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Chronic stress differentially alters mRNA expression of opioid peptides and receptors in the dorsal hippocampus of female and male rats
Author(s) -
Johnson Megan A.,
Contoreggi Natalina H.,
Kogan Joshua F.,
Bryson Matthew,
Rubin Batsheva R.,
Gray Jason D.,
Kreek Mary Jeanne,
McEwen Bruce S.,
Milner Teresa A.
Publication year - 2021
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.25115
Subject(s) - dentate gyrus , hippocampal formation , biology , granule cell , in situ hybridization , receptor , medicine , endocrinology , neuroscience , interneuron , granule (geology) , gene expression , inhibitory postsynaptic potential , gene , genetics , paleontology
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.