<i>Toxoplasma gondii</i> infection enhances testicular steroidogenesis in rats

Lim, Audrey; Kumar, V.; Dass, Shantala A. Hari; Vyas, Ajai

doi:10.1111/mec.12042

Cited by 117 publications

(125 citation statements)

References 43 publications

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“…In other words, T. gondii infection increases urinary excretion of α2u-globulins, and greater α2u-globulins in the infected urine is sufficient to signal greater attractiveness. Greater α2u-globulins production in the infected rats is congruent with the observations that these proteins require testosterone for synthesis and that T. gondii infection increases testosterone production in male rats (Kulkarni et al, 1985;Lim et al, 2013).…”

supporting

confidence: 77%

α2u-globulins mediate manipulation of host attractiveness in Toxoplasma gondii–Rattus novergicus association

et al. 2015

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Uninfected female rats (Rattus novergicus) exhibit greater attraction to the males infected with protozoan parasite Toxoplasma gondii. This phenomenon is contrary to the aversion towards infected males observed in multitude of other host-parasite associations. In this report, we describe a proximate mechanism for this anomaly. We demonstrate that T. gondii infection enhances hepatic production and urinary excretion of α2u-globulins in rats. We further demonstrate that α2u-globulins are sufficient to recapitulate male sexual attractiveness akin to effects of the infection. This manipulation possibly results in greater horizontal transmission of this parasite between the infected male and the uninfected female. It supports the notion that in some evolutionary niches parasites can alter host sexual signaling, likely leading to an increased rate of sexual transmission.

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confidence: 77%

α2u-globulins mediate manipulation of host attractiveness in Toxoplasma gondii–Rattus novergicus association

et al. 2015

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“…At the mechanistic level, reports on parasites that directly affect the neuronal system of their hosts or the levels of relevant hormones, such as testosterone, show that STDs, in principle, could easily manipulate the sexual behavior of their hosts. We only have to think of T. gondii, which enhances testicular testosterone production in male rats (Lim et al, 2013). In cats, infection with Feline Immunodeficiency Virus (FIV) and Feline Leukemia Virus (FeLV) has been correlated with enhanced plasma concentrations of sexual hormones, including testosterone (Tejerizo et al, 2012).…”

Section: Host Manipulation By Stds-rarely Evolved or Rarely Studied?mentioning

confidence: 99%

“…The production of these molecules would have a metabolic cost, the order of magnitude of which depends on the consumption of energy and limiting elemental resources that are required for its production or maintenance, relative to the overall metabolic demands of the parasite. It might be no coincidence that T. gondii triggers the synthesis of signaling compounds in its host, rather than producing these compounds itself (Gaskell et al, 2009;Prandovszky et al, 2011;Lim et al, 2013). Viruses depend completely on the metabolism of their host and, thus, should gain most when they manipulate the reallocation of host compounds, or the activity of existing signaling molecules, rather than inducing costly de-novo synthesis (Hoover et al, 2011).…”

Section: Why Don't All Parasites Manipulate?mentioning

confidence: 99%

“…T. gondii cysts in the brain of an infected host produce large amounts of dopamine and the neurotransmitter is exported into the surrounding tissue (Prandovszky et al, 2011). The commonly observed increase in testosterone levels in infected male rats involves an increase in the expression of those receptors in the testes that regulate the synthesis of testosterone (Lim et al, 2013). This finding might explain why enhanced levels of testosterone have been observed only in infected men (Flegr et al, 2008;Shirbazou et al, 2011), and for the multiple behavioral and psychological traits in which men and women with latent toxoplasmosis exhibit opposite trends (Flegr et al, 2011;Flegr, 2013b).…”

Section: Physiological Mechanismsmentioning

confidence: 99%

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Host Manipulation by Parasites: Cases, Patterns, and Remaining Doubts

Heil

2016

Front. Ecol. Evol.

109

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Parasites must overcome host immunity and change hosts for dispersal. Therefore, seemingly odd behaviors of parasitized animals, like those exhibited by "Zombie ants" or the "fatal attraction" of mammals to their predators, have been explained as the extended phenotype of parasites that manipulate their hosts for transmission enhancement. Manipulation has evolved in all major phylogenetic lineages of parasites but is not ubiquitous. In fact, the real frequency and relevance of manipulation is still matter of debate. Here, I highlight some of the most pertinent questions that arise if we aim at a broader understanding of the ecological relevance and evolutionary trajectory of manipulating parasites. Why are more parasites with a trophic mode of transmission manipulating their host than horizontally transmitted parasites? Why are the causal agents of sexually transmitted diseases (STDs) so rarely reported to manipulate their host? Why do parasites of animals usually manipulate their intermediate host, whereas many pathogens of plants manipulate their final host and then cause a "fatal attraction" of herbivores to the already infected plant? How can we distinguish manipulation effects from adaptive host responses to parasitization? Does manipulation cause a cost to certain parasites that can select against the evolution of manipulation? More emphasis should be put on direct comparisons among parasites of animals, plants, and humans. Manipulation for transmission enhancement should be studied in concert with manipulation for host immunity suppression, the molecular mechanisms that control the manipulation effect need to be deciphered, and we should test for alternative explanations for the observed phenotypic changes. Finally, we should quantify transmission rates and net fitness for manipulating and non-manipulating parasites, in ecologically realistic setups, to identify the forces that select against the evolution of manipulation. Ultimately, parasite net fitness represents the relevant outcome of any manipulation effect.Keywords: immunity, malaria, partner manipulation, pathogen, plant-enemy interaction, STDs, toxoplasmosis "FATAL ATTRACTION" AND MANIPULATING PARASITES Parasites represent a ubiquitous aspect in the life of multicellular organisms (Wood and Johnson, 2015) and most, if not all, of us have experienced how strongly an infection can interfere with our normal activities and well-being. Therefore, it might not appear to be too surprising when parasitized hosts exhibit behavioral alterations (see Glossary) as compared to healthy conspecifics.

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“…For example, behaviour-parasite feedbacks (discussed below) are often mediated by effects of parasites on host hormone levels [41,42] and, in some cases, appear to involve adaptive parasite manipulation of host neuroendocrine pathways [43,44]. Progress in understanding feedbacks between behaviour and multiple, interacting components of the overall neuroendocrine system should be invaluable for better understanding personalities.…”

mentioning

confidence: 99%