title: Influence of endometriosis on pain behaviors and muscle hyperalgesia induced by a ureteral calculosis in female rats.
abstract: Endometriosis and urinary calculosis can co-occur. Clinical studies have shown that both painful and non-painful endometriosis in women are associated with enhanced pain and referred muscle hyperalgesia from urinary calculosis, but the mechanisms underlying this phenomenon are still poorly understood. The aim of this study was to develop an animal model adequate to explore this viscero-visceral interaction in standardized conditions. Using a model of endometriosis previously developed to study reduced fertility and vaginal hyperalgesia, endometriosis (endo) or sham-endometriosis (sham-endo) was induced in rats by autotransplantation of small pieces of uterus (or, for sham-endo, fat) on cascade mesenteric arteries, ovary, and abdominal wall. After the endometrial, but not the fat autografts had produced fluid-filled cysts (3 weeks), urinary calculosis was induced by implanting an artificial stone into one ureter. Pain behaviors were monitored by continuous 24-h videotape recordings before and after stone implantation. Referred muscle hyperalgesia was assessed by measuring vocalization thresholds to electrical stimulation of the oblique musculature (L1 dermatome). The data were compared with previously reported data from rats that had received only the stone. Neither endo nor sham-endo alone induced pain behaviors. Following stone implantation, in endo rats compared to sham-endo and stone-only rats, pain behaviors specifically associated with urinary calculosis were significantly increased and new pain behaviors specifically associated with uterine pathology became evident. Muscle hyperalgesia was also significantly increased. To explore the relationship between the amount of endometriosis and that of ureteral pain behavior, two separate groups of endo rats were treated with either a standard non-steroidal anti-inflammatory drugs (ketoprofen) or placebo from the 12th to the 18th day after endometriosis induction. The stone was implanted on the 21st day. Ketoprofen treatment compared to placebo significantly reduced the size of the cysts and both ureteral and uterine pain behaviors post-stone implantation. The size of the cysts showed a significant linear correlation with the post-stone ureteral pain behaviors. In conclusion, endo increased pain crises and muscle hyperalgesia typically induced by a ureteral calculosis, and the ureteral calculosis revealed additional pain behaviors typically induced by uterine pathophysiology; and this enhancement was a function of the degree of endometriosis. This result closely reproduces the condition observed in humans and could be due to a phenomenon of 'viscero-visceral' hyperalgesia, in which increased input from the cyst implantation sites to common spinal cord segments (T10-L1) facilitates the central effect of input from the urinary tract.
authors.affiliation: Pathophysiology of Pain Laboratory, Department of Medicine and Science of Aging, 'G. D'Annunzio' University of Chieti, 66013 Chieti Scalo (CH),Italy Program in Neuroscience, Florida State University, Tallahassee, FL 32306-1270, USA Department of Biomorphology, 'G. D'Annunzio' University of Chieti, 66013 Chieti Scalo (CH), Italy.
authors.forename: Maria Adele
authors.initials: MA
authors.lastname: Giamberardino
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Berkley
authors.forename: Giannapia
authors.initials: G
authors.lastname: Affaitati
authors.forename: Rosanna
authors.initials: R
authors.lastname: Lerza
authors.forename: Lucia
authors.initials: L
authors.lastname: Centurione
authors.forename: Domenico
authors.initials: D
authors.lastname: Lapenna
authors.forename: Leonardo
authors.initials: L
authors.lastname: Vecchiet
mesh_terms: D000009:Abdominal Muscles; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D001522:Behavior, Animal; D003085:Colic / Q000188:drug therapy / Q000209:etiology / Q000503:physiopathology; D003560:Cysts / Q000473:pathology; D004715:Endometriosis / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D006930:Hyperalgesia / Q000188:drug therapy / Q000209:etiology / Q000503:physiopathology*; D007044:Hysterectomy; D007660:Ketoprofen / Q000494:pharmacology; D017699:Pelvic Pain / Q000188:drug therapy / Q000209:etiology / Q000503:physiopathology*; D011312:Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley; D014514:Ureteral Calculi / Q000150:complications*; D014599:Uterus
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D007660:Ketoprofen