Background: Some data show that different factors may influence the serotonin (5-HT) uptake rate. Our study aimed at evaluating the possible role of a protein kinase C (PKC) activator i.e., 4-beta-12-tetranecanoylphorbol-13-acetate (P-TPA) on the platelet 5-HT uptake of young and elderly subjects, through the measurement of the 5-HT uptake itself and H-3-paroxetine ([H-3]PAR) binding sites, which correspond to the transporter protein. Methods: Human platelets and 5-HT uptake were evaluated according to the method of Arora and Meltzer, while [H-3]PAR binding was performed following the Marazziti et al method. Results: The results showed that P-TPA reduced significantly the maximal velocity (Vmax) of 5-HT uptake, with no change in the Michaelis constant or in [H-3]PAR binding parameters, in platelets of both young and elderly subjects. Although this last group of subjects had a significantly lower Vmax than the other, the degree of inhibition was almost the same (75%) in both. Conclusions: These findings indicate that PKC decreases the 5-HT uptake rate by modifying the phosphorylation state of the transporter and with no change in the number of [H-3]PAR binding sites. The responsiveness of this pathway is identical in both young and elderly subjects. (C) 1999 Society of Biological Psychiatry.
Regulation of the platelet serotonin transporter by protein kinase C in the young and elderly
ROSSI, ALESSANDRA;PALEGO, LIONELLA;MAZZONI, MARIA ROSA;GIANNACCINI, GINO;LUCACCHINI, ANTONIO;
1999-01-01
Abstract
Background: Some data show that different factors may influence the serotonin (5-HT) uptake rate. Our study aimed at evaluating the possible role of a protein kinase C (PKC) activator i.e., 4-beta-12-tetranecanoylphorbol-13-acetate (P-TPA) on the platelet 5-HT uptake of young and elderly subjects, through the measurement of the 5-HT uptake itself and H-3-paroxetine ([H-3]PAR) binding sites, which correspond to the transporter protein. Methods: Human platelets and 5-HT uptake were evaluated according to the method of Arora and Meltzer, while [H-3]PAR binding was performed following the Marazziti et al method. Results: The results showed that P-TPA reduced significantly the maximal velocity (Vmax) of 5-HT uptake, with no change in the Michaelis constant or in [H-3]PAR binding parameters, in platelets of both young and elderly subjects. Although this last group of subjects had a significantly lower Vmax than the other, the degree of inhibition was almost the same (75%) in both. Conclusions: These findings indicate that PKC decreases the 5-HT uptake rate by modifying the phosphorylation state of the transporter and with no change in the number of [H-3]PAR binding sites. The responsiveness of this pathway is identical in both young and elderly subjects. (C) 1999 Society of Biological Psychiatry.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
