title: Stress differentially alters mu opioid receptor density and trafficking in parvalbumin-containing interneurons in the female and male rat hippocampus.
abstract: Stress differentially affects hippocampal-dependent learning relevant to addiction and morphology in male and female rats. Mu opioid receptors (MORs), which are located in parvalbumin (PARV)-containing GABAergic interneurons and are trafficked in response to changes in the hormonal environment, play a critical role in promoting principal cell excitability and long-term potentiation. Here, we compared the effects of acute and chronic immobilization stress (AIS and CIS) on MOR trafficking in PARV-containing neurons in the hilus of the dentate gyrus in female and male rats using dual label immunoelectron microscopy. Following AIS, the density of MOR silver-intensified gold particles (SIGs) in the cytoplasm of PARV-labeled dendrites was significantly reduced in females (estrus stage). Conversely, AIS significantly increased the proportion of cytoplasmic MOR SIGs in PARV-labeled dendrites in male rats. CIS significantly reduced the number of PARV-labeled neurons in the dentate hilus of males but not females. However, MOR/PARV-labeled dendrites and terminals were significantly smaller in CIS females, but not males, compared with controls. Following CIS, the density of cytoplasmic MOR SIGs increased in PARV-labeled dendrites and terminals in females. Moreover, the proportion of near-plasmalemmal MOR SIGs relative to total decreased in large PARV-labeled dendrites in females. After CIS, no changes in the density or trafficking of MOR SIGs were seen in PARV-labeled dendrites or terminals in males. These data show that AIS and CIS differentially affect available MOR pools in PARV-containing interneurons in female and male rats. Furthermore, they suggest that CIS could affect principal cell excitability in a manner that maintains learning processes in females but not males.
authors.affiliation: Brain and Mind Research Institute, Weill Cornell Medical College, 407 East 61st Street, New York, New York, 10065; Harold and Margaret Milliken Hatch Laboratory of Neuroendocrinology, The Rockefeller University, 1230 York Avenue, New York, New York, 10065.
authors.forename: Teresa A
authors.initials: TA
authors.lastname: Milner
authors.forename: Suzanne R
authors.initials: SR
authors.lastname: Burstein
authors.forename: Gina F
authors.initials: GF
authors.lastname: Marrone
authors.forename: Sana
authors.initials: S
authors.lastname: Khalid
authors.forename: Andreina D
authors.initials: AD
authors.lastname: Gonzalez
authors.forename: Tanya J
authors.initials: TJ
authors.lastname: Williams
authors.forename: Kathryn C
authors.initials: KC
authors.lastname: Schierberl
authors.forename: Annelyn
authors.initials: A
authors.lastname: Torres-Reveron
authors.forename: Keith L
authors.initials: KL
authors.lastname: Gonzales
authors.forename: Bruce S
authors.initials: BS
authors.lastname: McEwen
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Waters
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D003712:Dendrites / Q000378:metabolism; D018891:Dentate Gyrus / Q000166:cytology / Q000378:metabolism*; D005260:Female; D007395:Interneurons / Q000737:chemistry / Q000378:metabolism*; D008297:Male; D010320:Parvalbumins / Q000032:analysis*; D021381:Protein Transport; D051381:Rats; D017207:Rats, Sprague-Dawley; D017450:Receptors, Opioid, mu / Q000235:genetics / Q000378:metabolism*; D012727:Sex Characteristics; D013315:Stress, Psychological / Q000378:metabolism*
chemical_list: D010320:Parvalbumins; D017450:Receptors, Opioid, mu
keywords: acute stress; chronic stress; estrogens; opioids; sex differences