The effects of short-term exposure to crowding stress on the pancreatic islets morphology and glycemia in mice.
Behavior, pancreatic islets morphology and plasma glucose levels of male mice exposed for 2, 4, 24 and 48 hours to crowding stress were investigated. The crowding induced an intense turmoil state associated with enhanced irritability and aggressiveness among the specimens of all experimental groups. Violent fights occurred especially in the first 4--6 hours, generally with the death of 1--2 individuals from each group. The changes recorded in the pancreatic islets affected first (2 hours) exclusively the insulin-producing cells, and in subsequent intervals they progressively expanded over all cell types. The changes occurred during the experiment in all islet cell types; however the B-cells showed by far the most pronounced alterations irrespective of the studied time interval. Most changes suggested the stimulation of the entire gland secretory activity, but particularly of B-cells, which was also proved by low glycemia values recorded at 3 of the 4 crowding time intervals. On the other hand, some alterations, occurring first at 24 hours, were regarded as signs of a moderate B-cells secretory hypoactivity; they may partly support the slight hyperglycemia obtained at this time interval. The significance of the above short-term observations in the induction of glycoregulation disturbances, diabetes included, as well as the presumably mediation role of adrenal-cortex and -medulla hormones under stress conditions are discussed and correlated with findings reported in literature.