Acta Tropica 109 (2009) 141–145 Contents lists available at ScienceDirect Acta Tropica journal homepage: www.elsevier.com/locate/actatropica Taenia crassiceps infection disrupts estrous cycle and reproductive behavior in BALB/c female mice Marcela Arteaga-Silva a , José Antonio Vargas-Villavicencio b , Rosa María Vigueras-Villase˜ nor c , Mauricio Rodríguez-Dorantes b , Jorge Morales-Montor b,∗ a Departamento de Biología de la Reproducción, Universidad Autónoma Metropolitana, Iztapalapa, A.P. 55 535, México, D.F. 09340, Mexico b Departamento de Inmunología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, A.P. 70228, México, D.F. 04510, Mexico c Laboratorio de Histomorfología, Instituto Nacional de Pediatría, México, D.F., Mexico article info Article history: Received 4 April 2008 Received in revised form 21 June 2008 Accepted 17 October 2008 Available online 8 November 2008 Keywords: Cysticercosis Taenia crassiceps Parasite Infection Sexual behavior Estrous cycle abstract Previously, it has been shown that parasitic infections are able to alter the normal mammal physiology, at several extents. Thus, we investigated the effects on estrous cycle and sexual behavior induced by intraperitoneal infection with Taenia crassiceps in female host mice. Along the weeks of infection, parasites were collected from the peritoneal cavity of female mice, showing the maximum parasite load at 16 weeks. No parasites were found outside peritoneal cavity. Vaginal estrous cycle was monitored daily for 4, 8, 12 and 16 weeks of infection, and results compared against age-matched female mice. Female sexual behavior (FSB) tests were performed, one test per week. Immediately after the last behavioral test, blood was collected by cardiac puncture for steroid determinations. First of all, there was a strong tissular damage in the female reproductive tract in all infected females. The phases of the estrous cycle were interrupted at 12 and 16 weeks, with increased leukocytes and the presence of a few cornified epithelial cells and nucleated epithelial cells. The FSB decreased starting 6 weeks post infection. On the 16th week, all infected female mice ceased to exhibit sexual responses, and estradiol levels showed a significant decrease. Control mice continued showing FSB and the different phases of the estrous cycle throughout the observation period. Our results strength the notion that parasites may be considered as an evolutionary force in the reproductive ability of mammals. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Vertebrates exhibit great diversity in reproductive strategies. Although the evolution of vertebrate reproduction has been attributed to factors such as topography (Urban et al., 2008), unpredictable larval environments (Browne and Zippel, 2007), and predation (Bonenfant et al., 2007), selective pressure from parasites must also be considered (Todd, 2007; Kokko et al., 2008). Impor- tantly, sometimes authors ignore parasites, either unicellular or multicellular, as selective agents capable of influencing vertebrate evolution (Lampert and Schartl, 2008; Touchon and Warkentin, 2008). Most of the reports regarding the effect of parasitic infections on estrous cycling of several host species, were done mainly in proto- zoan infections (Akingbade, 1992; Heinonen et al., 1988; Elhassan et al., 1994), either natural or experimental, and concluded that ∗ Corresponding author. Tel.: +52 55 56223854; fax: +52 55 56223369. E-mail addresses: jmontor66@biomedicas.unam.mx, jmontor66@hotmail.com (J. Morales-Montor). cycling was disrupted as a result of interference with the endocrine control system. For instance, it has been shown that, in acute malaria, the sexual physiology of the female is strongly affected (Akingbade, 1992). In another related study, infection with Try- panosoma evansi impaired estrous activity in one Friesian Holstein heifer (Payne et al., 1993). An association between weight loss and disruption of ovarian activity has been well established in dairy cows (Heinonen et al., 1988) and infection of West African Dwarf ewes with Trypanosoma vivax leads to a decrease in plasma proges- terone serum levels until either recovery or death (Elhassan et al., 1994). Moreover, infection with Trypanosoma congolense induced changes in the length of estrous cycles, plasma progesterone and estradiol-17 beta levels in infected East African goats (Mutayoba et al., 1988). Furthermore, the alterations of the vaginal estrous cycle during the patent period of malaria in mice appeared as an increase in the occurrence and duration of the estrous phases. Akingbade (1992), showed a global and progressive increase in the blood concentration of estrogens and progesterone following the proliferation of Plasmodium berghei in mice. Indeed, in rodents the cornification and desquamation of the vaginal epithelium characterizing estrus are triggered by a brief 0001-706X/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.actatropica.2008.10.011