Excreted steroids in primate feces over the menstrual cycle and pregnancy.
ABSTRACT Techniques were established for the extraction and measurement of 17 beta-estradiol (E2) and progestins (P4) from feces of Old World primates. Studies were conducted to show the sensitivity of these measures, means of preserving fecal samples in the field, effects of urinary contamination, and means to eliminate these effects. Our results show that excreted steroid measures can be used to distinguish between mid-follicular and luteal phases in the menstrual cycle, and to identify pregnancy by Day 20 of gestation; the steroid measures can also be used to identify ovulatory levels of E2 and to establish the length of the menstrual cycle. Urine was shown to contaminate the fecal sample and to confound the estimate of steroid levels in feces; prolonged storage (less than 6 h) was shown to change the steroid estimate. Both urinary contamination and storage-dependent changes were eliminated by the addition of ethanol to the sample. Preliminary results also suggest that effects of dietary fiber on steroid hormone levels are minimal when controlled quantitatively by adjusting for water content of the fecal sample. We conclude that these measurements of excreted steroids provide a valid, noninvasive measure of physiological state of the hypothalamic-pituitary-ovarian axis among free-ranging animals in the field.
Full-textDOI: · Available from: Samuel K Wasser, Jun 10, 2015
- SourceAvailable from: George Wittemyer[Show abstract] [Hide abstract]
ABSTRACT: Non-invasive endocrine methods enable investigation of the relationship between ecological variation and ovarian activity and how this impacts on demographic processes. The underlying physiological factors driving high variation in inter-calving intervals among multi-parous African elephants offer an interesting system for such an investigation. This study investigates the relationship between Normalized Differential Vegetation Index (NDVI), an ecosystem surrogate measure of primary productivity, and fecal progestin concentrations among wild female elephants. Matched fecal samples and behavioral data on reproductive activity were collected from 37 focal individuals during the two-year study. Linear mixed models were used to explore the relationship between fecal 5alpha-pregnane-3-ol-20-one concentrations and the independent variables of NDVI, calf sex, female age, gestation day, and time since last parturition. Among both non-pregnant and pregnant females, fecal 5alpha-pregnane-3-ol-20-one concentrations were significantly correlated with time-specific NDVI indicating a strong relationship between ecological conditions and endocrine activity regulating reproduction. In addition, the age of a female and time since her last parturition impacted hormone concentrations. These results indicate that the identification of an individual's reproductive status from a single hormone sample is possible, but difficult to achieve in practice since numerous independent factors, particularly season, impact fecal hormone concentrations. Regardless of season, however, fecal 5alpha-pregnane-3-ol-20-one concentrations below 1 microg/g were exclusively collected from non-pregnant females, which could be used as a threshold value to identify non-pregnant individuals. Collectively the information generated contributes to a better understanding of environmental regulation of reproductive endocrinology in wild elephant populations, information salient to the management and manipulation of population dynamics in this species.Hormones and Behavior 04/2007; 51(3):346-54. DOI:10.1016/j.yhbeh.2006.12.013 · 4.51 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Fecal steroid analysis is an increasingly common non-invasive technique used in both captive and field studies to measure an animal's approximate hormonal levels and corresponding physiological state. Fecal collection in the field necessitates storage and transportation methods that will prevent the degradation of hormonal metabolites by fecal bacteria. To determine the most stable and therefore preferred method of storage, 48 fecal samples were collected from six captive female Cape ground squirrels (Xerus inauris). Each sample was randomly divided into three sub-samples to be processed for storage through freezing, drying, or preservation in ethanol. Frozen samples were stored at -20 degrees C, dried-treated samples were desiccated in a conventional oven at 40 degrees C for 4 h, and alcohol-treated samples were preserved in 3 ml of 95% ethanol. Samples were stored for 330 days followed by enzyme immunoassay analysis (EIA) to determine their progestogen and estrone conjugate (E(1)C) concentrations. Validations were performed to establish that the progestogen and E(1)C assays accurately measure fecal progestogen and estrone conjugate concentrations and were sensitive enough to detect biologically meaningful differences in these steroid metabolite concentrations in female X. inauris. Validation results showed a significant difference in progestogen concentrations of gravid females compared to sub-adults and non-gravid females. There was also a significant difference in estrone conjugates between sub-adult and adult females. Duration of storage time did not affect progestogen or estrone metabolite concentrations after being frozen for 3 months. Storage treatment results showed no significant difference between frozen and dried samples, but a significant difference was found between frozen and ethanol samples in both progestogen and estrone conjugate concentrations demonstrating that drying feces provides a reliable method for long-term preservation of fecal steroid concentrations and is the better alternative when freezing is not a viable option.General and Comparative Endocrinology 02/2007; 150(1):1-11. DOI:10.1016/j.ygcen.2006.06.010 · 2.67 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Since the pioneering paper "Measurement of Excreted Steroids in Macaca nemestrina" [Risler et al., American Journal of Primatology 12:91-100, 1987] was first published, field primatologists have been using fecal extraction techniques to examine adrenal and gonadal hormones. These techniques have allowed investigators to determine reproductive conditions in wild primates without causing any disruption to the populations. Over the years, many techniques have been developed to improve the ease of analysis, transportation, and purification. More of the processing can now be done in the field. This paper describes the methodology developed or adapted at the Wisconsin National Primate Research Center, and the factors involved in preparing fecal samples for steroid analysis. We provide information on the steps involved in extracting and purifying steroids from feces for measurement. The latest methods include field processing of samples, such as drying collected material or separating steroids from the fecal material by solid phase extraction (SPE). How samples are processed in the field determines the requirements for international transportation and the methods used in the laboratory. The pros and cons of the different processing methods are discussed. We also report on recent advances in laboratory quantification, with implications for steroid isolation prior to analysis. The different processes involved in isolating and measuring fecal steroids discussed here will enable investigators to understand the components necessary to ensure accurate and reliable results.American Journal of Primatology 09/2005; 67(1):159-74. DOI:10.1002/ajp.20175 · 2.14 Impact Factor