Aging, stress, and chronic disease interact to suppress plasma testosterone in Syrian hamsters

The effects of old age, chronic disease, and stress on testicular function were exmined in Syrian hamsters living on a 12-hr photoperiod. Plasma testosterone concentrations and testes weights were maintained in healthy hamsters (16-19 months of age), but chronic stress decreased plasma testosterone in these old hamsters and not in younger ones (8-11 months of age). Chronic disease in the form of congestive heart failure (CHF) in cardiomyopathic hamstere also decreased plasma testosterone and testes weights, although it is not clear what aspects of this disease affected testicular function. There was an interaction between disease and stress, in that chronic stress produced lower plasma testosterone and testes weights in hamsters with heart failure than in age-matched stressed, healthy hamsters. It appears that younger hamsters can maintain reproductive function during stress, but older ones may not be able to do so. Congestive heart failure in hamsters clearly impairs normal reproductive function by itself; it also makes them more susceptible in stress, so that combining stress and disease results in almost complex suppression of plasma testosterone levels.