Non-surgical artificial insemination using a GnRH analogue for ovulation induction during natural oestrus in African lions (Panthera leo)

Prolonged glucocorticoid administration affects oocyte morphology in cats (Felis catus) undergoing an ovarian stimulation protocol

While captivity-related stress and the associated rise in baseline glucocorticoid (GC) concentrations have been linked to ovarian quiescence in some felid species, no study has examined the effects of elevated GC on oocyte quality. This study examined the effects of exogenous GC administration on the ovarian response and oocyte quality of domestic cats after an ovarian stimulation protocol. Entire mature female cats were divided into treatment (n = 6) and control (n = 6) groups. Cats in the GC treatment (GCT) group were given 1 mg kg-1 oral prednisolone daily from Day 0-45. All cats (n = 12) were given 0.088 mg kg-1 day-1 progesterone orally from Day 0-37, before treatment with 75 IU eCG im to induce follicular growth on Day 40, followed by 50 IU hCG im 80 h later to induce ovulation. Cats were ovariohysterectomised 30 h after the hCG treatment. Blood samples were collected on Days 0, 10, 30 and 40 (prior to eCG treatment), 80 h after eCG treatment, and on Day 45 for cortisol, glucose, prednisolone, oestradiol, and progesterone analysis. Cortisol concentrations did not differ between treatment groups throughout the study. Mean glucose concentrations were higher in the GCT cats (P = 0.004). Prednisolone was undetectable in all samples. Oestradiol and progesterone concentrations confirmed that the eCG treatment stimulated follicular activity and ovulation in all cats. Following ovariohysterectomy, the ovarian responses were graded (1 = excellent, 4 = poor) and oocytes retrieved from the oviducts. Each oocyte was given a total oocyte score (TOS: using an 9-point scale, 8 = best) based on four parameters: oocyte morphology, size, ooplasm uniformity and granularity, and zona pellucida (ZP) thickness and variation. Ovulation was confirmed in all cats, with a mean of 10.5 ± 1.1 ovulations per cat. Ovarian mass, ovarian response, number of ovulations, and oocyte recovery did not differ between groups. Oocyte diameter did not differ between the groups, but the ZP was thinner in the GCT group (3.1 ± 0.3 μm vs. 4.1 ± 0.3 μm, P = 0.03). The TOS was similar between treatment and control cats, but the ooplasm grade was lower (1.5 ± 0.1 vs. 1.9 ± 0.1, P = 0.01) and there was a tendency for ZP grade to be poorer (0.8 ± 0.1 vs. 1.2 ± 0.2; P = 0.08) in the treatment group. In conclusion, the GC treatment resulted in morphological changes to oocytes collected following ovarian stimulation. Whether these changes would affect fertility warrants further investigation.

Postmortem Collection of Gametes for the Conservation of Endangered Mammals: A Review of the Current State-of-the-Art

The collection of gametes from recently deceased domestic and wildlife mammals has been well documented in the literature. Through the utilization of gametes recovered postmortem, scientists have successfully produced embryos in 10 different wildlife species, while in 2 of those, offspring have also been born. Thus, the collection of gametes from recently deceased animals represents a valuable opportunity to increase genetic resource banks, obviating the requirement for invasive procedures. Despite the development of several protocols for gamete collection, the refinement of these techniques and the establishment of species-specific protocols are still required, taking into account both the limitations and the opportunities. In the case of wildlife, the optimization of such protocols is impeded by the scarcity of available animals, many of which have a high genetic value that must be protected rather than utilized for research purposes. Therefore, optimizing protocols for wildlife species by using domestic species as a model is crucial. In this review, we focused on the current advancements in the collection, preservation, and utilization of gametes, postmortem, in selected species belonging to Equidae, Bovidae, and Felidae, both domestic and wildlife.

The challenge of assisted reproduction for conservation of wild felids - A reality check

Threats to the Earth's biodiversity are increasing exponentially, driven by human population growth and resource consumption. As many as one million wildlife species may disappear within the next few decades due to this human-induced extinction event. This represents our current reality and has profound implications for wildlife conservation. Within this context, application of assisted reproductive technology (ART) to conservation management is unlikely to mitigate broad-scale species loss, but for select species, such as wild cats, ART may determine if populations survive or disappear. In North American and European zoos, 20 of the world's 38 wild felid species are managed within structured breeding programs, but most are not sustainable with natural breeding alone. Zoo-based breeding programs are facing tenuous futures due to triage-based responses to this growing sustainability crisis. Theoretically, ART could benefit conservation management, but only by recognizing and addressing its present challenges. The application of ART to wildlife has been rarely successful, with only 62 mammal species (including 15 cat species) ever propagated by AI, and just 35 of these species (6 cats) reproduced following frozen semen AI. Even this most basic form of ART has a minimal impact on wildlife sustainability. The drivers of this deficit include lack of species-specific reproductive knowledge and limited access to animals for study, but also is exacerbated by a science-conservation disconnect that attempts to apply advanced reproductive technologies to species in which basic ART remains unproven. For a few felid species, these scientific challenges have been overcome and AI with frozen semen is becoming feasible as a practical management tool; for other felids, further research is needed. Non-scientific issues also impair our ability to use ART to implement global management plans. Political dysfunction, regulatory barriers and societal indifference create inertia that interferes with achieving meaningful progress in applying ART to wildlife. Collectively, these challenges may seem insurmountable but human resiliency is essential if we are to resolve these issues in a systematic manner. It will require expanding collaborative efforts substantially and intensifying efforts to conserve wildlife species that are literally running out of time. Our goal is to create a new reality that includes a sustainable future for wild felids and other imperiled wildlife species.

Provocative tests with Kisspeptin-10 and GnRH set the scene for determining social status and environmental impacts on reproductive capacity in male African lions (Panthera leo)

Understanding the hypothalamic factors regulating reproduction facilitates maximising the reproductive success of breeding programmes and in the management and conservation of threatened species, including African lions. To provide insight into the physiology and pathophysiology of the hypothalamic-pituitary-gonadal reproductive axis in lions, we studied the luteinising hormone (LH) and steroid hormone responses to gonadotropin-releasing hormone (GnRH) and its upstream regulator, kisspeptin. Six young (13.3 ± 1.7 months, 56.2 ± 4.3 kg) and four adult (40.2 ± 1.4 months, 174 ± 6 kg) male lions (Ukutula Conservation Centre, South Africa) were used in this study. Lions were immobilised with a combination of medetomidine and ketamine and an intravenous catheter was placed in a jugular, cephalic or medial saphenous vein for blood sampling at 10-min intervals for 220 min. The ten-amino acid kisspeptin which has full intrinsic activity (KP-10, 1 µg/kg) and GnRH (1 µg/kg) were administered intravenously to study their effects on LH and steroid hormone plasma concentrations, measured subsequently by ELISA and liquid chromatography tandem mass spectrometry (LC-MS/MS), respectively. Basal LH levels were similarly low between the age groups, but testosterone and its precursor levels were higher in the adult animals. Adult lions showed a significant LH response to KP-10 (10-fold) and GnRH (11-fold) administration (p < 0.05 and P < 0.001, respectively) whereas in young lions LH increased significantly only in response to GnRH. In adults alone, testosterone and its precursors steadily increased in response to KP-10, with no significant further increase in response to GnRH. Plasma levels of glucocorticoids in response to KP-10 remained unchanged. We suggest that provocative testing of LH and steroid stimulation with kisspeptin provides a new and sensitive tool for determining reproductive status and possibly an index of exposure to stress, environmental insults such as disease, endocrine disruptors and nutritional status. 272 words.

How Can We Introduce ART into Wild Felid Conservation in Practice? Joint Experience in Semen Collection from Captive Wild Felids in Europe

Simple Summary

Artificial reproductive techniques (ART), such as cryopreservation of sperm cells and artificial insemination, are useful tools for species conservation. However, there is relatively little information published about their introduction into clinical practice for wild felids. The aim of this paper was to describe how those techniques were applied by three European teams in various species of wild felids. In total, this article presents 22 semen collection attempts in 12 species of wild felids, 15 of which were successful and resulted in the collection of at least one million spermatozoa. The failures in obtaining spermatozoa were most probably due to (1) male infertility, (2) wrong age/non-breeding season, or (3) recent multiple copulations. The cases presented in the article confirm that although ART have been introduced into clinical practice, they are mostly used in cases of infertility, not as routine breeding tools. Greater involvement of zoological gardens and private breeders is required, as many chances for preservation of valuable material are lost.

Abstract

Although artificial reproductive techniques (ART) are considered to be a valuable tool for species conservation, information about their introduction into clinical practice for wild felids is limited. The aim of this paper was to jointly describe cases of non-experimental sperm collection from males of various species of wild felids, performed by three European centers focused on feline reproduction. In total, the article presents 22 attempts of semen collection in 12 species of wild felids. The reasons for semen collection were: fertility assessment (10 cases), artificial insemination (5 cases), sperm rescue (postmortem collection for cryopreservation, 5 cases), and sperm banking (in vivo collection for cryopreservation, 2 cases). Semen collection was successful (defined as at least 1 × 10⁶ spermatozoa) in 15 cases. The failures in obtaining spermatozoa were most probably due to (1) male infertility, (2) wrong age/non-breeding season, or (3) recent multiple copulations. The cases presented here confirm that although ART have been introduced into clinical practice, they are mostly used in cases of infertility, not as routine breeding tools. Higher involvement of zoological gardens and private breeders is required, as many chances for preservation of valuable material are lost.

Successful Laparoscopic Oviductal Artificial Insemination in the Endangered Tsushima Leopard Cat (Prionailurus bengalensis euptilurus)

Simple Summary

The Tsushima leopard cat is an endangered wild felid that lives solely on Tsushima Island, Nagasaki, Japan. Approximately, only 100 Tsushima leopard cats can be found in the wild, and there are concerns that the population will further reduce due to habitat degradation and traffic accidents. In 1994, Japan’s Ministry of the Environment (MOE) developed a conservation and breeding project for the Tsushima leopard cat. The MOE is working with the Japanese Association of Zoo and Aquariums for ex situ conservation of this species. However, considering genetic diversity, it is difficult to conduct captive breeding programs using only natural breeding; hence, assisted reproductive technologies are required. This study aimed to breed Tsushima leopard cats using artificial insemination (AI) by depositing sperms into the oviducts. Ovulation was artificially induced in two females, laparoscopically inseminated with fresh sperms into the oviducts. The pregnancies were monitored via fecal levels of progestogens and radiography. One female had spontaneous delivery of a female kitten 66 days post-AI. This is the first successful case of AI in a Tsushima leopard cat.

Abstract

The Tsushima leopard cat (Prionailurus bengalensis euptilurus) is an endangered wild felid that lives solely on Tsushima Island, Nagasaki, Japan. Japan’s Ministry of the Environment is working with the Japanese Association of Zoo and Aquariums for ex situ conservation of this species. However, considering genetic diversity, it is difficult to conduct captive breeding programs by natural breeding alone; hence, assisted reproductive technologies are required. This study aimed to breed Tsushima leopard cats, which otherwise cannot be paired, using laparoscopic oviductal artificial insemination (AI). Female Tsushima leopard cats (female 1, aged 7 years; female 2, aged 6 years) were treated with 200 IU equine chorionic gonadotropin, followed by administration of 1000 IU porcine luteinizing hormone (pLH) after 96 h to induce ovulation. Laparoscopic AI was performed 32 h post-pLH administration. Females 1 and 2 were inseminated in the oviduct with 2.4 × 10⁶ and 3.3 × 10⁶ motile spermatozoa, respectively, collected from two males. Pregnancy was confirmed by radiography 45 and 51 days post-AI in females 1 and 2, respectively; one fetus was found in female 2. Moreover, female 2 had spontaneous delivery of a female kitten 66 days post-AI. This is the first successful case of AI in a Tsushima leopard cat.

Identification of Circular RNAs in the Anterior Pituitary in Rats Treated with GnRH

Simple Summary

The pituitary gland, an important endocrine organ, can secrete a variety of reproductive hormones under the action of hypothalamus-secreted gonadotropin-releasing hormone. Circular RNAs are a class of RNA molecules with stable covalently closed circular structures. In this study, we performed RNA sequencing of GnRH-treated rats to identify differentially expressed circRNAs in the anterior pituitary. The results revealed 1433 related circRNAs, 14 of which were differentially expressed. We predicted targeted relationships between the differentially expressed circRNAs and FSHb-LHb-associated miRNAs. In all, a total of 14 circRNAs were identified that may act on the secretion and regulation of reproductive hormones in GnRH-treated rats.

Abstract

The pituitary gland, an important endocrine organ, can secrete a variety of reproductive hormones under the action of hypothalamus-secreted gonadotropin-releasing hormone (GnRH) and plays important roles in animal reproduction. Circular RNAs (circRNAs) are a class of RNA molecules with stable covalently closed circular structures. CircRNAs are equipped with miRNA response elements (MREs), which can regulate the expression of target genes by competitively binding miRNAs. However, whether the expression levels of circRNAs in the pituitary gland change under the action of GnRH and whether such changes can further affect the secretion of reproductive hormones are still unclear. In this study, we performed RNA sequencing (RNA-Seq) of GnRH-treated rats to identify differentially expressed circRNAs. The results revealed 1433 related circRNAs, 14 of which were differentially expressed. In addition, we randomly selected five differentially expressed circRNAs and tested their relative expression levels by RT-qPCR, the results of which were consistent with the RNA sequencing results. Finally, we predicted targeted relationships between the differentially expressed circRNAs and FSHb-LHb-associated miRNAs. In all, a total of 14 circRNAs were identified that may act on the secretion and regulation of reproductive hormones in GnRH-treated rats. Our expression profiles of circRNAs in the anterior pituitaries of rats treated with GnRH can provide insights into the roles of circRNAs in mammalian development and reproduction.

Monitoring ovarian function and detecting pregnancy in felids: A review

Reliable detection and monitoring of estrus and pregnancy is essential to the effective ex situ conservation of endangered felids. Here, we review the current methods used to detect estrus and pregnancy in felids and describe the advantages and limitations of each. A total of 194 felid-focused publications were reviewed. The methods used included behavioral assessments (61 publications across 24 species), hormone monitoring (124 studies across 28 species), fecal protein monitoring (two studies in cheetah), ultrasonography (31 publications across seven species), vaginal cytology (22 publications across nine species), and laparoscopy (70 publications across 19 species). Behavior-based assessments of reproductive state are often inconsistent and unreliable in felids; thus hormone measurement is the most frequently used method for monitoring estrous cycles (66% of studies). In non-domestic felids, non-invasive fecal- or urine-based hormone metabolite analyses are preferred to blood assessments (66% of endocrine-based publications). While the measurement of fecal estrogen and progestin metabolites are useful for the retrospective assessment of ovarian activity, their use for real-time detection of estrus is limited. Vaginal cytology, laparoscopy and ultrasonography provide an acute and immediate determination of reproductive state but usually require anesthesia or sedation, which can prevent ovulation and cause abortions; thus, their use for pregnancy diagnosis is limited. Fecal progesterone or prostaglandin F_2α metabolites can be used to detect pregnancy in most felids (the exception being fecal progestins for Lynx spp.), but only during mid-to-late gestation. Urinary relaxin measurement is a promising method for earlier pregnancy diagnosis (30-40% duration of gestation) but is presently limited by poor assay sensitivity due to the lack of a feline-specific relaxin antibody. Elevated levels of fecal immunoglobulin J chain have been investigated as a tool to detect pregnancy in cheetah (>80% accuracy), but research is lacking on other species. We conclude that there is no single 'best method' for monitoring ovarian activity and detecting pregnancy in felids, and current best practice would involve a combination of existing methods. Non-invasive methods for detecting estrus and pregnancy in felids (e.g., accelerometry and infrared thermography) should also be considered to augment existing methods.

Reproductive biology and biotechnologies in wild felids

Conservation strategies in natural habitats as well as in breeding centers are necessary for maintaining and reinforcing viable populations of wild felids. Among the fundamental knowledge that is required for conservation breeding, a solid understanding of reproductive biology is critical for improving natural breeding and enhance genetic diversity. Additionally, it offers the opportunity to develop assisted reproductive technologies (ARTs) in threatened and endangered species. Conservation breeding and reproductive biotechnologies of wild felids have advanced in the past decade. It has been clearly shown that female felids have species and individual patterns of reproductive cycles and respond differently to exogenous hormones. In males, several species still have poor semen quality often due to the loss of genetic diversity in small populations. To overcome the challenges of natural breeding (incompatibility between individuals or suboptimal environment) and mitigate inbreeding, artificial insemination, embryo production and embryo transfer have been further developed in 24 wild cat species. Major factors limiting ART success are inconsistent responses to ovarian stimulation, variable quality of gametes and embryos, and preparation of recipient females. Additional approaches including stem cell technologies have been explored for future medical applications. However, there still is a critical need for better knowledge of feline reproductive biology and improvement of ARTs efficiency to increase the genetic diversity and create sustainable populations of wild felids.

Positive Reinforcement Conditioning as a Tool for Frequent Minimally Invasive Blood and Vaginal Swab Sampling in African Lions (Panthera Leo)

Information regarding the physiology of African lions is scarce, mainly due to challenges associated with essential routine research procedures. The aim of this experiment was to test the possibility of training six captive lionesses by positive reinforcement conditioning (PRC) to voluntarily allow the collection of vaginal swabs and blood samples. This was done with the final goal of avoiding frequent anesthesia, and potentially stressful management during reproduction research. All lionesses mastered basic clicker and targeting principles within 2 weeks. Routine sampling was possible after 20 weeks of training, enabling the collection of about 750 vaginal swabs and 650 blood samples over 18 months. The animals remained calm and cooperative during all sessions, and demonstrated curiosity in the training. PRC training of captive lionesses proved to be a suitable, minimally invasive method for repeated collection of vaginal swabs and blood. Additionally, PRC may serve as behavioral enrichment for African lions in captive settings. Compared to chemical or physical restraining methods, this noninvasive management approach may reduce distress and physiological negative side effects, thus opening up new avenues for feline research.

Reproductive cycle stage assessment using vaginal cytology evaluation in African lions (Panthera leo)

Vaginal cytology evaluation is an economic, non-invasive technique for indirect monitoring of fluctuations in estrogen concentrations, and thus progression of the estrous cycle. This technique is widely used in domestic dogs for determining timing of artificial insemination. There, however, are only a few reports on the vaginal cytology of non-domestic felids, including lions. This study was conducted, therefore, to describe the vaginal epithelial changes throughout the reproductive cycle of African lions, and to investigate the efficacy of vaginal cytology assessments for predicting reproductive stages. During a 12-month period, reproductive behavioral data and vaginal swabs were collected daily from five lionesses. In total, 541 vaginal smears were evaluated for the proportion of mucosal epithelial cells, neutrophils, bacterial cells, and amount of mucous, cellular debris. One single swab with a large proportion of superficial cells, absence of neutrophils, large number of bacteria, without cellular debris was sufficient for detecting lionesses in estrus. Likewise, one cytology sample with a large proportion of parabasal and intermediate cells, few neutrophils, few bacteria, and large amount of mucous, cellular debris enabled detection of females in advanced diestrus or gestation. To distinguish lionesses in early diestrus from those in an inter-estrous period, at least two consecutive swabs were necessary for satisfactory classification. Overall, evaluation of vaginal cytology samples was an effective technique for differentiation among different stages of the reproductive cycle, confirmation of estrus, and pregnancy diagnosis in lionesses. This technique, therefore, has the potential for application in classifying different stages of the reproductive cycle in other feline species.