Interactions Among Different Devices and Electrical Stimulus on the Electroejaculation of Captive Agoutis (Dasyprocta leporina)

Relationship between season and spermatozoa traits of captive-reared agoutis from Brazilian semiarid

For the development of efficient management and conservation strategies for wild rodent species, understanding the aspects related to their reproduction, including the interaction of this physiological function with the environment, is essential. This study aimed to evaluate the impacts of weather changes derived from a semiarid region's dry and rainy seasons on the epididymal sperm characteristics of red-rumped agouti (Dasyprocta leporina), a histricognath rodent, still little studied, which inhabits the Brazilian Caatinga. The sperm from the epididymal cauda of 14 agoutis were collected, seven individuals per season (dry and rainy). Samples were evaluated for kinetic parameters, membrane structural and functional integrity, mitochondrial activity, morphology, and morphometry. The environmental variables were measured: maximum air temperature, relative humidity, wind speed, solar radiation, and the total rainfall for dry and rainy seasons were, respectively, 36.2 and 34.1 °C, 66.8 and 80.1%, 4.0 and 1.9 m/s, 527.3 and 441.8 W/m2, and 0.2 and 517.7 mm. There were strong correlations between some sperm parameters and environmental variables, mainly those related to the acquisition of sperm mobility. Sperm concentration and the number of sperm collected were higher in the dry (1028.7 sperm/mL × 10⁶ and 1361.2 × 106 sperm) than in the rainy season (758.9 sperm × 10⁶/mL and 714.6 sperm × 106). During the rainy season, there were fewer sperm defects, higher sperm metrics, and higher membrane structural integrity with mitochondrial activity. Regarding motility patterns, the increases during the rainy season stand out in total and progressive motility, VAP, VSL, VCL, and subpopulations of rapid sperm. In summary, our results suggest that the adverse climatic conditions of the dry season in the semiarid region, mainly high solar radiation and temperature, considerably impair the epididymal sperm quality of red-rumped agoutis. On the contrary, the largest amount of sperm was obtained during this season, probably due to compensatory and adaptive mechanisms of the species to enable its reproduction throughout the year.

Cryopreservation efficiency of red-rumped agouti (Dasyprocta leporina) sperm obtained from different origins through epididymal retrograde flushing or electroejaculation

This study investigated whether the origin of sperm (epididymal vs. ejaculate) affects the cryopreservation efficiency in agouti (Dasyprocta leporina). Five sexually mature agoutis underwent electroejaculation, resulting in obtaining four semen samples. After 15 days, the same animals were euthanized, and through retrograde flushing, sperm samples were obtained from the epididymis tails. In both collection methods, samples were evaluated for sperm parameters (sperm concentration, motility, vigor, membrane integrity, osmotic response, and morphology). Then, samples were diluted in ACP 109c, added with 20% egg yolk, and a final concentration of 6% glycerol. Finally, the samples were packaged in 0.25 mL straws and frozen in liquid nitrogen. After one week, samples were thawed and evaluated in the same way as fresh samples, with the addition of membrane integrity analysis using fluorescent probes (C-FDA/PI) and computerized analysis (CASA). Immediately after obtaining the sperm, samples obtained directly from the epididymis presented higher values (P ≤ 0.05) than those obtained by electroejaculation concerning the parameters of volume, sperm concentration, and total number of sperm (1,398.25 ± 206.0 x106 and 184.5 ± 78.0 x106 sperm). On the other hand, in the classical evaluation of the other sperm parameters and the computerized analysis (CASA) after thawing, such as total motility, no statistical differences were observed between sperm from both origins (ejaculate: 16.7 ± 8.2% and epididymal: 24.8 ± 12.0%, P > 0.05). This demonstrates the possibility of direct application of the cryopreservation protocol for agouti (D. leporina) sperm obtained via the epididymis or ejaculate.

Synergistic effects of follicle-stimulating hormone and epidermal growth factor on in vitro maturation and parthenogenetic development of red-rumped agouti oocytes

Although oocyte in vitro maturation (IVM) is routinely used for in vitro embryo production in mice and rats, its use in wild rodents remains unexplored. Evidence suggests that hormone and growth factor supplementation influence oocyte meiotic resumption. This study evaluated the synergistic effects of follicle-stimulating hormone (FSH) and epidermal growth factor (EGF) on the IVM and parthenogenetic development of red-rumped agouti oocytes. Initially, we evaluated the IVM rates, mature oocyte quality, oocyte morphometry, and early embryonic development during IVM in the presence of 10, 50, and 75 mIU/mL FSH. No differences among the FSH concentrations were observed for IVM rates, oocyte morphometry, cumulus cell expansion, and viability. Although oocytes matured with 50 mIU/mL FSH showed a higher rate of cumulus expansion index (CEI), only oocytes matured with 10 mIU/mL FSH resulted in morulae after chemical activation (7.9% ± 4.2%). Thus, 10 mIU/mL FSH was used for further experiments. We subsequently evaluated the synergistic effects of 10, 50, and 100 ng/mL EGF and 10 mIU/mL FSH on the same parameters. No differences among the groups were observed in IVM rates, oocyte morphometry, and cumulus viability. Nevertheless, FSH with 10 ng/mL EGF showed a CEI superior to that of the other groups. Furthermore, oocytes matured with FSH alone or with both FSH and 10 or 50 ng/mL EGF developed morulae after activation (5.8%-8.3%). In conclusion, oocytes matured with 10 mIU/mL FSH and 10 ng/mL EGF are recommended for use in red-rumped agouti oocyte IVM, as they positively influence embryonic development.

Morphological, morphometric, ultrastructural, and functional evaluation of red-rumped agouti (Dasyprocta leporina) sperm during epididymal transit

The red-rumped agouti (Dasyprocta leporina) is a hystricognath rodent with reproductive anatomical peculiarities presenting as an intra-abdominal testes-epididymis complex. This study was carried out to describe, for the first time, details related to the morphological and functional changes in sperm along the epididymal transit in agoutis. The testes-epididymal complexes were sampled from seven sexually mature agoutis. Sperm from different epididymal regions (caput, corpus, and cauda) were collected using the floating technique, and their morphology, morphometry, ultrastructure, mitochondrial activity, membrane structural integrity, and kinetic parameters were determined. The number of sperm collected (823.5 ×10⁶ sperm) was higher in the epididymis cauda. No significant differences in normal sperm morphology among the different epididymal regions (caput, 82.42%; corpus, 86.71%; and cauda, 88.86 %) were observed. The mean head length, head width, and tail length were highest in the caput (5.15 µm, 3.44 µm, and 32.04 µm, respectively), decreasing along the epididymal transit. Ultrastructure by scanning electron microscopy (SEM) revealed agglomeration of spermatozoa from caput and corpus, thus, enabling analysis of the gametes from only the epididymal cauda with clarity. Sperm from epididymis cauda showed the greatest proportion of membrane integrity and mitochondrial activity, followed by those from corpus and caput (79.71 %, 58.9 %, 47.7 %, respectively). Significant increase in total motility, progressive motility, velocity average pathway -VAP, velocity straightline - VSL, velocity curvilinear - VCL, and rapid sperm in the caput-corpus-cauda direction were observed. These novel data contribute to the knowledge of sperm maturation in the red-rumped agouti.

Evaluation of sperm membrane functionality during epididymal transit in red-rumped agouti (Dasyprocta leporina)

We studied the sperm membrane functionality through the epididymal transit by comparing different hypoosmotic solutions and verifying possible associations among osmotic response and functional parameters of sperm in red-rumped agouti (Dasyprocta leporina). For this purpose, epidydimal sperm from six sexually mature male agoutis were collected via flotation. Then, analyses of sperm parameters and hypoosmotic swelling test using different hypoosmotic solutions (0 mOsm/l, 50 mOsm/l, and 200 mOsm/l) in different regions of the epididymis (caput, corpus, and cauda) were performed. There was an increase (P < 0.05) in the values for sperm concentration, total number of sperm recovered, total and progressive motility, average path velocity, straightline velocity, curvilinear velocity, rapid and medium subpopulations following the caput-corpus-cauda direction. Regardless the hypoosmotic solution, agouti sperm membrane presented similar functional integrity in all the epididymal regions. Moreover, the highest (P < 0.05) osmotic responses were reached at the use of 50 mOsm/l solution in comparison to 0 mOsm/l and 200 mOsm/l for all the regions. Significant correlations among osmotic response and some sperm kinetic parameters were especially observed in epidydimal caput, while no correlations were found in the region of the cauda. In summary, red-rumped agouti sperm present similar membrane functionality during epidydimal transit, but there are evident correlations among such functionality and sperm kinetic parameters, especially at the caput region. Moreover, we indicate the use of a 50 mOsm/l hypoosmotic solution for the analysis of this parameter through the hypoosmotic swelling test.

Reproductive Technologies Used in Male Neo-Tropical Hystricomorphic Rodents

This review, which is the first of two, focuses on the male reproductive anatomy and reproductive technologies used in Neo-tropical hystricomorphic rodents with the potential for domestication, which are the agouti (Dasyprocta leporina), the capybara (Hydrochoerus hydrochaeris) and the paca (Cuniculus paca). We consider over seventy references spanning from 1965 to 2020, with the majority of work being done in the past twenty years. Knowledge of the reproductive tract and reproductive technologies is critical to the conservation and preservation of these species. Although all three animals had similarities in their anatomy, such as no overt scrotums and testes located intra-abdominally in the inguinal region, some had unique features-for example, the agouti and the paca had penile spines, and two lateral penile cartilages. High spermatogenic efficiency was noted in the agouti and the paca, making them good candidates for increasing their reproductive performance in conservation programs. A review of the literature has shown that there is increasing work taking place on the reproductive technologies used in these animals; however, a lot of work is still lacking, as, to the author's knowledge, standard protocols and artificial insemination procedures are yet to be established.

Morphology and immunolocalization of aquaporins 1 and 9 in the agouti (Dasyprocta azarae) testis excurrent ducts

This study investigated the morphology and immunoexpression of aquaporins (AQPs) 1 and 9 in the rete testis, efferent ducts, epididymis, and vas deferens in the Azara's agouti (Dasyprocta azarae). For this purpose, ten adult sexually mature animals were used in histologic and immunohistochemical analyses. The Azara's agouti rete testis was labyrinthine and lined with simple cubic epithelium. Ciliated and non-ciliated cells were observed in the epithelium of the efferent ducts. The epididymal cellular population was composed of principal, basal, apical, clear, narrow, and halo cells. The epithelium lining of vas deferens was composed of the principal and basal cells. AQPs 1 and 9 were not expressed in the rete testis. Positive reaction to AQP1 was observed at the luminal border of non-ciliated cells of the efferent ducts, and in the peritubular stroma and blood vessels in the epididymis, and vas deferens. AQP9 was immunolocalized in the epithelial cells in the efferent ducts, epididymis and vas deferens. The morphology of Azara's agouti testis excurrent ducts is similar to that reported for other rodents such as Cuniculus paca. The immunolocalization results of the AQPs suggest that the expression of AQPs is species-specific due to differences in localization and expression when compared to studies in other mammals species. The knowledge about the expression of AQPs in Azara's agouti testis excurrent ducts is essential to support future reproductive studies on this animal, since previous studies show that AQPs may be biomarkers of male fertility and infertility.

Understanding how environmental factors influence reproductive aspects of wild myomorphic and hystricomorphic rodents

Myomorphic and hystricomorphic rodents are vital for maintaining various ecosystems around the planet. This review enables a better understanding of how these rodents respond to environmental factors and adapt to climate adversities. Innumerable factors, such as photoperiod, rainfall, and temperature, can impair or contribute to the quality of rodent reproductive parameters. Prolonged animal exposure to high ambient temperatures alters thermoregulation mechanisms and causes testicular and ovarian tissue degeneration and hormonal deregulation. Photoperiod influences the biological circannual rhythm and reproductive cycles of rodents because it strongly regulates melatonin secretion by the pineal gland, which modulates gonadotropic hormone secretion. Rainfall quantity directly regulates the abundance of fruits in an ecosystem, which modulates the reproductive seasonality of species which are most dependent on a seasonal fruit-based diet. Species with a more diversified fruit diet have smaller reproductive seasonality. As such, habitats are chosen by animals for various reasons, including the availability of food, sexual partners, intra-and inter-specific competition, and predation. This knowledge allows us to monitor and establish management plans to aid in conservation strategies for wild rodent species.

Natural Habitat, Housing, and Restraint of Six Selected Neotropical Animals in Trinidad and Tobago with the Potential for Domestication

This paper highlights the natural habitat, housing, and restraint needs of 6 Neotropical animals that are found in Trinidad and Tobago with the potential for domestication: agouti (Dasyprocta leporina), lappe/paca (Cuniculus paca/Agouti paca), capybara (Hydrochoerus hydrochaeris), manicou/opossum (Didelphis marsupialis insularis), collared peccary (Tayassu tajacu/Pecari tajacu), and red brocket deer (Mazama americana). The year of the earliest reference cited was 1950 and the most recent was 2018, with over 100 references being used. The average density, home range size, social group, and housing requirements were also examined as these factors would play a role in designing enclosures. A number of different physical and chemical restraint techniques were also discussed. Information from other species within the same genus was incorporated as some of the animals did not have sufficient literature.