formazans and Nerve-Degeneration

Progressive degeneration and intraneuronal Lewy bodies made of filamentous alpha-synuclein (alpha-syn) in dopaminergic cells of the nigrostriatal system are characteristics of Parkinson's disease (PD). Glucose uptake is reduced in some of the brain regions affected by PD neurodegenerative changes. Defects in mitochondrial activity in the substantia nigra have been observed in the brain of patients affected by PD and substantia nigra lesions can induce the onset of a secondary parkinsonism. Thus, energy starvation and consequently metabolic impairment to dopaminergic neurons may be related to the onset of PD. On this line, we evaluated the effect of nutrient starvation, reproduced 'in vitro' by glucose deprivation (GD), in primary mesecephalic neuronal cultures and dopaminergic-differentiated SH-SY5Y cells, to evaluate if decreased glucose support to dopaminergic cells can lead to mitochondrial damage, neurodegeneration and alpha-syn misfolding. Furthermore, we investigated the effect of dopamine (DA) treatment in the presence of a DA-uptake inhibitor or of the D(2)/D(3) receptor (D(2)R/D(3)R) agonist quinpirole on GD-treated cells, to evaluate the efficacy of these therapeutic compounds. We found that GD induced the formation of fibrillary aggregated alpha-syn inclusions containing the DA transporter in dopaminergic cells. These alterations were accompanied by dopaminergic cell death and were exacerbated by DA overload. Conversely, the block of DA uptake and D(2)R/D(3)R agonist treatment exerted neuroprotective effects. These data indicate that glucose starvation is likely involved in the induction of PD-related pathological changes in dopaminergic neurons. These changes may be counteracted by the block of DA uptake and by dopaminergic agonist treatment.

Topics: alpha-Synuclein; Analysis of Variance; Animals; Benzothiazoles; Cell Death; Cells, Cultured; Dopamine; Dopamine Agents; Dopamine Plasma Membrane Transport Proteins; Embryo, Mammalian; Formazans; Gene Expression Regulation; Glucose; Mesencephalon; Mice; Mitochondria; Nerve Degeneration; Nerve Tissue Proteins; Neurons; Protein Transport; Receptors, Dopamine D2; Tetrazolium Salts; Thiazoles

The effect of partially obstructing the urethra on the nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) activity in neurons of the intramural ganglia of the monkey (Macaca fascicularis) bladder was examined by light and electron microscopy. Partial urethral ligation was done in adult male monkeys. The animals were sacrificed 2, 4 weeks after partial urethral obstruction. This was compared to controls (normal and sham operated). Urethral obstructed animals were observed to have increased urinary frequency and decreased urinary flow rate. Two weeks after urethral obstruction, the overall NADPH-d activity in the intramural ganglia of the bladder base was enhanced compared to control animals. The frequency of intensely stained NADPH-d positive neurons was increased compared to the control animals. About one-third of intensely stained NADPH-d positive neurons appeared to undergo degenerative changes. At 4 weeks after urethral obstruction, a wide occurrence of NADPH-d positive neurons in advanced stages of degeneration in the bladder base was observed. Cellular debris was strewn among normal looking ganglion cells and along the nerve processes. The proportion of intensely stained NADPH-d positive neurons was relatively lower than the controls. The total number of NADPH-d positive neurons and the nerve fibres in the entire bladder was significantly reduced when compared to control animals. Electron microscopy showed some NADPH-d activity in intramural ganglion cells in 2 weeks after partial urethral obstruction. NADPH-d reaction product (formazan) was deposited on the membranes of the rough endoplasmic reticulum, and the outer membranes of some mitochondria in the intramural neuron. At 4 weeks after urethral obstruction, NADPH-d was present in the membrane of the mitochondria and some mitochondria appeared swollen with disrupted cristae. Present results show that NADPH-d activity in neurons of the intramural ganglia of the monkey (Macaca fascicularis) urinary bladder was increased after two weeks and reduced after 4 weeks of partial urethral obstruction. It is speculated that the increased NADPH-d activity associated with partial urethral obstruction would lead to neuronal damage and death, which may contribute to detrusor overactivity. However, it warrants further investigation to understand the mechanism of neuronal cell death after partial urethral obstruction.

Topics: Animals; Cell Count; Cell Death; Endoplasmic Reticulum, Rough; Enzyme Activation; Formazans; Ganglia; Histocytochemistry; Macaca fascicularis; Male; Microscopy; Microscopy, Electron; Mitochondrial Membranes; NADPH Dehydrogenase; Nerve Degeneration; Neuronal Plasticity; Neurons; Urethral Obstruction; Urinary Bladder

1 Two cannabinoid receptors, CB1 and CB2, have been identified. The CB1 receptor is preferentially expressed in brain, and the CB2 receptor in cells of leukocyte lineage. We identified the mRNA for the CB1 receptor in human neuroblastoma SH-SY5Y cells, and the mRNA and protein for the CB2 receptor in human microglia and THP-1 cells. 2 Delta(9)-and Delta(8)-tetrahydrocannabinol (THC) were toxic when added directly to SH-SY5Y neuroblastoma cells. The toxicity of Delta(9)- THC was inhibited by the CB1 receptor antagonist SR141716A but not by the CB2 receptor antagonist SR144528. The endogenous ligand anandamide was also toxic, and this toxicity was enhanced by inhibitors of its enzymatic hydrolysis. 3 The selective CB2 receptor ligands JWH-015 and indomethacin morpholinylamide (BML-190), when added to THP-1 cells before stimulation with lipopolysaccharide (LPS) and IFN-gamma, reduced the toxicity of their culture supernatants to SH-SY5Y cells. JWH-015 was more effective against neurotoxicity of human microglia than THP-1 cells. The antineurotoxic activity of JWH-015 was blocked by the selective CB2 receptor antagonist SR144528, but not by the CB1 receptor antagonist SR141716A. This activity of JWH-015 was synergistic with that of the 5-lipoxygenase (5-LOX) inhibitor REV 5901. 4 Cannabinoids inhibited secretion of IL-1beta and tumor necrosis factor-alpha (TNF-alpha) by stimulated THP-1 cells, but these effects could not be directly correlated with their antineurotoxic activity. 5 Specific CB2 receptor ligands could be useful anti-inflammatory agents, while avoiding the neurotoxic and psychoactive effects of CB1 receptor ligands such as Delta(9)-THC.

Topics: Astrocytes; Camphanes; Cannabinoid Receptor Modulators; Cannabinoids; Cell Line; Cytokines; Dronabinol; Formazans; Gene Expression; Humans; Indoles; Indomethacin; L-Lactate Dehydrogenase; Ligands; Microglia; Monocytes; Morpholines; Nerve Degeneration; Neurotoxicity Syndromes; Piperidines; Pyrazoles; Receptor, Cannabinoid, CB1; Receptor, Cannabinoid, CB2; Reverse Transcriptase Polymerase Chain Reaction; Rimonabant; RNA, Messenger; Temporal Lobe; Tetrazolium Salts