Ovarian hormones influence corticotropin releasing factor receptor colocalization with delta opioid receptors in CA1 pyramidal cell dendrites

Abstract

Stress interacts with addictive processes to increase drug use, drug seeking, and relapse. The hippocampal formation (HF) is an important site at which stress circuits and endogenous opioid systems intersect and likely plays a critical role in the interaction between stress and drug addiction. Our prior studies demonstrate that the stress-related neuropeptide corticotropin-releasing factor (CRF) and the delta-opioid receptor (DOR) colocalize in interneuron populations in the hilus of the dentate gyrus and stratum oriens of CA1 and CA3. While independent ultrastructural studies of DORs and CRF receptors suggest that each receptor is found in CA1 pyramidal cell dendrites and dendritic spines, whether DORs and CRF receptors colocalize in CA1 neuronal profiles has not been investigated. Here, hippocampal sections of adult male and proestrus female Sprague-Dawley rats were processed for dual label pre-embedding immunoelectron microscopy using well-characterized antisera directed against the DOR for immunoperoxidase and against the CRF receptor for immunogold. DOR-immunoreactivity (-ir) was found presynaptically in axons and axon terminals as well as postsynaptically in somata, dendrites and dendritic spines in stratum radiatum of CA1. In contrast, CRF receptor-ir was predominantly found postsynaptically in CA1 somata, dendrites, and dendritic spines. CRF receptor-ir frequently was observed in DOR-labeled dendritic profiles and primarily was found in the cytoplasm rather than at or near the plasma membrane. Quantitative analysis of CRF receptor-ir colocalization with DOR-ir in pyramidal cell dendrites revealed that proestrus females and males show comparable levels of CRF receptor-ir per dendrite and similar cytoplasmic density of CRF receptor-ir. In contrast, proestrus females display an increased number of dual-labeled dendritic profiles and increased membrane density of CRF receptor-ir in comparison to males. We further examined the functional consequences of CRF receptor-ir colocalization with DOR-ir in the same neuron using the hormone responsive neuronal cell line NG108-15, which endogenously express DORs, and assayed intracellular cAMP production in response to CRF receptor and DOR agonists. Results demonstrated that short-term application of DOR agonist SNC80 inhibited CRF-induced cAMP accumulation in NG108-15 cells transfected with the CRF receptor. These studies provide new insights on opioid-stress system interaction in the hippocampus of both males and females and establish potential mechanisms through which DOR activation may influence CRF receptor activity.

Post-synaptic Density-95 (PSD-95) Binding Capacity of G-protein-coupled Receptor 30 (GPR30), an Estrogen Receptor That Can Be Identified in Hippocampal Dendritic Spines

“…We have demonstrated that CRHR1-IR is in dendritic spines of CA1 neurons (22), and E2 is involved is sex differences seen in stress-related changes in hippocampal-dependent behavior and cognition (48). Although GPR30 is associated with CRHR1 in vitro, the CRHR1-CT also contains a PDZ ligand sequence (-STAV) and can also co-immunoprecipitate with PSD-95.…”

“…All methods were approved by the Weill Medical College of Cornell University Institutional Animal Care and Use Committee (IACUC) as well as by The Rockefeller University IACUC and conform to the National Institutes of Health guidelines. Estrous cycle phases were determined as reported previously (22). Animals at both pro-and diestrus were used in the immunohistochemistry studies.…”

“…Electron Microscopy and Ultra-structural Analysis-Electron microscopy (EM) and ultra-structural analyses were as previously described (22). Briefly, single-labeled immuno-peroxidase activity was processed first for immuno-histochemistry using an avidin-biotin complex (Vector Laboratories).…”

Sex differences in stress responses: a critical role for corticotropin-releasing factor

“…Sex differences in the distribution of CRF receptors are also found in hippocampal CA1 dendrites [69]. In CA1, female rats have more CRF receptors in delta opioid receptor-containing dendrites than males [69]. These structural sex differences could lead to sex differences in interactions between CRF and endogenous opioids.…”

“…In fact, this sex difference in CRF 1 receptor distribution is associated with increased anxiety in males following local administration of CRF into the DR [68]. Sex differences in the distribution of CRF receptors are also found in hippocampal CA1 dendrites [69]. In CA1, female rats have more CRF receptors in delta opioid receptor-containing dendrites than males [69].…”