Variation in the extraction efficiency of estradiol and progesterone in moist and lyophilized feces of the black howler monkey (Alouatta pigra): alternative methods

Abstract

Several fecal steroid extraction techniques have been developed to measure the ovary function in different species of mammals. However, regardless of the method of extraction and the sample type chosen, it has been observed that they can yield results with different percentages of recuperation. The objective of this study was to determine whether the type of substratum, solvent and extraction method used have any influence on the extraction efficiency in the feces of Alouatta pigra (black howler monkey). For this purpose we used two methods: agitation and ebullition. With each method, we utilized moist and lyophilized feces. The validation of radioimmunoassay method was accurate and precise for quantify estradiol and progesterone in lyophilized feces of A. pigra. To both of which ethanol and methanol, absolute and at 80%, were added, besides the hormones 125I-Estradiol and 125I-Progesterone. The extraction efficiency for 125I-Estradiol was from 87.72 ± 3.97 to 41.24 ± 2.67%, and for 125I-Progesterone from 71.15 ± 4.24 to 42.30 ± 1.19% when we used the agitation method. Whereas with the ebullition method, the extraction efficiency for 125I-Estradiol ranged from 86.89 ± 2.66 to 71.68 ± 3.02% and for 125I-Progesterone from 98.31 ± 1.26 to 85.40 ± 1.98%. Due to the differences found in these assays, which depend on the method used, the type of feces employed and the type of solvent added to them, we recommend the ebullition method and the lyophilized feces of A. pigra for extracting the hormones, since in moist feces there may exist variables which might interfere in the quantification of 125I-Estradiol and 125I-Progesterone.

Endocrinology of Howler Monkeys: Review and Directions for Future Research

“…The authors argued that endocrine differences documented in this study corresponded to the limited food intake exhibited by females compared to males, suggesting that the measured thyroid levels accurately represented to metabolic state of these individuals. Besides biological validations, the effi ciency by which hormonal metabolites are recovered from samples using different extraction methods may need to be assessed to optimize endocrine studies, as has been done for estrogen and progesterone in black howler monkeys (Torres-Pelayo et al 2011 ). These authors assessed whether the type of substrate (moist versus lyophilized feces), organic solvent (80 or 100 % ethanol versus methanol), and extraction method (agitation versus ebullition) affected the extraction effi ciency of estrogens and progestins in fecal samples of black howler monkeys.…”

Changes in Fecal Estrogen Levels and Sexual Behavior in Captive Sichuan Snub‐Nosed Monkeys (Rhinopithecus roxellana) Following a Male Replacement

“…Intra‐ and interassay coefficients of variation were 7.88% ( n = 10) and 8.43% ( n = 4), respectively. Fecal estrogen assays using the same methods have been validated in a variety of primates [Hernández‐López et al, ; Kugelmeier et al, ; Torres‐Pelayo et al, ], and studies in a closely related colobine monkey have validated the use of fecal estradiol RIA to measure concentrations of fecal estrogens to monitor ovarian function [Lu et al, , ].…”