Rita Levi-Montalcini

Nerve growth factor.

Nerve growth factor (NGF) is a signaling protein [4] and growth factor implicated in a wide range of development and maintenance functions. NGF was discovered through a series of experiments in the 1950s on the development of the chick [5] nervous system. Since its discovery, NGF has been found to act in a variety of tissues throughout development and adulthood. It has been implicated in immune function, stress response, nerve maintenance, and in neurodegenerative diseases. It is named for its effect on the critical role it plays in the growth and organization [6] of the nervous system during embryonic development.

Essential role of the nerve growth factor in the survival and maintenance of dissociated sensory and sympathetic embryonic nerve cells in vitro

Abstract Sensory and sympathetic nerve cells were dissociated by trypsinization and cultured in CO 2 -conditioned liquid media. Eagles medium alone and Eagles medium supplemented with 10% horse serum proved to be inadequate for the survival and maintenance of these cells. Addition of a specific protein factor (nerve growth factor) at a concentration of 0.05 μg per milliliter of the culture medium, resulted in the survival and maintenance of the sensory and sympathetic nerve cells. These results add new evidence in support of the concept that the NGF plays an essential role in the life of the above cells.

THE NERVE GROWTH FACTOR

T w i c e d u r i n g t h e p a s t 12 y e a r s w e h a v e had t h e p r i v i l e g e of p r e s e n t i n g o u r work on t h e “ n e r v e growth f a c t o r ” t o t h e New York Academy of S c i e n c e s . T h e f i r s t t i m e w a s i n t h e f a l l of 1951, w h e n w e r e p o r t e d on t h e d i s c o v e r y of a d i f f u s i b l e n e r v e growth f a c t o r i n m o u s e s a r c o m a s 180 a n d 37, w h i c h s e l e c t i v e l y e n h a n c e s t h e growth a n d d i f f e r e n t i a t i o n of t h e s y m p a t h e t i c g a n g l i a i n t h e c h i c k embryo.’ T h e s e c o n d t i m e w a s i n t h e f a l l of 1959, w h e n w e r e p o r t e d on t h e d i q c o v e r y b y S t a n l e y C o h e n a n d myse l f of a p o t e n t n e r v e growth f a c t o r i n t h e m o u s e s a l i v a r y g l a n d s . We a l s o d i s c u s s e d , on t h a t occ a s i o n , t h e e f f e c t s of a s p e c i f i c a n t i s e r u m t o t h e s a l i v a r y n e r v e growth f a c t o r on t h e s y m p a t h e t i c g a n g l i a of newborn mammals.’ We now p r e s e n t t h e r e s u l t s of o u r r e c e n t i n v e s t i g a t i o n s on some a s p e c t s of t h e n e r v e growth f a c t o r a s w e l l as t h e r e s u l t s of pharm a c o l o g i c a l e x p e r i m e n t s on i m m u n o s y m p a t h e c t o m i z e d a n i m a l s . As t h e f i r s t in t h i s session, w e f e e l h o w e v e r , t h a t it may b s u s e f u l t o g i v e f i r s t a br ie f s u r v e y of t h e e x t e n s i v e work per forme3 dur ing t h e s e p a s t y e a r s o n t h e r e m a r k a b l e a g e n t w h i c h is now known as “ t h e n e r v e growth f a c t o r ” , o r more si.mply a s t h e N.G.F. I n 1918, E l m e r B u e k e r r e p o r t e d i n t h e A n a t o w i c a l Records o n t h e r e s u l t s of a bold and i m a g i n a t i v e e x p e r i m e n t h e h a d per formed i n t h e c h i c k embryo. T h e e x p e r i m e n t c o n s i s t e d of t h e i m p l a n t a t i o n of a f r a g m e n t of m o u s e s a r c o m a 180 i n t o t h e body w a l l of t h r e e d a y c h i c k embryos . T h e e x p e r i m e n t w a s performed i n order t o see w h e t h e r r a p i d l y growing t i s s u e s s u c h a s t h i s t y p e of s a r c o m a would p r o v i d e a s u i t a b l e f ie ld for motor a n d s e n s o r y f i b e r s emerging from t h e a d j a c e n t s p i n a l c o r d a n d s e n s o r y g a n g l i a . T h e e m b r y o s b e a r i n g t h e t r a n s p l a n t w e r e s a c i f i c e d f i v e d a y s la te r . I t w a s found t h a t s e n s o r y , bu t no motor f i b e r s h a d b r a n c h e d i n t o t h e tumor a n d a t t h e s ame t i m e t h e g a n l i a provid ing for t h e i n n e r v a t i o n of t h e n e o p l a s t i c t i s s u e app e a r e d a b o u t 33 p e r c e n t l a r g e r t h a n c o n t r a l a t e r a l g a n g l i a . T h e a u t h o r c o n c l u d e d t h a t “ s a r c o m a 180 t r a n s p l a n t s w e r e r e s p o n s i b l e for t h e hyper t rophy a n d h y p e r l a s i a o b s e r v e d i n t h e l u m b o s a c r a l g a n g l i a bec a u s e of i n t r i n s i c p h y s j c o c h e m i c a l p r o p e r t i e s a n d m e c h a n i c s of growth. ”I In a more e x t e n s i v e a n a l y s i s of t h i s phenomenon by t h e same a u t h o r

Multiple sclerosis patients express increased levels of β-nerve growth factor in cerebrospinal fluid

We describe the measurement of beta-nerve growth factor (NGF) content in cerebrospinal fluid (CSF) from multiple sclerosis (MS) patients compared with CSF from age-matched normal subjects using a specific sandwich immunoassay (ELISA). During acute attacks patients exhibit a significant increase of NGF content compared to controls. In contrast during remission the mean NGF levels in CSF markedly decrease. These results strongly indicate that increased NGF production in CSF is a characteristic feature of the MS inflammatory response.

Nerve growth factor control of neuronal expression of angiogenetic and vasoactive factors

In postnatal tissues, angiogenesis occurs in nontumoral conditions on appropriate stimuli. In the nervous tissue, hypoxia, neural graft, increased neural function, and synaptic activity are associated with neoangiogenesis. We have investigated the occurrence of neoangiogenesis in the superior cervical ganglia (scg) of newborn rats treated for 8–21 days with 6-hydroxy-dopamine (6-OHDA), nerve growth factor (NGF), or 6-OHDA + NGF. The two latter treatments induced a significant increase in scg size. However, the increase after combined treatment far exceeded that of NGF alone. Similarly, histological and histochemical analysis revealed neuronal hypertrophy and endothelial cell hyperplasia associated with stromal hypertrophy (as described by laminin immunostaining) and increased vascular bed (as revealed by platelet/endothelial cell adhesion molecule-1 immunostaining) in 6-OHDA + NGF-treated pups. NGF, either alone or associated with 6-OHDA, also induced a significant up-regulation of NADPH diaphorase, neuronal nitric oxide synthase, and vascular endothelial growth factor expression in scg neurons. The present investigation suggests that the increase of scg size induced by NGF and 6-OHDA + NGF is associated with neoangiogenesis, and that the induction of vasoactive and angiogenic factors in neurons represents a further and previously undisclosed effect of NGF.

Experimental and clinical evidence of neuroprotection by nerve growth factor eye drops: Implications for glaucoma

Elevated intraocular pressure (IOP) in glaucoma causes loss of retinal ganglion cells (RGCs) and damage to the optic nerve. Although IOP is controlled pharmacologically, no treatment is available to restore retinal and optic nerve function. We evaluated the effects of NGF eye drops in a rat model of glaucoma. We also treated 3 patients with progressive visual field defects despite IOP control. Glaucoma was induced in rats through injection of hypertonic saline into the episcleral vein. Initially, 2 doses of NGF (100 and 200 μg/mL) were tested on 24 rats, and the higher dose was found to be more effective. Glaucoma was then induced in an additional 36 rats: half untreated and half treated with 200 μg/mL NGF QID for 7 weeks. Apoptosis/survival of RGCs was evaluated by histological, biochemical, and molecular analysis. Three patients with advanced glaucoma underwent psychofunctional and electrofunctional tests at baseline, after 3 months of NGF eye drops, and after 3 months of follow-up. Seven weeks of elevated IOP caused RGC degeneration resulting in 40% cell death. Significantly less RGC loss was observed with NGF treatment (2,530 ± 121 vs. 1,850 ± 156 RGCs/mm2) associated with inhibition of cell death by apoptosis. Patients treated with NGF demonstrated long lasting improvements in visual field, optic nerve function, contrast sensitivity, and visual acuity. NGF exerted neuroprotective effects, inhibiting apoptosis of RGCs in animals with glaucoma. In 3 patients with advanced glaucoma, treatment with topical NGF improved all parameters of visual function. These results may open therapeutic perspectives for glaucoma and other neurodegenerative diseases.

The nerve growth factor: its role in growth, differentiation and function of the sympathetic adrenergic neuron.

Publisher Summary This chapter discusses the role of nerve growth factor (NGF) in the growth, differentiation, and function of the sympathetic adrenergic neuron. In the course of the divergence of cell lineages among the 10-12 billions of nerve cells that build the vertebrate nervous system, the sympathetic nerve cell is the first to acquire structural and biochemical differentiative marks. In the 3-day chick embryo or in the 6-week, 1-cm-long human embryo, two thin bands of undifferentiated cells migrate from their site of origin, the neural crest, and move along the sides of the diminutive, still open, neural tube into the underlying mesenchymal tissue. A few of these cells assemble as two strands and segregate from other neural crest derivatives, which give origin to sensory neurons, neural supporting elements, pigment, cartilage, and connective tissue. The two cellular strands consist of loosely packed cells with no differentiating marks designated as the primary sympathetic trunks. They segregate, in turn, into two components: one of these moves in a dorsolateral direction and gives rise to the segmentally arranged paravertebral ganglia, which settle in close apposition to the motor roots of spinal nerves; and the other migrates in a ventromedial direction in the pre-aortal region and forms the prevertebral sympathetic ganglia, which extend from the thoracic to the pelvic region.

Nerve Growth Factor and Autoimmune Diseases

The initiation of a humoral immune response to a foreign antigen is a complex biologic process involving the interaction of many cell types and their secreted products. Autoimmune diseases, which are characterized by an abnormal activation of the immune system, probably result from the failure of normal self-tolerance mechanisms. The etiology of such illnesses, however, is far from being understood. While there have been extensive studies on the participation of the immune and endocrine systems in autoimmune diseases, few have dealt with nervous system-mediated immunoregulation in such situations. Evidence continues to grow suggesting that nerve growth factor (NGF), first identified for its activity in promoting the growth and differentiation of sensory and sympathetic neurons, may exert a modulatory role on neuroimmunoendocrine functions of vital importance in the regulation of homeostatic processes. Newly detected NGF-responsive cells belong to the hemopoietic-immune system and to populations in the brain involved in neuroendocrine functions. NGF levels are elevated in a number of autoimmune states, along with increased accumulation of mast cells. NGF and mast cells both appear to be involved in neuroimmune interactions and tissue inflammation. Moreover, mast cells themselves synthesize, store, and release NGF, proposing that alterations in normal mast cell behaviors may provoke maladaptive neuroimmune tissue responses whose consequences could have profound implications in inflammatory disease states, including those of an autoimmune nature. This review focuses on these cellular events and presents a working model which attempts to explain the close interrelationships of the neuroendocrinoimmune triade via a modulatory action of NGF.

A proposed autacoid mechanism controlling mastocyte behaviour

Evidence is provided here supporting the existence of a novel autacoid mechanism negatively modulating mast cell behaviour in response to noxious stimuliin vivo; hence, the denomination “autacoid local inflammation antagonism” (ALIA). In particular, as lipid amides of theN-acylethanolamine type have been reported to accumulate in tissues in degenerative inflammatory conditions, we examined whether theseN-acylated lipids could exert regulatory effects on mast cell activationin vivo. The results reported show that both long- and short-chainN-acylethanolamines, when systemically administered, are effective in reducing mast cell degranulation induced by local injection of substance P in the earpinna of developing rats. These and other data suggest that the endogenous production ofN-acylethanolamines may constitute a local autocrine/paracrine response for the negative feedback control of mast cell responses to various activating signals. Such a process may be of physio-pathological relevance in the regulation of functional neuroimmune-mast cell interactions.

Analysis of the effects of the antiserum to the nerve growth factor in adult mice.

Abstract The effect of the nerve growth factor antiserum (NGF-AS) on adult mice has been studied at morphological and biochemical levels. A 5-day treatment of 3-month-old mice results in a marked volume reduction of sympathetic chain ganglia. This decrease in volume appears to be due in part to cell death, but to a major extent to atrophy of residual neurons. A severe impairment of the sympathetic function also obtains, as indicated by a marked decrease of catecholamine uptake and content in peripheral organs. A few weeks after the end of treatment, a gradual and progressive recovery of the sympathetic function ensues, and the nerve cells regain their normal appearance. These results are described in connection with the problem of the site of action of NGF antibodies in immature and in fully differentiated sympathetic neurons.