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- Owman, Christer, et al.
(författare)
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Chronic nicotine treatment eliminates asymmetry in striatal glucose utilization following unilateral transection of the mesostriatal dopamine pathway in rats
- 1989
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Ingår i: Neuroscience Letters. - 0304-3940. ; 102:2-3, s. 279-283
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Tidskriftsartikel (refereegranskat)abstract
- Partial hemitransection was performed through a knife lesion at the meso-diencephalic level in rats to sever the mesostriatal dopamine system. During the subsequent 2 weeks the animals received 0.125 mg/kg/h of nicotine continuously via an osmotic minipump implanted s.c. To achieve prompt high nicotine levels, 4 i.p. injections of 0.5 mg/kg nicotine were, in addition, given during the first 2 h following the lesion. The total treatment corresponded to a mean plasma level of 50 ng/ml nicotine, measured at the end of the experiment. Control animals received corresponding volumes of 0.9% saline. Quantitative autoradiographic analysis of the glucose utilization in the caudate nucleus using Sokoloff's [14C]2-deoxyglucose method demonstrated a 16% side-to-side difference in the lesioned control animals, whereas the asymmetry was counteracted by the nicotine treatment. Although there was an overall tendency to a lower rate of glucose utilization (by 6%) in the nicotine-treated animals compared to the controls receiving saline only, the difference was not statistically significant. The eliminated asymmetry probably reflects an increased survival of the dopamine neurons and/or of striatal nerve cells on the lesioned side due to protective effects of nicotine resulting from desensitization of nicotinic-type cholinergic receptors following continuous administration of the drug.
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2. |
- Terasmaa, A, et al.
(författare)
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Modulation of [(35)S]GTPgammaS binding to chinese hamster ovary cell membranes by D(2(short)) dopamine receptors
- 2000
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Ingår i: Neuroscience Letters. - 0304-3940. ; 280:2, s. 135-138
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Tidskriftsartikel (refereegranskat)abstract
- Rat dopamine D(2short) expressed in Chinese hamster ovary (CHO) cells were characterized by means of activation of [(35)S]-guanosine 5'-O-(gamma-thiotriphosphate) ([(35)S]GTPgammaS) binding and inhibition of [(3)H]raclopride binding. Among 18 dopaminergic ligands studied dopamine, NPA, apomorphine and quinpirole were full agonists in activation of [(35)S]GTPgammaS binding, while seven ligands were partial agonists with efficacies from 16 to 69% of the effect of dopamine and seven ligands were antagonists having no effect on the basal level of [(35)S]GTPgammaS binding, but inhibited dopamine-dependent activation in a dose-response manner. Despite the different efficacies, the potencies of all 18 ligands to modulate [(35)S]GTPgammaS binding revealed a good correlation with their potencies to inhibit [(3)H]raclopride binding in the CHO cell membranes. This indicates that the binding of the ligand to the receptor determines its potency, but has no direct correlation with its intrinsic activity.
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