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Putative role of presynaptic alpha7* nicotinic receptors in nicotine stimulated increases of extracellular levels of glutamate and aspartate in the ventral tegmental area.
Synapse. 2000 Dec 15; 38(4):375-83.S

Abstract

We have previously provided evidence that the stimulatory action of systemic nicotine on dopamine release in the rat nucleus accumbens is initiated in the ventral tegmental area (VTA), and that it appears to be mediated partly through an indirect, presynaptic mechanism. Thus, it was found that blockade of N-methyl-D-aspartate (NMDA) receptors in the VTA attenuates the enhancing effect of nicotine on extracellular levels of dopamine in the nucleus accumbens. Moreover, the nicotine-induced dopamine output in the nucleus accumbens was found to be blocked by pretreatment with methyllycaconitine (MLA) in the VTA, indicating a role for alpha7* nicotinic acetylcholine receptors (nAChRs) in this mechanism. Thus, nicotine may exert its effects in the VTA through stimulation of alpha7* nAChRs localized on excitatory amino acid (EAA)ergic afferents. To test this hypothesis, we here measured extracellular concentrations of glutamate and aspartate in the VTA in response to systemic nicotine, with or without concurrent infusion of MLA in the VTA, using microdialysis in anaesthetized rats. Since the medial prefrontal cortex is an important source of EAA input to the VTA, we also assessed the density of alpha-bungarotoxin binding sites in the VTA in rats lesioned bilaterally in the prefrontal cortex with ibotenic acid and in sham-lesioned rats by means of quantitative autoradiography. Nicotine (0.5 mg/kg, s.c.) significantly increased extracellular levels of both aspartate and glutamate in the VTA. MLA (0.3 mM) infused locally in the VTA prevented the nicotine-induced increase in glutamate and aspartate levels. Ibotenic acid lesions of the prefrontal cortex decreased the density of alpha-bungarotoxin binding sites in the VTA by about 30%. These data indicate that nicotine increases the extracellular levels of excitatory amino acids in the VTA through stimulation of nAChRs in the VTA and that part of the alpha7* nAChR population in the VTA is localized on neurons originating in the prefrontal cortex.

Authors+Show Affiliations

Karolinska Institutet, Department of Physiology and Pharmacology, Section of Neuropsychopharmacology, S-171 77 Stockholm, Sweden.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

11044884

Citation

Schilström, B, et al. "Putative Role of Presynaptic Alpha7* Nicotinic Receptors in Nicotine Stimulated Increases of Extracellular Levels of Glutamate and Aspartate in the Ventral Tegmental Area." Synapse (New York, N.Y.), vol. 38, no. 4, 2000, pp. 375-83.
Schilström B, Fagerquist MV, Zhang X, et al. Putative role of presynaptic alpha7* nicotinic receptors in nicotine stimulated increases of extracellular levels of glutamate and aspartate in the ventral tegmental area. Synapse. 2000;38(4):375-83.
Schilström, B., Fagerquist, M. V., Zhang, X., Hertel, P., Panagis, G., Nomikos, G. G., & Svensson, T. H. (2000). Putative role of presynaptic alpha7* nicotinic receptors in nicotine stimulated increases of extracellular levels of glutamate and aspartate in the ventral tegmental area. Synapse (New York, N.Y.), 38(4), 375-83.
Schilström B, et al. Putative Role of Presynaptic Alpha7* Nicotinic Receptors in Nicotine Stimulated Increases of Extracellular Levels of Glutamate and Aspartate in the Ventral Tegmental Area. Synapse. 2000 Dec 15;38(4):375-83. PubMed PMID: 11044884.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Putative role of presynaptic alpha7* nicotinic receptors in nicotine stimulated increases of extracellular levels of glutamate and aspartate in the ventral tegmental area. AU - Schilström,B, AU - Fagerquist,M V, AU - Zhang,X, AU - Hertel,P, AU - Panagis,G, AU - Nomikos,G G, AU - Svensson,T H, PY - 2000/10/25/pubmed PY - 2001/2/28/medline PY - 2000/10/25/entrez SP - 375 EP - 83 JF - Synapse (New York, N.Y.) JO - Synapse VL - 38 IS - 4 N2 - We have previously provided evidence that the stimulatory action of systemic nicotine on dopamine release in the rat nucleus accumbens is initiated in the ventral tegmental area (VTA), and that it appears to be mediated partly through an indirect, presynaptic mechanism. Thus, it was found that blockade of N-methyl-D-aspartate (NMDA) receptors in the VTA attenuates the enhancing effect of nicotine on extracellular levels of dopamine in the nucleus accumbens. Moreover, the nicotine-induced dopamine output in the nucleus accumbens was found to be blocked by pretreatment with methyllycaconitine (MLA) in the VTA, indicating a role for alpha7* nicotinic acetylcholine receptors (nAChRs) in this mechanism. Thus, nicotine may exert its effects in the VTA through stimulation of alpha7* nAChRs localized on excitatory amino acid (EAA)ergic afferents. To test this hypothesis, we here measured extracellular concentrations of glutamate and aspartate in the VTA in response to systemic nicotine, with or without concurrent infusion of MLA in the VTA, using microdialysis in anaesthetized rats. Since the medial prefrontal cortex is an important source of EAA input to the VTA, we also assessed the density of alpha-bungarotoxin binding sites in the VTA in rats lesioned bilaterally in the prefrontal cortex with ibotenic acid and in sham-lesioned rats by means of quantitative autoradiography. Nicotine (0.5 mg/kg, s.c.) significantly increased extracellular levels of both aspartate and glutamate in the VTA. MLA (0.3 mM) infused locally in the VTA prevented the nicotine-induced increase in glutamate and aspartate levels. Ibotenic acid lesions of the prefrontal cortex decreased the density of alpha-bungarotoxin binding sites in the VTA by about 30%. These data indicate that nicotine increases the extracellular levels of excitatory amino acids in the VTA through stimulation of nAChRs in the VTA and that part of the alpha7* nAChR population in the VTA is localized on neurons originating in the prefrontal cortex. SN - 0887-4476 UR - https://www.unboundmedicine.com/medline/citation/11044884/Putative_role_of_presynaptic_alpha7__nicotinic_receptors_in_nicotine_stimulated_increases_of_extracellular_levels_of_glutamate_and_aspartate_in_the_ventral_tegmental_area_ L2 - https://doi.org/10.1002/1098-2396(20001215)38:4<375::AID-SYN2>3.0.CO;2-Y DB - PRIME DP - Unbound Medicine ER -