Carmen Alvarado

Improvement of leucocyte functions in ovariectomised aged rats after treatment with growth hormone, melatonin, oestrogens or phyto-oestrogens

Ageing is accompanied by an impairment of the physiological activity of the nervous, endocrine and immune system, as well as in neuroendocrine-immune communication. However, age-related changes in this communication axis have been scarcely studied. In mammals, the process of ageing is associated with an important decline in the secretion of several hormones, such as growth hormone (GH), melatonin (MEL) and oestrogens (Os). Ovariectomy, a model of menopause in rats, has been found to lead to premature immunosenescence. In the present study, the effect of ovariectomy and the role of replacement therapies with GH, MEL, O and natural phyto-oestrogens (POs) have been assessed on several functions in leucocytes from the spleen and the axillary nodes of intact and ovariectomised rats. Chemotaxis, lymphoproliferative response to the mitogen concanavalin A (Con A), the release of interleukin-2 (IL-2) and the natural killer (NK) cell activity have been investigated. Age-controlled rats were used to compare immune functions in hormone treated aged rats with those in younger untreated animals. In all experimental groups, the immune impairment caused by ageing and ovariectomy was partially or completely reversed by hormone treatments. Since the immune system is a marker of health and a predictor of longevity, the results suggest that treatment with hormones could slow down the effects of the ageing process.

Improvement of immune cell functions in aged mice treated for five weeks with soybean isoflavones.

Abstract:  Aging is associated with an impaired immune system as well as with a decline of several hormones, such as estrogens. Dietary phytoestrogens have been proposed as an alternative to hormone replacement therapy. The beneficial action of soybean compounds is probably due to isoflavones, whose role as immunomodulators has been investigated with increasing interest. The aim of the present work was to study whether a 5‐week administration of a diet enriched in soybean isoflavones and green tea could influence the immune function of mice that were sham‐operated or ovariectomized. Natural killer activity (NK) and lymphoproliferation in response to the mitogens concanavaline A (Con A) and lipopolysaccharide (LPS), were studied in peritoneal leukocytes. Both treatments with soybean or green tea plus soybean were highly effective in improving these immune parameters with respect to control groups. Since the immune system is a marker of health and a predictor of longevity, an adequate treatment with isoflavones could be useful in slowing down the effects of the aging process through an improvement in the two relevant immune functions studied.

Effect of Growth Hormone Treatment on Lymphocyte Functions in Old Male Rats

Introduction: 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). Objective: The aim of the present work was to study whether GH replacement therapy in old male rats could improve several lymphocyte functions. Methods: 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. Results: 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. Conclusion: 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.