Folia Morphol. Vol. 71, No. 1, pp. 39–44 Copyright © 2012 Via Medica O R I G I N A L A R T I C L E ISSN 0015–5659 www.fm.viamedica.pl Immunohistochemical identification and localisation of gastrin and somatostatin in endocrine cells of human pyloric gastric mucosa I. Kasacka1, W. Łebkowski2, I. Janiuk3, J. Łapińska1, A. Lewandowska1 1Department of Histology and Cytophysiology, Medical University of Bialystok, Poland 2Department of Neurosurgery, Medical University of Bialystok, Poland 3Department of Morphology Vertebrates, Siedlce University of Natural Sciences and Humanities, Siedlce, Poland [Received 22 September 2011; Accepted 18 November 2011] The detailed description of the distribution of endocrine cells G and D producing important hormones that regulate activation of other cells in the human stomach may be a valuable source of information for opinions about mucosa changes in different diseases of the alimentary tract. The density and distribution of immu- noreactive G and D cells in the pylorus of humans (donors of organs) were evaluat- ed. The pylorus samples were collected after other organs were harvested for transplantation. The number of G cells in the pyloric mucosa of healthy people was higher than the number of D cells. G and D cells were distributed between columnar cells of epithelium mucosa. Multiform endocrine cells generally occurred: gastrin in the middle third of the mucosa and somatostatin cells in the basal half of the pyloric mucosa. The investigation of the pyloric part of the healthy human stomach showed a characteristic distribution of cells that reacted with antisera against gastrin and somatostatin. (Folia Morphol 2012; 71, 1: 39–44) Key words: G-cells, D-cells, immunohistochemistry, human pylorus INTRODUCTION ation [12, 19]. Too much acid can lead to peptic Gastrointestinal hormones are secreted by endocrine ulcer disease, gastroesophageal reflux disease, and cells, which are distributed throughout the mucosa of stress-related erosion/ulcer disease. Too little acid can the gastrointestinal tract. Endocrine cells play an im- interfere with the absorption of certain nutrients, pre- portant regulatory role in the gastrointestinal tract. dispose to enteric infection, and interfere with the Gastrin, somatostatin, and other gastrointestinal absorption of some medications [17] hormones regulate the functions of the gastrointesti- Important regulators of gastric acid secretion are nal tract such as secretion of intestinal and fundic gastrin G cells and somatostatin D cells. Gastrin, the glands, and nutrient and drug absorption [17, 20]. main stimulant of acid secretion during meal inges- The secretion of hydrochloric acid is an important tion, is produced in G cells of the gastric antrum and function of the human stomach. Gastric acid aids duodenal mucosa, but the major source of serum protein digestion, facilitates the absorption of iron, gastrin is antral G cells [19, 24]. The pyloric gland calcium, and vitamin B12, and prevents bacterial over- area, the hallmark of which is the gastrin or G cell, growth [7, 17]. In humans, acid is continuously se- comprises 20% of the antrum [5]. The pyloric gland creted by parietal cells of gastric mucosa and is pre- also contains D cells, which produce somatostatin. cisely regulated by a variety of neurocrine, paracrine, Somatostatin is the main inhibitor of basal gastric and endocrine signals in order to achieve the correct acid secretion. The regulation of gastric acid secretin amount of acid secretion required by the specific situ- is achieved by the interplay between two major gas- Address for correspondence: Prof. dr hab. I. Kasacka, Department of Histology and Cytophysiology, Medical University of Bialystok, ul. Kilińskiego 1, 15–089 Bialystok, Poland, tel: +48 85 748 54 58, tel/fax: +48 85 748 55 16, e-mail: [email protected] 39 Folia Morphol., 2012, Vol. 71, No. 1 tric endocrine cells: the gastrin G cell and the soma- After brain death was diagnosed and the indi- tostatin D cell. Each of these agents acts directly on vidual’s death was recognized by the Committee, the parietal cell as well as indirectly by modulating organ samples of about 1 cm2 were taken from each the secretion of neuroendocrine cells [19]. body (from the same part of the pylorus) after the Gastrin indirectly stimulates acid secretion other organs (kidneys, liver, heart) were harvested through induction of histamine release from entero- for transplantation. chromaffin-like (ECL) cells. Histamine subsequently Ethical issues stimulates gastric acid secretion through H2 recep- tors on parietal cells [3, 18, 29]. Increased acid le- The study protocol was approved by the Ethics vels then stimulate putative chemoreceptors on py- Committee of the Medical University of Białystok loric D cells to secrete somatostatin and block fur- (R-I-002/345/2007), and written informed consent was ther release of gastrin and gastric acid. Thus gastric obtained from each participant or from members acid secretion is regulated by a negative feedback of the patient’s family. mechanism involving somatostatin [6, 18]. The tissues were immediately fixed in Bouin’s The alterations in the relative numbers of gas- solution and routinely embedded in paraffin. The trin G cells and somatostatin D cells may play a key stomach sections were cut perpendicular to the role in gastroduodenal disease. mucosal surface and included the entire depth of Due to the difficulties in obtaining human sam- the mucosa. Specimens were stained with haema- ples our current level of knowledge concerning the toxylin and eosin (H+E) for general histological DNES cells is founded on the results of research con- examination, and processed for immunohistochem- ducted on animals. istry for the detection of gastrin and somatostatin. The limited data available regarding the descrip- tion of the endocrine cells of the human gastrointes- Light microscopic immunohistochemistry tinal tract is based on a restricted number of sam- Procedure. The paraffin blocks were cut into ples collected during surgical procedures or biop- 4-mm sections (3 sections from each subject) and at- sies. In the present paper, the authors investigated tached to positively charged glass slides. the distribution, morphology, and number of G cells Immunohistochemistry was performed using an and D cells in the healthy human pyloric gastric EnVision Plus-HRP Detection Kit (Dako; Glostrup, mucosa, in order to provide basic materials for study- Denmark) [4]. Immunostaining was performed us- ing gastrointestinal endocrinology, gastroenterolo- ing the following protocol. Paraffin-embedded sec- gy, and prevention of disease in the digestive sys- tions were deparaffinised and hydrated in alcohols. tem, and its treatment. For antigen retrieval, the sections were subjected to pretreatment in a pressure chamber heating for MATERIAL AND METHODS 1 min at 21 psi (one pound force per square inch Nineteen donors of organs with normal gastric [1 psi] equates to 6.895 kPa, conversion factor provid- mucosa were used in the study. There were 10 men ed by United Kingdom National Physical Laborato- with mean age 43.9 years, range from 21 to 65 years, ry) at 125°C using Target Retrieval Solution Citrate with mean body weight 83.25 kg and 9 women with pH 6.0 S 2369 (Dako; Glostrup, Denmark). After mean age 46.3 years; range from 19 to 58 years being cooled to room temperature, sections were with mean body weight 66.33 kg. incubated with Peroxidase Blocking Reagent S 2001 Each patient was treated in the Intensive Care (Dako; Glostrup, Denmark) for 10 minutes to block Unit due to brain damage caused by brain injury or endogenous peroxidase activity. by cerebral haemorrhage, and only in a few cases The sections were incubated overnight at 4°C in was the brain damage secondary in origin due to a humidified chamber with the diluted polyclonal primary cardiac arrest. Patients were artificially ven- rabbit: anti-gastrin (1:800, A 0568 Dako; Glostrup, tilated and received circulatory support and Denmark), and anti-somatostatin human antiserum parenteral and enteral nutrition. No one received (1:20 000; H-031-30 Phoenix Pharmaceutical Inc.), steroids. followed by incubation with secondary antibody Each patient presenting clinical symptoms of (conjugated to horseradish peroxidase-labelled poly- brain death was considered as an organ donor. The mer). Bound antibodies were visualized by 1-min irreversible brain damage was confirmed by special incubation with liquid 3,3’-diaminobenzidine sub- clinical examination and with angiography (no blood strate chromogen. The sections were finally coun- flow within the brain arteries). terstained in Vector QS haematoxylin, mounted, and 40 I. Kasacka et al., G and D cells in human pyloric evaluated under light microscope. Appropriate A washing with Wash Buffer S 3006 (Dako; Glostrup, Denmark) was performed between each step. The specificity tests performed for the gastrin and somatostatin antibody included: negative control, where the antibodies were replaced by normal rab- bit serum (Vector Laboratories; Burlingame, CA) at the respective dilution, and positive control was done for specific tissue recommended by producer. Quantitative analysis Immunopositive cells were counted in 5 visual fields in one section, each field being 0.785 mm2, at a magnification of 200¥ (20¥ the lens and 10¥ the B eyepiece). Three specimens in each of the 19 sub- jects were analysed. The analysis of the preparations and their pho- tographic documentation were performed with an Olympus B¥50 light microscope with a video cir- cuit and a Pentium 120 PC computer with NIS Ele- ments AR 3.10 NIKON software for microscope im- age analysis. The cell count was expressed as the mean num- ber of G and D cells per visual field. Statistical analysis All the presented data were statistically analy- sed by means of the software package Statistica Figure 1A, B. Photomicrographs illustrating the distribution of cells immunoreactive for gastrin in the human stomach (glands of Version 7.0. Descriptive statistics (mean, SD) were the pyloric mucosa).