Nerve growth factor serum levels in treatment-resistant schizophrenic patients following electroconvulsive therapy.

BACKGROUND: Electroconvulsive Therapy (ECT) has been widely applied to treat schizophrenia (SCZ) in the presence of resistance to pharmacotherapy. The mechanism of action of ECT in schizophrenia has not been fully clarified, though its intrinsic mechanism presents analogies with some neurobiological processes mediated by nerve growth factor (NGF). OBJECTIVES: The aim of this study was to investigate in patients with treatment-resistant schizophrenia (TRS) the effect of ECT on acute and long-term NGF serum levels and the association with the clinical outcomes. METHODS: Twelve male inpatients with TRS underwent eight sessions of ECT. Blood samples were collected during the first and the eighth ECT at the following time points: 5 minutes before the induction of seizure and then at 0, 5, 15 and 30 minutes after seizure. RESULTS: Following ECT treatment, a substantial clinical improvement in symptom severity was indicated by a significant reduction in the Positive and Negative Syndrome Scale (PANSS) total and subscales scores. Even though the baseline NGF levels showed an increase over time, there were no statistical differences in NGF at time 0 at the first and the eighth ECT session. Furthermore, no correlation was observed between the severity of schizophrenic symptoms and NGF levels. CONCLUSIONS: This is the first study addressing peripheral NGF during ECT treatment in TRS, as well as the first study in which NGF has been evaluated in different ECT sessions at various time points. These findings may potentiate the knowledge about the neurotrophic effects of ECT and the role of NGF in synaptic plasticity related to possible mechanisms of schizophrenia treatment.

The role of cytokines in head and neck squamous cell carcinoma: A review.

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common malignancy worldwide, accounting for approximately 6% of all cancer cases and responsible for an estimated 1-2% of all cancer deaths. Much research evidence has accumulated in the recent years on the changes in the expression of pro-inflammatory and, to a lesser extent, anti-inflammatory cytokines, that (i) may have a role in the malignant transformation of HNSCC, (ii) may be used as diagnostic markers in the sera of patients because of their excessive production by the tumor cells and (iii) may act as possible immunotherapeutic targets. Among pro-inflammatory cytokines, interleukin-8 (IL--8) has been reported to have an important role in cancer invasion, angiogenesis and metastasis. Recent studies have shown an increased concentration of IL--8 in patients with HNSCC and a positive association with lymph node metastasis and tumor classification, although IL--8 was not significantly associated with shorter overall survival and cancer progression-free survival. Additional evidence on the pathological mechanism of origin, invasion, and metastasis of HNSCC, as well as a better understanding of the implications of cytokines, chemokines and growth factors, are of paramount importance for the advancement of research in head and neck oncology.

Levels of NGF, p75NGFR and ChAT immunoreactivity in brain of adult and aged microencephalic rats.

Methylazoxymethanol (MAM)-induced microencephalic aged animals with reduced cortical mass and unmodified basal nucleus were used to study the relationship between cells that produce and cells that utilize NGF. Total cortical ChAT activity of MAM 2, 19 and 27 month old animals was reduced compared to their age-matched controls. To verify whether the reduction of enzyme activity can be ascribed to changes in or ablation of projecting neurons, we carried out immunohistochemical analysis of ChAT and low affinity NGF receptor (p75NGFR) in the basal nucleus of control and MAM-treated animals. ChAT and p75NGFR immunostaining of basal forebrain cholinergic neurons showed morphological changes in MAM animals, as revealed by cellular atrophy, reduced dendritic arborization and decreased staining intensity. In the cerebral cortex of microencephalic animals, reduced levels of NGF compared to controls were observed at all examined ages. These results suggest that MAM treatment induces long-lasting ablation of cortical NGF-synthesizing cells leading to reduced trophic support to basal forebrain cholinergic neurons, which might be responsible for the cellular atrophy observed in the basal nucleus.

Cholecystokinin-8 and nerve growth factor: two endogenous molecules working for the upkeep and repair of the nervous system.

Cholecystokinin-8 (CCK-8), the small peptide initially described as a gastric factor involved in the regulation of feeding behavior, is today recognized as one of the most abundant neurotransmitters/ neuropeptides in brain and is an important signal factor for the peripheral and central nervous systems. In the past twenty years, many studies have focused on possible clinical applications of this peptide and its receptor ligands in psychiatric diseases and gastrointestinal pathologies. Recently it has been suggested that CCK-8 may also have a neuroprotective role, thus opening a new field of interest around the physiology and the pharmacology of this neuropeptide and its receptors. It has been demonstrated that CCK-8 counteracts neuronal deficit following chemical or surgical lesions in both the central and peripheral nervous systems and that Nerve Growth factor (NGF) is involved in the CCK-induced recovery process. By using selective CCK receptor antagonists it has been demonstrated that CCK-8, when injected intraperitoneally, has the ability to stimulate NGF synthesis in brain and peripheral organs by a mechanism that involves the activation of CCK receptors. As has been widely reported, NGF is an essential survival and differentiative factor for selective neuronal populations of the PNS and CNS and plays a role in the events of degeneration and repair of the nervous system in diseases with different etiologies, e.g. neurodegenerative and autoimmune diseases as well as diabetes-associated pathologies. The possibility of using NGF in therapy has been evaluated and systemic and intracerebral NGF treatment have been tested in patients and animal models. Although the results of these studies are encouraging, the difficulty to predict and/or eliminate the side effects of NGF/NGF antibody treatment has made it difficult to fully evaluate the potential of the beneficial effects. In this context recent results obtained in our laboratories may offer a new prospective for the pharmacological approaches to the diseases associated with altered NGF production and functions. The data of our recent observations on NGF and CCK-8 is covered in this review.

Nerve growth factor in neurological and non-neurological diseases: basic findings and emerging pharmacological prospectives.

Nerve growth factor (NGF) is known to be essential for the survival of peripheral and brain neurons, and according to more recent studies also for a variety of cells localized in the immune system. Basic and preclinical findings published in the last 15-20 years have prospected the hypothesis that NGF can be pharmaceutically useful for promoting healing in certain peripheral and central neurological insults. We have recently provided evidence that NGF applied topically, has a therapeutic potentiality for human corneal and pressure ulcers, and more recently in vasculitis induced by rheumatoid arthritis. This review will summarize previous and ongoing evidence supporting the role of NGF in the nervous and immune system and discuss NGF potentiality as a pharmacological tool for basic and clinical studies.

Increased plasma levels of substance P in vernal keratoconjunctivitis.

PURPOSE: The increase of nerve growth factor (NGF) plasma levels in vernal keratoconjunctivitis (VKC) patients has been demonstrated previously. Results of numerous studies in vitro and in vivo have shown that NGF modulates the synthesis of substance P (SP), a neuropeptide involved in the pathogenesis of human allergic diseases. In this study the involvement of SP in this allergic conjunctivitis is investigated, along with its relationship with NGF and other systemic and local markers of VKC. METHODS: Competitive radioimmunoassays were used to detect the levels of SP in plasma, the levels of eosinophil cationic protein, and the total and specific immunoglobulin E in the serum of 11 patients with VKC and in 11 healthy matched controls. Plasma levels of nerve growth factor (NGF) were measured in all VKC patients and controls using an immunoenzymatic assay. Histologic evaluation was performed in tarsal and bulbar conjunctival specimens obtained in biopsies from 8 VKC patients and 4 control subjects. RESULTS: Patients with VKC show a significant increase of SP and NGF plasma levels (P < 0.003 and P < 0.001, respectively), and an increase of eosinophil cationic protein and immunoglobulin E levels in the serum (P < 0.001 and P < 0.002, respectively). Mast cells, eosinophils, and lymphocytes were also significantly increased in the conjunctiva of VKC patients. Interestingly enough, VKC patients with the highest NGF plasma levels also showed the highest SP levels. CONCLUSIONS: The data show the involvement of SP in VKC and suggest that SP with NGF could modulate the allergic response in this disease, probably through an interaction with inflammatory cytokines.

Cholecystokinin-8 enhances nerve growth factor synthesis and promotes recovery of capsaicin-induced sensory deficit.

Alterations of nerve growth factor (NGF) expression have been demonstrated during peripheral nerve disease and the impaired expression or synthesis and transportation of NGF has been correlated with the pathogenesis of several peripheral neuropathies. Since exogenous NGF administration seems to cause undesired side-effects, therapeutical strategies based on the regulation of endogenous synthesis of NGF could prove useful in the clinical treatment of these disorders. The aim of the present study was to analyse the effects of exogenous peripheral administration of the neuropeptide cholecystokinin-8 (CCK-8) on endogenous NGF synthesis, NGF mRNA and distribution of peripheral neuropeptides which are known to be regulated by this neurotrophin. To address these questions we studied the effects of capsaicin (CAPS) before and after the administration of CCK-8 on NGF levels, NGF mRNA expression and localization, and the concentration of substance P (SP) and calcitonin gene-related peptide (CGRP) in peripheral tissue These studies demonstrate that administration of the CCK-8 induces an increase of NGF protein and mRNA in peripheral tissue. NGF level in paw skin of CAPS/CCK-8-treated mice is 3 fold higher than in controls (1241+/-110 pg gr(-1) of tissue wet weight versus 414+/-110 pg gr(-1) of controls) and nearly 6 fold higher than in CAPS-treated mice (1241+/-110 pg gr(-1) versus 248+/-27 pg gr(-1)). The increase of NGF is correlated with the recovery of impaired nocifensive behaviour and with an overexpression of SP and CGRP. The evidence that CCK-8 promotes the recovery of sensory deficits suggests a potential clinical use for this neuropeptide in peripheral neuropathies.

Cholecystokinin-8 regulation of NGF concentrations in adult mouse brain through a mechanism involving CCK(A) and CCK(B) receptors.

1. Nerve growth factor (NGF), a powerful agent for the growth, differentiation and regeneration of lesioned cells of the central and peripheral nervous systems, has in recent years been indicated as a potential therapeutic agent capable of reversing the processes of cell damage in neurodegenerative events in man. Since NGF does not cross the blood-brain barrier and central NGF administration requires invasive surgical procedures, the discovery of substances modulating in vivo NGF synthesis in the brain will be extremely useful for a possible clinical use of NGF. 2. The aim of the present study to analyse if the content of NGF in the brain of adult mice can be affected by peripheral administration of cholecystokinin-8 (CCK-8), a well known neuropeptide which has stimulant actions on neurons in the brain and promotes a variety of neurobehavioural effects both in man and rodents. 3. The dose-response and time course effects of an i.p. injection of CCK-8 on the NGF concentrations in the hippocampus, cortex, hypothalamus and pituitary of adult male mice were analysed by use of a sensitive immunoenzymatic assay for NGF. The effects of pretreatment with selective CCK(A) and CCK(B) receptor antagonists and atropine on the NGF response to CCK injection were also studied. 4. The effects of CCK-8 were dose- and time-dependent and the injection of 8 nmol kg(-1) resulted in a 3 fold increase of NGF levels in the hypothalamus and pituitary, and about a 60% increase in the hippocampus. No effects were observed in the cortex. Pretreatment with a selective CCK(A) receptor antagonist blocked the CCK-induced NGF increase in the hypothalamus and pituitary. In the hippocampus the same effect was obtained with a CCK(B) receptor antagonist. Pretreatment with atropine suppressed the CCK-induced effects on NGF levels in all the brain regions examined. 5. Our results showing that i.p. injection with CCK-8 can modulate NGF levels in the brain through a mechanism which seems, in part, to be mediated via the vagal afferents, indicate that this neuropeptide may represent a useful pharmacological approach to enhance endogenous NGF levels in neuropathologies associated with a neurotrophin deficit.

Schistosoma mansoni infection enhances the levels of NGF in the liver and hypothalamus of mice.

Schistosoma mansoni infection in adult mice is known to cause granulomas in the liver and intestine. Using a specific enzyme-linked immunoassay, it was found that Schistosoma mansoni infection enhances the level of nerve growth factor in the liver and surprisingly also in the hypothalamus. Exogenous administration of purified NGF antibodies inhibits NGF biological activity both in the hypothalamus and liver and drastically reduces the number of NGF-responsive cells, the mast cells, present in liver granuloma. These findings and those reported by others showing the effect of NGF on cells of the immune system support the hypothesis that this molecule plays a role in neuroendocrine-immune interactions.

Cholecystokinin-8 promotes recovery of sympathectomy induced by 6-hydroxydopamine in adult mice.

We used an experimental model of sympathetic neuropathy to investigate the effects of intraperitoneal cholecystokinin-8 (CCK-8) administration on the recovery of injured peripheral neurones. After treatment of adult mice with 6-hydroxydopamine (6-OHDA), which known to induce peripheral sympathectomy, nerve growth factor (NGF) in peripheral tissue first increased and then rapidly decreased to baseline levels. Following this observation, sympathectomised mice were treated with CCK-8 starting when the NGF levels lowered toward the control value. Our results show that injections with 8 nmol/kg of CCK-8 promote not only recovery of noradrenergic innervation but also NGF and neuropeptide Y (NPY) synthesis in peripheral tissue. This latter observation suggests that the effect of CCK-8 might be mediated through the stimulation of NGF synthesis.

Monosodium glutamate increases NGF and NPY concentrations in rat hypothalamus and pituitary.

The effects of MSG treatment on NGF and NPY levels were analysed in the hypothalamus, pituitary, adrenal, thyroid and testis of adult rats. Daily i.v. injections of MSG (1 g kg-1 for 1 week) induced an increase of NGF in the hypothalamus (control (C) = 378 +/- 54; saline (S) = 369 +/- 36; MSG = 479 +/- 35 pg g-1 tissue; p < 0.001) and pituitary (C = 310 +/- 34; S = 376 +/- 114; MSG = 576 +/- 98 pg g-1 tissue; p < 0.01). Hypothalamic and pituitary NPY concentrations were also altered in the MSG-treated rats. Compared with saline-treated rats, the NPY concentration increased by 43% in the hypothalamus and 37.5% in the pituitary of MSG-treated rats. No significant changes in NGF and NPY content were found in the adrenal or thyroid of treated animals. These results suggest that hypothalamic and pituitary NGF and NPY levels may be involved in the control of neuroendocrine functions that are affected by MSG treatment.

Nerve growth factor stimulates production of neuropeptide Y in human lymphocytes.

The production of neuropeptide Y (NPY) in lymphocytes obtained from human tonsils was investigated using radioimmunoassay. While unstimulated lymphocytes did not produce detectable amounts of NPY, NPY synthesis was induced after cell activation. Our results show that the addition of nerve growth factor (NGF) to unstimulated lymphocytes has an effect similar to that of mitogens, both leading to production of NPY. The study of purified B and T cells confirmed that only activated cells are able to synthesize NPY. The stimulatory effect of NGF on NPY production is not a common characteristic of all lymphocytes: only unstimulated T cells respond to NGF by synthesizing NPY. No such effects is seen in purified B cells.

Modification of lymphoid and brain nerve growth factor levels in systemic lupus erythematosus mice.

In the present work we investigated the production of nerve growth factor (NGF) in the brain and peripheral tissues of female NZB/W F1 mice, a well characterized model of murine lupus. Our results indicate that while no significant difference in the NGF content was observed in the sera and tissues of NZB/W mice and its parental strains during the first months of life, the levels of circulating NGF and the NGF content in the kidneys significantly increase in the autoimmune mice during the development of the disease. The NGF-producing brain regions showed a decrease in NGF concentration in 8 month-old NZB/W mice. Moreover, we found a modification of the NGF concentration in the spleens of autoimmune mice at 5 and 8 months. Our data support the hypothesis of a correlation between NGF and the inflammatory state of systemic lupus erythematosus (SLE) and indicate that NGF could have a role in the pathogenesis of this disease.

RT-PCR ELISA method for the analysis of neurotrophin mRNA expression in brain and peripheral tissues.

The levels of nerve growth factor (NGF) and brain derived neurotrophic factor (BDNF) in brain and periphery are susceptible to changes during development and as result of different physiopathological conditions, such as stress and aging and during the onset and progression of neurological and autoimmune diseases. Despite the sensitive methods for measurement of neurotrophin protein levels in different tissues, no easily applicable methods to evaluate changes in the level of NGF and BDNF mRNA expression within physiological range have been described. This study reports the development of a reproducible and simple procedure for measurement of neurotrophin mRNA expression in brain and peripheral tissues based upon an enzyme linked immunosorbent assay (ELISA) detection system of reverse transcriptase-polymerase chain reaction (RT-PCR) products. The major advantages of this RT-PCR ELISA procedure is to allow the co-amplification of diverse mRNAs starting from small amounts of tissues; to contemporaneously test a large number of samples; to be rapid and to use only commercial reagents and widely available equipment. The procedure could also be useful in studies addressed to measure the pattern of expression of molecules involved in the pathogenesis of neurodegenerative and inflammatory diseases, such as neuropeptides and cytokines.

The effect of chronic ethanol intake on brain NGF level and on NGF-target tissues of adult mice.

The effect of ethanol consumption on the forebrain and hypothalamus of adult mice was investigated. A consistent decrease of biological activity and of nerve growth factor (NGF) immunoreactivity was observed in the hippocampus and hypothalamus of alcohol-treated mice. Biochemical studies also indicate that chronic ethanol intake causes a reduction in the level of choline-acetyltransferase in the septum, hippocampus and striatum, but not in the cortex and other brain regions. This study provides evidence that long-term ethanol intake causes impairment of brain NGF level and of the cholinergic enzyme, regulated by NGF, suggesting that NGF synthesis and/or biological activity is affected in alcohol-related brain neuropathology.

Cold water swimming stress alters NGF and low-affinity NGF receptor distribution in developing rat brain.

We have previously shown that the nerve growth factor (NGF) is released into the bloodstream following intraspecific fighting behaviour and that the level released correlates with the number of fighting episodes. We subsequently reported that NGF and its messenger RNA are present in identified hypothalamic nuclei and increase following intermale fighting behaviour. This report provides data showing that in 16-day-old rats cold water swimming stress (CWSS) alters the distribution of low-affinity NGF-Receptors (p75NGFR) and NGF levels in the central nervous system. A significant increase of NGF level was observed in the cortex, while the p75NGFR immunoreactivity decreased in neurons of the septum, nucleus basalis and striatum. Choline acetyltransferase activity in forebrain tissues remained at baseline levels. Our result suggests that NGF and p75NGFR, involved in the development and differentiation of the nervous system, are affected by stress.

Behavioural anxiolytic effects of low-dose anabolic androgenic steroid treatment in rats.

The use of anabolic androgenic steroids (AAS) in supratherapeutic doses has been associated with aggressive behaviour as well as with severe affective and psychotic symptoms. These symptoms usually follow a chronic exposure for several months. However, AAS also may have milder effects with hypomania-like features such as an increase in confidence, energy and self-esteem. We have studied the short-term effects on male rat behaviour in a modified open-field test of the AAS Metenolon administered three times at a low dose (0.01 mg/kg/week x 3). The control rats showed indications of increased timidity and aversive learning following retesting, a reaction that was absent in the AAS-treated rats. The AAS-treated rats showed less fear or anticipatory anxiety compared to control animals. Furthermore, the suppressed marking behaviour and altered morphological allometric relationships were compatible with a modified social and sexual competence in the AAS treated rats.

Serum NGF levels increase during lactation and following maternal aggression in mice.

In the present study, serum levels of nerve growth factor (NGF) were assessed in virgin and in lactating female CD-1 mice. In the case of the lactating females, NGF levels were assessed both under basal conditions and 60 and 180 min following a 10 min encounter with a male or a nonlactating female mouse. Basal serum NGF levels of lactating females were higher than those of virgin females but did not increase significantly above base after an aggressive encounter with a male or a female conspecific. Female intruders were attacked in a ritualized manner. In contrast, males received numerous bites to vulnerable regions of their body. A positive correlation was found between serum NGF levels and pattern of aggression in females confronting male conspecifics. Thus, in lactating mice, serum NGF levels following an aggressive encounter relate to the specific pattern of behavior the female uses to defend the offspring.

Postnatal cocaine exposure affects neonatal passive avoidance performance and cholinergic development in rats.

Wistar rat pups received either cocaine HCl (25 mg/kg) or saline (0.9% NaCl) SC from postnatal days 1-11. On days 12 (acquisition) and 13 (retention), they underwent a passive avoidance task (step-off response; grid foot-shock at 0.35 mA). Slight deficits were found in cocaine-treated subjects for latency to step-off during acquisition and for generalized increase in the number of trials to criterion in retention. On postnatal day 13, the level of choline acetyltransferase (ChAT) enzymatic activity and the distribution of ChAT neuronal immunoreactivity in forebrain structures were examined. These morphometric and biochemical studies demonstrate a decrease of cholinergic enzymes in the septum, while the remaining basal forebrain cholinergic regions were unaffected.

The effect of long-term alcohol intake on brain NGF-target cells of aged rats.

It was reported that chronic exposure to ethanol causes a loss of hippocampal pyramidal cells and of brain cholinergic neurons in both laboratory animals and humans. In the present study, it was hypothesized that nerve growth factor (NGF), a trophic agent for the survival and maintenance of basal forebrain cholinergic neurons (FCN), might be affected by the neurodegenerative events which occur during ethanol consumption. To test this hypothesis, we used aged rats (14 months) exposed for 16 weeks to 40 g/kg per day of undiluted wine. Our experiments showed that chronic alcohol consumption causes a reduction of NGF in the hippocampus (HI) and of choline acetyltransferase (ChAT) activity in both the septum and the HI and a reduction in the distribution of NGF-receptors (NGF-R) in the septum and nucleus of Meynert. Intracerebral injection of NGF in alcohol-exposed rats results in a return to normal levels of ChAT enzymatic activity and NGF-R expression. These experiments indicate that the damaging effect of alcohol on the FCN is also associated with impairment of central NGF-target structures.