Wild Rats Research Articles

Genetic and biological insights into Hydatigera taeniaeformis in invasive black rats from southern Chile

IntroductionThis study investigates the genetic variability of Hydatigera taeniaeformis in black rats (Rattus rattus), a common tapeworm that infects cats and rodents worldwide. Despite its widespread presence and zoonotic potential, little is known about the genetic diversity of this parasite in the Americas.MethodsWe conducted DNA barcoding analysis using mitochondrial cox1 gene sequences using samples collected from 171 invasive wild black rats, captured in the temperate rainforest of Southern Chile. We also included two adult parasites isolated from road killed Kodkods (Leopardus guigna), a small felid species native to the Americas.ResultsOur findings revealed only two haplotypes, suggesting low genetic variability in a parasite that arrived in the Americas with the Spanish colonization.DiscussionThese haplotypes are more closely related to parasite populations from Peru, Africa, Australia, and Europe, suggesting an origin linked to the Spanish colonization, possibly from North Africa via the Canary Islands. The study also analyzed infection rates, parasite size, and their correlation with host body size, age, and weight, revealing significant patterns. These results provide new insights into the biogeography and genetic diversity of H. taeniaeformis in a new geographical area, enhancing our understanding of its evolutionary history.

Metagenomics and selective culture reveal the major transfer and prevalence of antibiotic resistance genes in Tibetan Plateau animals

The Tibetan Plateau, despite being the highest and least populated plateau on the Earth, harbors antibiotic-resistant bacteria (ARBs) as well as antibiotic resistance genes (ARGs) in its pristine environment and animals. There is, however, limited knowledge regarding antibiotic resistance in Tibetan Plateau animals. Here, fecal samples of grazing yaks and intestinal content samples of wild rats were collected at altitudes of 2920m and 4360m and subjected to selective culture, PCR, and metagenomic sequencing. The results revealed a higher antibiotic resistance rate in low-altitude regions than in high-altitude regions. The simultaneous presence of bacteria exhibiting different antibiotic resistance phenotypes across multiple samples suggests the potential emergence of multidrug-resistant strains within the animal gut microbiota. Pseudomonas spp. and Escherichia coli were the predominant ARBs. In contrast to low-altitude regions with frequent human activities, ARG dissemination in the Tibetan Plateau did not show a significant correlation with mobile genetic elements. ARGs in high-altitude regions relied more on vertical gene transmission. This study expands our knowledge of antibiotic resistance in grazing and wild animals inhabiting the Tibetan Plateau, thereby highlighting the potential threat posed by antibiotic resistance in this region.

The first survey of endoparasite infection in the brown rat (Rattus norvegicus) from a synanthropic environment in Hungary

Urban rats are significant reservoirs of zoonotic endoparasites, posing serious health risks to humans. This study aimed to detect common endoparasites in wild brown rats (Rattus norvegicus) in Budapest, addressing the current lack of endoparasite surveys in Hungary. Carcasses of 131 rats collected following extermination were examined. Three zoonotic helminths were identified: Hymenolepis nana and Hymenolepis diminuta in the jejunum, and Calodium hepaticum in the liver. Additionally, non-zoonotic parasites were detected, including Eimeria spp., Entamoeba muris, Heterakis spumosa, Nippostrongylus brasiliensis, Eucoleus gastricus, Aonchotheca annulosa, Syphacia muris (intestine), and Trichosomoides crassicauda (urinary bladder). Helminth infection prevalence was 83.9 %, with no noticeable differences in prevalence or infection intensity between sexes. These findings highlight the potential public health risk posed by zoonotic parasites in urban rat populations, emphasising the importance of surveillance to mitigate possible human infection. The findings indicate that rats from Budapest harbour similar parasites to those in neighbouring regions. Further large-scale studies are recommended to better understand the parasitic landscape in Hungary's rat populations, leveraging data from rat control programs.

Analysis Pork Contamination in Beef Meatballs through Polymerase Chain Reaction in Palu City

The need for halal products is essential, particularly among various processed beef products like meatballs, which are popular among nearly the entire community. These products are susceptible to issues of meat counterfeiting for greater economic gain. This study aims to determine the smallest DNA concentration that can still be detected and to assess whether there is any pork contamination in meatballs circulating in Palu City using Polymerase Chain Reaction (PCR). This test uses four DNA samples obtained from fresh meat to test the specificity of the primer: wild boar, rat, and goat DNA samples as comparisons, and pig DNA as a positive control. The presence of DNA bands in the agarose gel electrophoresis visualization results indicates that DNA amplification has occurred, meaning that the sample can be detected. The analysis results showed that the primer used (Cyt-b) had good specificity for detecting pork DNA, while the absolute pork DNA concentration of 0.01 ng/µL and the reference meatball DNA with a concentration of 0.01% are the smallest limits that can still be detected using PCR. Of the four meatball samples from Palu City, one sample produced a DNA band, indicating that the sample contains or is contaminated with pig DNA. This method is valid as it meets the specificity test and demonstrates a good detection limit.

The evolutionary history of wild and domestic brown rats (Rattus norvegicus).

The brown rat (Rattus norvegicus) occupies nearly every terrestrial habitat with a human presence and is one of our most important model organisms. Despite this prevalence, gaps remain in understanding the evolution of brown rat commensalism, their global dispersal, and mechanisms underlying contemporary adaptations to diverse environments. In this Review, we explore recent advances in the evolutionary history of brown rats and discuss key challenges, including finding and accurately dating historical specimens, disentangling histories of multiple domestication events, and synthesizing functional variation in wild rat populations with the development of laboratory strains. Advances in zooarchaeology and population genomics will usher in a new golden age of research on the evolutionary biology of brown rats, with positive feedbacks on their use as biomedical models.

Highly pathogenic avian influenza virus H5N1 clade 2.3.4.4b in wild rats in Egypt during 2023

ABSTRACT We detected highly pathogenic avian influenza A(H5N1) virus in wild rats collected from a rural area in Giza, Egypt, near poultry farms, markets, and backyard flocks. Sequence and phylogenetic analyses indicated that the virus from the rats belonged to clade 2.3.4.4b, which has been the predominant virus genotype circulating in Egypt and worldwide since 2021-2022. Active surveillance of avian influenza viruses in wild and domestic mammals is recommended to prevent further spread to mammals and humans.

Capillaria hepatica (syn. Calodium hepaticum) infection and factors influencing infection carriage in rats (Rattus spp.) in Hong Kong

Capillaria hepatica (syn. Calodium hepaticum) (Bancroft, 1893) is a nematode, which colonises the liver of a wide range of hosts including humans. The worldwide prevalence of infection in the genus Rattus can be as high as 100% and the Norway rat (R. norvegicus) and black rat (R. rattus) are considered the main host species. This study is the first to investigate the epidemiology of C. hepatica infection in wild rats trapped in various geographical locations in Hong Kong. Four species of trapped rats were identified, with 65% being R. norvegicus, followed by 30% R. tanezumi (Asian house rat), 4% R. andamanensis (Sikkim rat), and 1% Niviventer huang (South China white-bellied rat). The overall prevalence of C. hepatica infection was 36.7% (81/221) (95% CI 30.4–43.4) and R. norvegicus was the most common rat species trapped during this study, with the highest prevalence of C. hepatica infection. Two risk factors for host infection were skin wounds and geographical region, whilst sex, body weight, stage of development, and presence of ectoparasites were not risk factors for this infection. Gross hepatic lesions were absent in 17% of infected rats and when present, were not pathognomonic for the infection. Infected rats lacked severe hepatic inflammation or fibrosis, indicating that rats tolerate the infection well. Egg production was observed in the livers of 69% of infected rats, which emphasizes their role as reservoirs of this zoonotic parasite. Several infected rats in this study were trapped inside residential buildings, which highlights the zoonotic risk of C. hepatica to humans following the potential ingestion of embryonated eggs from contaminated food, water, or soil.

Study about environmental naturally fungi infection in pet animals with experimental study

The current study was designed to investigate Environmental and natural fungi infection in pet animals and then experimentally to study fungi effects on tissues. Naturally infectious samples were fifty swabs in different pet animals (dogs, cats, rats, pigeons, and chickens) from the veterinary hospital of Eden Square in January 202. The findings were Cladosporum spp at (16%) ; Aspergillus flavus, Aspergillus niger at (14%); Rhizopus spp at (8%); Aspergillus ochraceus, Aspergillus terreus, and Penicillium chrysogenum at (6%); Chrysosporium spp, and Cryptococcus neoformans at (4%); Aspergillus fumigatus , Aspergillus ustus and Fusarium spp at (2%) in percentage with other unknown fungi. In doge, only 9 (9/50) samples of fungi, mainly Aspergillus flavus at (33.3%) with cladogram spp.at (22.3%). In cats, also 9 (9/50), mainly Penicillium spp at (22.25 %). In wild rats, fifty cotton swabs showed 12 (12/50) mainly Aspergillus niger, besides Rhizopus spp. At (25%). While in pigeons, only 10 (10/50), mainly Aspergillus niger, Cladosporum spp., and Cryptococcus neoformans at (20%). In chicken, only 5 (5/50), mainly Aspergillus ochraceus at (40%). Fifty albino mice aged 6-8 weeks and 25± 3gm body weight. They were separated in plastic cages and kept for adaptation at 2-3 weeks in the Animal House of the College of Veterinary Medicine, and they were fed standard pellets and water. These animals were divided into 5 groups containing 10 mice each: 1st one: control group treated with normal saline; 2nd Group infected with 0.1ml of Aspergillus flatus intraperitoneally; 3rd group infected with Aspergillus ochraceus 0.1ml intraperitoneally (IP); 4th group infected with 0.1ml Aspergillu niger IP; 5th group mice infected with Cryptococcus neoformans 0.1ml IP at single dose. After 3 weeks animals were scarified. Histopathological examination, in general, reports high incidences of necrotic lesions with granuloma and severe destructive changes, mainly in areas containing fungi hyphae that appear very clearly enclosed to necrotic and inflammatory foci, lung tissues suffering from prominent interstitial pneumonia with thick exudation, mainly fibrinous type. Liver tissues show massive necrosis with Kupfer cells and other inflammatory cell proliferation and evidence of apoptosis. Kidney samples appear with heavy degenerative changes ranging from swelling tubules to necrosis associated with severe inflammation caused by pyelonephritis and phlebitis. also, we saw fungi in the affected area. Spleen shows severe depletion and megakaryocyte proliferation and necrotic lesion. Fungi naturally infects occurs in pet animals and can transmitted to other animals in different environmental; area and can causes severe pathological lesions.

Molecular detection of toxoplasmosis in wild rats using loop-mediated isothermal amplification assay.

Toxoplasmosis is caused by the parasite Toxoplasma gondii. Cats are the only known hosts that excrete resistant oocysts. Wild rats serve as crucial reservoirs and intermediate hosts for T. gondii's survival and dissemination. Consuming soil and water containing oocysts can lead to illness. This study aimed to estimate the prevalence of toxoplasmosis in wild rats through molecular detection as an indicator of environmental contamination in Surabaya. One hundred rats were collected from the three areas (housing, dense settlements, and traditional markets) and distributed into the five zones: West, East, Central, North, and South of Surabaya. Brain tissue samples were extracted using a Geneaid™ (New Taipei City, Taiwan) DNA isolation kit and analyzed through the loop-mediated isothermal amplification (LAMP) method. The study analyzed brain tissue from 100 wild rats, consisting of 77 Rattus tanezumi and 33 Rattus norvegicus, displaying 30% LAMP positivity. The study revealed that 30% (30/100) of wild rats tested were infected with T. gondii. The molecular prevalence rate in male rats was 32.35% (22/68), compared to females with 25% (8/32). 41.9% of the housing population, 33.3% of traditional markets, and 22.6% of dense settlements had the highest molecular prevalence. The high positive molecular rate at the trapping site can be attributed to cats and dense populations. Thirty percentage wild rats were tested positive for toxoplasmosis in Surabaya, East Java, Indonesia using LAMP method. Implementing strict control and monitoring is crucial in preventing the transmission of diseases from wild rats to humans. It is necessary to carry out further research related to genetic analysis of T. gondii to determine the type of T. gondii that infects animals and humans in Surabaya through bioassay and molecular test.

Molecular characterizations of Cryptosporidium spp. in brown rat (Rattus norvegicus) from an animal feedlot in Xinjiang, China.

Cryptosporidium infection is a common occurrence in rodents worldwide. In this study, 435 wild brown rats were captured from an animal feedlot in Xinjiang, China, with a fecal sample obtained directly from the rectal contents of each rat. The DNA extracted from these fecal samples was analyzed for Cryptosporidium spp. using PCR targeting the SSU rRNA gene. The prevalence of Cryptosporidium infection in brown rats was found to be 5.5% (24 out of 435). Interestingly, the infection rates varied among different animal enclosures, with rates of 0% in the chicken coop (0/51), cowshed (0/3), and varying rates in other areas including the sheepfold (6.1%, 6/98), the pigsty (7.6%, 10/132), the dovecote (7.0%, 5/71), and outdoor environments (3.8%, 3/80). The study identified three species and one genotype of Cryptosporidium, namely C. occultus (n = 10), C. parvum (n = 4), C. ditrichi (n = 1), and Cryptosporidium rat genotype IV (n = 9). Additionally, two of the C. parvum isolates were successfully subtyped as IIdA19G1 (n = 2) at the gp60 gene. These results offer valuable insights into the prevalence and genetic diversity of Cryptosporidium in brown rats within the region.

Exploring the Potential of Muridae as Sentinels for Human and Zoonotic Viruses.

In recent years, the transmission of viruses from wildlife to humans has raised significant public health concerns, exemplified by the COVID-19 pandemic caused by the betacoronavirus SARS-CoV-2. Human activities play a substantial role in increasing the risk of zoonotic virus transmission from wildlife to humans. Rats and mice are prevalent in urban environments and may act as reservoirs for various pathogens. This study aimed to evaluate the presence of zoonotic viruses in wild rats and mice in both urban and rural areas, focusing on well-known zoonotic viruses such as betacoronavirus, hantavirus, arenavirus, kobuvirus, and monkeypox virus, along with other viruses occasionally detected in rats and mice, including rotavirus, norovirus, and astrovirus, which are known to infect humans at a high rate. A total of 128 animals were captured, including 70 brown rats (Rattus norvegicus), 45 black rats (Rattus rattus), and 13 house mice (Mus musculus), and feces, lung, and liver were collected. Among brown rats, one fecal sample tested positive for astrovirus RNA. Nucleotide sequencing revealed high sequence similarity to both human and rat astrovirus, suggesting co-presence of these viruses in the feces. Murine kobuvirus (MuKV) was detected in fecal samples from both black (n = 7) and brown (n = 6) rats, primarily from urban areas, as confirmed by sequence analysis. These findings highlight the importance of surveillance and research to understand and mitigate the risks associated with the potential transmission of pathogens by rodents.

Immunosuppression with cyclosporine versus tacrolimus shows distinctive nephrotoxicity profiles within renal compartments.

Calcineurin inhibitors (CNIs) are the backbone for immunosuppression after solid organ transplantation. Although successful in preventing kidney transplant rejection, their nephrotoxic side effects contribute to allograft injury. Renal parenchymal lesions occur for cyclosporine A (CsA) as well as for the currently favored tacrolimus (Tac). We aimed to study whether chronic CsA and Tac exposures, before reaching irreversible nephrotoxic damage, affect renal compartments differentially and whether related pathogenic mechanisms can be identified. CsA and Tac were administered chronically in wild type Wistar rats using osmotic minipumps over 4 weeks. Functional parameters were controlled. Electron microscopy, confocal, and 3D-structured illumination microscopy were used for histopathology. Clinical translatability was tested in human renal biopsies. Standard biochemical, RNA-seq, and proteomic technologies were applied to identify implicated molecular pathways. Both drugs caused significant albeit differential damage in vasculature and nephron. The glomerular filtration barrier was more affected by Tac than by CsA, showing prominent deteriorations in endothelium and podocytes along with impaired VEGF/VEGFR2 signaling and podocyte-specific gene expression. By contrast, proximal tubule epithelia were more severely affected by CsA than by Tac, revealing lysosomal dysfunction, enhanced apoptosis, impaired proteostasis and oxidative stress. Lesion characteristics were confirmed in human renal biopsies. We conclude that pathogenetic alterations in the renal compartments are specific for either treatment. Considering translation to the clinical setting, CNI choice should reflect individual risk factors for renal vasculature and tubular epithelia. As a step in this direction, we share protein signatures identified from multiomics with potential pathognomonic relevance.

Comparative Analysis of Consumer Preferences and Nutritional Composition of Wild and Farmed African Giant Rat. (Cricetomys gambianus) in Mampong Ashanti of Ghana

The African giant rat is one of Ghana's most common animals sought after as a source of meat (game). Local hunters use unhealthy means to hunt these animals, so attempts have been made to domesticate African giant rats in Ghana. Nevertheless, certain local consumers have articulated concerns, suggesting that wild giant rats' meat is more tender and leaner than those domestically farmed. The study was carried out to investigate consumer preference, sensory attributes, proximate composition, and acceptability of meats from wild and farmed African giant rats in Mampong Ashanti municipality in the Ashanti Region of Ghana. The study was conducted from November to December 2023. A survey was carried out among the residents of Asante Mampong using a structured questionnaire, with 500 individuals aged 20 years and older randomly selected to participate. Twenty (20) animals comprising ten (10) wild and ten (10) farmed African giant rats were used for the sensory and proximate analyses in a completely randomised design. Statistical Package for Social Sciences software was used for data analysis. Most participants (57%) preferred meat from wild African giant rats to their farmed counterparts, while only 7% indicated an equal fondness for both. Respondents with Islamic faith showed a preference for the meat of farmed African giant rats because of halal slaughter. The proximate composition of the raw giant rat meat was not affected by the sex since the values were very similar. However, wild African giant rat meat showed significantly (P =0.05) better proximate composition than the farmed ones. Except for meat colour and tenderness, meat from wild giant rats showed significantly (P = 0.05) better sensory properties than the meat from the farmed animals. This study concludes that meat sourced from giant African rats raised on farms is safer, has an impressive protein content, and has moderate fat levels.

Identification of Mites in Wild Rats in Simpang Limun Traditional Wet Market Area, Medan - Indonesia

Background: Among human diseases are infectious diseases transmitted by animals to humans, called zoonoses. Rats carry ectoparasites that act as biological vectors in the transmission of zoonoses. Mites are ectoparasites of rats that cause various zoonoses, namely murine typhus, rat mite dermatitis, and others. The study aims to identify species of wild rats in the study area based on their morphology and presentation of mite-infected rats and mite species in wild rats in Simpang Limun traditional wet market in Medan, Indonesia. Methods: This cross-sectional study used a purposive sampling technique. Primary data were collected in the Simpang Limun traditional wet market area of Medan, namely in the first area; M. Nawi Harahap Street, and the second area; Kemiri I Street. Every afternoon for four consecutive days, ten baited rat traps were deployed in each area. The captured rats were anesthetized, identified, and examined for mites by combing and then identified under a microscope. Results: From 65 total wild rat samples, the majority of species found was Rattus tanezumi 60 (92.3%), followed by Rattus norvegicus 5 (7.7%). The identified mite species were Laelaps echidninus (84.5%) and Laelaps nuttalli (15.5%). Conclusion: Nearly all of the wild rats found were of Rattus tanezumab species, and the most common mite species identified was Laelaps echinus in Medan's Simpang Limun traditional wet market area. This has a significant medical impact, resulting in increased potential for zoonosis transmission and indirectly to the surrounding residents in Medan's Simpang Limun traditional wet market area.

Evolution and genetic characterization of Seoul virus in wild rats Rattus norvegicus from an urban park in Lyon, France 2020-2022.

Seoul virus (SEOV) is an orthohantavirus primarily carried by rats. In humans, it may cause hemorrhagic fever with renal syndrome (HFRS). Its incidence is likely underestimated and given the expansion of urban areas, a better knowledge of SEOV circulation in rat populations is called for. Beyond the need to improve human case detection, we need to deepen our comprehension of the ecological, epidemiological, and evolutionary processes involved in the transmission of SEOV. We performed a comprehensive serological and molecular characterization of SEOV in Rattus norvegicus in a popular urban park within a large city (Lyon, France) to provide essential information to design surveillance strategies regarding SEOV. We sampled rats within the urban park of 'La Tête d'Or' in Lyon city from 2020 to 2022. We combined rat population genetics, immunofluorescence assays, SEOV high-throughput sequencing (S, M, and L segments), and phylogenetic analyses. We found low structuring of wild rat populations within Lyon city. Only one sampling site within the park (building created in 2021) showed high genetic differentiation and deserves further attention. We confirmed the circulation of SEOV in rats from the park with high seroprevalence (17.2%) and high genetic similarity with the strain previously described in 2011 in Lyon city. This study confirms the continuous circulation of SEOV in a popular urban park where the risk for SEOV transmission to humans is present. Implementing a surveillance of this virus could provide an efficient early warning system and help prepare risk-based interventions. As we reveal high gene flow between rat populations from the park and the rest of the city, we advocate for SEOV surveillance to be conducted at the scale of the entire city.

Detection of Cryptosporidium spp. in Wild Rats (Rattus spp.) in Surabaya, East Java

Cryptosporidiosis is a waterborne zoonosis caused by Cryptosporidium, which is a parasite that causes infection of the small intestine and leads to acute diarrhea in both humans and animals. Wild rats (Rattus spp.) are known to carry many zoonotic pathogens including Cryptosporidium. Given their close proximity to humans in urban environments, the likelihood of disease transmission is high. This study aims to detect the Cryptosporidium spp. infection in wild rats in Surabaya City, East Java Province. Intestinal fecal samples were collected using necropsy. The flotation test and Ziehl-Neelsen stain were used to observe the presence of Cryptosporidium under the microscope. The results showed that 69 samples were positive for Cryptosporidium spp. in the oocyst stage, which appeared dark pink with a clear cavity and the size of the oocysts ranged from 2-6 μm. The high incidence of cryptosporidiosis in wild rats is a potential health threat to both animals and humans.

Approach/Avoidance Behavior to Novel Objects is Correlated with the Serotonergic and Dopaminergic Systems in the Brown Rat (Rattus norvegicus)

The brown rat (Rattus norvegicus) is known to show three types of behavioral responses to novel objects. Whereas some rats are indifferent to novel objects, neophobic and neophilic rats show avoidance and approach behavior, respectively. Here, we compared the dopaminergic, serotonergic, and noradrenergic systems immunohistochemically among these rats. Trapped wild rats and laboratory rats were first individually exposed to the novel objects in their home cage. Wild rats were divided into neophobic and indifferent rats depending on their behavioral responses. Similarly, laboratory rats were divided into neophilic and indifferent rats. Consistent with the behavioral differences, in the paraventricular nucleus of the hypothalamus, Fos expression in corticotropin-releasing hormone-containing neurons was higher in the neophobic rats than in the indifferent rats. In the anterior basal amygdala, the neophobic rats showed higher Fos expression than the indifferent rats. In the posterior basal amygdala, the neophobic and neophilic rats showed lower and higher Fos expressions than the indifferent rats, respectively. When we compared the neuromodulatory systems, in the dorsal raphe, the number of serotonergic neurons and Fos expression in serotonergic neurons increased linearly from neophobic to indifferent to neophilic rats. In the ventral tegmental area, Fos expression in dopaminergic neurons was higher in the neophilic rats than in the indifferent rats. These results demonstrate that approach/avoidance behavior to novel objects is correlated with the serotonergic and dopaminergic systems in the brown rat. We propose that the serotonergic system suppresses avoidance behavior while the dopaminergic system enhances approach behavior to novel objects.

Helminth community of Nectomys squamipes naturally infected by Schistosoma mansoni in an endemic area in Brazil: A comparison of 22 years apart

The municipality of Sumidouro in the state of Rio de Janeiro, southeastern Brazil, is considered an area with low endemicity of Schistosoma mansoni. In this municipality, the wild water rat Nectomys squamipes is a wild reservoir of S. mansoni. A helminth community survey was carried out on N. squamipes populations in Sumidouro from 1997 to 1999. In the present study, we compared the helminth fauna and the helminth community structure of N. squamipes with a recent survey after a 22-year time interval, considering that the prevalence of S. mansoni infection in humans remained stable and that the area showed the same environmental characteristics. Seventy-three host specimens of N. squamipes collected between 1997 and 1999 and 21 specimens collected in 2021 were analyzed in this study. Seven helminth species were found in each collection period. The nematode Syphacia evaginata was recorded for the first time in N. squamipes in 2021. Syphacia venteli was the most abundant species in both periods and the most prevalent in 2021. During the period from 1997 to 1999, the most prevalent species was Hassalstrongylus epsilon. Significant differences in prevalence and abundance in relation to host sex were observed only for S. mansoni in 1997–1999. Significant differences in the abundance of the helminth species over time were observed only in Physaloptera bispiculata. Hassalstrongylus epsilon, S. venteli and S. mansoni were the dominant species in both periods. Litomosoides chagasfilhoi, Echinostoma paraensei paraensei and P. bispiculata became dominant, codominant and subordinate, respectively, over time. In conclusion, the helminth community of N. squamipes remained stable, with similar species richness, prevalence and abundance values and low beta-diversity over time. The occurrence of S. mansoni in the water rat has remained stable for decades, highlighting its importance for schistosomiasis control.

Characterizing Adrenal Insuffciency in a Rat Model of Prader-Willi Syndrome: Insights into Hypothalamic-Pituitary-Adrenal Axis Dysregulation

Prader-Willi Syndrome (PWS) is a complex genetic disorder with distinct developmental stages. In the first stage, PWS manifests as failure to thrive, hypotonia and feeding diffculty in infants. This is followed by hyperphagia, hypogonadism, and behavioral challenges which characterize the later stage of this disease. Hypothalamic-pituitary dysregulation is believed to be responsible for many aspects of the PWS phenotype, potentially contributing to several of the hallmark characteristics of this disorder. Changes in the ability of the central nervous system to respond to stressors by integrating and responding to insults to the homeostatic state are well documented in PWS, and adrenal insuffciency may further complicate endocrine dysfunction in PWS. The inability of PWS patients to respond to stress may be due to alterations at any or all three levels of the hypothalamo-pituitary-adrenal (HPA) axis. In this study, we sought to investigate the hypothesis that adrenal insuffciency in Magel2-deficient rats, a model of PWS, is at least in part due to loss of pituitary secretory capacity, since disruption of Magel2 expression, as is observed in PWS patients, is known to affect vesicular traffcking and secretion. To address this hypothesis, anterior pituitaries collected from Magel2-deficient and wild type rats were dispersed and aliquoted. The following day, cells were treated with either 0.1, 1.0, 10, 100, or 1000 nM of corticotrophin-releasing hormone (CRH). Following a 60 minute incubation, media were collected for the assessment of adrenocorticotropin (ACTH) by radioimmunoassay. We also collected pituitary cells for measurement of intracellular content of ACTH. Our results showed that cells from Magel2-deficient rats had decreased basal ACTH secretion, but remained responsive to CRH stimulation, albeit to a lesser degree than cells isolated from wild type animals. This suggests a pituitary deficiency in the response to hypothalamic factors (e.g. CRH) that normally control ACTH release. It is also possible that the other two levels of the HPA axis are altered in PWS. We now are investigating potential alterations in CRH prohormone processing or release (i.e. hypothalmic deficiencies) and responsiveness of the adrenal gland itself to ACTH administration. Furthermore, we have investigated circulating levels of cortisol in stressed and non-stressed animals to determine if the Magel2 rat model recapitulates the the aberrant stress response observed in PWS patients. Through this investigation of Magel2’s potential contributions to adrenal insuffciency, we hope to advance the understanding of PWS pathophysiology and lay the groundwork for developing new treatment strategies. This work has been paid for through a grant from the Foundation for Prader-Willi Research. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Investigating the Role of CART/GPR160 Signaling in Stress-Induced Anorexia

Stress-induced anorexia represents a conserved adaptive response across diverse species. While this response can be crucial for survival in specific situations, it may become detrimental when prolonged stress exposure leads to unhealthy eating patterns, contributing to eating disorders like anorexia nervosa and bulimia. Feeding behavior is intricately connected to the stress response, as stress levels can influence appetite and energy expenditure. Central to the stress response are corticotropin-releasing hormone (CRH)-producing neurons, which secrete CRH, stimulating the production of ACTH in the pituitary gland and subsequently triggering the release of cortisol, a stress hormone, from the adrenal glands. The presence of CRH in the hypothalamus, a brain region involved in controlling feeding, suggests a complex interplay where stress and metabolic signals converge. One such signal is the peptide cocaine- and amphetamine-regulated transcript (CART) which has been shown to regulate feeding behavior, satiety, and metabolic function by signaling through its receptor GPR160 and downstream glucagon-like peptide (GLP)-1 signaling. In this study, we hypothesize that CART/GPR160 signals within CRH-producing neurons to control feeding behavior and stress responses. To test this hypothesis, we used a multifaceted approach, utilizing both wild type and GPR160-floxed rats in which GPR160 was knocked down specifically in CRH neurons using an AAV-Cre under the control of the CRH promoter injected bilaterally into the paraventricular nucleus. We monitored food and water intake, investigated CRH secretion from hypothalamic explants treated with CART, and assessed physiological changes in GPR160, CART, and other related molecules in various brain regions following acute stress. We also examined the effects of GPR160 knockdown in PVN neurons on plasma cortisol levels in response to restraint stress. While further studies are necessary to fully define the roles of CART and GPR160 in stress responses and feeding behavior control, our preliminary findings indicate that this ligand-receptor pair could serve as a novel therapeutic target for treating psychiatric diseases related to eating disorders. NIH. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.