoidance when compared with aged matched nontreated controls. These findings resulted to be associated with increased immunopositivity to progenitor cells in the SVZ. The possible functional implications of these data are discussed.

Aging↗

PubMed2002

Intraocular production and release of nerve growth factor after iridectomy.

PURPOSE: To determine the presence of nerve growth factor (NGF), NGF mRNA, and NGF receptor (TrkA) in rabbit ocular tissues, and whether changes occur in NGF and NGF mRNA levels after experimental iridectomy. METHODS: Immunohistochemistry for NGF and TrkA and in situ hybridization for NGF mRNA were performed on rabbit cornea, iris, ciliary body, and lens in the basal state. Quantification of NGF mRNA and NGF protein levels in these tissues was performed by RT-PCR and immunoenzymatic assay, respectively. A time course of NGF concentration in the aqueous humor and the expression of NGF mRNA in iris and ciliary body were performed after the iridectomy and were compared with levels in a sham-treated group (paracentesis). RESULTS: Cornea, iris, ciliary body, and lens expressed NGF mRNA, NGF protein, and TrkA in the basal state. The highest levels of NGF were detected in the iris (8938.0 +/- 3968.1 pg/g), and the lowest were in the aqueous humor (22.8 +/- 9.7 pg/mL). Experimental iridectomy induced a transient increase of NGF concentration in the aqueous humor that reached its peak 4 hours after the experimental injury (464.4 +/- 29.9 pg/mL versus the control group 101.6 +/- 18.8 pg/mL; P < 0.001) and returned to baseline value after 7 days. A significant increase of NGF mRNA was also observed 1 hour and 4 hours after the iridectomy in the iris (1 hour, 788 +/- 85 OD; 4 hours, 760 +/- 81 OD versus baseline, 246 +/- 32 OD; P < 0.0001) and ciliary body (1 hour, 330 +/- 19 OD; 4 hours, 453 +/- 52 OD versus baseline, 219 +/- 37 OD; P < 0.05), but not in the cornea, lens, or any tissues from the control group. CONCLUSIONS: NGF is present and produced in the anterior segment of the eye and is released in the aqueous humor in the basal state. Experimental iridectomy induces increased production of NGF in the iris and in the ciliary body and an increased concentration of NGF in the aqueous humor.

Animals↗

PubMed1998

A role of the thymus and thymosin-alpha1 in brain NGF levels and NGF receptor expression.

Using neonatal rats we investigated the role of the thymus and thymosin-alpha1 (T-alpha1) in brain NGF levels, NGF receptor (p75NGFr) expression, as well as the activity of choline acetyl-transferase, a cholinergic enzyme regulated by NGF. It is shown that early postnatal thymectomy causes a decrease in NGF in the hippocampus and cortex and p75NGFr distribution in the basal forebrain cholinergic neurons (FBCN). Intracerebral T-alpha1 injection in thymectomized animals induces a recovery, albeit not complete, of both NGF and p75NGFr. These findings indicate that thymectomy affects both the brain NGF producing and responding cells and that T-alpha1 may be one of the thymic hormones involved in the regulation of cerebral NGF synthesis.

Adjuvants, Immunologic↗

PubMedDate not supplied

Nerve growth factor produced by activated human monocytes/macrophages is severely affected by ethanol.

Ethanol intake impairs immune function and increases the incidence of infection in the host. Although the precise cellular target of this immunotoxic action is still unknown, findings of several studies have shown that ethanol acts on the immune response predominantly by interfering with the ability of blood monocyte-derived macrophages to produce cytokines and growth factors. Nerve growth factor (NGF) represents a key molecule in monocyte/macrophage-mediated responses. Thus, we tested the hypothesis that exposure to ethanol would affect NGF synthesis as well as expression of NGF receptor trkA in this cell population. Because NGF has been reported to affect the synthesis of proinflammatory cytokines, we also evaluated whether the production of tumor necrosis factor-alpha would be affected by ethanol-mediated changes in NGF synthesis. The study results demonstrated that the acute exposure of lipopolysaccharide-activated human monocyte/macrophage cultures to ethanol led to a sharp decrease in endogenous-produced NGF, which is associated with a reduced expression of high-affinity NGF receptor on cell membrane, and to a concomitant impairment of tumor necrosis factor-alpha production. Taken together, the current findings support the suggestion that a new mechanism exists by which ethanol can compromise the efficiency of the mononuclear phagocyte system in dealing with infection and host inflammatory response.

Cells, Cultured↗