(376) Sex differences in an early life stress mouse model of comorbid mood disorder and urogenital pain.
s The Journal of Pain S69 of the left and right CeA to bladder nociception using optogenetic and pharmacological techniques. Global activation of the right CeA using Nestin driven expression of channelrhodopsin (ChR2) increased pain like responses to noxious bladder distension; activation of the left CeA using the same technique had no effect on bladder nociception. Using NeuN and cFos immunohistochemistry respectively, we determined that this asymmetric physiological response is not due to the basal or optogenetically activated number of neurons within each nucleus. The intricacies of left and right CeA bladder pain modulation were further investigated by limiting ChR2 expression to specific cell types and administering neuropeptides into each nucleus during bladder distension. To better understand the on going role of each nucleus in bladder pain modulation, we also globally inhibited the left and right CeA during bladder distension using Nestin driven halorhodospin. Inhibition of the left CeA increased pain like responses to noxious bladder distension, suggesting an on going anti nocicieptive role for this nucleus; inhibition of the right CeA had no effect on bladder nociception. Overall, these data suggest complementary antiand pro nociceptive roles of the left and right CeA in visceral pain modulation. (376) Sex differences in an early life stress mouse model of comorbid mood disorder and urogenital pain I Fuentes, O Eller, A Pierce, and J Christianson; University of Kansas Medical Center, Kansas City, KS Functional pain disorders are diagnosed nearly twice as often in women as inmen; however, approximately half of bothmale and female chronic pelvic pain patients present with comorbid mood disorders, such as depression and anxiety. Exposure to early life stress or adversity is commonly reported among these patient populations and has been attributed to dysfunction within the hypothalamic pituitary adrenal (HPA) axis. We used a mouse model of neonatal maternal separation (NMS) that exhibits increased urogenital hypersensitivity and dysfunction to evaluate potential sex differences in comorbid chronic pain and mood disorders. Voluntary exercise has been shown to attenuate symptoms attributed to HPA axis dysfunction; therefore, we also investigated the effect of voluntary wheel running on NMS induced comorbidities. Male and female NMS mice displayed increasedmicturition frequency, aswell as urogenital hypersensitivity, evidences as decreased perigenital mechanical withdrawal thresholds and increased visceromotor response to bladder/vaginal distention, respectively. Anhedonic behavior, measured as reduced sucrose consumption in a two choice preference test, was observed in male NMS mice, while female NMS mice consumed more sucrose than naEURive counterparts. Despite apparent sex differences, trends towards a correlation between anhedonia and urogenital sensitivity and dysfunction were observed in bother male and female NMS mice. Histological evidence of increased mast cell degranulation was observed in bladder, vagina, and prostate of NMSmice, as well as in the duramater, which has been implicated in migraine. Voluntary exercise prevented ans/or reversed all of these observations while also increasing hippocampal mRNA levels of brain derived neurotrophic factor (BDNF) and differentially affecting glucocorticoid and mineralocorticoid receptor levels in male and female mice. Together, these data suggest that, despite displaying similar urogenital phenotypes, male and female mice are differentially susceptible to NMS induced mood disorders and voluntary exercise may initiate beneficial, yet somewhat variable, sex dependent mechanisms. Supported by NIH grants R01DK099611 and R01DK103872. (377) Is pain a consequence of tissue remodeling in interstitial cystitis/bladder pain syndrome? F Kullmann, A Wolf Johnston, S Bastacky, and L Birder; University of Pittsburgh, Pittsburgh, PA Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic pelvic pain syndrome characterized by suprapubic pain, urinary frequency and urgency, for which no reliable treatments exist. A comparable disease in domestic cats termed feline interstitial cystitis (FIC) exhibits nearly all characteristics and symptoms of human IC/BPS. We used this model to investigate structural and functional alterations in the bladder that may underlie mechanisms contributing to pain. FIC urothelium exhibited elevated levels of proinflammatory mediators PGE2 and cyclooxygenase 2 (COX2) similar to previous reports in IC patient bladder. PGE2 is involved in promoting neovascularization, a prominent feature in IC patient bladder, which was corroborated by histological findings of FIC bladders. Further, similar to findings in IC patients, we previously reported significantly elevated levels of nerve growth factor (NGF) in bladder mucosa from FIC cats. Recent findings have shown that NGF as well as inflammatory mediators (such as PGE2) may be involved in augmented collagen deposition. In this regard, FIC cat bladders exhibited patchy areas of increased collagen deposition as compared to healthy cats. Although expression of the tight junction associated protein ZO 1 and apoptotic markers (BAX and cleaved caspase 3) were not significantly altered, we did find increased urothelial proliferation, evidenced by mucosal von Brunn's nests, suggestive of tissue remodeling. These results suggest that increase in inflammatory/ pro angiogenic factors within the bladder urothelium and lamina propria may underlie tissue remodeling and neovascularization. Urothelial PGE2 may play a prominent role in these processes. As the urothelium is involved in sensory mechanisms and highly influenced by the underlying vasculature, these changes may alter the communication and transmission of sensory information between different cellular components (urothelium, nerves, smooth muscle) and may contribute to altered bladder sensations and pain reported in IC/BPS patients. (378) Optogenetic inhibition sensory neurons mediating bladder nociception A Mickle, V Samineni, S Park, G Shin, M Pullen, J Grajales Reyes, T Lake, J Rogers, and R Gereau; Washington University, Saint Louis, MO Pain associated with interstitial cystitis/bladder pain syndrome (IC/ BPS is severe and detrimental to quality of life. The underlying pathophysiology behind this pain is poorly understood. A greater understanding of the role of nociceptors in IC/BPS would be greatly beneficial in the development of new treatments. Here we employed optogenetic inhibition to study the role of Nav1.8+ sensory neurons in bladder pain. The light activated proton pump, Archaerhodopsin (Arch) fused to EYFP was selectively expressed in Nav1.8 neurons (nociceptors) to enable optogenetic inhibition of neuronal firing. Histological studies confirmed the expression of Arch EYFP in sensory neurons projecting to the bladder. Electrophysiological analysis of these bladder projecting sensory neurons confirmed robust light induced inhibition of action potential firing. To study the impact of optogenetic inhibition of these Nav1.8+ neurons on bladder nociception, we assessed the visceromotor response (VMR) during graded bladder distension (10 70 mmHg) both prior to and during activation of Arch in bladder sensory afferents. We found a dramatic decrease in VMR response when Nav1.8+ Arch is activated in the bladder. Additionally, using fully implantable wireless mLEDs, we found that activation of Arch in Nav1.8+ neurons can reduce abdominal hypersensitivity associated with cyclophosphamide induced bladder inflammation in awake, freely moving mice. Altogether, these preliminary studies suggest that inhibition of the Nav1.8 subpopulation of sensory neurons decreases evoked and referred bladder pain in mice. Further studies utilizing this approach will help elucidate the cellular basis of bladder pain in chronic bladder pain syndromes. This work is supported by an NIH Director's Transformative Research Award (TR01 NS081707) and Exploratory Technologies to Understand the Control of Organ Function by the Peripheral Nervous System for SPARC Award (U18 EB021793) to RG and JR, as well as U54 DK104279 awarded to RG.
The journal of pain official journal of the American Pain Society