The role of histamine in the initiation of the posttraumatic regeneration of the submandibular gland in rats

Abstract

It is found that both a stimulative and an inhibitory effect on histamine receptors retard the initiation and development of the posttraumatic regeneration of the subrnandibular gland. The selective blockade of H2 receptors does not lead to a compensatory hypertrophy of the paired gland. Key Words: salivary glands; histamine receptors; regenerationThe large salivary glands are organs with weak reparative regeneration. Anatomically these organs are rich in mast cells, which are situated close to each acinus and undergo massive degranulation in trauma (sialotomy). Many drugs [6] adrninistered intravenously cause histamine release from mast cells to the blood. The process of posttraumatic regeneration is a determined program [5], the fulfillment of which depends on the initial state of the organism and initiation factors [1,3]. The most common opinion is that the role of histamine is of a dual nature in the processes of proliferation depending on the dose [8][9][10][11][12].The aim of the present investigation was to study the role of histamine in the initiation of the posttraumatic regeneration of the submandibular gland (SMG). For this purpose the effect of endogenous histamine was either increased by means of exogenous histamine or decreased due to the selective blockade of H t or H 2 histamine receptors at the moment of trauma of the gland, after which the result of developing hypertrophy was assessed. MATERIALS AND METHODSExperiments were carried out on 109 outbred rats of both sexes weighing 150-300 g. Sialotomy was performed under combined anesthesia produced by i. p. administration of hexenal at 75 mg/kg and local infiltration of 2% novocain in the neck region. Then 1/3 of the right SMG was resected from the side of the lower pole through a medial incision of the neck skin and muscles. The bleeding was stopped by tamponade and interrupted sutures were put on the wound. A week later the animals were sacrificed with a lethal dose of hexenal. The body was then weighed and both SMG and the thymus were isolated. The organs and resected gland were dried at ll0~ to achieve of a constant mass. The result of reparative regeneration was assessed based on the determination of the resected weight, the weight of the gland at sacrifice, and the theoretical weight calculated according to a formula [2]. The percent of SMG regeneration and the percent change of paired gland weight were determined from these values.