The endocrinology of musth in the male Asiatic elephant (Elephas maximus): Serum estradiol, serum LH and serum, fecal and urinary testosterone

摘要

Efforts to breed the endangered Asian elephant in captivity have historically been difficult because of our primitive understanding of musth. Long-term endocrinological studies of musth are needed; however, it is often difficult and dangerous to collect serum from the musth male.;Serum, urine and fecal samples were collected along with behavioral data from 11 male Asiatic elephants. Methods of testosterone analysis were developed, validated and subsequently performed on all serum, urine and fecal material. Serum samples were additionally analyzed for estradiol and LH. All endocrine data were analyzed for significant differences during behavioral musth for the purpose of developing techniques valuable for the study and understanding of this phenomenon.;Animals ranging from 10-30 years of age experienced musth but older elephants experienced a greater incidence of musth. Significantly more testosterone was secreted in the serum by animals in musth and by musth animals 21-30 years old than by non-musth and musth animals 15-20 years old respectively. Serum estradiol concentrations were significantly elevated during musth and were correlated with serum testosterone and aggressive behavior. Serum LH begins to rise 4 weeks prior to musth symptoms and quickly drops after musth symptoms have started.;Concentrations of urinary and fecal testosterone were significantly elevated during musth and positive linear relationships were observed between serum, urinary and fecal testosterone values. After injection of $sp{14}$C testosterone into one male Asiatic elephant, 57% of the radioactivity was excreted in the feces, 7% in the urine and 36% was not recovered. Testosterone excretion in the feces peaked 48-58 hours post-injection whereas the majority of urinary testosterone was excreted within 24 hours. Nearly 100% of steroids in the feces and 30% of steroids in the urine were unconjugated. In-vivo metabolized $sp{14}$C testosterone was separated by HPLC and demonstrated five distinct peaks of radioactivity. One of these peaks co-eluted with testosterone standard, however, the largest peaks were less-polar metabolites.;In conclusion, Serum testosterone, estradiol and LH concentrations can be used to potentially quantitate or predict musth and non-invasive fecal and/or urinary testosterone assay procedures can be used successfully to monitor and further study musth.