Hormonal induction of spermatozoa from amphibians with Rana temporaria and Bufo bufo as anuran models

Abstract

The use of hormonally induced spermatozoa expressed in urine (HISu) is a valuable component of reproduction technologies for amphibians. Five protocols for sampling HISu from the European common frog (Rana temporaria) were compared: (1) pituitary extracts, (2) 0.12 µg g–1 luteinising hormone-releasing hormone analogue (LHRHa), (3) 1.20 µg g–1 LHRHa, (4) 11.7 IU g–1 human chorionic gonadotrophin (hCG) and (5) 23.4 IU g–1 hCG (g–1 = per gram bodyweight). From 1 to 24 h after administration we assessed the number and concentration of spermatozoa in spermic urine and in holding water, and in urine the percentage of motile spermatozoa and their progressive motility. The protocol using 1.20 µg g–1 LHRHa gave the highest total sperm numbers (650 × 106) and the highest percentage (40%) of samples with sperm concentrations above 200 × 106 mL–1. The percentage motility and progressive motility was similar from all protocols. Considerable amounts of spermatozoa were expressed by R. temporaria into their holding water. We tested hormonal priming and spermiation in the common toad (Bufo bufo) using 0.13 µg g–1 LHRHa administered 24 h before a final spermiating dose of 12.8 IU g–1 hCG. No spermatozoa were expressed in holding water. Priming resulted in 35% more spermatozoa than without; however, there were no differences in sperm concentrations. Primed B. bufo produced spermatozoa with significantly higher percentage motility, but not progressive motility, membrane integrity, or abnormal spermatozoa than unprimed males.