Reptiles are highly susceptible to anthropogenic activities as a result of their narrow geographical ranges and habitat specialization, making them a conservation concern. Geckos represent one of the mega-diverse reptile lineages under pressure; however, limited assisted reproductive technologies currently exist for these animals. Exogenous pregnant mare serum gonadotropin (PMSG) has been found to exhibit follicle stimulating hormone-like action and has been routinely used to alter reproductive hormones of vertebrates in assisted reproductive protocols. The purpose of this study was to determine the effects of serial injections of 20 IU and 50 IU PMSG on circulating testosterone concentrations, testicular dynamics, and semen production in a model species of gecko. Twenty-four captive-bred, adult, male leopard geckos (Eublepharis macularius) were divided into three treatment groups and administered a once-weekly injection of either PMSG or saline for a total of nine weeks. Ultrasonographic testicular measurements, electrostimulation for semen collection, and venipuncture were performed on days 0, 21, 42, and 63. Right unilateral orchidectomies and epididymectomies were performed in all animals on day 63; tissues were submitted for histopathology. PMSG treated geckos had significantly higher testicular volumes and weights, spermatozoa motility, and spermatozoa concentrations compared with controls. However, there were no significant differences in testosterone concentrations by treatment or time. Under the conditions outlined, PMSG is effective at stimulating spermatogenesis and increasing testicular size, but not effective at increasing testosterone concentrations in the leopard gecko between October–December in the Northern hemisphere.

No abstract

OBJECTIVE To measure plasma and tissue activities of alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase (AST), creatine kinase, and γ-glutamyltransferase in 2 snake species. ANIMALS 6 banded water snakes (Nerodia fasciata) and 6 diamondback water snakes (Nerodia rhombifer). PROCEDURES Blood was collected via the ventral tail vein to measure plasma enzyme activities. Animals were then euthanized, and samples of 9 tissues were collected from each snake: skeletal muscle, cardiac muscle, liver, spleen, lung, kidney, testicle, pancreas, and gallbladder. Tissues were frozen for 30 days, then homogenized and processed. Supernatants were collected and analyzed within 24 hours of processing. A linear mixed model was used to determine differences in enzyme activity between tissues and species and assess interactions between tissues and species. RESULTS Activities of all enzymes were found to differ significantly among tissues. There were also significant differences between species for all enzyme activities, except AST activity. The kidney had the highest alanine aminotransferase and γ-glutamyltransferase activities. Alkaline phosphatase activity was significantly highest in liver and kidney tissues than in other tissue. Creatine kinase activity was highest in skeletal muscle, followed by cardiac muscle and kidney. AST activity was present in all tissues evaluated, but was highest in liver, kidney, and cardiac muscle in both species. CLINICAL RELEVANCE Results reinforced the importance of characterizing the origin of tissue enzymes in reptiles to improve our understanding of biochemistry results and highlighted the differences that can exist in tissue enzyme activities between closely related species.