Effects of long-term chronic stress on the lymphoid organs and blood leukocytes of the rat (Rattus norvegicus)

Abstract

Exposure of adult female rats (Rattus norvegicus (Berkenhout,1769)) to restraint (1 h) and after a gap of 4 h to forced swimming exercise for 15 min daily for 12 weeks resulted in a significant decrease in (i) weight of the body and lymphoid organs (spleen, thymus, and axillary lymph node), (ii) counts of total leukocytes and their subpopulation (lymphocytes, neutrophils, monocytes, eosinophils, and basophils), and (iii) healthy cells of all lymphoid organs and a significant increase in the count of apoptotic cells in all the lymphoid organs. One month after cessation of exposure to stressors (recovery group), all the parameters did not significantly differ from stress-group rats. The results may indicate that either deleterious effects of long-term chronic exposure to stress are not reversible or the 4-week recovery period is not sufficient to restore normalcy.