PubMed · 6080767
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L Telivuo. 1967. [Monitoring during anesthesia].. https://pubmed.ncbi.nlm.nih.gov/6080767/
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Clinical studies have demonstrated an excess of transition metals, including zinc and iron, in the substantia nigra (SN) of Parkinson's patients. In the present study, the neurotoxic effect of zinc was investigated using iron as a positive control. Addition of zinc or iron to brain homogenates increased lipid peroxidation. Zinc was less potent than iron in inducing lipid peroxidation. Coincubation with desferrioxamine prevented zinc- and iron-induced lipid peroxidation. Furthermore, glutathione (GSH), S-nitroso-N-acetylpenicillamine, or melatonin inhibited zinc-induced lipid peroxidation. The oxidative effect of zinc was further investigated in anesthetized rats. Seven days after intranigral infusion of zinc, lipid peroxidation was elevated in the infused SN, and dopamine content and tyrosine hydroxylase-positive axons were decreased in the ipsilateral striatum. Zinc was less potent than iron in inducing neurodegeneration in vivo. L-Buthionine-[S,R]-sulfoximine pretreatment (i.c.v.), which depletes cellular GSH levels, enhanced zinc-induced oxidative injuries in the nigrostriatal dopaminergic system. Moreover, simultaneous infusion of zinc and iron appeared to augment oxidative injuries in rat brain. Taken together, our results demonstrate that intranigral infusion of zinc caused degeneration of the nigrostriatal dopaminergic system in rat brain. Furthermore, coexistence of zinc and iron augmented oxidative injuries in rat brain. These findings indicate that both zinc and iron contribute to the etiology of Parkinsonism.
Extracellular glutamate levels were measured by microdialysis in the prefrontal cortex (PFC) of anaesthetised rats in response to a short, experimenter-provoked mechanical movement of the animal head. Movement caused significant, nerve impulse-independent elevations of glutamate levels (maximum increase, 300+/-30% of baseline). This study reveals a possible artifact in the measurement of extracellular glutamate concentrations by microdialysis and suggests that, in awake animals, treatments associated with stimulation of motor activity can cause non-specific efflux of glutamate in the PFC.
In radioligand binding assays, AH-9700 (1-[2-(3,4-dihydro-6,7-dimethyl-2-naphthalenyl)ethyl]pyrrolidine fumarate) had high affinity for sigma receptors and moderate affinity for muscarinic receptors. The affinity of AH-9700 for sigma(1) receptors was significantly reduced in the presence of 5'-guanylyl-imidodiphosphate (GppNHp). In isolated bladder strips of rats, AH-9700 inhibited carbachol-induced contractions. In anesthetized rats, i.v. administration of AH-9700 and typical sigma receptor ligands, (+)-pentazocine and 1,3-di-o-tolylguanidine (DTG), but not oxybutynin, dose-dependently inhibited rhythmic isovolumetric reflex bladder contractions. AH-9700 and oxybutynin suppressed the amplitude of rhythmic bladder contractions. On the other hand, at doses lower than used i.v., the i.c.v. administration of AH-9700 or the sigma receptor ligands inhibited rhythmic bladder contractions without suppressing the amplitude. This inhibitory effect of AH-9700 was markedly reduced by pretreatment with i.c.v. pertussis toxin. These results suggest that AH-9700 exerts a marked anti-micturition reflex effect through central sigma receptors possibly related to pertussis toxin-sensitive Gi/o-proteins and a moderate spasmolytic effect based on its peripheral anti-muscarinic activity.