Despite recent advances in our understanding of pain mechanisms, there has been little-to-no overall improvement in the clinical management of postoperative pain. It is now recognized that effective postoperative pain management depends on key predictors, especially patient sex. Preclinical and clinical data indicate that, while postoperative pain levels show little-to-no sex-dependent dimorphisms, there are significant sex-based differences in analgesic efficacy, safety profile and abuse/addiction potential of current drugs used to treat postoperative pain. Hence, there is an urgent need to customize postoperative pain management schemes as based on sex-specific pain pharmacology. Our long-term goal is to define sex-dependent postoperative pain mechanisms, and utilize this knowledge to provide more effective postoperative pain management schemes. Our recent published and preliminary data show that a preclinical model of post-operative surgical incision pain leads to a sex-dependent up-regulation of prolactin (PRL) via extra-pituitary mechanisms at surgical sites and in the spinal cord. The PRL receptor (Prlr) is more responsive in female sensory neurons than in males. Moreover, administration of a Prlr antagonist at surgical sites, and especially in the spinal cord, suppresses postoperative hypersensitivity only in females and across all pain modalities. The objective of this proposal is to define peripheral and spinal mechanisms responsible for female-specific regulation of postoperative pain by the PRL system (i.e. PRL and Prlr). Our central hypothesis is that extra-pituitary PRL regulates postoperative pain in a female-specific manner via both peripheral and spinal mechanisms. The rationale is that understanding mechanisms contributing to the female-specific effects of PRL and Prlr on postoperative pain will 1) greatly expand knowledge of sex differences in pain mechanisms; and 2) provide translational potential for the development of novel therapeutic strategies specifically tailored for postoperative pain management in females. Our hypothesis is tested by interconnected yet independent aims.
Aim 1 evaluates surgery-induced PRL and Prlr plasticity in peripheral terminals and innate immune cells at surgical sites, and central terminals and glia in spinal cord of female and males.
Aim 2 defines the influences of sensory neurons, innate immune cells and glia in peripheral and spinal mechanisms of PRL- mediated regulation of postoperative hypersensitivity and ongoing pain in females and males.
Aim 3 examines the regulation of nociceptor excitability by PRL in nave and operated females and males. The proposed study is innovative since if defines the sex-dependent role of extra-pituitary PRL in regulating postoperative pain, and pathways for specific regulation of postoperative pain in females. The proposed research is significant as it advances our knowledge of sex differences in postoperative pain mechanisms, and has substantial translational potential for new sex-based postoperative pain management strategies.

Public Health Relevance

Despite recent advances in our understanding of pain mechanisms, there has been little or no overall improvement in the clinical management of postoperative pain. Here we propose a novel role for the hormone prolactin (PRL) as a sex-specific mechanism that can selectively contribute to the development of postoperative pain in females. This conceptually innovative hypothesis has important implications for both the scientific and medical fields by expanding our understanding of sex-dependent postoperative pain mechanisms that can be targeted in the future by personalized treatment strategies to decrease human pain and suffering.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
1R01GM112747-01A1
Application #
8962348
Study Section
Surgery, Anesthesiology and Trauma Study Section (SAT)
Program Officer
Cole, Alison E
Project Start
2015-09-15
Project End
2019-07-31
Budget Start
2015-09-15
Budget End
2016-07-31
Support Year
1
Fiscal Year
2015
Total Cost
$301,188
Indirect Cost
$103,688
Name
University of Texas Health Science Center
Department
Dentistry
Type
Schools of Dentistry
DUNS #
800772162
City
San Antonio
State
TX
Country
United States
Zip Code
78229
Patil, Mayur J; Hovhannisyan, Anahit H; Akopian, Armen N (2018) Characteristics of sensory neuronal groups in CGRP-cre-ER reporter mice: Comparison to Nav1.8-cre, TRPV1-cre and TRPV1-GFP mouse lines. PLoS One 13:e0198601
Brackley, Allison Doyle; Gomez, Ruben; Guerrero, Kristi A et al. (2017) A-Kinase Anchoring Protein 79/150 Scaffolds Transient Receptor Potential A 1 Phosphorylation and Sensitization by Metabotropic Glutamate Receptor Activation. Sci Rep 7:1842
Mecklenburg, Jennifer; Patil, Mayur J; Koek, Wouter et al. (2017) Effects of local and spinal administrations of mu-opioids on postoperative pain in aged versus adult mice. Pain Rep 2:
Bertin, Samuel; Aoki-Nonaka, Yukari; Lee, Jihyung et al. (2017) The TRPA1 ion channel is expressed in CD4+ T cells and restrains T-cell-mediated colitis through inhibition of TRPV1. Gut 66:1584-1596
Grattan, David R; Akopian, Armen N (2016) Oscillating from Neurosecretion to Multitasking Dopamine Neurons. Cell Rep 15:681-682
Green, Dustin P; Patil, Mayur J; Akopian, Armen N (2016) Influence of hypophysectomy, ovariectomy and gonadectomy on postoperative hypersensitivity in rats. Glob Anesth Perioper Med 2:171-175
Akopian, Armen (2016) Role of TRP ion channels in physiology and pathology. Semin Immunopathol 38:275-6
Green, Dustin; Ruparel, Shivani; Gao, Xiaoli et al. (2016) Central activation of TRPV1 and TRPA1 by novel endogenous agonists contributes to mechanical allodynia and thermal hyperalgesia after burn injury. Mol Pain 12:
Patil, M; Henry, M; Goffin, V et al. (2016) (300) Prolactin regulates sensory neurons in a female-specific manner at their peripheral and central terminals and not at their cell bodies. J Pain 17:S51
Brackley, Allison Doyle; Gomez, Ruben; Akopian, Armen N et al. (2016) GRK2 Constitutively Governs Peripheral Delta Opioid Receptor Activity. Cell Rep 16:2686-2698

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