The effect of stress on the migration of leucocytes into the peritoneal cavity of rats following injection of an inflammatory agent

Although previous studies have shown that the injection of exogenous corticosteroids suppresses the inflammatory response, no study has been made on the effect on inflammation of endogenous corticosteroids released in response to stress. In the present study a reduction was observed in the total number of leucocytes migrating into the peritoneal cavity of stressed rats in response to the injection of an inflammatory agent. The reduction in total counts was due to a stress-induced reduction of both polymorph and mononuclear cells. Permeability studies and blood leucocyte counts were conducted to determine the mode of action of the stress-induced reduction of leucocyte migration. In the case of the polymorphs. evidence is presented to implicate both a reduced release of these cells into the blood stream from storage sites and a blockade of the increased vascular permeability. The situation is not as clear for the mononuclear cells where no change in the circulating levels of these cells was observed in either stressed or control rats following induction of an inflammatory response.