ABSTRACT
The study was aimed at investigating in vivo and in vitro the involvement of the cGMP/cGMP-dependent protein kinase (PKG) signaling pathway in MPP(+)-induced cytosolic phospholipase A(2) (cPLA(2)) activation of dopaminergic neurons. MPP(+) activated neuronal nitric oxide synthase (NOS)/soluble guanylyl cyclase/cGMP pathway in mouse midbrain and striatum, and in pheochromocytoma cell line 12 cells, and caused an upward shift in [Ca(2+)](i) level in the latter. The activation was accompanied by increases in total and phosphorylated cPLA(2), and increased arachidonic acid release. Effects of selective inhibitors [2-oxo-1,1,1-trifluoro-6,9-12,15-heneicosatetraene (AACOCF(3)), (E)-6-(bromomethylene)tetrahydro-3-(1-naphthalenyl)2h-pyran-2-one (BEL)] indicated the main impact of cPLA(2) on arachidonic acid release in pheochromocytoma cell line 12 cells. Treatment of the cells with the protein kinase inhibitors GF102610x, UO126, and KT5823, and with the nitric oxide synthase (NOS) inhibitor NNLA revealed the involvement of protein kinase C (PKC) and extracellular signal-regulated kinases 1 and 2 (ERK 1/2), with the possible key role of PKG, in cPLA(2) phosphorylation at Ser505. Inhibitors of cPLA(2) and PKG increased viability and reduced MPP(+)-induced apoptosis of the cells. Our results indicate that the neuronal NOS/cGMP/PKG pathway stimulates cPLA(2) phosphorylation at Ser505 by activating PKC and ERK1/2, and suggest that up-regulation of this pathway in experimental models of Parkinson's disease may mediate dopaminergic neuron degeneration and death through activation of cPLA(2).
Subject(s)
Arachidonic Acid/metabolism , Cyclic GMP-Dependent Protein Kinases/metabolism , Nerve Degeneration/enzymology , Parkinsonian Disorders/enzymology , Phospholipases A2, Cytosolic/metabolism , Substantia Nigra/enzymology , Animals , Calcium/metabolism , Catalytic Domain/drug effects , Catalytic Domain/physiology , Cell Death/drug effects , Cell Death/physiology , Cyclic GMP/metabolism , Cyclic GMP-Dependent Protein Kinases/antagonists & inhibitors , Enzyme Activation/drug effects , Enzyme Activation/physiology , Enzyme Inhibitors/pharmacology , Extracellular Signal-Regulated MAP Kinases/antagonists & inhibitors , Extracellular Signal-Regulated MAP Kinases/metabolism , In Vitro Techniques , Mice , Mice, Inbred C57BL , Models, Biological , Nerve Degeneration/chemically induced , Nerve Degeneration/physiopathology , Nitric Oxide Synthase Type I/drug effects , Nitric Oxide Synthase Type I/metabolism , PC12 Cells , Parkinsonian Disorders/physiopathology , Phospholipases A2, Cytosolic/antagonists & inhibitors , Protein Kinase C/antagonists & inhibitors , Protein Kinase C/metabolism , Rats , Serine/metabolism , Signal Transduction/drug effects , Signal Transduction/physiology , Substantia Nigra/drug effects , Substantia Nigra/physiopathologyABSTRACT
The aim of the present study was to examine the differences in fat oxidation between endurance trained (ET) and untrained (UT) women. Eight ET and nine UT women performed a progressive cycle ergometer test until exhaustion. The rate of fat oxidation was similar at low work rates (Subject(s)
Lipid Metabolism/physiology
, Physical Endurance/physiology
, Physical Fitness/physiology
, Acyl-CoA Dehydrogenases/blood
, Adult
, Body Composition/physiology
, Citrate (si)-Synthase/blood
, Exercise Test
, Female
, Glycogen/metabolism
, Humans
, Kinetics
, Lipase/blood
, Muscle Fibers, Skeletal/physiology
, Muscle, Skeletal/cytology
, Muscle, Skeletal/metabolism
, Muscle, Skeletal/physiology
, Oxidation-Reduction
, Oxygen Consumption/physiology
, Pulmonary Gas Exchange/physiology
