The effect of prolonged administration of lithium on the level of dopamine D2 receptor mRNA in the rat striatum and nucleus accumbens.

In the present study the alterations in the levels of mRNA coding for dopamine receptor D2, were determined in the rat striatum (STR) and the nucleus accumbens septi (NAS), in dependence on duration of lithium administration. The levels of mRNA coding for D2 receptor (determined using an in situ hybridization technique) were determined after 1, 7 and 14 days of lithium administration (LiCl, 6 mEq/kg, p.o.), at 3 and 24 h after the last dose of the drug. This treatment resulted in the increase in the levels of mRNA coding for dopamine receptor D2 in all brain regions examined and the effect depended on the time after lithium administration. However, the effect was most pronounced in the shell region of NAS, 24 h after the 14-day treatment.