Hyperprolactinemia is not associated with hyperestrogenism in noncycling African elephants (Loxodonta africana)

Prado-Oviedo, Natalia A.; Malloy, Elizabeth J.; Deng, Xinyang; Brown, Janine L.

doi:10.1016/j.ygcen.2013.03.035

Cited by 14 publications

(22 citation statements)

References 57 publications

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“…Therefore, it is likely there are multiple features of the elephant’s social experience, including the number of groupings as well as the compatibility of social partners, which influence physiology. In other species, such stress responses can be modified by estrous cycle status; i.e., under estrogen vs. progesterone exposure, and not always in the same direction [ 29 , 90 , 91 , 92 ]; however, in the case of African elephants, all hyperprolactinemic elephants were acyclic, with low concentrations of progestagens [current study] and estrogens [ 8 ]. Additional research into prolactin’s role as an indicator of social stress in managed elephants, and studies investigating the impact of social management strategies on incidence of hyperprolactinemia are highly recommended, as are explorations of other markers of stress (glucocorticoids, behavior) as they pertain to pituitary-ovarian function.…”

Section: Discussionmentioning

confidence: 99%

“…Hyperprolactinemia for African elephants was defined as an average prolactin concentration over the 12-month sampling period of ≥18 ng/ml, similar to Prado-Oviedo et al [ 8 ], which lacked a temporal pattern [ 19 ]. Cut-off values were calculated for Asian elephants and determined to be < or ≥14 ng/ml.…”

Section: Methodsmentioning

confidence: 99%

“…There is considerably more information available on what does not cause acyclicity than what does. For example, several conditions known to be associated with infertility in other species have been found not to be related to ovarian problems in African elephants, such as hyperandrogenism [ 7 ], hyperestrogenism [ 8 ], thyroid derangements, pituitary dysfunction [ 9 , 10 ] or elevated cortisol [ 10 , 11 ]. Another disproven theory is that acyclic zoo elephants have exhausted their supply of ovarian follicles; i.e., undergone a premature ‘menopause’.…”

Section: Introductionmentioning

confidence: 99%

“…In addition to hypothalamic inhibition by dopamine, other factors can stimulate prolactin synthesis or have a suppressive effect on dopaminergic tone: vasoactive intestinal polypeptide, estradiol, serotonin, oxytocin, thyrotropin-releasing hormone (TSH) and vasopressin [ 29 ]. Of these, studies of estradiol and thyroid hormones (TSH, T 3 , T 4 ), have found no relation to elevated prolactin in elephants [ 8 , 10 ]. Another cause could be stress, as prolactin is often secreted in response to physical or psychological stressors [ 30 , 31 ], but cortisol has not been found to be related to prolactin levels in elephants [ 10 ].…”

Section: Introductionmentioning

confidence: 99%

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Reproductive Health Assessment of Female Elephants in North American Zoos and Association of Husbandry Practices with Reproductive Dysfunction in African Elephants (Loxodonta africana)

et al. 2016

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As part of a multi-institutional study of zoo elephant welfare, we evaluated female elephants managed by zoos accredited by the Association of Zoos and Aquariums and applied epidemiological methods to determine what factors in the zoo environment are associated with reproductive problems, including ovarian acyclicity and hyperprolactinemia. Bi-weekly blood samples were collected from 95 African (Loxodonta africana) and 75 Asian (Elephas maximus) (8–55 years of age) elephants over a 12-month period for analysis of serum progestogens and prolactin. Females were categorized as normal cycling (regular 13- to 17-week cycles), irregular cycling (cycles longer or shorter than normal) or acyclic (baseline progestogens, <0.1 ng/ml throughout), and having Low/Normal (<14 or 18 ng/ml) or High (≥14 or 18 ng/ml) prolactin for Asian and African elephants, respectively. Rates of normal cycling, acyclicity and irregular cycling were 73.2, 22.5 and 4.2% for Asian, and 48.4, 37.9 and 13.7% for African elephants, respectively, all of which differed between species (P < 0.05). For African elephants, univariate assessment found that social isolation decreased and higher enrichment diversity increased the chance a female would cycle normally. The strongest multi-variable models included Age (positive) and Enrichment Diversity (negative) as important factors of acyclicity among African elephants. The Asian elephant data set was not robust enough to support multi-variable analyses of cyclicity status. Additionally, only 3% of Asian elephants were found to be hyperprolactinemic as compared to 28% of Africans, so predictive analyses of prolactin status were conducted on African elephants only. The strongest multi-variable model included Age (positive), Enrichment Diversity (negative), Alternate Feeding Methods (negative) and Social Group Contact (positive) as predictors of hyperprolactinemia. In summary, the incidence of ovarian cycle problems and hyperprolactinemia predominantly affects African elephants, and increases in social stability and feeding and enrichment diversity may have positive influences on hormone status.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Reproductive Health Assessment of Female Elephants in North American Zoos and Association of Husbandry Practices with Reproductive Dysfunction in African Elephants (Loxodonta africana)

et al. 2016

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“…This elephant resumed cycling and became pregnant 3 years after the initial study (Lueders et al, ). However, in over 20 years of monitoring the North American captive elephant population, only non‐cycling African elephants have been diagnosed with hyperprolactinemia, and none have resumed cycling; leading to the hypothesis that the two conditions are linked (Brown & Lehnhardt, ; Brown et al, ; Brown et al, ; Dow & Brown, ; Prado‐Oviedo, Malloy, Xinyi, & Brown, ).…”

Section: Introductionmentioning

confidence: 99%

Prolonged ovarian acyclicity is associated with a higher likelihood of developing hyperprolactinemia in zoo female African elephants

2018

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Hyperprolactinemia is a common disorder of the hypothalamic‐pituitary axis, and a cause of ovarian dysfunction in women. Currently, over half of non‐cycling African elephant females in North America also are hyperprolactinemic, suggesting a similar link between these two conditions may exist. The objective of this study was to determine the relationship between acyclicity and prolactin status by comparing mean prolactin concentrations of bi‐weekly samples collected over a 1‐year period in 2012 with 20 years of historical weekly progestagen data to assess cyclicity. Females were categorized as: 1) non‐cycling with an average prolactin concentration of 15 ng/ml or greater (HIGH; n = 17); 2) non‐cycling with an average prolactin concentration below 15 ng/ml (LOW; n = 16); and 3) typical temporal patterns of progestagen and prolactin secretion (NORMAL; n = 45), and evaluated based on length of time (in years) they had experienced ovarian inactivity. Results showed that the majority of HIGH prolactin elephants had been acyclic for at least 5 years, and in a number of cases (n = 9) for over 10 years. By contrast, most of the LOW prolactin elephants had experienced acyclicity for less than 5 years. Finally, there was a positive association between duration of acyclicity and mean prolactin concentrations, with an increase in the likelihood of having higher prolactin concentrations the longer an individual was acyclic. This study highlights the importance of longitudinal hormonal datasets to examine temporal changes in biological functioning and better understand the etiology of infertility problems.

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Potential contribution of alpha‐fetoprotein level to biomarker of pregnancy outcome in Asian elephants

Zeng,

Huang,

Huang

et al. 2024

Veterinary Medicine & Sci

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Alpha‐fetoprotein (AFP) is a structural serum glycoprotein that plays vital roles in reproduction and mammalian development. Analysis of serum prolactin (PRL) is considered one of the useful methods for diagnosing pregnancy in Asian elephants. However, the expression profiles of AFP in pregnant and nonpregnant Asian elephants remain unclear, nor is the relationship with PRL. In this study, serum seven gonadal hormones and AFP in three pregnant and seven nonpregnant Asian elephants were analysed by via radioimmunoassay (RIA) and enzyme‐linked immunosorbent (ELISA) assay. We found that the mean (±SD) concentration of prolactin (PRL) in pregnant (136.782 ± 30.987 ng/mL) elephants was significantly higher than that in nonpregnant elephants (52.803 ± 21.070 ng/mL; p ≤ 0.0005). The mean (±SD) concentration of AFP in pregnant elephants (11.598 ± 0.824 ng/mL) was significantly higher than that in nonpregnant elephants (7.200 ± 2.283 ng/mL; p ≤ 0.05). Furthermore, the AFP concentration was positively correlated with the PRL concentration in the 10 Asian elephants studied. In conclusion, our findings suggest that serum AFP concentration is a potential biomarker of pregnancy outcomes in Asian elephants.

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Hyperprolactinemia is not associated with hyperestrogenism in noncycling African elephants (Loxodonta africana)

Cited by 14 publications

References 57 publications

Reproductive Health Assessment of Female Elephants in North American Zoos and Association of Husbandry Practices with Reproductive Dysfunction in African Elephants (Loxodonta africana)

Reproductive Health Assessment of Female Elephants in North American Zoos and Association of Husbandry Practices with Reproductive Dysfunction in African Elephants (Loxodonta africana)

Prolonged ovarian acyclicity is associated with a higher likelihood of developing hyperprolactinemia in zoo female African elephants

Potential contribution of alpha‐fetoprotein level to biomarker of pregnancy outcome in Asian elephants

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