Abstract
Simple SummaryThe corpus luteum is a transient endocrine gland on the mammalian ovary, and its main function is to produce progesterone. Knowledge about the corpus luteum in felids is very limited and luteolytic and luteotrophic factors which regulate its maintenance and regression are not extensively studied. Information about corpus luteum function is needed to understand breeding strategies and to successfully implement assisted reproductive techniques for felids, of which most of the species are threatened. The aim of this study was to reveal the effect of luteinizing hormone on cultured luteal cells from corpora lutea obtained from selected felids and to investigate the protein expression of steroidogenic enzyme 3β-hydroxysteroid dehydrogenase by immunohistology.The objective of this study was to investigate the effect of luteinizing hormone (LH) on steroidogenic luteal cells obtained from corpora lutea (CL) of the domestic cat and selected wild felids. Luteal cells were isolated enzymatically from CL at different developmental stages and cultured for two days in the presence and absence of 100 ng/mL LH, respectively. Functionality was assessed by progesterone (P4) accumulation in cell culture media determined by ELISA. In addition, steroidogenic function was confirmed using immunohistochemistry for 3β-hydroxysteroid dehydrogenase (HSD3B). The enzymatic method allowed for the isolation of mostly small luteal cells in all investigated felids. Treatment with LH resulted in an increase in P4 secretion of cultured luteal cells obtained from CL in the formation stage (African lion) and development/maintenance stage (domestic cat (p < 0.05), Javan leopard), whereas luteal cells from more advanced stages of luteal development (regression) responded moderately or not at all to LH stimulation (domestic cat, Asiatic golden cat, Asiatic lion). The protein signal for HSD3B on CL was visible until development/maintenance. In conclusion, this study shows that LH promotes P4 production in luteal cells only until the onset of regression, when morphological signs are visible on the CL of felids and HSD3B is no longer detectable.
Highlights
There are 38 wild felids listed on the IUCN Red List, and 25 of them are classified as near threatened, vulnerable or endangered
We previously described that the enzymatic isolation method we used allowed us to obtain small luteal cells (SLC) from domestic cat corpora lutea (CL) almost exclusively because luteal cells (LLC) were fragile and got lost by this method [20]
Our data indicate that the previously established enzymatic isolation method of small luteal cells in the domestic cat can be successfully applied to other felid species, but the ratio of isolated SLC to LLC may be different in comparison to the domestic cat
Summary
There are 38 wild felids listed on the IUCN Red List, and 25 of them are classified as near threatened, vulnerable or endangered (https://www.iucnredlist.org). The main causes of felid population decline are due to habitat loss and fragmentation, humanwildlife conflicts, the illegal pet trade and traditional medicine [1]. To protect species from extinction, ex situ and in situ conservation programs have been established, but success depends on knowledge on the reproduction cycles of felids. There are species whose reproductive biology have never been described [2]. There is a critical need for more information about reproductive biology of felids to improve natural breeding or for the application in assisted reproductive techniques (ART) [4,5]
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