Identification of serotonin transporter mRNA in rat platelets

Total RNA was isolated from rat platelets by guanidinium - acid - phenol extraction, and mRNA for the serotonin (5-hydroxytryptamine) transporter (5HTt) was identified. From a typical starting sample of 20 mL of rat blood (similar to 9 x 10(9) platelets), 14 to 17 mu g of total platelet RNA was obtained. Northern blot analysis, using P-32-labeled 5HTt cDNA as a probe, identified similar to 3.3 kb long 5HTt mRNA. After rehybridization with cyclophilin cDNA, similar to 1 kb long mRNA for cyclophilin, which could serve as a reference for 5HTt mRNA quantification, was also identified. Densitometric analysis demonstrated clearly measurable signals for both mRNAs. The possibility of quantification of rat platelet 5HTt mRNA should enable parallel studies on 5HTt gene expression in platelets and brain of the same animal, and the evaluation of the platelet model at the molecular genetic level.