Increased adenylyl cyclase type 1 mRNA, but not adenylyl cyclase type 2 inthe rat hippocampus following antidepressant treatment

The adenylyl cyclase (AC) system is affected by several types of antidepres sant treatments, and increased activity in this system is linked to the the rapeutic action of antidepressants. The present study was undertaken to com pare the effects: of single-dose acid long-term treatment with the selectiv e serotonin reuptake inhibitor, citalopram (10 mg/kg, i.p.), on the AC syst em in the male rat brain of Wistar rats. Furthermore, we compared the effec ts of long-term citalopram and lithium treatments on the AC system. Long-te rm citalopram, but not single-dose administration, increased the AC type 1 mRNA in the hippocampus, whereas type 2 mRNA was unaffected. Long-term lith ium treatment also increased AC1 in the hippocampus. However, lone-term cit alopram treatment did not increase AC type 1 protein, basal or forskolin-st imulated AC activity, but CTP increased AC activity in the hippocampus. Thi s may indicate enhanced AC/G protein coupling. Thus, citalopram may increas e cAMP signalling by acting on components of the AC system without affectin g the protein level of the AC type 1. (C) 2000 Elsevier Science B.V. All ri ghts reserved.