Topical application of hormone gonadotropin‐releasing hormone (GnRH‐A) stimulates reproduction in the endangered Texas blind salamander (Eurycea rathbuni)

Abstract

We present a landmark success of a pilot study in the noninvasive, topical hormonal stimulation of reproduction of salamanders using Texas blind salamanders (Eurycea rathbuni) as a model species. Improved reproduction is a critical milestone in the conservation of imperiled species. Captive reproduction of amphibians is often challenging due to specific and ambiguous environmental cues for each species. The Texas blind salamander is a federally listed troglobitic amphibian found only in the Edwards Aquifer beneath San Marcos, Texas. This species is long-lived, paedomorphic, and obligately aquatic. As with other cave-dwelling organisms, Texas blind salamanders exhibits delayed reproductive maturity and low reproductive output. The US Fish & Wildlife San Marcos Aquatic Resources Center maintains a captive assurance population of wild individuals to supplement natural populations in the case of a catastrophic impacts on the wild population. Despite housing this species since the 1980s, unassisted reproductive events remain infrequent and unpredictable. In 2020, we developed the noninvasive use of the topical application of GnRH-A to stimulate reproduction in 12 females combined with 12 males during a pilot study, that resulted in 11 clutches over a five-month period.

Gamete Collection, Artificial Fertilization and Captive-Rearing of Eggs in a Terrestrial-Breeding Anuran with Parental Care: Alytes obstetricans

“…Hormone administration in amphibians is commonly performed intraperitoneally or subcutaneously in the dorsal lymph sacs, but alternative non-invasive routes have been tested. Hormones have been administrated topically [34][35][36] and through intranasal application [37].…”

Ecological Civilization COP 15 and Amphibian Sustainability through Reproduction Technologies, Biobanking, and Conservation Breeding Programs (RBCs)

“…These species include most plethodontids, which include many threatened species, and that comprise 65% of salamander species [52]. Alternative administration methods for hormones include topical or nasal application [60,201,212]. Hormone injection has been used successfully for larger salamanders [60,120,207], including for the commercial production of Chinese giant salamanders [Andrias clade ; 60].…”

Oral administration of GnRH via a cricket vehicle stimulates spermiation in tiger salamanders (Ambystoma tigrinum)

“…More simply, ovulation in African clawed frogs ( Xenopus laevis ) resulted from the passive absorption of human chorionic gonadotropin (hCG) via a water bath [ 30 ]. Similarly, dermal application of GnRH to Texas blind salamanders ( Eurycea rathbuni ) stimulated reproduction [ 31 ], which is likely due to the porous nature of their skin as an obligate aquatic species. However, dermal administration of hormones in terrestrial caudates has not been examined.…”