Time-related response of central serotonergic function to lithium administration.

The possibility of "acute" (1 hr) changes in serotonergic function by lithium chloride (LiCl) administration was investigated in the rat corpus striatum and frontal cerebral cortex: an increase in 5-HT biosynthesis in vivo and 5-HIAA levels was observed in both areas. After chronic LiCl treatment (14 days) only cortical 5-HIAA levels were reduced. These changes were not correlated with plasma lithium levels. Consequently, LiCl "acutely" (1 hr) probably enhances striatal and cortical serotonergic transmission, this response varying with time of treatment as a result of possible neuronal compensatory mechanisms.