ORIGINAL ARTICLE Association between gallstone-evoked pain, inflammation and proliferation of nerves in the gallbladder: A possible explanation for clinical differences RENE HENNIG 1 , JIANG ZANLI 1 , TAREK OSMAN 1 , IRENE ESPOSITO 2 , TEWELDE BERHANE 3 , MORTEN VETRHUS 3 , KARL SØNDENAA 4 , MARKUS W. BU ¨ CHLER 1 & HELMUT FRIESS 1 Departments of 1 Surgery and 2 Pathology, University of Heidelberg, Heidelberg, Germany, 3 Department of Surgery, Stavanger University Hospital, Stavanger, Norway, and 4 Institute of Surgical Sciences, University of Bergen, Bergen, Norway Abstract Objective. To investigate whether enhanced neuroproliferation could be involved in the pathogenesis of gallstone pain. Material and methods. Gallbladders from 117 patients with gallstones and 43 controls were examined. The gallbladder samples were immunostained against the pan-neuronal marker PGP 9.5 and the number of nerves and nerve area per tissue area estimated. Results. More nerves and an increased nerve area per tissue area were found in uncomplicated symptomatic gallstone disease. In comparison, acute cholecystitis displayed a significantly (p  /0.01) decreased number of nerves and nerve area per tissue area. In both categories, the gallbladder neck contained more nerves (p  /0.06 and 0.04, respectively) and an increased nerve area per tissue area (p  /0.034 and 0.008, respectively) than the body. Conclusions. Uncomplicated disease showed enhanced neuroproliferation, significantly more in the gallbladder neck, whereas significantly fewer nerves were observed in acute cholecystitis. Nerve growth alteration may play a role in uncomplicated gallstone pain but the pathology may be different in inflammation. Key Words: Cholecystitis, gallstones, nerve growth alteration, pain, PGP 9.5 Introduction Gallstones are the cause of a common and ancient disease and nowadays can be found in 20% of women and 8% of men in screening of Western populations [1,2]. However, around 70% of these are asymptomatic. The diagnosis of symptomatic gallstones is based primarily on a combination of pain attacks and ultrasonographic demonstration of gallstones [3]. When inflammation supervenes, fe- ver, increased inflammatory markers and ultrasono- graphic signs may be present but are not consistent [4]. Therefore, it is difficult to make an objective clinical distinction between simple pain attacks and complicated disease [5]. Furthermore, people with gallstones may have unspecific abdominal symptoms not unlike those in people without gall- stones and determination of exact symptoms caused by gallstones may pose a further diagnostic challenge [5,6]. The sheer numbers of those needing medical attention warrant further research in this area and a better understanding of the disease has wide implications [7]. There are indications that acute inflammation is a different disease or expression of gallstone disease than simple pain attacks, as the gender difference is statistically different and 39% of the patients have never experienced simple pain attacks prior to the clinical appearance of gallbladder inflammation [8]. Hyperplastic vasoactive intestinal peptide (VIP) nerves have been suggested to cause gallbladder relaxation, stasis and mucosal fluid imbalance and may therefore contribute to gallstone formation [9]. Correspondence: Rene Hennig, MD, Department of Surgery, University of Heidelberg, Im Neuenheimer Feld 110, DE-69120 Heidelberg, Germany. Tel:  / 49 6221 5636 253. Fax:  /49 6221 566 903. E-mail: rene.hennig@med.uni-heidelberg.de Scandinavian Journal of Gastroenterology, 2007; 42: 878  884 (Received 25 October 2006; accepted 10 January 2007) ISSN 0036-5521 print/ISSN 1502-7708 online # 2007 Taylor & Francis DOI: 10.1080/00365520701207074