Effects of vinconate, a novel vinca alkaloid, on spatial learning deficits induced by the basal forebrain lesion in rats

Effects of vinconate on age-related alterations in [3H]MK-801, [3H]glycine, sodium-dependent D-[3H]aspartate, [3H]FK-506 and [3H]PN200-110 binding in rats

We investigated the effects of age and (+/-)-methyl-3-ethyl-2,3,3a,4-tetrahydro-1 H-in-dolo[3,2,1-de] [1,5] naphthyridine-6-carboxylate hydrochloride (vinconate), an indolonaphthyridine derivative, on calcium channels, neurotransmitter receptor systems and immunophilin in Fischer rat brain using quantitative receptor autoradiography. [3H]MK-801, [3H]glycine, sodium-dependent D-[3H]aspartate, [3H]FK-506 and [3H]PN200-110 were used to label N-methyl-D-aspartate (NMDA) receptors, glycine receptors, excitatory amino acid transport sites, FK-506 binding proteins (FKBP) and voltage-dependent L-type calcium channels, respectively. [3H]Glycine and sodium-dependent D-[3H]aspartate binding significantly decreased in the frontal cortex, parietal cortex, striatum, nucleus accumbens, hippocampus, thalamus, substantia nigra and cerebellum of 24 month old rats in comparison with 6 month old animals. In contrast, [3H]MK-801, [3H]FK-506 and [3H]PN200-110 binding showed no significant changes in the brain of 24 month old rats. Intraperitoneal chronic treatment with vinconate (10 and 30 mg/kg, once a day for 4 weeks) dose-dependently ameliorated the significant reduction in [3H]glycine and sodium-dependent D-[3H]aspartate binding in the brain of 24 month old rats. These results demonstrate that glycine receptors and excitatory amino acid transport sites are more susceptible to aging processes than NMDA receptors, immunophilin and voltage-dependent L-type calcium channels. Furthermore, our findings suggest that vinconate may have a beneficial effect on age-related changes in glycine receptors and excitatory amino acid transport sites.

Effects of vinconate on neurotransmitter receptor systems in aged rat brain

We investigated the effects of age and (±)-methyl-3-ethyl-2,3,3a,4-tetrahydro-1 H-indolo[3,2,1-de][1,5]naphthyridine-6-carboxylate hydrochloride (vinconate), an indolonaphthyridine derivative, on neurotransmitter receptor systems in the rat brain using quantitative receptor autoradiography. [(3)H]Quinuclidinyl benzilate (QNB), [(3)H]hemicholinium-3 (HC) and [(3)H]muscimol were used to label acetylcholine receptors, high-affinity choline uptake sites and γ-aminobutyric acid(A) (GABA(A)) receptors, respectively. [(3)H]QNB, [(3)H]HC and [(3)H]muscimol binding decreased in any brain areas of 24-month-old (aged) rats in comparison with 6-month-old (adult) animals. Chronic treatment with vinconate (10 and 30 mg/kg, i.p., once a day for 4 weeks) partly ameliorated the reduction in [(3)H]QNB, [(3)H]HC and [(3)H]muscimol biding in aged rat brains. This effect was especially noted in [(3)H]muscimol binding. The results suggest that vinconate may have beneficial effects on age-related changes in neurotransmitter receptor systems.

Effect of vinconate on the extracellular levels of dopamine and its metabolites in the rat striatum: microdialysis studies

The effects of (+/-)-methyl-3-ethyl-2,3,3 alpha, 4-tetrahydro-1H- indolo[3,2,1-de][1,5]naphthyridine-6-carboxylate hydrochloride (vinconate), an indolonaphthyridine derivative, on the extracellular levels of dopamine and its metabolites in the rat striatum were examined using brain microdialysis. Single administration of vinconate (10, 100 mg/kg i.p.) increased the extracellular level of dopamine and its metabolites. This enhancing effect of vinconate was antagonized by scopolamine (10 microM), a muscarinic receptor antagonist, which was added to the perfusate from 30 min before vinconate treatment. These findings suggest that vinconate, even when systemically administered, enhances the endogenous release of dopamine in the striatum, probably via the stimulation of presynaptic muscarinic receptors.

Involvement of brain serotonergic function in lidocaine-induced convulsions in mice

Influences of drug-induced manipulations of central serotonergic function on lidocaine- and pentylenetetrazol (PTZ)-induced convulsions were examined in mice. Agents that suppressed serotonergic transmission increased, whereas drugs that facilitated serotonin (5-HT) function decreased the incidence of lidocaine-induced convulsions. These treatments had similar influences on the incidence of PTZ-induced convulsions. Lidocaine (10(-5)-10(-3) M) reduced the stimulation evoked [3H]5-HT release from cortical slices, followed with an increased spontaneous [3H] overflow at higher concentrations. These results may suggest that brain 5-HT neurons are causally involved as inhibitory neurons in lidocaine-induced convulsions as in the case of PTZ-induced convulsions.

Effect of vinconate against regional age-related changes in the gerbil brain

We investigated age-related changes in the binding sites of muscarinic acetylcholine, forskolin, adenosine 3',5'-cyclic monophosphate (cAMP), and of a voltage-dependent L-type calcium channel blocker in the gerbil brain using receptor autoradiography. [3H]Quinuclidinyl benzilate (QNB), [3H]forskolin, [3H]cAMP, and [3H]PN200-110 were used to label muscarinic receptors, adenylate cyclase, cAMP-dependent protein kinase, and L-type calcium channels, respectively. In middle-aged animals (16-month-old gerbils), [3H]QNB, [3H]PN200-110, [3H]forskolin, and [3H]cAMP binding sites were elevated in the hippocampal region compared with that of young gerbils (4 weeks old). Further, a significant elevation in [3H]forskolin binding was seen in the nucleus accumbens. In contrast, [3H]QNB, [3H]PN200-110, and [3H]forskolin binding sites were reduced in the cerebellum, neocortex and thalamus, and hypothalamus in middle-aged animals, respectively. [3H]cAMP binding was not altered in other regions except for an elevation in the hippocampus. Thus, the age-related alterations in receptor binding may proceed by different mechanisms in various brain regions. Chronic vinconate treatment partly modulated the age-related alterations in [3H]QNB, [3H]forskolin, and [3H]cAMP binding in the hippocampus, but not that of [3H]PN200-110. Vinconate also regulated the age-related changes in [3H]forskolin binding in the nucleus accumbens. These results indicate that the age-related alterations in the binding sites of muscarinic acetylcholine, forskolin, cAMP, and L-type calcium channel blocker occur in particular in the hippocampus. Further, they suggest that a novel vinca alkaloid derivative, vinconate, can partly modulate age-related changes in these binding sites.