title: The distribution of dopamine D1 receptor and mu-opioid receptor 1 receptor immunoreactivities in the amygdala and interstitial nucleus of the posterior limb of the anterior commissure: relationships to tyrosine hydroxylase and opioid peptide terminal systems.
abstract: Mismatches between dopamine innervation and dopamine D1 receptor (D1) distribution have previously been demonstrated in the intercalated cell masses of the rat amygdala. Here the distribution of enkephalin and beta-endorphin immunoreactive (IR) nerve terminals with respect to their mu-opioid receptors is examined in the intercalated cell masses, along with a further immunohistochemical analysis of the dopamine/D1 mismatches. A similar analysis is also made within the extended amygdala. A spatial mismatch in distribution patterns was found between the mu-opioid receptor-1 immunoreactivity and enkephalin IR in the main intercalated island of the amygdala. Discrete cell patches of dopamine D1 receptor and mu-opioid receptor-1 IR were also identified in a distinct region of the extended amygdala, the interstitial nucleus of the posterior limb of the anterior commissure, medial division (IPACM), which displayed sparse tyrosine hydroxylase or enkephalin/beta-endorphin IR nerve terminals. Furthermore, distinct regions of the main intercalated island that showed dopamine/D1 receptor matches (the rostral and rostrolateral parts) were associated with strong dopamine and cyclic AMP regulated phosphoprotein, 32 kDa-IR in several D1 IR neuronal cell bodies and dendrites, whereas this was not the case for the dopamine/D1 mismatch areas (the rostromedial and caudal parts) of the main intercalated island. The lack of correlation between the terminal/receptor distribution patterns suggests a role for volume transmission for mu-opioid receptor- and dopamine D1 receptor-mediated transmission in distinct regions of the amygdala and extended amygdala. This may have implications for amygdaloid function, where slow long lasting responses may develop as a result of volume transmission operating in opioid peptide and dopaminergic communication.
authors.affiliation: Department of Cellular and Molecular Medicine, University of Ottawa, 451 Smythe Road, Ottawa, Ontario K1H 8M5, Canada. kjaco031@uottawa.ca
authors.forename: K X
authors.initials: KX
authors.lastname: Jacobsen
authors.forename: M
authors.initials: M
authors.lastname: Höistad
authors.forename: W A
authors.initials: WA
authors.lastname: Staines
authors.forename: K
authors.initials: K
authors.lastname: Fuxe
mesh_terms: D000679:Amygdala / Q000166:cytology / Q000378:metabolism*; D000818:Animals; D001931:Brain Mapping; D004745:Enkephalins / Q000378:metabolism*; D007150:Immunohistochemistry / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D017450:Receptors, Opioid, mu / Q000378:metabolism*; D012686:Septal Nuclei / Q000166:cytology / Q000378:metabolism*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
chemical_list: D004745:Enkephalins; C485765:Oprm1 protein, rat; D017448:Receptors, Dopamine D2; D017450:Receptors, Opioid, mu; D014446:Tyrosine 3-Monooxygenase