Biology of Reproduction, Vol 11, 102-107, Copyright © 1974 by Society for the Study of Reproduction

Pituitary Responsiveness to Luteinizing Hormone-Releasing Hormone during Delayed Implantation in the Spotted Skunk (Spilogale putorius latifrons): Validation of LH Radioimmunoassay

¹ Department of Biological Sciences, University of Idaho, Moscow, Idaho 83843,2 and Department of Animal Sciences, Washington State University, Pullman, Washington 991633

The double antibody radioimmunoassay procedure of Niswender et al. (1968) has been validated for the spotted skunk, demonstrating the precision, sensitivity, and specificity of the method of assay as formulated by Midgley et al. (1969). Pituitary responsiveness during the prolonged preimplantation period exhibited by the skunk was investigated by injecting (im) a submaximal dosage of purified synthetic luteinizing hormone-releasing hormone (400 ng/0.2 ml acidified saline) once each month to pregnant skunks (N = 4-7) in February, March, and April (8, 4, and 1 wk prior to implantation, respectively). A preinjection blood sample was drawn (time T = 0) via jugular cannula and subsequent postinjection samples were taken at T = 15, 30, 45, 60, 90, 120, and 240 min. Such injections elicited a fourfold increase in plasma LH within 15 min. However, no significant difference in pituitary responsiveness to the releasing hormone was observed between these months. Pregnant animals (N = 3-4) injected with acidified saline only, showed no such rise in LH levels. These results suggest that the prolonged preimplantation period of the spotted skunk is not a result of pituitary inability to respond to hypothalamic control during this period.