EFFECTS OF CHRONIC ETHANOL-CONSUMPTION AND AGING ON 5-HT2A RECEPTORS AND 5-HT REUPTAKE SITES

The serotonergic system in brain is adversely affected by both aging a nd chronic ethanol consumption. The present study examined the combine d effects of aging and chronic ethanol consumption on two components o f the serotonergic system. Serotonin (5-HT) reuptake sites and 5-HT2A receptors were quantitated in brain areas of 5-, 14-, and 24-month-old male Fischer 344 rats that were pair-fed a control or 6.6% (v/v) etha nol-containing liquid diet on a chronic basis. The regions examined in clude those containing the cell bodies and projections of serotonergic neurons. These experiments demonstrated the sensitivity of the seroto nergic system of male Fischer 344 rats to both aging and chronic ethan ol consumption. In control rats, aging was associated with a decline i n the concentration of 5-HT2A receptors in the nucleus accumbens and f our cortical regions: frontal, parietal, piriform, and cingulate corte x 5-HT2A receptors were also reduced in the frontal, parietal, and cin gulate cortex of aged ethanol-fed rats. In contrast, 5-HT reuptake sit es were increased in older rats in the frontal cortex, nucleus accumbe ns, amygdala, and CA3 region of the hippocampus. If comparable changes in 5-HT2A receptors and 5-HT reuptake sites occur in elderly humans, they may contribute to ethanol consumption, and lead to cognitive and other age-related problems. These changes may also alter the effective ness of serotonergic drugs used in the treatment of alcoholism and men tal disorders. The effects of chronic ethanol consumption were more li mited. The only significant ethanol effect was an increase of 5-HT2A r eceptors in the nucleus accumbens of 5-month-old ethanol-fed rats.