Thymus-dependent reversibility of physiological and isoproterenol evoked age-related parameters in athymic (nude) and old normal mice.

In order to assess the relationship between the thymus and aging processes, a linear age-dependent parameter in mice such as the response of the submandibular gland to an injection with isoproterenol has been evaluated in athymic (nude) and thymectomized Balb/c mice. The IPR-induced DNA synthesis is reduced in both experimental groups when compared to untreated normal littermates and is recovered by grafting a neonatal thymus. Moreover, the impairment of IPR response in old animals is recovered to young levels by grafting one neonatal thymus one month before test. Neonatal thymus grafts in old recipients are also able to correct their abnormal serum levels of triiodothyronine and insulin. The influence of neonatal thymus on such non-immunological and age-related parameters suggests that this gland can control aging processes, probably through its implication with the endocrine system.