Experimental Chagas disease: the influence of sex and psychoneuroimmunological factors

Abstract

The eects of gender and psychoneuroimmunological factors resulting from the social environment and status of males were investigated with regard to the concentrations of testosterone and corticosterone and the course of Trypanosoma cruzi infection in mice. Hormone concentrations varied considerably; and only testosterone concentrations showed a tendency to be higher in dominant males. Females kept singly developed lower and more similar parasitaemias than males kept singly or together with a female. This dierence was signi®cant when comparing groups of females or males. Within groups of male mice, parasitaemia was strongly correlated with the social position, being high in inferior males and low in dominant ones. The importance of these ®ndings is that they clearly prove that chronic social stress in males strongly aects the course of infection with T. cruzi.

Brief Communication: Latent toxoplasmosis and salivary testosterone concentration—Important confounding factors in second to fourth digit ratio studies

“…As noted in previous studies (Flegr et al, 2005;Hodková et al, 2007), a case control study cannot confirm whether Toxoplasma infection induces changes in the 2D:4D ratio, or whether low 2D:4D ratio subjects (i.e., subjects with higher testosterone concentrations) have a higher probability of acquiring Toxoplasma infection. High concentrations of testosterone are known to have immunosuppressive effects (Roberts et al, 2001;Schuster and Schaub, 2001), which could result in a higher probability of acquiring Toxoplasma infection. It must be stressed, however, that the lower concentration of testosterone in Toxoplasma-infected females makes the immunosuppression based explanation of the association between Toxoplasma infection and low 2D:4D ratio less likely.…”

“…Recently, an association between left hand 2D:4D ratio and infection with a common protozoan parasite Toxoplasma gondii (worldwide prevalence varies between 20 and 70% in different countries, depending on climate, hygiene standards, and eating habits) has been observed (Flegr et al, 2005). The probability of infection with this intracellular parasite is expected to correlate negatively with the activity of the cellular arm of the immune sys-tem, which is known to be inhibited by a high concentration of steroid hormones (Roberts et al, 2001;Schuster and Schaub, 2001). However, Toxoplasma is also known to induce behavioral and neurophysiological changes in infected human or animal hosts.…”

Social status does not predict responses to Seoul virus infection or reproductive success among male Norway rats

“…For example, subordinate male cynomolgus monkeys are more likely to develop infection following inoculation with influenza virus than are dominant males (Cohen et al, 1997). Similarly, subordinate mice exhibit immunosuppression and are more susceptible to infection with viruses, such as Moloney virus, and parasites, including Trypanosoma cruzi, than their dominant counterparts (Bartolomucci et al, 2001;de Groot et al, 2002;Ebbesen et al, 1991;Raab et al, 1986;Schuster and Schaub, 2001). Reduced immunocompetence among subordinate males may be caused by elevated corticosterone concentrations in response to antagonistic interactions (Blanchard et al, 1993(Blanchard et al, , 1995Raab et al, 1986;Sapolsky, 2005).…”

Body height, body mass index, waist-hip ratio, fluctuating asymmetry and second to fourth digit ratio in subjects with latent toxoplasmosis

“…with more pronounced random deviations from the right-left symmetry of the body, have been shown to be typically more prone to infections (Watson & Thornhill, 1994 ;Møller, 1996). Susceptibility to several infections also positively correlates with prenatal and adult testosterone levels (Zuk & McKean, 1996 ;Schuster & Schaub, 2001). The average testosterone level in humans and other mammalian species can be estimated on the basis of the 2D : 4D ratio, i.e.…”