Nonneuronal cells mediate neurotrophic action of vasoactive intestinal peptide.

Abstract

Abstract. The developmental regulation of neuronal survival by vasoactive intestinal peptide (VIP) was investigated in dissociated spinal cord-dorsal root ganglion (SC-DRG) cultures. Previous studies demonstrated that VIP increased neuronal survival in SC-DRG cultures when synaptic transmission was blocked with tetrodotoxin (TTX). This effect was further investigated to determine if VIP acted directly on neurons or via nonneuronal cells. For these studies, SC-DRG cells were cultured under conditions designed to provide preparations enriched for a particular cell type: astrocyte-enriched background cell (BG) cultures, meningeal fibroblast cultures, standard mixed neuron-nonneuron (STD) cultures, and neuronenriched (N) cultures. Addition of 0.1 nM VIP to TTX-treated STD cultures for 5 d prevented the TTXmediated death and the death that occurred naturally during development in culture, whereas the same treatment on N cultures did not prevent neuronal cell death. Conditioned medium from VIP-stimulated BG cultures prevented neuronal cell death when added to the medium (10 % of total volume) of N cultures treated with TTX. The same amount of conditioned medium from BG cultures that were not treated with VIP had no protective action on N cultures. Conditioned medium from N or meningeal fibroblast cultures, either with or without VIP treatment, did not prevent TTX-mediated cell death in N test cultures. These data indicate that VIP increases the availability of neurotrophic survival-promoting substances derived from nonneuronal cultures, the most likely source being astroglial cells. This study suggests that VIP has a role in mediating a neuron-glia-neuron interaction that influences the trophic regulation of neuronal survival.N 'EtJRO~AL cell death is characteristic of most developing neural systems in vertebrates. The extent (30-80%) of neuronal death that occurs during development indicates that the regulation of this process is of fundamental importance to the determination of nervous system structure (see Berg, 1982). Although a great deal of descriptive data has been reported concerning the magnitude and ubiquity of this neuronal cell loss, little is known of the mechanism that regulates the process during development. It is clear that electrical activity plays an important role in determining neuronal survival during this regressive phase of development. For example, blockage of electrical activity with ~t-bungarotoxin attenuates the naturally occuring cell death in spinal motorneurons (Pittman and Oppenheim, 1978) and in trochlear nucleus in vivo (Creazzo and Sohal, 1979).Studies with cultured spinal cord-dorsal root ganglion (SC-DRG) ~ neurons have shown that during development in 1. Abbreviations used in this paper: BG, astrocyte-enriched background; GFAP, glial fibrillary acidic protein; N, neuronal; NF, neurofilament protein; NSE, neuron-specific enolase; SC-DRG, spinal cord-dorsal root ganglion; STD, standard cultures composed of neurons and nonneuronal cells; TTX, tetrodotoxin; VIP, vasoactive intestinal ...

Effects of the Vasoactive Intestinal Peptide (VIP) and Related Peptides on Glioblastoma Cell Growth in Vitro

“…The expression of VIP-selective high-affinity binding sites in glial cells (Brenneman et al, 1987;Gozes et al, 1991), in the human glioma cell line U-343 Mgcl 2:6 (Nielsen et al, 1990), and in the human glioblastoma XF-498L (Fabry et al, 2000) has been reported previously, and it has been demonstrated that the neuroprotective effects of VIP or PACAP could be observed for very low concentrations, close to the femtomolar range (Kong et al, 1999;Offen et al, 2000). However, data from the present studies are, as far as we know, an unprecedented characterization of VIP-selective binding sites with such a very high affinity, in the femtomolar range.…”

A femtomolar-acting neuroprotective peptide.

“…2-wk old astroglial (17, 39) cultures (confluent 75-cm 2 flasks) were washed three times with PBS and conditioned medium was collected (10 ml PBS/flask) during a 3-h incubation with 0.1 nM VIP (an amount previously shown to be optimal for releasing neurotrophic activity from astroglial cells, references 18,19). The medium was centrifuged (3,000 g for 10 min) and dialyzed (3.5-kD cutoff) against 50 mM sodium phosphate buffer, pH 7.0, 4 Њ C. Neuroprotection was assayed initially in tetrodotoxin-blocked spinal cord cultures.…”

“…The ADNF secretagogue, VIP, has been shown to prevent neurotoxicity associated with the HIV envelope protein (GP120, reference 22) as well as against neurotoxicity associated with the beta amyloid peptide which is deposited in the brains of Alzheimer's disease patients (23). The mechanisms of these VIP effects are probably due to its ability to promote the secretion of neuroprotective substances from glial cells (18)(19)(20)(21). Here, we test the hypothesis that VIP's neuroprotective actions are mediated in part through ADNF.…”

“…VIP has been shown to interact with high affinity receptors present on glial cells (17), resulting in the release of survivalpromoting substances (18,19), among which are a glial-derived cytokine (IL-1-␣ references 8,20), and protease nexin I, a serine protease inhibitor (21). However, the neuronal survivalpromoting effects of the VIP-conditioned medium were observed at very low concentrations that could not be attributed to IL-1 or protease nexin I released from astroglia.…”

Le facteur trophique ADNF-9, un tout petit dans le pays des grands !.

“…contre des atteintes très variées incluant l'excitotoxicité par les analogues du glutamate et la toxicité de la protéine d'enveloppe gp120 du VIH. Brenneman avait toutefois observé il y a dix ans que cet effet du VIP n'était pas direct et passait obligatoirement par la stimulation d'astrocytes [2]. Un certain nombre de facteurs neuroprotecteurs peuvent être produits par les astrocytes mais un paramètre troublait les auteurs : l'activité neurotrophique pouvait être obtenue à l'aide de milieu conditionné astrocytaire extrêmement dilué, trop pour que des facteurs « classiques » puissent être impliqués.…”