Effect of growth hormone treatment on lymphocyte functions in old male rats

Age-related changes in the communication between the neuroendocrine and the immune system have been scarcely studied. Aging in mammals is associated with an impairment of the immune response, especially regarding lymphocyte functions. Furthermore, the endocrine system is also affected by aging, one of the most significant changes being the decrease in the secretion of several hormones such as growth hormone (GH).

The aim of the present work was to study whether GH replacement therapy in old male rats could improve several lymphocyte functions.

Spleen and axillary node lymphocytes from old (24 months of age) male Wistar rats were used in the present study to investigate the effect of GH (2 mg/kg daily during 10 weeks) on chemotaxis, lymphoproliferative response to the mitogen concanavalin A, interleukin 2 release and natural killer cell activity.

We have found that the administration of GH can reduce or even reverse the age-related changes observed in these key immune function parameters. Moreover, we have observed that the recovery of such immune functions is able to reach similar values as those exhibited by young control animals of 6 months of age.

Considering that the immune system is a marker of health and a predictor of longevity, hormone replacement therapies with GH, by increasing the immune function and thus delaying or slowing down some aspects of the aging process, could facilitate successful aging.