1,721,111 research outputs found
Androgen levels and female social dominance in Lemur catta
No full textMorphological and behavioural traits which improve agonistic power are subject to intrasexual selection and, at the proximate level, are influenced by circulating androgens. Because intrasexual selection in mammals is more intense among males, they typically dominate females. Female social dominance is therefore unexpected and, indeed, rare. Ring–tailed lemurs (Lemur catta) are sexually monomorphic primates in which all adult females dominate all males. The goal of our study was to test the prediction that female dominance in this species is associated with high androgen levels. Using two captive groups, we collected data on agonistic behaviour and non–invasively assessed their androgen concentrations in faeces and saliva by enzyme immunoassay. We found that adult female L. catta do not have higher androgen levels than males. However, during the mating season there was a twofold increase in both the androgen levels and conflict rates among females. This seasonal increase in their androgen levels was probably not due to a general increase in ovarian hormone production because those females showing the strongest signs of follicular development tended to have low androgen concentrations. At the individual level neither the individual aggression rates nor the proportion of same–sexed individuals dominated were correlated with their androgen levels. We conclude that female dominance in ring–tailed lemurs is neither based on physical superiority nor on high androgen levels and that it is equally important to study male subordination and prenatal brain priming effects for a complete understanding of this phenomenon
Assessment of female reproductive status in captive-housed Hanuman langurs (Presbytis entellus) by measurement of urinary and fecal steroid excretion patterns
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Patterns of Urinary and Fecal Steroid Excretion during the Ovarian Cycle and Pregnancy in the African Elephant (Loxodonta africana)
No full textAssessment of ovarian function in the African elephant (Loxodonta africana) by measurement of 5α-reduced progesterone metabolites in serum and urine
No full textWe have previously shown that 5α-pregnane-3,20-dione (5αDHP), and 5α-pregnane-3-ol-20-one (5α-P-3-OH) are the major luteal and circulating progestins in the African elephant. Therefore, the aim of the present study was to determine (1) circulating levels and patterns of secretion of 5α-DHP in relation to progesterone (P4) throughout the ovarian cycle, (2) the presence and relative abundance of 5α-reduced progestins in urine and (3) whether their measurement in urine would provide a non-invasive method for monitoring luteal function. Urine samples were collected weekly throughout a total of 13 ovarian cycles from 5 females. In addition, matched blood samples were collected during 6 cycles from 2 of the 5 animals. All hormone measurement, were carried out by enzymeimmunoassay following extraction. Urine was hydrolyzed prior to extraction. Profiles of P4 and 5α-DHP in serum followed a similar cyclic pattern and both measurements were significantly correlated (r = 0.78–0.98, mean 0.89, P < 0.001). Concentrations of 5α-DHP were, however, 10–20 fold higher than those of P4. I addition, 5α-DHP measurements showed a more pronounced luteal phase increase than that of immunoreactive P4. HPLC co-chromatography confirmed the presence of large amounts of 5α-P-3-OH in urine as a single immunoreactive peak, whereas 5α-DHP was present in very low levels and measurable only as one of several immunoreactive substances. Measurements of urinary 5α-P-3-OH were significantly correlated to serum 5α-DHP measurements in each of the 6 cycles (r = 0.72–0.93, mean 0.81, P < 0.001), whereas correlation coefficients between urinary and serum 5α-DHP values were generally lower (r = 0.34–0.83, mean 0.69) and significant in only 4 of the 6 cycles. Accordingly, only urinary excretion of 5α-P-3-OH, but not of 0.15–0.20 μ/mg Cr in the follicular phase and 10-fold elevated levels (1.8–2.2 μg/mg Cr) in the luteal phase. Based on the intervals between successive luteal phase increases in urinary 5α-P-3-OH, a mean cycle length of 14.1 ± 1.8 weeks, comprising a follicular phase of 5.0 ± 0.9 weeks and a luteal phase of 9.1 ± 1.4 weeks was determined for the 13 cycles studied. The results indicate that measurements of 5α-P-3-OH in urine provide a reliable non-invasive method for monitoring luteal function in the African elephant
Measurement of faecal steroids for monitoring ovarian function in New World primates, Callitrichidae
No full textMeasurement of immunoreactive progesterone, pregnanediol and oestradiol in faeces collected throughout ovarian cycles in three species of callitrichid primates is reported. Faecal hormone concentrations were compared with plasma progesterone profiles during PGF2 alpha-controlled (n = 7) and natural (n = 8) cycles in Callithrix jacchus and Saguinus fuscicollis, respectively, and with urinary oestrone conjugates during five cycles in Saguinus oedipus. Unconjugated steroids, which predominated over enzyme hydrolysable conjugates in samples from all species, were used to generate cycle profiles. According to results from HPLC, oestrone and oestradiol accounted for virtually all oestrogen immunoreactivity, and oestradiol most often predominated, whereas large amounts of nonspecific immunoreactivity were detected by both progesterone and pregnanediol assays. Faecal progestins were excreted in a cyclic manner in all species; luteal phase values were on average five- to tenfold higher than corresponding follicular phase values. Significant increases in mean amounts of faecal progestins were seen within 48 h of the post-ovulatory rise in plasma progesterone. Although a similar trend was also seen for faecal oestradiol, a clear and consistent luteal phase increase was seen only in Callithrix jacchus and this generally occurred later than that of progestins. The results indicate that faecal progestin analysis provides a useful method for noninvasive reproductive assessment in callitrichid primates. In particular, measurement of immunoreactive pregnanediol enables a multispecies application of a single assay methodology for comparative studies on callitrichid reproductive function
Comparison of different enzymeimmunoassays for assessment of adrenocortical activity in primates based on fecal analysis
No full textDisplay of preceptive behaviors in relation to urinary and fecal progestin levels over the ovarian cycle in female tufted capuchin monkeys
No full textAndrogen levels and female social dominance in Lemur catta
No full textvon Engelhardt N, Kappeler PM, Heistermann M. Androgen levels and female social dominance in Lemur catta. PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON SERIES B-BIOLOGICAL SCIENCES. 2000;267(1452):1533-1539
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