title: Tyrosine kinase B and C receptors in the neostriatum and nucleus accumbens are co-localized in enkephalin-positive and enkephalin-negative neuronal profiles and their expression is influenced by cocaine.
abstract: Single- and double-label immunohistochemistry were used to determine the extent to which the tyrosine kinase B and C receptors, are expressed in enkephalin-immunopositive or enkephalin-immunonegative neuronal profiles in the rat neostriatum and nucleus accumbens. Results indicate that tyrosine kinase B and C receptors are co-localized in both enkephalin-positive and enkephalin-negative neurons in both of these nuclei, which suggests that these receptors influence both the striatal-pallidal (enkephalin) and striatal-ventral mesencephalic (substance P/dynorphin) pathways. We also examined the influence of acute or repeated injections of cocaine on the number of tyrosine kinase B and C receptors immunoreactive neuronal profiles in the rat neostriatum and nucleus accumbens. Following an acute injection of cocaine (15 mg/kg, i.p.), there were significant decreases in the number of tyrosine kinase B and C receptors immunoreactive profiles in specific regions of the neostriatum and nucleus accumbens relative to saline-pretreated rats. One or 14 days following the last of seven daily injections of 15 mg/kg cocaine or saline there were no differences in the numbers of tyrosine kinase B or C receptors immunoreactive neuronal profiles between these treatment groups.Collectively, the present results indicate that tyrosine kinase B and C receptors in the neostriatum and nucleus accumbens are co-localized in enkephalin-positive and enkephalin-negative neuronal profiles, which suggests that the striatal medium spiny neurons expressing tyrosine kinase B and C receptors include those that project to the pallidum or the ventral mesencephalon. The current results also show that an acute injection of cocaine results in a decrease in the number of tyrosine kinase B and C receptors immunoreactive neuronal profiles in specific regions of the nucleus accumbens and neostriatum, indicating that cocaine-induced increases in extracellular dopamine in the striatal complex result in compensatory decreases in the expression of tyrosine kinase B and C receptors.
authors.affiliation: Laboratory of Neuropsychopharmacology, Department of Pharmacology, R-612, Boston University School of Medicine, 715 Albany Street, Boston 02118, USA.
authors.forename: A Y
authors.initials: AY
authors.lastname: Freeman
authors.forename: J-J
authors.initials: JJ
authors.lastname: Soghomonian
authors.forename: R C
authors.initials: RC
authors.lastname: Pierce
mesh_terms: D000818:Animals; D003042:Cocaine / Q000494:pharmacology*; D004745:Enkephalins / Q000032:analysis / Q000096:biosynthesis*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D008297:Male; D017072:Neostriatum / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D009714:Nucleus Accumbens / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020813:Receptor, trkB / Q000032:analysis* / Q000096:biosynthesis; D020812:Receptor, trkC / Q000032:analysis* / Q000096:biosynthesis
chemical_list: D004745:Enkephalins; D020813:Receptor, trkB; D020812:Receptor, trkC; D003042:Cocaine