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Chronic stress differentially alters mRNA expression of opioid peptides and receptors in the dorsal hippocampus of female and male rats.

TitleChronic stress differentially alters mRNA expression of opioid peptides and receptors in the dorsal hippocampus of female and male rats.
Publication TypeJournal Article
Year of Publication2021
AuthorsJohnson MA, Contoreggi NH, Kogan JF, Bryson M, Rubin BR, Gray JD, Kreek MJeanne, McEwen BS, Milner TA
JournalJ Comp Neurol
Date Published2021 Jan 22
ISSN1096-9861
Abstract

Chronic immobilization stress (CIS) results in sex-dependent changes in opioid peptide levels and receptor subcellular distributions within the rat dorsal hippocampus, which are paralleled with an inability for males to acquire conditioned place preference (CPP) to oxycodone. Here, RNAScope in situ hybridization was used to determine the expression of hippocampal opioid peptides and receptors in unstressed (US) and CIS estrus female and male adult (∼2.5 months old ) Sprague Dawley rats. In all groups, dentate granule cells expressed PENK and PDYN; additionally, numerous interneurons expressed PENK. OPRD1 and OPRM1 were primarily expressed in interneurons, and to a lesser extent, in pyramidal and granule cells. OPRK1-was expressed in sparsely distributed interneurons. There were few baseline sex differences: US females compared to US males had more PENK-expressing and fewer OPRD1-expressing granule cells and more OPRM1-expressing CA3b interneurons. Several expression differences emerged after CIS. Both CIS females and males compared to their US counterparts had elevated: (1) PENK-expressing dentate granule cells and interneurons in CA1 and CA2/3a; (2) OPRD1 probe number and cell expression in CA1, CA2/3a and CA3b and the dentate gyrus; and (3) OPRK1-expressing interneurons in the dentate hilus. Also, CIS males compared to US males had elevated: (1) PDYN expression in granule cells; (2) OPRD1 probe and interneuron expression in CA2/3a; (3) OPRM1 in granule cells; and (4) OPRK1 interneuron expression in CA2/3a. The sex-specific changes in hippocampal opioid gene expression may impact network properties and synaptic plasticity processes that may contribute to the attenuation of oxycodone CPP in CIS males.

DOI10.1002/cne.25115
Alternate JournalJ Comp Neurol
PubMed ID33483980
Grant ListR01 HL136520 / HL / NHLBI NIH HHS / United States
HL098351 / NH / NIH HHS / United States
MH041256 / MH / NIMH NIH HHS / United States
none / / Hope for Depression Research Foundation /
HL136520 / NH / NIH HHS / United States
R01 DA008259 / DA / NIDA NIH HHS / United States
MH102065 / MH / NIMH NIH HHS / United States
R01 HL098351 / HL / NHLBI NIH HHS / United States
DA08259 / DA / NIDA NIH HHS / United States