Autoradiography and in situ hybridisation were used to examine age-dependent changes in adenosine receptors in male rats and to determine if life-long (94 weeks) intermittent ethanol consumption had any additional effect. Adenosine A2A receptors in striatum, as assessed by [3H]CGS 21680 binding, decreased by approximately 20% between the ages 6 and 99 weeks. Since dopamine D2 receptors and the mRNA for preproenkephalin also decreased there appears to be a loss of A2A-D2 receptor-bearing striatopallidal cells. Life-long ethanol consumption had no additional effect. Adenosine A1 receptors, as determined by [3H]DPCPX binding, did not decrease with age in any region of the brain, but increased slightly in the cerebellum. In substantia nigra, the increase in [3H]DPCPX binding upon addition of GTP was eliminated. Surprisingly, the amount of A1 receptor mRNA decreased significantly with age in most of the examined regions, including the cerebellum. There was no additional effect of ethanol treatment. It is suggested that age alters the number of cells that express A2A receptors, the turnover of A1 receptors, and in some regions their coupling to G proteins, but that life-long intermittent ethanol exposure has little additional effect.
Copyright 1998 Elsevier Science B.V.