Effect of dibutyryl cyclic AMP and isoproterenol on 7β-hydroxycholesterol cytotoxicity and esterification in spontaneous transformed cell lines derived from astrocyte primary cultures

AbstractIncubation of spontaneous transformed cells derived from astrocyte primary cultures with 30 μM 7β-hydroxycholesterol (7β-OH-CH) which is lethal to the cells or with 150 μM isoproterenol reduces the intracellular level of cAMP (4- and 2-fold respectively). Treatment of the cultures with 0.5 mM dibutyryl (db)-cAMP and 7β-OH-CH increases 3-fold the intracellular level of cAMP and both, db-cAMP and isoproterenol, raise the lethal effect of 7β-OH-CH and its esterification on C-3-OH by naturally occurring fatty acids (metabolite). Kinetics studies of net steryl-3-esters hydrolysis revealed that db-cAMP and isoproterenol lower that of cholesteryl-3-esters (2-fold) whereas the opposite is found for the metabolite. These data demonstrate that (i) high cAMP intracellular levels modulate differently the net hydrolysis of cholesteryl-3-esters and metabolite, (ii) isoproterenol acts otherwise than cAMP on 7β-OH-CH esterification, (iii) the cytotoxicity of 7β-OH-CH is linked to its own esterification. The accumulation of metabolite subsequent to db-cAMP or isoproterenol treatment as a result of acyl-CoA:cholesterol acyl transferase activation is discussed

Implications du pyruvate dans le métabolisme de lignées astrocytaires spinales spontanément transformées

MONTPELLIER-BU Médecine UPM (341722108) / SudocPARIS-BIUP (751062107) / SudocMONTPELLIER-BU Médecine (341722104) / SudocSudocFranceF

NEW PHOSPHORUS CONTAINING HETEROCYCLIC COMPOUNDS, SUGAR ANALOGUES, AND COMPOSITIONS HAVING ANTI-CANCER ACTIVITY CONTAINING THE SAME

The invention provides new anticancer compounds of formula (1) such as defined in the present description. The invention also provides pharmaceutical compositions to be used in human or veterinary medicine, comprising at least one compound of formula (1). The present invention further relates to a compound of formula (1) such as defined in the present description, for use as a drug. The invention further relates to the use of a compound of formula (1) for manufacturing a human or animal anticancer pharmaceutical composition

Salicylate enables cochlear arachidonic-acid-sensitive NMDA receptor responses.

International audienceCurrently, many millions of people treated for various ailments receive high doses of salicylate. Consequently, understanding the mechanisms by which salicylate induces tinnitus is an important issue for the research community. Behavioral testing in rats have shown that tinnitus induced by salicylate or mefenamate (both cyclooxygenase blockers) are mediated by cochlear NMDA receptors. Here we report that the synapses between the sensory inner hair cells and the dendrites of the cochlear spiral ganglion neurons express NMDA receptors. Patch-clamp recordings and two-photon calcium imaging demonstrated that salicylate and arachidonate (a substrate of cyclooxygenase) enabled the calcium flux and the neural excitatory effects of NMDA on cochlear spiral ganglion neurons. Salicylate also increased the arachidonate content of the whole cochlea in vivo. Single-unit recordings of auditory nerve fibers in adult guinea pig confirmed the neural excitatory effect of salicylate and the blockade of this effect by NMDA antagonist. These results suggest that salicylate inhibits cochlear cyclooxygenase, which increased levels of arachidonate. The increased levels of arachidonate then act on NMDA receptors to enable NMDA responses to glutamate that inner hair cells spontaneously release. This new pharmacological profile of salicylate provides a molecular mechanism for the generation of tinnitus at the periphery of the auditory system

NKCC1 Phosphorylation Stimulates Neurite Growth of Injured Adult Sensory Neurons: NKCC1 and regenerative growth

Peripheral nerve section promotes regenerative, elongated neuritic growth of adult sensory neurons. While the role of chloride homeostasis, through the regulation of ionotropic GABA receptors, in the growth status of immature neurons in the central nervous system begins to emerge, nothing is known of its role in the regenerative growth of injured adult neurons. To analyze the intracellular Cl- variation following a sciatic nerve section in vivo, gramicidin perforated-patch recordings were used to study muscimol-induced currents in mice dorsal root ganglion neurons isolated from control and axotomized neurons. We show that the reversal potential of muscimol-induced current, EGABA-A was shifted towards depolarized potentials in axotomized neurons. This was due to Cl- influx since removal of extracellular Cl- prevented this shift. Application of bumetanide, an inhibitor of NKCC1 cotransporter and EGABA-A recordings in sensory neurons from NKCC1-/- mice, identified NKCC1 as being responsible for the increase in intracellular Cl- in axotomized neurons. In addition, we demonstrate with a phospho-NKCC1 antibody that nerve injury induces an increase in the phosphorylated form of NKCC1 in dorsal root ganglia that could account for intracellular Cl- accumulation. Time-lapse recordings of the neuritic growth of axotomized neurons show a faster growth velocity in comparison with control. Both bumetanide, the intrathecal injection of NKCC1 siRNA and the use of NKCC1-/- mice demonstrated that NKCC1 is involved in determining the velocity of elongated growth of axotomized neurons. Our results clearly show that NKCC1-induced increase in intracellular chloride concentration is a major event accompanying peripheral nerve regeneration

Pyruvate modifies glycolytic and oxidative metabolism of rat embryonic spinal cord astrocyte cell lines and prevents their spontaneous transformation.

This study aimed to provide detailed data on mitochondrial respiration of normal astrocyte cell lines derived from rat embryonic spinal cord. Astrocytes in early passages (EP), cultured without pyruvate for more than 35 passages, defined here as late passages (LP), undergo spontaneous transformation. To study initial steps in cell transformation, EP data were compared with those of LP cells. LP cells had reduced glycolysis, fewer mitochondria and extremely low oxidative rates, resulting from a dysfunction of complexes I and II + III of the respiratory chain. Treatment of EP cells with pyruvate until they were, by definition, LP cultures prevented transformation of these cells. Pyruvate-treated EP cells had more mitochondria than normal cells but slightly lower respiratory rates. The increase of mitochondrial content thus appears to act as a compensatory effect to maintain oxidative phosphorylation in these LP 'non-transformed' cells, in which mitochondrial function is reduced. However, pyruvate treatment of transformed LP cells during additional passages did not significantly restore their oxidative metabolism. These data highlight changes accompanying spontaneous astrocyte transformation and suggest potential targets for the control of astrocyte proliferation and reaction to various insults to the central nervous system