Extracting Hormones from Elephant Tail Hairs-Spring 2024

Hormone monitoring has been critical in assessing animal physiology, and there has been an increasing interest in extracting hormones from keratinized structures, which circumvent logistical limitations of urine and blood plasma. The long life spans and unique reproductive cycles of elephants makes studying their endocrinology essential for their conservation. We sought to answer if cortisol, testosterone, and progesterone could be extracted and quantified from the tail hairs of zoo African bush elephants (Loxodonta africana) and Asian elephants (Elephas maximus). Following extraction, we wanted to date the concentrations of hormones within the tail hair using growth rates from prior research and the literature. This is particularly important for three of the studied elephants, one of whom was acrylic and two of whom were recently transferred between zoos. Tentative data indicates cortisol and progesterone can be extracted from tail hairs, but continued work is required to fully realize our research goals.

Hello! My name is Trent Grasso and I will be presenting my research on the extraction of hormones from elephant tail hairs. So, monitoring hormones is essential in assessing the welfare and physiology of animals. It can tell us a lot about their reproductive status their stress levels among other relevant factors. Typically, when we extract hormones, it’s from matrices like blood plasma and urine. However these only provide a short-term record of an animal’s hormonal concentrations and the act of extracting these matrices can itself induce stress in the animal which in turn affects the hormone concentrations. So recently there’s been an interest in extracting hormones from keratin structures since the hormones are deposited in the keratin and stays there over time and as more keratin grows more hormones are deposited and over time you get this nice stable record of an animal’s hormone concentrations. Hair in particular has arisen as one of the most well studied and reliable matrices from which to extract hormones it’s been studied in multiple m including non-human primates and bears but for my research I want to focus on elephants since elephants have very long and unique reproductive cycles that can complicate breeding efforts for conservation so having an easier way to monitor their reproductive health over a long period of time is essential for conservation efforts going forward. We specifically chose elephant tail hairs since they were easier to collect and they are particularly thick which means a lot of hormone can be extracted from relatively little sample. Previous research was able to extract cortisol from a group of Asian elephants but other hormones have not been tested from elephant tail hairs and no hormones have been tested from African elephant tail hairs. So for my research I studied tail hairs from four female Asian elephants from the Smithsonian National Zoo and three African elephants from the Maryland Zoo in Baltimore, two females and one male and the hormones we tested were progesterone, which plays important roles in maintaining pregnancy; testosterone, which is the primary male sex hormone; and cortisol, which induces metabolic changes in response to stress. And the ultimate goal of our study was to extract hormones from the tail hairs quantify them and then using growth rate we had previously collected for these elephants as well as from the literature see if we could calibrate concentrations of hormones in the tail hair with qualitative events in the elephant’s life. So tentative work we’ve done for this project we were able to extract cortisol from one tail hair from a female African elephant named Anna from the Maryland Zoo the tail hair was about 70 centimeters long which based on the growth rate for her we estimated to represent about 5 years, and then we were also able to successfully extract cortisol and progesterone from two of the female Asian elephants the National Zoo. We also, thanks to the keepers, we were able to measure the growth rate of all the elephant tail hairs which across the board was on average two millimeters per week, however it varied over time and it varied between species, with Asian elephant tail hair growing a lot more variably but generally at a faster rate than African elephant tail hair. Our initial plan this semester was to continue extracting and processing samples we already had but then we acquired samples from new elephants that we deemed particularly important for studying elephant endocrinology. The first was a female African elephant named Nancy who lived at the National Zoo up until her death in 2004. Nancy’s tail hairs we deemed important for two reasons. One, they were particularly long and thick; they were about 50 centimeters long and five times thicker than any of the other elephant tail hairs, which means we could get finer chronological resolution when cutting up her sample her tail hair into smaller samples that we would then drill into powder for extraction. Additionally and more importantly, Nancy was acyclic which is a common problem for for female elephants in zoos where they’re unable to reproduce being able to see the physiological and hormonal underpinnings of acyclity in a female elephant over a long period of time will be an important step in moving towards resolving that issue. We also got tail hairs from a mother-daughter Duo of Asian elephants Trong Nhi and Nhi Linh who were transferred to the National Zoo in October 2022. While their tail hairs are not as long nor as thick, we estimate based on their length that the tail hairs encompass their transfer from their previous Zoo to the National Zoo and we want to see if we can track any hormonal changes that may have occurred during that process not only in them but in other elephants from the zoo that we have samples for. Our work this semester has been mostly cutting these tail hairs at regular intervals from which we drill by hand into about 10 milligrams of powder although the length of the intervals depend on the size of the individual hair. For example for the elephants we had tail hairs from previously the intervals were about 3 cm but for Nancy whose tail hairs were a lot thicker and the interval was decreased to half a centimeter. Going forward into the summer we hope to continue drilling and processing the samples from these three elephants as well as the other samples we have then moving towards extracting the hormone and assaying it so we can quantify it and comparing that to growth rates we’ve collected and from literature to make our final hormonal calendar. For this project I’d like to thank George Mason University College of Science for funding it and the keepers at the Maryland Zoo and the Smithsonian National Zoo not only for allowing us to collect tail hair samples but for taking time to measure growth rate in accordance with our protocol. I’d also like to thank my PI Dr. Kathleen Hunt Who provided a lot of useful guidance and help me understand a lot of the underpinnings in endocrinology for this project. And here are my references.