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Melatonin triggers PKA activation in the rodent malaria parasite Plasmodium chabaudi
Author(s) -
Gazarini Marcos L.,
Beraldo Flávio H.,
Almeida Fabiana M.,
Bootman Martin,
Da Silva Aline M.,
Garcia Célia R. S.
Publication year - 2011
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1111/j.1600-079x.2010.00810.x
Subject(s) - melatonin , plasmodium chabaudi , biology , second messenger system , microbiology and biotechnology , stimulation , intracellular , medicine , endocrinology , parasitemia , plasmodium falciparum , immunology , malaria
Calcium (Ca 2+ ) is a critical regulator of many aspects of the Plasmodium reproductive cycle. In particular, intra‐erythrocyte Plasmodium parasites respond to circulating levels of the melatonin in a process mediated partly by intracellular Ca 2+ . Melatonin promotes the development and synchronicity of parasites, thereby enhancing their spread and worsening the clinical implications. The signalling mechanisms underlying the effects of melatonin are not fully established, although both Ca 2+ and cyclic AMP (cAMP) have been implicated. Furthermore, it is not clear whether different strains of Plasmodium use the same, or divergent, signals to control their development. The aim of this study was to explore the signalling mechanisms engaged by melatonin in P. chabaudi , a virulent rodent parasite. Using parasites at the throphozoite stage acutely isolated from mice erythrocytes, we demonstrate that melatonin triggers cAMP production and protein kinase A (PKA) activation. Interestingly, the stimulation of cAMP/PKA signalling by melatonin was dependent on elevation of Ca 2+ within the parasite, because buffering Ca 2+ changes using the chelator BAPTA prevented cAMP production in response to melatonin. Incubation with melatonin evoked robust Ca 2+ signals within the parasite, as did the application of a membrane‐permeant analogue of cAMP. Our data suggest that P. chabaudi engages both Ca 2+ and cAMP signalling systems when stimulated by melatonin. Furthermore, there is positive feedback between these messengers, because Ca 2+ evokes cAMP elevation and vice versa . Melatonin more than doubled the observed extent of parasitemia, and the increase in cAMP concentration and PKA activation was essential for this effect. These data support the possibility to use melatonin antagonists or derivates in therapeutic approach.