Enzyme-immunoassay for the measurement of luteinizing hormone in the serum of African elephants (Loxodonta africana)

Circulating patterns of progesterone and luteinizing hormone (LH) in the elephant have been well characterized, and routine monitoring of these hormones is now viewed as a valuable tool for making informed decisions about the reproductive management of elephants in captivity. Currently, LH monitoring in elephants is done with radio-immunoassays (RIAs); unfortunately, the use of radioactive materials in RIAs limits their application to institutions with laboratory facilities equipped for the storage and disposal of radioactive waste. Enzyme-immunoassays (EIAs) offer an inexpensive and more zoo-friendly alternative to RIA. This work reports on an EIA capable of quantifying circulating LH in African elephants. The EIA employs a biotin label and microtiter plates coated with goat anti-mouse gamma globulin. LH surges in African elephants (n=3) increased fivefold over baseline concentrations (1.00+/-0.1 ng/ml vs. 0.2+/-0.1 ng/ml) and occurred 19.3+/-0.2 days apart. Ovulatory LH surges were associated with an increase in serum progestogens from 4.8+/-0.4 ng/ml to 11.7+/-0.4 ng/ml. The ability to quantify reproductive hormones in elephants via EIA is an important step in the process of making endocrine monitoring more accessible to zoos housing these species. (C) 2002 Wiley-Liss, Inc.