Ricardo A. Valdez

Steroid hormone production by parasites: the case of Taenia crassiceps and Taenia solium cysticerci.

Many examples of reciprocal endocrine interactions between parasites and hosts have been found in insects, arthropods and mammals. Cysticercosis produced by Taenia solium metacestodes is a widely distributed parasite infection that affects the human and the pig. Taenia crassiceps experimental murine cysticercosis has been used to explore the role of biological factors involved in host-parasite interactions. We had shown that T. crassiceps cysticercosis affects the serum concentration of steroid hormones and the reproduction behavior of the male mice host. In an effort to understand the biology of the parasite, we had investigated the parasite capacity to produce sex steroids. For this purpose, T. crassiceps cysticerci were incubated in the presence of different steroid precursors. TLC and recrystallization procedures showed that testosterone is produced from 3H-androstenedione in cysticerci. The conversion of 3H-testosterone to androstenedione, although present is much less significant. In addition, we had studied the production of testosterone by T. solium cysticerci. For this purpose, cysticerci were dissected from pork meat and incubated as above described. The results showed that T. solium cysticerci also produce testosterone. We have speculated about the importance of androgens in the growth of T. crassiceps cysticerci and found that the addition of the antiandrogen flutamide to the culture media of the parasites significantly decreased 3H-thymidine incorporation. We therefore hypothesized, that the ability of cysticerci to produce testosterone from steroid precursors might be important for the parasite growth and development.

Metabolism of steroid hormones by Taenia solium and Taenia crassiceps cysticerci

Previous in vitro experiments showed that both, Taenia crassiceps and Taenia solium cysticerci have the ability to metabolize exogenous androstenedione to testosterone. Here we evaluate on the capacity of both cysticerci to synthesize several sex steroid hormones, using different hormonal precursors. Experiments using thin layer chromatography (TLC) showed that both cysticerci were able to produce (3)H-hydroxyprogesterone, (3)H-androstenedione and (3)H-testosterone when (3)H-progesterone was used as the precursor. They also synthesized (3)H-androstenediol and (3)H-testosterone when (3)H-dehydroepiandrosterone was the precursor. In addition, both cysticerci interconverted (3)H-estradiol and (3)H-estrone. These results, strongly suggest the presence and activity of the Delta4 and Delta5 steroid pathway enzymes, 3beta-hydroxysteroid dehydrogenase/Delta(5-4) isomerase-like enzyme (3beta-HSD), that converts androstenediol into testosterone; and the 17beta-hydroxysteroid dehydrogenase that interconverts estradiol and estrone, in both types of cysticerci.

Impact of Taenia solium neurocysticercosis upon endocrine status and its relation with immuno-inflammatory parameters

Neurocysticercosis (NC) is a parasitic disease caused by the infiltration of the larval stage of Taenia solium in the central nervous system. Clinical presentations are heterogeneous and particularly depend, on the age and gender of the host. We designed a clinical study to evaluate the hormonal changes associated with neurocysticercosis and the relationships between disease heterogeneity, endocrine and immunological status. A total of 50 patients and 22 healthy subjects were included. A precise clinical and radiological description of disease for each patient was recorded. A broad hormonal profile was assessed for each participant and, in a sub-group of patients, immunological features were also evaluated. Compared with controls, all patients had lower dehydroepiandrosterone (DHEA) concentration; male patients also had lower concentrations of 17β-estradiol and higher concentrations of luteinising hormone (LH). In the clinically severe patients, lower concentrations of progesterone and androstenedione were found in women. Higher concentrations of follicle stimulating hormone (FSH) and lower concentrations of testosterone were found in men when compared with the less clinically severe patients. Significant correlations were found between estradiol and IL-10 in male patients, and between dehydroepiandrosterone (DHEA) and IL-1β, and androstenedione and IL-17 in female patients. To our knowledge the present study constitutes the first demonstration that the presence of T. solium larvae in the central nervous system can modify the host environment by the induction of endocrine and immunological changes. These results provide a stimulating background to analyse the repercussions of these changes on the course of the disease and on patient reproductive health.

Stress in Wildlife Species: Noninvasive Monitoring of Glucocorticoids

Depression and stress are related pathologies extensively studied in humans. However, this relationship is not well known in animals kept in zoos and even less known in wild animals. In zoo animals, acute and chronic stress caused by difficulties in coping with stressors such as public presence and noise, among others, can induce the appearance of repetitive pathological behaviors such as stereotypies, many times associated with organic pathologies that deeply affect their health and welfare. In the wild, factors such as deforestation, habitat fragmentation, lack of food and water, and human disturbances are potential causes of acute and chronic stress for the resident fauna. Glucocorticoids (GC) have been extensively used as stress indicators in many species including humans. Since chase and handling of wild animals immediately raise their GC serum levels, noninvasive methods have been developed to assess stress without interference caused by sample collection. The hormones and their metabolites can be measured in various body fluids and excreta and detect basal feedback free hormone concentrations as well as the response to ACTH and handling. In order to study the influence of disturbing factors we have measured GC as stress indicators by noninvasive techniques in dolphins and felids (ocelots, jaguarundis and margays) and cortisol and testosterone in spider monkeys.

Taenia solium cysticerci synthesize androgens and estrogens in vitro.

Cysticerci from Taenia solium develop in the pig muscle and cause severe diseases in humans. Here we report on the capacity of T. solium cysticerci to synthesize sex steroid hormones. T. solium cysticerci were dissected from infected pork meat. Parasites were incubated for different periods in culture media plus antibiotics and tritiated steroid precursors. Blanks and parasite culture media were extracted and analyzed by thin-layer chromatography (TLC) in two different solvent systems. In some experiments, the scoleces were incubated separately. Results showed that T. solium cysticerci transform [3H]androstenedione to [3H]testosterone in a time-dependent manner. The production was confirmed in two different solvent systems. The incubation with [3H]testosterone yielded only small amounts of [3H]androstenedione. The recrystallization procedure further demonstrated that the metabolite identified by TLC was testosterone. The isolated scoleces incubated in the presence of [3H]androstenedione yielded [3H]testosterone and small quantities of [3H]17β-estradiol. The results reported here demonstrate that T. solium cysticerci have the capacity to synthesize steroid hormones.

The key steroidogenic enzyme 3β-hydroxysteroid dehydrogenase in Taenia solium and Taenia crassiceps (WFU)

Larval and adult stages of Taenia solium and Taenia crassiceps WFU strain were analyzed by histochemical and biochemical methods to determine the existence of steroid pathways. The presence of the key enzyme 3β-hydroxisteroid-dehydrogenase (3β-HSD) was examined in frozen sections of cysticerci obtained from mice and segments of tapeworms obtained from the intestine of hamsters. 3β-HSD activity was detected by nitroblue-tetrazolium products after incubation with dehydroepiandrosterone, androstendiol, or pregnenolone. Tapeworm tissues exhibited 3β-HSD activity in the subtegumentary areas of the neck and immature proglottids following incubation with androstendiol, as well as surrounding the testes in mature proglottids. T. solium cysticerci exhibited 3β-HSD activity in the subtegumentary tissues. The synthesis of steroid hormones involving the activity of 3β-HSD was studied in cysticerci or tapeworms incubated in the presence of tritiated steroid precursors. The culture media were analyzed by thin layer chromatography and showed synthesis of androstendiol, testosterone, and 17β-estradiol by cysticerci, androstendiol, and 17β-estradiol by tapeworms. The results strongly suggest the activity of 3β-HSD in taeniid parasites that have at least a part of the enzymatic chain required for androgen and estrogen synthesis and that the enzymes are present in the larval stage and from the early strobilar stages to the mature proglottids.

How Stressed are Birds in an Urbanizing Landscape? Relationships Between the Physiology of Birds and Three Levels of Habitat Alteration

Abstract. In this study we measured two physiological traits (levels of corticosterone and immunoglobulin) in two species of landbirds, the Canyon Towhee (Melozone fusca) and Inca Dove (Columbina inca), occupying three degrees of human alteration of a subtropical mountain landscape: forest edges, croplands, and urban sites. We found that both physiological variables differed by species and habitat condition. In both species, corticosterone concentration was significantly higher in croplands. But immunoglobulin concentration behaved differently, in C. inca being highest at urban sites, where in M. fusca it was lowest. Contrary to expectation, we only found one strong significant relationship between both physiological variables: M. fusca in urban areas. Our results suggest that 30% of the towhees captured in urban areas are under chronic stress. Results for body condition support this hypothesis, as the condition of towhees in urban areas was poorer, suggesting physiological vulnerability. Although we expected the density of both species to be high in urban areas because of the amount and predictability of resources, we found a significantly lower density of M. fusca in urban areas, suggesting that the habitat variables influencing the physiological condition of M. fusca affected its population density. In summary, our results suggest that a substantial proportion of Canyon Towhees in the urban area studied have physiological limitations, while the Inca Dove seems to have an appropriate physiological response despite low values for body condition in urban areas.

Parasites and steroid hormones: corticosteroid and sex steroid synthesis, their role in the parasite physiology and development

In many cases parasites display highly complex life cycles that include the penetration and permanence of the larva or adults within host organs, but even in those that only have one host, reciprocal, intricate interactions occur. Evidence indicates that steroid hormones have an influence on the development and course of parasitic infections. The host genders susceptibility to infection, and the related differences in the immune response are good examples of the host-parasite interplay. However, the capacity of these organisms to synthesize their own steroidogenic hormones still has more questions than answers. It is now well-known that many parasites synthesize ecdysteroids, but limited information is available on sex steroid and corticosteroid synthesis. This review intends to summarize some of the existing information in the field. In most, but not all parasitosis the hosts hormonal environment determines the susceptibility, the course, and severity of parasite infections. In most cases the infection disturbs the host environment, and activates immune responses that end up affecting the endocrine system. Furthermore, sex steroids and corticosteroids may also directly modify the parasite reproduction and molting. Available information indicates that parasites synthesize some steroid hormones, such as ecdysteroids and sex steroids, and the presence and activity of related enzymes have been demonstrated. More recently, the synthesis of corticosteroid-like compounds has been shown in Taenia solium cysticerci and tapeworms, and in Taenia crassiceps WFU cysticerci. In-depth knowledge of the parasites endocrine properties will contribute to understand their reproduction and reciprocal interactions with the host, and may also help designing tools to combat the infection in some clinical situations.

Steroidogenic capacity of Trypanosoma cruzi trypomastigotes

American Trypanosomiasis is caused by the hemoflagellate Trypanosoma cruzi (T. cruzi) and affects millions of persons causing variable degrees of digestive and heart disturbances. As far as we concerned, T. cruzi capacity to synthesize steroid hormones has not been investigated. Therefore, the aim of this work was to investigate the capacity of T. cruzi trypomastigotes to transform tritiated steroid precursors into androgens and estrogens. The T. cruzi Tulahuén strain was obtained from mice blood. The trypomastigotes were cultured for 6 and 24h in Dulbbecos modified Eagles medium plus FCS and antibiotics. Tritiated dehydroepiandrosterone or androstendione were added to the culture media and parasites were incubated for 6 or 24h. The cultures were centrifuged and ether extracted. The steroids were analyzed by thin layer chromatography (TLC) in two solvent systems. After incubation with 3H-androstenedione, T. cruzi trypomastigotes synthesized 3H-testosterone (T), 3H-17beta-estradiol (E2) and 3H-estrone (E1). Metabolism of 3H-DHEA by the parasites yielded 3H-androstendione and 3H-androstendiol at 6h of incubation. The recrystallization procedure further demonstrated the 3H-androstendiol and 3H-17beta-estradiol syntheses. Results indicate for the first time that T. cruzi trypomastigotes produce androgens and estrogens when incubated in the presence of steroid precursors and suggest the presence of active parasite steroidogenic enzymes.

The Effect of Environmental Manipulation on Behavior, Salivary Cortisol, and Growth of Piglets Weaned at 14 Days of Age

Environmental enrichment can be a useful tool to reduce belly nosing behaviors in early weaned piglets. The aim of this study was to assess the effect of environmental enrichment on behavior, salivary cortisol, and productivity of piglets weaned at 14 days of age. The study assigned 112 piglets (line Camborough 22 of PIC™) into 2 treatments, control and enriched, and observed them for 192 hr in 3 periods: 14 to 28 days of age (Phase 1), 28 to 42 days of age (Phase 2), and 42 to 54 days of age (Phase 3). The study obtained saliva samples in each phase from 56 piglets selected randomly from each group for cortisol determination. Comparisons between both treatments and phases included the following: proportion of time belly nosing, latency of approaching a person, average levels of salivary cortisol, and daily weight gain. Belly nosing was higher and latency of approaching a person lower in the control group than in the enriched one (p < .05 and p < .01). Belly nosing was lower in Phase 3 (p < .05); latency of approaching a person was higher in Phase 1 with respect to Phase 2, and this was higher with respect to Phase 3 (p < .01). There were no differences in salivary cortisol levels between treatments or phases. Weight gain was higher in the enriched group (p < .001). Environmental enrichment in piglets weaned at 14 days of age resulted in a reduced proportion of time nosing, reduced latency of response to humans, and better growth than piglets in barren environments.