The effect of cyclic AMP on the growth of <i>Toxoplasma gondii</i><i>in vitro</i>

, Choi, W Y; , Nam, H W; , Youn, J H; , Kim, D J; , Kim, W K; , Kim, W S

doi:1990.28.2.71

Korean J Parasito > Volume 28(2):1990 > Article

Original Article


Korean J Parasitol. 1990 Jun;28(2):71-78. English. Published online Mar 20, 1994. http://dx.doi.org/10.3347/kjp.1990.28.2.71
Copyright © 1990 by The Korean Society for Parasitology


The effect of cyclic AMP on the growth of Toxoplasma gondiiin vitro
W Y Choi,H W Nam,J H Youn,D J Kim,W K Kim and W S Kim
Catholic Institute of Parasitic Diseases, Catholic University Medical College, Seoul 137-701, Korea.


Abstract
To assess the role of cAMP on the growth and proliferation of Toxoplasma in HL-60 cells we tested the effect of exogenous cAMP and cAMP analogues to the co-culture system of Toxoplasma and HL-60 cells. cAMP, dbcAMP, and br-cAMP stimulated the growth of Toxoplasma at a specific concentration, i.e., 10⁰ mM, 10⁰ mM, and 10^-1 mM, respectively. There were differences in growth induction kinetics and in the rate of promotion. These results were further verified by treating the co-culture with adenylate cyclase activator, pNHppG, cAMP phosphodiesterase activators, imidazole and A23187, and cAMP phosphodiesterase inhibitors, IBMX, compound 48/80, and theophylline, separately. When the cytosolic cAMP levels increased by the reagents mentioned above, Toxoplasma in the cytoplasm of HL-60 cells stimulated to proliferate more rapidly with concentration-dependent modes compared to the control, and vice versa. It is suggested that some mechanisms are activated by the high levels of cAMP in the cytoplasm, which result in the stimulation of Toxoplasma proliferation.

Figures


	Fig. 1 Kinetics of uptake of [³H]-uracil into infected (•-•) and uninfected (○--○) HL-60 cells with Toxoplasma. Cells were incubated with ³H-uracil for 2 hr pulsely at 12 hr interval.

Fig. 2
Effect of cAMP on the growth of Toxoplasma in HL-60 cells. Various concentrations of cAMP, 0.5 mM (○--○) , 1mM(□--□), 5mM (•…•), and 10 mM (▪--▪) treated at the time of inoculation of Toxoplasma, and the cells were labeled with ³H-uracil(left) and ³H-thymidine(right) for 2 hr, Effect of cAMP was described as a ratio of ³H-uracil uptake to control which was not treated.


	Fig. 3 Effect of dbcAMP on the growth of Toxoplasma in HL-60 cells. Various concentrations of dbcAMP, 0.5 mM (○--○) , 1 mM(□--□), 5 mM (•…•), and 10 mM (▪--▪) were treated at the time of inoculation of Toxoplasma. Refer to th legend of Fig. 2.


	Fig. 4 Effect of 8-br-cAMP on the growth of Toxoplasma in HL-60 cells. Various concentrations of 8-br-cAMP, 0.05 mM (○--○) , 0.1 mM(□--□), 0.5 mM (•…•), and 1 mM (▪--▪) were treated at the time of inoculation of Toxoplasma. Refer to th legend of Fig. 2.


	Fig. 5 Effect of guanylyl imidodiphosphate(pNH-ppG; adenylate cyclase activator) on the growth of Toxoplasma in HL-60 cells. Various concentrations of pNHppG, 0.01 mM (○--○) , 0.05 mM(□--□), 0.1 mM (•…•), and 0.5 mM (▪--▪) were treated at the time of inoculation of Toxoplasma. Refer to th legend of Fig. 2.


	Fig. 6 Effect of A23187(cAMP phosphodiesterase activator) on the growth of Toxoplasma in HL-60 cells. Various concentrations of A23187, 0.5 µg/ml (○--○) , 1.0 µg/ml (□--□), 5.0 µg/ml (•…•), and 10 µg/ml (▪--▪) were treated at the time of inoculation of Toxoplasma. Refer to th legend of Fig. 2.


	Fig. 7 Effect of imidazole(cAMP) phosphodiesterase activator) on the growth of Toxoplasma in HL-60 cells. Various concentrations of imidazole, 0.1 mM (○--○) , 0.5 mM(□--□), 1.0 mM (•…•), and 5 mM (▪--▪) were treated at the time of inoculation of Toxoplasma. Refer to th legend of Fig. 2.


	Fig. 8 Effect of IBMX (cAMP phosphodiesterase inhibitor) on the growth of Toxoplasma in HL-60 cells. Various concentrations of IBMX, 0.1 mM (○--○) , 0.5 mM(□--□), 1.0 mM (•…•), and 5 mM (▪--▪) were treated at the time of inoculation of Toxoplasma. Refer to th legend of Fig. 2.


	Fig. 9 Effect of theophylline (cAMP phosphodiesterase inhibitor) on the growth of Toxoplasma in HL-60 cells. Various concentrations of theophylline, 0.1 mM (○--○) , 0.5 mM(□--□), 1.0 mM (•…•), and 5 mM (▪--▪) were treated at the time of inoculation of Toxoplasma. Refer to th legend of Fig. 2.


	Fig. 10 Effect of compound 48/80(cAMP phosphodiesterase inhibitor) on the growth of Toxoplasma in HL-60 cells. Various concentrations of compound 48/80, 0.1 mg/ml (○--○) , 0.5 mg/ml(□--□), 1.0 mg/ml (•…•), and 5 mg/ml (▪--▪) were treated at the time of inoculation of Toxoplasma. Refer to th legend of Fig. 2.

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