ADAPTIVE-CHANGES IN THE RAT DOPAMINERGIC TRANSMISSION FOLLOWING REPEATED LITHIUM ADMINISTRATION

In the present study the alterations in the contents of dopamine (DA) and metabolites, as well as in the levels of mRNA coding for DA recept or D-2, were determined in the rat striatum (STR) and nucleus accumben s septi (NAS), in correlation with the duration of lithium administrat ion. Single or subchronic (3 days) administration of lithium produced less consistent effects as far as the levels of DA and metabolites are concerned; however, following 7 or 14 days of lithium administration, the DA release from terminals was significantly attenuated and the ef fect was more pronounced in NAS. After the same time of treatment, the increase in the levels of mRNA coding for the D-2 receptor was increa sed; this might be interpreted as an adaptive change to the decreased dopaminergic transmission following the prolonged administration of li thium.