The proteomic analysis of mouse choroid plexus secretome reveals a high protein secretion capacity of choroidal epithelial cells.

Choroid plexuses (CP) are involved in multiple functions related to their unique architecture and localization at the interface between the blood and cerebrospinal fluid compartments. These include the release by choroidal epithelial cells (CEC) of biologically active molecules, such as polypeptides, which are distributed globally to the brain. Here, we have used a proteomic approach to get an unbiased overview of the proteins that are secreted by primary cultures enriched in epithelial cells from mice CP.

Neuroprotective activity of antazoline against neuronal damage induced by limbic status epilepticus.

Imidazoline drugs exert neuroprotective effects in cerebral ischaemia models. They also have effects against mouse cerebellar and striatal neuronal death induced by N-methyl-D-aspartate (NMDA) through the blockade of NMDA currents. Here, we investigated the effects of antazoline on NMDA toxicity and current in rat hippocampal neuronal cultures, and on an in vivo model of status epilepticus.

Proteomic analysis of astrocytic secretion in the mouse. Comparison with the cerebrospinal fluid proteome.

Astrocytes, the most abundant cell type in the central nervous system, are intimately associated with synapses. They play a pivotal role in neuronal survival and the brain inflammatory response. Some astrocytic functions are mediated by the secretion of polypeptides.

Inhibition of voltage-gated Ca2+ channels by antazoline.

We showed recently that imidazolines exert neuroprotection against hypoxia and NMDA toxicity in cerebellar and striatal neuronal cultures, through a voltage-dependent blockade of glutamatergic NMDA receptors. Here, we report that in striatal neuronal cultures from mouse embryos the imidazoline compound, antazoline, inhibits voltage-gated Ca2+ channels by acting at a phencyclidine-like site. This effect was fast, fully reversible, voltage-dependent and predominant on P/Q- and N-type Ca2+ channels.

Akt mediates the anti-apoptotic effect of NMDA but not that induced by potassium depolarization in cultured cerebellar granule cells.

Apoptosis of cultured cerebellar granule neurons (CGNs) deprived of serum is prevented by K+ depolarization or moderate concentrations of N-methyl-d-aspartate (NMDA). Here, we have examined the role of the serine/threonine kinase Akt in these protective effects. The exposure of mouse CGNs to NMDA or K+ depolarization increased the phosphorylation of Akt, compared with that measured in cells incubated in a physiological K+ concentration.

Imidazoline-induced neuroprotective effects result from blockade of NMDA receptor channels in neuronal cultures.

Imidazolines have been shown to be neuroprotective in focal and global ischemia in the rat. However, their mechanism of action is still unclear. We have studied the neuroprotective effects of imidazolines against NMDA-induced neuronal death and hypoxic insult in cerebellar and striatal neuronal cultures.

mGluR7-like receptor and GABA(B) receptor activation enhance neurotoxic effects of N-methyl-D-aspartate in cultured mouse striatal GABAergic neurones.

Presynaptic metabotropic glutamate receptors (mGluRs) of group III constitute possible targets for putative neuroprotective drugs acting against glutamate excitotoxic insults. Indeed, in glutamatergic cerebellar granule neurones in culture, high concentrations of L-2-amino-4-phosphonobutyrate (L-AP4, above 0.3 mM, thus activating mGluR7) inhibit NMDA-induced cell death.

mGluR7-like metabotropic glutamate receptors inhibit NMDA-mediated excitotoxicity in cultured mouse cerebellar granule neurons.

Glutamate-induced glutamate release may be involved in the delayed neuronal death induced by N-methyl-D-aspartate (NMDA). In order to examine a possible modulatory effect of the presynaptic group III mGluRs on glutamate excitotoxicity, the effect of L-2-amino-4-phosphonobutyrate (L-AP4) was examined on NMDA-induced delayed death of mouse cerebellar granule neurons in culture. We found that L-AP4, at high concentration (in the millimolar range), inhibited in a non-competitive manner the NMDA-induced toxicity.

Different routes of Ca2+ influx in NMDA-mediated generation of nitric oxide and arachidonic acid.

Nitric oxide and arachidonic acid act as inter- and intracellular messengers in the central nervous system. It is well known that the NMDA-mediated generation of nitric oxide and arachidonic acid is dependent on extracellular Ca2+. However, the role of voltage-dependent calcium channels (VDCCs) in this regard is poorly understood.

The CaM-kinase II inhibitor KN-62 blocks NMDA but not kainate stimulation of NO synthesis.

We have studied the effect of CaM-kinase II inhibition induced by KN-62 on NO synthesis mediated by the activation of NMDA and kainate receptors in striatal neurones. KN-62 partially inhibited NMDA-mediated NO synthesis but the effect of kainate on NO production was unaffected by the specific CaM-kinase II inhibitor. Ionomycin-induced cGMP production and the NMDA-mediated superoxide generation by nNOS were also inhibited by KN-62.

Involvement of divalent ions in the nitric oxide-induced blockade of N-methyl-D-aspartate receptors in cerebellar granule cells.

We have previously shown that nitric oxide blocks the N-methyl-D-aspartate (NMDA) receptor without affecting the agonist binding site. We now report that in cerebellar granule cells nitric oxide decreases the NMDA channel conductance and open probability, in voltage-dependent and -independent manners, respectively, by acting on an extracellular site different from the redox, glycine, and pH modulatory sites of the receptor-channel complex. This inhibition is not additive with those of Mg2+ and Zn2+.

[The role of nitric oxide and superoxides in the neurotoxicity of glutamate].

Glutamate is the major neurotransmitter of the mammalian brain. Stimulation of glutamate receptors, especially the subgroup of NMDA receptors, induces nitric oxide and arachidonic acid synthesis in neurons. These agents freely diffuse across membranes and thus can play roles of messengers in particular brain functions.

Blockade of nitric oxide synthesis by tyrosine kinase inhibitors in neurones.

In striatal neurones in culture, N-methyl-D-aspartate-(NMDA), kainate-(Kai) and K(+)-dependent cGMP production is entirely mediated via nitric oxide (NO). Low concentrations of lavendustin-A (< or = 0.3 microM), a highly specific tyrosine kinase inhibitor, reduced irreversibly and in a time-dependent manner NMDA-stimulated cGMP production.

Glutamate receptors induce a burst of superoxide via activation of nitric oxide synthase in arginine-depleted neurons.

We have previously shown in cultured cerebellar granule neurons (Lafon-Cazal, M., Pietri, S., Culcasi, M.

Nitric oxide, superoxide and peroxynitrite: putative mediators of NMDA-induced cell death in cerebellar granule cells.

In this study, we analysed the implication of superoxide (O2-.) and nitric oxide (NO.) free radicals and their resulting product peroxynitrite (ONOO-) in the neuronal death induced by the activation of the glutamatergic receptor of the N-methyl-D-aspartate (NMDA) subtype using cultured cerebellar granule cells.

NMDA-dependent superoxide production and neurotoxicity.

Neuronal injury resulting from acute brain insults and some neurodegenerative diseases implicates N-methyl-D-aspartate (NMDA) glutamate receptors. The fact that antioxidants reduce some types of brain damage suggests that oxygen radicals may have a role. It has been shown that mutations in Cu/Zn-superoxide dismutase (SOD), an enzyme catalysing superoxide (O2.

Non-classical glutamate receptors, blocked by both NMDA and non-NMDA antagonists, stimulate nitric oxide production in neurons.

In striatal neurons in primary culture, kainate and domoate stimulated cGMP production, whereas two other analogs of glutamate which act at non-NMDA receptors, alpha-amino-3-hydroxy-5-methyl-isoxazole-4-propionate (AMPA) and quisqualate were ineffective. However, both agonists stimulated cGMP accumulation on neurons pretreated with concanavalin A, a lectin which is known to prevent desensitization of AMPA receptors. We show here that such a treatment also potentiated the kainate-stimulated cGMP production.

Measurement of gamma-enolase release, a new method for selective quantification of neurotoxicity independently from glial lysis.

We have developed a sensitive enzymatic-immunoassay to quantify the level of gamma-enolase (a specific neuronal enzyme) which is released from cultured cells after exposure to various toxins. We show that this method can estimate selectively neuronal cell death without significantly interfering with glial cell death. Indeed, no gamma-enolase is released when glial cells are killed with free-radical producing agents.

A nitric oxide (NO) synthase inhibitor accelerates amygdala kindling.

In response to NMDA receptor activation, hippocampal, striatal and cerebellar neurons synthesize nitric oxide (NO), which in turn elevates cGMP levels via guanylate cyclase. NO is increasingly being considered as a transsynaptic retrograde messenger, involved in neuronal plasticity. The effect of an inhibitor of NO synthase, L-NG-nitroarginine (NOArg), was studied on amygdala kindling and on kindled seizures in rats.

A Nitric Oxide Synthase Activity Selectively Stimulated by NMDA Receptors Depends on Protein Kinase C Activation in Mouse Striatal Neurons.

In mouse striatal neurons in primary culture, the maximal increase in intracellular cyclic guanosine monophosphate level evoked by N-methyl-d-aspartic acid (NMDA) receptor activation was twice that induced by kainate, KCl and ionomycin. Quisqualate was almost inactive. All responses were mediated by nitric oxide (NO) production since they were blocked by haemoglobin (a NO scavenger) and by l-NG-monomethylarginine and l-NG-nitroarginine, the effects of both arginine analogues being reversed by an excess of l-arginine.

Pharmacological characterization of octopamine-sensitive adenylate cyclase in the flight muscle of Locusta migratoria L.

Octopamine stimulates (20-30-fold) the adenylate cyclase activity in a broken cell preparation of locust flight muscle. This stimulation is mediated by one receptor with an apparent affinity of 3.3 X 10(-6) M.

In vitro occurrence of m-octopamine in the cultured cephalic ganglion of Locusta migratoria L. after L-dopa administration.

Cephalic ganglia of the locust Locusta migratoria L. were cultured in the presence of L-DOPA and inhibitors of dopa decarboxylase or dopamine beta hydroxylase. The addition of L-DOPA to the culture medium resulted in a marked increase of m-octopamine, following higher levels of dopamine.

[Neuroendocrine control of blood lipids in the locust, Locusta migratoria].

In order to determine the best conditions, the influence of various parameters on the haemolymph lipid concentration were studied. These parameters are the age, the sex and the feeding of the animals, the time and the number of the haemolymph sample-taking and the temperature of the locust culture. A large in vivo increase in haemolymph lipid concentration was obtained in locusts which received extracts of the whole CC and of their glandular or neurohemal lobes.

[Presence of substances immunoreactively related to enkephalin in an insect, Locusta migratoria].

Application of specific radioimmunoassays to various extracts of the locust showed that nervous tissues and specially the optic lobes contain enkephaline-like material. However these immunoreactive substances present an apparent higher molecular weight (700--1 000 dalton) than those of the controls, as tested by chromatography on Sephadex G 25.