[Effects of hormones on aging of the CNS, the immune system and the skin in rats].

In a previous communication to the RANM two years ago, some data were presented supporting the role of GH, melatonin and estrogens in the prevention of aging of bone, liver metabolism and vascular activity. Additional data were presented about the beneficial effect of these hormones on the Central nervous System (CNS). In the present communication results obtained since that time on the CNS, the immunitary system and the skin will be presented. A total of 140 male and female rats have been investigated. Animals have been decapitated every 6 months starting with 2 and finishinf with 24 months. Another group of 64 rats from both sexes has been submitted to different treatments over 10 weeks, between 22 and 24 months of age. Males have been treated with GH and melatonin. Females were divided in two groups: intact and castrated at 12 months of age. The first group was treated with GH and melatonin and the second with these two and additionally with estradiol and with Phytosoya. Total number of neurones in the hilus of the dentate gyrus has been counted in Nissl stained cerebral cuts. Neurogenesis was estimated by staining with BrdU. Immunitary function was estimated measuring NK activity, chemiotaxis and lymphoproliferative activity in response to Concanavaline A in cultures of leucocytes obtained from axillary nodes and spleen of the animals as well as liberation of IL2 to the medium. An age dependent reduction in the number of neurones has been registrated in male and female rats, without influence of the ovariectomy. A dramatic reduction in neurogenesis has been also detected in both sexes. GH stimulates total number of neurones but does not modify neurogenesis, so a reduction in apoptosis has been considered. This seems to be supported by the reduction in nucleosomes and the increase in Bcl2 observed in cerebral homogenates. Immunitary functions show an age dependent reduction that gets worse with ovariectomy. GH treatment enhances all affected functions as well as estrogens and in some cases melatonin. The skin is also deteriorated by age and that is translated in a reduction of epidermal thickness, an increase in dermical fat and a lowering in the numer of ibroblasts. All these alterations are recovered with GH and melatonin. Keratinocytes from old animals in culture show an increase in nucleosomes nd a reduction in Bcl2 that is restaured with GH and melatonin.