AGING-INDUCED CHANGES IN BRAIN REGIONAL SEROTONIN RECEPTOR BINDING: EFFECT OF CARNOSINE

Monoamine neurotransmitter, serotonin (5-HT) has its own specific receptors in both pre- and post-synapse. In the present study the role of carnosine on aging-induced changes of [H-3]-5-HT receptor binding in different brain regions in a rat model was studied. The results showed that during aging (18 and 24 months) the [H-3]-5-HT receptor binding was reduced in hippocampus, hypothalamus and pons-medulla with a decrease in their both B-max and K-D but in cerebral cortex the [H-3]-5-HT binding was increased with the increase of its only B-max. The aging-induced changes in [H-3]-5-HT receptor binding with carnosine (2.0 mu g/kg/day, intrathecally, for 21 consecutive days) attenuated in (a) 24-month-aged rats irrespective of the brain regions with the attenuation of its B-max except hypothalamus where both B-max and K-D were significantly attenuated, (b) hippocampus and hypothalamus of 18-month-aged rats with the attenuation of its B-max, and restored toward the [H-3]-5-HT receptor binding that observed in 4-month-young rats. The decrease in pons-medullary [H-3]-5-HT binding including its B-max of 18-month-aged rats was promoted with carnosine without any significant change in its cerebral cortex. The [H-3]-5-HT receptor binding with the same dosages of carnosine in 4-month-young rats (a) increased in the cerebral cortex and hippocampus with the increase in their only B-max whereas (b) decreased in hypothalamus and pons-medulla with a decrease in their both B-max and K-D. These results suggest that carnosine treatment may (a) play a preventive role in aging-induced brain region-specific changes in serotonergic activity (b) not be worthy in 4-month-young rats in relation to the brain regional serotonergic activity. (C) 2016 IBRO. Published by Elsevier Ltd. All rights reserved.