CHANGES OF LYMPHOCYTE BETA-ADRENERGIC RECEPTORS AND PLATELET SEROTONIN REUPTAKE SITES IN AGING AND DEMENTIAS

We have studied the kinetic constants of beta-adrenergic receptors in lymphocytes and of serotonin uptake sites in platelets from adult and elderly volunteers and from aged patients with a diagnosis of multi-in farct dementia (MID) or senile dementia of Alzheimer's type (SDAT). Th e results showed that in the physiological aging process, beta-adrener gic receptor density is reduced and 5HT transport system is enhanced. MID is associated to a loss of beta-adrenoceptor affinity and a slight increase in the capacity of 5HT uptake. The kinetic constants of both beta-adrenergic receptors in lymphocytes and 5HT uptake sites in plat elets from SDAT patients were comparable to those observed in the adul t population, being thus different from those found in the aged matche d volunteers. These changes could be interpreted as resulting from com pensatory mechanisms that replaced altered plasma monoamine concentrat ions. The apparent absence of such changes in SDAT patients could sugg est the lack of these compensatory effects.