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.

Circulating NGF antibody alters the distribution of NG2 and CD56 positive cells in the brain of an animal model of inflammatory disorder.

Using an animal model of endogenous Nerve Growth Factor (NGF) deprivation, we have investigated the effect of this molecule on the distribution of NG2 and CD56-positive cells in the brain of normal and of Experimental Allergic Encephalomyelitis (EAE) rats. We found that the number of these cells is significantly altered in the SubVentricular Zone (SVZ) and in other brain regions. These findings indicate that NGF might be implicated in the regulation of the antigen expressed by oligodendrocyte progenitors (NG2) and of the neural cell adhesion molecule (CD56/NCAM). Both antigens are associated with mechanisms of brain repair thus providing additional evidence for a major role of NGF in the brain response to pathological conditions such as EAE. Acknowledgements.--We thank Prof. R. Levi-Montalcini for her stimulating discussions. We also thank Dr. L. Aloe for critical reading of the manuscript. This study was supported by Proj. Strategico CNR, by AISM and by Fondazione CARISBO, Bologna. Dr. V. Triaca is a recipient of a fellowship from the AISM.

Role of cholecystokinin-8 in nerve growth factor and nerve growth factor mRNA expression in carrageenan-induced joint inflammation in adult rats.

OBJECTIVES: The aim of our study was to investigate the role of cholecystokinin-8 (CCK-8), which is able to induce the synthesis of nerve growth factor (NGF), in the joint inflammation of carrageenan-injected rats. METHODS: Adult rats were injected in the ankle joint with carrageenan, with or without CCK-8 or a CCK receptor antagonist (proglumide), and tissue swelling, NGF levels and NGF mRNA expression were assessed. RESULTS: Expression of NGF and NGF mRNA increased transiently after carrageenan injection. This effect was not altered by CCK-8 injection but was inhibited by the CCK receptor antagonist. The decrease in NGF level after treatment with the antagonist was concurrent with an increase in paw swelling. CONCLUSIONS: The results demonstrate that, whereas CCK-8 has no anti-inflammatory action in carrageenan-injected animals, proglumide induces a worsening of inflammation and reduces the expression of both NGF and NGF mRNA in inflamed ankle joints. Our data point to a regulatory action of CCK-8 on NGF synthesis during acute synovitis and suggest a role for NGF in the healing phase of inflammation.

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.

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.

Nerve growth factor and neuropeptides circulating levels in systemic sclerosis (scleroderma).

OBJECTIVE: To determine the circulating levels of nerve growth factor (NGF), neuropeptide Y (NPY), and vasoactive intestinal peptide (VIP) in systemic sclerosis (SSc), and to correlate these levels with clinical and laboratory features. METHODS: Forty four patients with SSc were evaluated for circulating NGF (immunoenzymatic assay), NPY and VIP (radioimmunoassay), anticentromere and antitopoisomerase I autoantibodies, lung disease (pulmonary function tests with carbon monoxide transfer factor (TLCO), ventilation scintiscan with 99mTc DTPA radioaerosol, high resolution computed tomography (HRCT), pulmonary pressure (echo colour Doppler)), heart disease (standard and 24 ECG, echocardiography), cutaneous involvement (skin score), joint involvement (evidence of tender or swollen joints, or both), peripheral nervous system (PNS) involvement (electromyography), rheumatoid factor, angiotensin converting enzyme (fluorimetric method), von Willebrand factor (ELISA), and erythrocyte sedimentation rate (ESR) (Westergren). RESULTS: Circulating NGF levels in SSc were significantly increased compared with controls (p<0.00001) and significantly higher in the diffuse than in the limited subset of patients (p<0.01). Patients with articular disease had significantly higher levels of NGF. A significant indirect correlation between NGF levels and TLCO was detected (p<0.01), but no correlation was found between NGF and HRCT, DTPA, skin score, PNS involvement and angiotensin converting enzyme and von Willebrand factor levels, antitopoisomerase or anticentromere antibodies, and ESR. NGF levels increased progressively as the disease worsened. Similarly, VIP circulating levels were significantly increased in patients with SSc (p<0.001), whereas the increase of NPY levels did not reach statistical significance. However, both neuropeptides, following the same trend as NGF, increased as the disease worsened (skin score and lung disease). CONCLUSIONS: The increase of NGF and VIP in patients with SSc, the former in the diffuse subset of the disease, and in patients with prominent articular disease, may suggest a link between neurotransmitters and the disease pathogenesis. Neuropeptide circulating levels seem to increase only in patients with the most severe disease.

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.

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.

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.

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.

Cholecystokinin-8 protects central cholinergic neurons against fimbria-fornix lesion through the up-regulation of nerve growth factor synthesis.

In this study, we demonstrate that cholecystokinin-8 (CCK-8) induces an increase in both nerve growth factor (NGF) protein and NGF mRNA in mouse cortex and hippocampus when i.p. injected at physiological doses. By using fimbria-fornix-lesioned mice, we have also demonstrated that repeated CCK-8 i.p. injections result in recovery of lesion-induced NGF deficit in septum and restore the baseline NGF levels in hippocampus and cortex. Parallel to the effects on NGF, CCK-8 increases choline acetyltransferase (Chat) activity in forebrain when injected in unlesioned mice and counteract the septo-hippocampal Chat alterations in fimbria-fornix-lesioned mice. To assess the NGF involvement in the mechanism by which CCK-8 induces brain Chat, NGF antibody was administrated intracerebrally to saline- and CCK-8-injected mice. We observe that pretreatment with NGF antibody causes a marked reduction of NGF and Chat activity in septum and hippocampus of both saline- and CCK-8-injected mice. This evidence indicates that the CCK-8 effects on cholinergic cells are mediated through the synthesis and release of NGF. Taken together, our results suggest that peripheral administration of CCK-8 may represent a potential experimental model for investigating the effects of endogenous NGF up-regulation on diseases associated with altered brain cholinergic functions.

Overexpression of tumour necrosis factor alpha in the brain of transgenic mice differentially alters nerve growth factor levels and choline acetyltransferase activity.

Tumour necrosis factor alpha (TNF-alpha) is a pleiotrophic cytokine synthesized primarily by macrophages and monocytes, which exerts a variety of biological activities during inflammatory responses, immune reactions, and wound healing. Within the central nervous system (CNS), the basal levels of TNF-alpha are almost undetectable, but increase after neurological insults. Using transgenic mice expressing high levels of TNF-alpha in the CNS, we investigated the effect of this cytokine on the levels of brain nerve growth factor (NGF), a neurotrophin playing a crucial role in the development, maintenance and regeneration of basal forebrain cholinergic neurons. The immunoenzymatic assay and in situ hybridization revealed that the constitutive expression of NGF decreased in the hippocampus, increased in the hypothalamus, while remained unchanged in the cortex. Moreover, septal cholinergic neurons which receive trophic support from NGF produced in the hippocampus display loss of choline acetyltransferase immunoreactivity, suggesting that the reduced availability of NGF may influence negatively the synthesis of brain cholinergic neurons. These observations indicate that the basal level of brain NGF can be influenced negatively or positively by local expression of TNF-alpha and that this cytokine, through dose-dependent regulation of NGF synthesis and release, may be involved in neurodegenerative events associated with aging.

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.

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.

High-dose anabolic androgenic steroids modulate concentrations of nerve growth factor and expression of its low affinity receptor (p75-NGFr) in male rat brain.

The effects of treatment with a high dose of nandrolone or testosterone on nerve growth factor (NGF) levels and NGF low-affinity receptor (p75-NGFr) distribution in the brain were analyzed. Nandrolone, subcutaneously injected in rats for several weeks, caused an increase of NGF levels in the hippocampus and septum and a decrease in the hypothalamus. The number of p75-NGFr-immunoreactive neurons and the p75-NGFr expression levels were reduced in the septum and vertical and horizontal Broca's bands. Testosterone injections caused an increase of NGF levels in the hippocampus, septum, and occipital cortex and induced an upregulation of p75-NGFr in the forebrain NGF target regions. This testosterone effect suggests that nandrolone and testosterone affect brain NGF target cells by a different mechanism(s). Nandrolone may interfere with NGF transport and/or utilization by forebrain neurons, causing an altered p75-NGFr expression and NGF accumulation as a consequence. Since NGF is known to maintain forebrain neurons and to regulate neurobehavioral functions, including memory, learning, and defensive behavior, it is possible to hypothesize that this neurotrophin may play a role in the mechanism of action of anabolic androgenic steroids (AAS) in the brain and be associated with endocrine and behavioral dysfunctions occurring due to AAS abuse.

Increased circulating nerve growth factor is directly correlated with disease activity in juvenile chronic arthritis.

OBJECTIVE: To determine the circulating serum concentrations of nerve growth factor (NGF) and compare them with indices of disease activity in juvenile chronic arthritis. METHODS: NGF concentrations were evaluated with a two site immunoenzymatic assay (ELISA), in 17 children with systemic, 39 with polyarticular, and 24 with pauciarticular onset juvenile chronic arthritis. Each subset was divided according to different variables, appropriate to each subset, reflecting active and inactive disease. RESULTS: NGF concentrations were significantly higher in children with systemic [254 (SD 256.1) pg ml-1; P < 0.001], polyarticular [165.2 (300.8) pg ml-1; P < 0.05], and pauciarticular [106.8 (111.8) pg ml-1; P < 0.005] onset juvenile chronic arthritis than in controls. In all subsets, NGF concentrations were higher in the active than in the inactive phase of the disease. A significant direct correlation between NGF concentrations and erythrocyte sedimentation rate was found both in the systemic and in the polyarticular onset juvenile chronic arthritis. CONCLUSIONS: The increase in NGF concentrations in all juvenile chronic arthritis subsets and the correlation with disease activity suggest that NGF may take an active part in joint inflammation.

Nerve growth factor circulating levels are increased in Kawasaki disease: correlation with disease activity and reduced angiotensin converting enzyme levels.

OBJECTIVE: To investigate the serum levels of nerve growth factor (NGF) and their possible relationship with disease activity in Kawasaki disease. METHODS: Twelve children with Kawasaki disease, 12 healthy children (afebrile controls), and 12 children with high fever related to upper respiratory tract viral infections (URTVI) were enrolled in the study. Serum NGF levels were measured by an ELISA method before and after therapy. In addition, angiotensin converting enzyme (ACE), and erythrocyte sedimentation rate (ESR), complete hemochrome, and C-reactive protein were tested as indicators of endothelial injury and disease activity, respectively. RESULTS: NGF levels were strikingly increased in the acute phase of Kawasaki disease (1219.54 +/- 1660.29 pg/ml) and decreased in the inactive phase of the disease (277.08 +/- 245.64 pg/ml), while remaining significantly higher than controls (6.5 +/- 2.03 pg/ml). In febrile patients with URTVI, NGF levels (30.18 +/- 44.70 pg/ml) were moderately but significantly increased compared to afebrile controls, but remarkably lower in respect to active and inactive Kawasaki disease. In active Kawasaki disease, ACE values were significantly lower than in healthy children (2.8 +/- 1.7 vs 10.1 +/- 4.2 pmol/ml/min; p < 0.001) and increased during the inactive phase, but remaining lower than in controls (4.8 +/- 2.7 pmol/ml/min); ESR, hemoglobin level, and platelet count showed significant correlation with NGF, while ACE levels showed a significant inverse correlation with ESR and NGF. CONCLUSION: In Kawasaki disease, NGF increased together with decreased ACE may be linked to a diffuse vascular inflammatory process. NGF and ACE levels remained abnormal even when there was no clinical sign of disease activity. This may indicate that the disease process is not in complete remission and suggests careful and prolonged cardiac followup until their normalization.

Changes in human plasma nerve growth factor level after chronic alcohol consumption and withdrawal.

Numerous studies reported in recent years have shown that withdrawal from chronic consumption of drugs induces high levels of anxiety, both in humans and in animal models. In the present study, we demonstrated that withdrawal from chronic consumption of either ethanol or heroin causes a significant increase in plasma nerve growth factor, suggesting that the resulting anxiety condition triggers the release of this molecule. Although the functional significance of this phenomenon needs to be better defined, it is hypothesized that the increased levels of circulating nerve growth factor might be involved in homeostatic adaptive and/or reparative mechanisms.

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.