Pathological Responses in Asian House Shrews (Suncus murinus) to the Naturally Acquired Orientia tsutsugamushi Infection

Scrub typhus is a re-emerging disease caused by Orientia tsutsugamushi, transmitted by mites belonging to the family Trombiculidae. Humans and rodents acquire the infection by the bite of larval mites/chiggers. Suncus murinus, the Asian house shrew, has been reported to harbor the vector mites and has been naturally infected with O. tsutsugamushi. The present study aimed to localize and record O. tsutsugamushi in the tissues and the host response in shrews naturally infected with O. tsutsugamushi. Sheehan's modified May-Grunwald Giemsa staining was carried out in 365 tissues from 87 animals, and rickettsiae were documented in 87 tissues from 20 animals. Immunohistochemical (IHC) staining, using polyclonal antibodies raised against selected epitopes of the 56-kDa antigen, was carried out, and 81/87 tissue sections were tested positive for O. tsutsugamushi. By IHC, in addition to the endothelium, the pathogen was also demonstrated by IHC in cardiomyocytes, the bronchiolar epithelium, stroma of the lungs, hepatocytes, the bile duct epithelium, the epithelium and goblet cells of intestine, the tubular epithelium of the kidney, and splenic macrophages. Furthermore, the pathogen was confirmed by real-time PCR using blood (n = 20) and tissues (n = 81) of the IHC-positive animals. None of the blood samples and only 22 out of 81 IHC-positive tissues were tested positive by PCR. By nucleotide sequencing of the 56-kDa gene, Gilliam and Karp strains were found circulating among these animals. Although these bacterial strains are highly virulent and cause a wide range of pathological alterations, hence exploring their adaptive mechanisms of survival in shrews will be of significance. Given that the pathogen localizes in various organs following a transient bacteremia, we recommend the inclusion of tissues from the heart, lung, intestine, and kidney of reservoir animals, in addition to blood samples, for future molecular surveillance of scrub typhus.

Microbiological assessment of Suncus murinus bred and managed as laboratory animals

Suncus murinus is gaining prominence as a laboratory animal; however, there is no generally accepted method for microbiological monitoring. This study aimed to apply non-serological microbiological monitoring of laboratory mice for S. murinus and identify the subdominant species obtained by culture methods for microbial assessment. Culture and PCR were used to test S. murinus for the laboratory mice test panels including 10 bacterial species and orthohantaviruses, all of which were negative. The species that grew sub-dominantly in rectal feces were identified as Aeromonas hydrophila, which is pathogenic to mammals. These results indicate that microbiological monitoring should be used to detect pathogens directly from S. murinus, not from sentinel animals, due to the host-specific microbial environment.

Effect of cholecystokinin on small intestinal motility in suncus murinus

In a fasting gastrointestinal tract, a characteristic cyclical rhythmic migrating motor complex (MMC) occur that comprises of three phases: I, II, and III. Among these, phase III contractions propagate from the stomach to the lower intestine in mammals, including humans, dogs, and Suncus murinus (suncus). Apart from the phase III of MMC propagating from the stomach, during the gastric phase II, small intestine-originated strong contractions propagate to the lower small intestine; however, the mechanism of contractions originating in the small intestine has not been clarified. In this study, we aimed to elucidate the role of cholecystokinin (CCK) in small intestinal motility. Administration of sulfated CCK-8 in phase I induced phase II-like contractions in the small intestine, which lasted for approximately 10-20 min and then returned to the baseline, while no change was observed in the stomach. Contractions of small intestine induced by CCK-8 were abolished by lorglumide, a CCK1 receptor antagonist. Gastrin, a ligand for the CCK2 receptor, evoked strong contractions in the stomach, but did not induce contractions in the small intestine. To examine the effect of endogenous CCK on contractions of small intestinal origin, lorglumide was administered during phase II. However, there was no change in the duodenal motility pattern, and strong contractions of small intestinal origin were not abolished by treatment with lorglumide. These results suggest that exogenous CCK stimulates contractions of small intestine via CCK1 receptors, whereas endogenous CCK is not involved in the strong contractions of small intestinal origin.

Epidemiology of Group A rotavirus in rodents and shrews in Bangladesh

Rodents and shrews live in close proximity to humans and have been identified as important hosts of zoonotic pathogens. This study aimed to detect Group A rotavirus (RVA) and its potential risk factors in rodents and shrews in Bangladesh. We captured 417 small mammals from 10 districts with a high degree of contact between people and domestic animals and collected rectal swab samples between June 2011 and October 2013. We tested the swab samples for RVA RNA, targeting the NSP3 gene segment using real-time reverse transcription-polymerase chain reaction (rRT-PCR). Overall, RVA prevalence was the same (6.7%) in both rodents and shrews. We detected RVA RNA in 5.3% of Bandicota bengalensis (4/76; 95% CI: 1.4-12.9), 5.1% of B. indica (4/79; 95% CI: 1.4-12.4), 18.2% of Mus musculus (4/22; 95% CI: 5.2-40.3), 6.7% of Rattus rattus (6/90; 95% CI: 2.5-13.9), and 6.7% of Suncus murinus (10/150; 95% CI: 3.2-11.9). We found significantly more RVA in males (10.4%; OR: 3.4; P = 0.007), animals with a poor body condition score (13.9%; OR: 2.7; P = 0.05), during wet season (8.3%; OR: 4.1; P = 0.032), and in urban land gradients (10.04%; OR: 2.9; P = 0.056). These findings form a basis for understanding the prevalence of rotaviruses circulating among rodents and shrews in this region. We recommend additional molecular studies to ascertain the genotype and zoonotic potential of RVA circulating in rodents and shrews in Bangladesh.

Trichoblastomas derived from the facial skin with tactile hair in aged house musk shrews (Suncus murinus)

BACKGROUND

Benign hair follicle tumors are relatively rare cutaneous neoplasms arising from hair follicle differentiation. These tumors are slow-growing solitary papules or nodules in the head, face or neck. The aim of this study was to describe 2 cases of trichoblastomas in tactile hair skin incidentally encountered in aged house musk shrews (Suncus murinus). In addition, this case report clarifies whether the characteristics in the tactile hair skin of Suncus murinus are different from those in humans and other animals.

CASE PRESENTATION

The animals were investigated the characteristics of the clinical findings, hematological and serum biochemical profiles (particularly, serum amyloid A levels (vSAA)), and histopathological results. Suncus murinus with the facial tumor showed weight loss and coarse fur. Hematological examinations indicated microcytic and normochromic anemia. Although few apparent changes were serum biochemically found in Suncus murinus, vSAA levels moderately increased and revealed inflammatory reactions. These lesions histopathologically showed the basaloid islands comprising peripheral palisading and dilated microcysts containing variable admixtures of free-floating cells such as neoplasm cells, giant cells, clear cells, mononuclear cells and erythrocytes.

CONCLUSIONS

The author concluded that trichoblastomas in Suncus murinus revealed growth and morphological characteristics that recapitulate part of embryological development in the tactile hair follicles. In the histological structure, their trichoblastomas in the tactile hair skin were different from those found in humans and animals such as cats, dogs and other wildlife.

Molecular cloning of cholecystokinin (CCK) and CCK-A receptor and mechanism of CCK-induced gastrointestinal motility in Suncus murinus

Cholecystokinin (CCK) is a peptide hormone mainly secreted by small intestinal endocrine I-cells and functions as a regulator of gallbladder contraction, gastric emptying, gastrointestinal (GI) motility, and satiety. The cellular effects of CCK in these peripheral tissues are predominantly mediated via CCK-A receptors which are found in smooth muscles, enteric neurons, and vagal afferent neurons in humans and animal models. Although various functions of CCK have been reported to be neurally mediated, it can also stimulate contraction via the CCK receptor on the smooth muscle. However, the entire underlying neural and cellular mechanisms involved in CCK-induced GI contractions are not clearly understood. Here, we first determined the cDNA and amino acid sequences of CCK and CCK-A receptor along with the distributions of cck mRNA and CCK-producing cells in house musk shrew (Suncus murinus, the laboratory strain named as suncus) and examined the mechanism of CCK-induced contraction in the GI tract. Mature suncus CCK-8 was identical to other mammalian species tested here, and suncus CCK-A receptor presented high nucleotide and amino acid homology with that of human, dog, mouse, and rat, respectively. Suncus CCK mRNA and CCK-producing cells were found mainly in small intestine and colon. In the organ bath study, CCK-8 induced dose-dependent contractions in the suncus stomach, duodenum, and jejunum, and these contractions were inhibited by atropine and CCK-A receptor antagonist. These results suggest that CCK-8-induced contraction is mediated in the myenteric cholinergic neural network and that CCK-A receptor is partly responsible for CCK-8-induced contractions. This study indicates that suncus is a useful animal model to study the functions of CCK involved in GI motility.

Insights Into Acute and Delayed Cisplatin-Induced Emesis From a Microelectrode Array, Radiotelemetry and Whole-Body Plethysmography Study of Suncus murinus (House Musk Shrew)

Purpose: Cancer patients receiving cisplatin therapy often experience side-effects such as nausea and emesis, but current anti-emetic regimens are suboptimal. Thus, to enable the development of efficacious anti-emetic treatments, the mechanisms of cisplatin-induced emesis must be determined. We therefore investigated these mechanisms in Suncus murinus, an insectivore that is capable of vomiting.

Methods: We used a microelectrode array system to examine the effect of cisplatin on the spatiotemporal properties of slow waves in stomach antrum, duodenum, ileum and colon tissues isolated from S. murinus. In addition, we used a multi-wire radiotelemetry system to record conscious animals’ gastric myoelectric activity, core body temperature, blood pressure (BP) and heart rate viability over 96-h periods. Furthermore, we used whole-body plethysmography to simultaneously monitor animals’ respiratory activity. At the end of in vivo experiments, the stomach antrum was collected and immunohistochemistry was performed to identify c-Kit and cluster of differentiation 45 (CD45)-positive cells.

Results: Our acute in vitro studies revealed that cisplatin (1–10 μM) treatment had acute region-dependent effects on pacemaking activity along the gastrointestinal tract, such that the stomach and colon responded oppositely to the duodenum and ileum. S. murinus treated with cisplatin for 90 min had a significantly lower dominant frequency (DF) in the ileum and a longer waveform period in the ileum and colon. Our 96-h recordings showed that cisplatin inhibited food and water intake and caused weight loss during the early and delayed phases. Moreover, cisplatin decreased the DF, increased the percentage power of bradygastria, and evoked a hypothermic response during the acute and delayed phases. Reductions in BP and respiratory rate were also observed. Finally, we demonstrated that treatment with cisplatin caused inflammation in the antrum of the stomach and reduced the density of the interstitial cells of Cajal (ICC).

Conclusion: These studies indicate that cisplatin treatment of S. murinus disrupted ICC networking and viability and also affected general homeostatic mechanisms of the cardiovascular system and gastrointestinal tract. The effect on the gastrointestinal tract appeared to be region-specific. Further investigations are required to comprehensively understand these mechanistic effects of cisplatin and their relationship to emesis.

Seasonal abundance of Leptotrombidium deliense, the vector of scrub typhus, in areas reporting acute encephalitis syndrome in Gorakhpur district, Uttar Pradesh, India

The rickettsial pathogen Orientia tsutsugamushi, causing scrub typhus, has been implicated as a major cause of acute encephalitis syndrome (AES) in many places in India including Gorakhpur district of Uttar Pradesh. Seasonal abundance of the principal vector mite of the pathogen, Leptotrombidium deliense, its animal hosts, and prevalence of infection on them are important attributes in the assessment of outbreaks of the disease. Hence, these aspects were investigated, seasonally, in rural villages of Gorakhpur district, where peak incidence of AES cases were reported. A total of 903 animals (rodents/shrews) was collected using 6484 Sherman traps in eight study villages (14% overall trap rate). A sum of 5526 trombiculid mites comprising 12 species was collected from 676 live rodents/shrews screened. Suncus murinus, the Asian house shrew was the predominant species (67%). Among trombiculids, the principal vector mite, L. deliense, was predominant (64.7%) and its infestation index (i.e., average number of chiggers per host animal) was 5.3. The L. deliense infestation index was higher during July to November with a peak in October. Out of 401 animal sera samples screened, 68% were positive for antibodies against O. tsutsugamushi. Of 465 blood samples tested by nested PCR, seven were positive for the 56 kDa gene of O. tsutsugamushi. In conventional PCR, 41 out of 265 samples were positive for the 60 kDa groEL gene of O. tsutsugamushi. Among the 5526 mite samples, tested as 352 pools through nested PCR, four pools were positive for 56 kDa gene. Phylogenetic analysis of 56 and 60 kDa genes confirmed circulation of Karp and TA678 (rodents) and TA678 (mite) serotypes of O. tsutsugamushi in Gorakhpur. Peak incidence of AES in Gorakhpur district occurs during the rainy season (July-October), coinciding with the peak abundance of L. deliense. These results indicate involvement of L. deliense as the vector mite transmitting the scrub typhus pathogen O. tsutsugamushi to humans in the rural areas of Gorakhpur district, India.

First Detection of Bartonella spp. in Small Mammals from Rice Storage and Processing Facilities in Myanmar and Sri Lanka

(1) Background: Bartonella spp. are zoonotic bacteria with small mammals as main reservoirs. Bartonella spp. prevalence in small mammals from Myanmar and Sri Lanka are yet unknown. (2) Methods: Small mammals were snap trapped in Sri Lanka and Myanmar in urban surroundings. Spleens-derived DNA was screened for Bartonella spp. using conventional PCR based on three target genes. Positive samples were sequenced. (3) Results: 994 small mammals were collected comprising 6 species: Bandicota bengalensis, Bandicota indica, Rattus exulans, Rattus rattus, Mus booduga, and Suncus murinus. In Myanmar, the Bartonella prevalence in Bandicoot rats (68.47%) was higher than in Rattus rattus (41.67%), Rattus exulans (21.33%), and Suncus murinus (3.64%). Furthermore the prevalence in Myanmar (34%, n = 495) was twice as high as in Sri Lanka (16%, n = 499). In Sri Lanka, Bartonella spp. occurred almost exclusively in R. rattus. In Myanmar, Bartonella kosoyi was mainly detected (56%), followed by Bartonella sp. KM2529 (15%), Bartonella sp. SE-Bart D (12%) and Bartonella henselae (1%). In Sri Lanka, B. phoceensis (60%) and Bartonella sp. KM2581 (33%) were predominant. (4) Conclusions: Bartonella spp. were detected in all investigated small mammal species from Myanmar and Sri Lanka for the first time. Bartonella kosoyi and B. henselae are zoonotic. As these small mammals originated from urban settlements, human bartonellosis seems likely to occur.

The inhibitory effect of somatostatin on gastric motility in Suncus murinus

Gastric contractions show two specific patterns in many species, migrating motor contractions (MMC) and postprandial contractions (PPCs), that occur in the fasted and fed states, respectively. In this study, we examined the role of somatostatin (SST) in gastric motility both in vivo and in vitro using the Asian house shrew (Suncus murinus). We performed in vivo recordings of gastric motility and in vitro organ bath experiments using S. murinus, which was recently established as a small laboratory animal for use in tests of gastrointestinal motility. SST (1.65 µg kg⁻¹ min⁻¹) was intravenously administered during phase II of MMC and PPCs. Next, the effect of SST on motilin-induced gastric contractions at phase I of MMC was measured. Cyclosomatostatin (CSST), an SST receptor antagonist, was administered at the peak of phase III of MMC. In addition, the effect of SST (10⁻¹¹–10⁻⁹ M) on motilin-induced gastric contractions was evaluated using an organ bath experiment in vitro. In conscious, free-moving S. murinus, the administration of SST decreased the occurrence of the spontaneous phase II of MMC and PPCs. Pretreatment with SST and octreotide suppressed the induction of motilin-induced gastric contractions both in vivo and in vitro. Administration of CSST before the peak of spontaneous phase III contractions had no effect on gastric contractions. Endogenous SST is not involved in the regulation of gastric MMC and PPCs, but exogenous SST suppresses spontaneous gastric contractions. Thus, SST would be good for treating abnormal gastrointestinal motility disorders.

GLP-1 receptors are involved in the GLP-1 (7-36) amide-induced modulation of glucose homoeostasis, emesis and feeding in Suncus murinus (house musk shrew)

GLP-1 receptor agonists are used for the treatment of type 2 diabetes but they may reduce appetite and cause nausea and emesis. We investigated if GLP-1 (7-36) amide can modulate glucose homoeostasis, emesis and feeding via an exendin (9-39)-sensitive mechanism in Suncus murinus. The effect of GLP-1 (7-36) amide on glucose homeostasis was examined using an intraperitoneal glucose tolerance test. In conscious fasted animals, food and water consumption and behavior were measured for 1 h following drug administration. c-Fos expression in the brain was measured using immunohistochemistry. GLP-1 (7-36) amide reduced blood glucose levels dose-dependently. Exendin (9-39) did not modify blood glucose levels but suppressed the glucose-lowering effect of GLP-1 (7-36) amide. GLP-1 (7-36) amide inhibited food and water intake, induced emesis and elevated c-Fos expression in the brainstem and hypothalamic nuclei in the brain. Exendin (9-39) antagonised the inhibition of food and water intake and emesis induced by GLP-1 (7-36) amide and the effects on c-Fos expression in the hypothalamus and brainstem, excepting for the bed nucleus of the stria terminalis. These data suggest that the action of GLP-1 (7-36) amide to modulate blood glucose, suppress food and water intake and induce emesis involve GLP-1 receptors in the hypothalamus and brainstem.

Composition of gut and oropharynx bacterial communities in Rattus norvegicus and Suncus murinus in China

Background

Rattus norvegicus and Suncus murinus are important reservoirs of zoonotic bacterial diseases. An understanding of the composition of gut and oropharynx bacteria in these animals is important for monitoring and preventing such diseases. We therefore examined gut and oropharynx bacterial composition in these animals in China.

Results

Proteobacteria, Firmicutes and Bacteroidetes were the most abundant phyla in faecal and throat swab samples of both animals. However, the composition of the bacterial community differed significantly between sample types and animal species. Firmicutes exhibited the highest relative abundance in throat swab samples of R. norvegicus, followed by Proteobacteria and Bacteroidetes. In throat swab specimens of S. murinus, Proteobacteria was the predominant phylum, followed by Firmicutes and Bacteroidetes. Firmicutes showed the highest relative abundance in faecal specimens of R. norvegicus, followed by Bacteroidetes and Proteobacteria. Firmicutes and Proteobacteria had almost equal abundance in faecal specimens of S. murinus, with Bacteroidetes accounting for only 3.07%. The family Streptococcaceae was most common in throat swab samples of R. norvegicus, while Prevotellaceae was most common in its faecal samples. Pseudomonadaceae was the predominant family in throat swab samples of S. murinus, while Enterobacteriaceae was most common in faecal samples. We annotated 33.28% sequences from faecal samples of S. murinus as potential human pathogenic bacteria, approximately 3.06-fold those in R. norvegicus. Potential pathogenic bacteria annotated in throat swab samples of S. murinus were 1.35-fold those in R. norvegicus.

Conclusions

Bacterial composition of throat swabs and faecal samples from R. norvegicus differed from those of S. murinus. Both species carried various pathogenic bacteria, therefore both should be closely monitored in the future, especially for S. murinus.

Supplementary information

Supplementary information accompanies this paper at 10.1186/s12917-020-02619-6.

Genetic Diversity and Phylogeography of Thottapalayam thottimvirus (Hantaviridae) in Asian House Shrew (Suncus murinus) in Eurasia

Murid and cricetid rodents were previously believed to be the principal reservoir hosts of hantaviruses. Recently, however, multiple newfound hantaviruses have been discovered in shrews, moles, and bats, suggesting a complex evolutionary history. Little is known about the genetic diversity and geographic distribution of the prototype shrew-borne hantavirus, Thottapalayam thottimvirus (TPMV), carried by the Asian house shrew (Suncus murinus), which is widespread in Asia, Africa, and the Middle East. Comparison of TPMV genomic sequences from two Asian house shrews captured in Myanmar and Pakistan with TPMV strains in GenBank revealed that the Myanmar TPMV strain (H2763) was closely related to the prototype TPMV strain (VRC66412) from India. In the L-segment tree, on the other hand, the Pakistan TPMV strain (PK3629) appeared to be the most divergent, followed by TPMV strains from Nepal, then the Indian-Myanmar strains, and finally TPMV strains from China. The Myanmar strain of TPMV showed sequence similarity of 79.3-96.1% at the nucleotide level, but the deduced amino acid sequences showed a high degree of conservation of more than 94% with TPMV strains from Nepal, India, Pakistan, and China. Cophylogenetic analysis of host cytochrome b and TPMV strains suggested that the Pakistan TPMV strain was mismatched. Phylogenetic trees, based on host cytochrome b and cytochrome c oxidase subunit I genes of mitochondrial DNA, and on host recombination activating gene 1 of nuclear DNA, suggested that the Asian house shrew and Asian highland shrew (Suncus montanus) comprised a species complex. Overall, the geographic-specific clustering of TPMV strains in Asian countries suggested local host-specific adaptation. Additional in-depth studies are warranted to ascertain if TPMV originated in Asian house shrews on the Indian subcontinent.

GDF15 Induces Anorexia through Nausea and Emesis

Growth differentiation factor 15 (GDF15) is a cytokine that reduces food intake through activation of hindbrain GFRAL-RET receptors and has become a keen target of interest for anti-obesity therapies. Elevated endogenous GDF15 is associated with energy balance disturbances, cancer progression, chemotherapy-induced anorexia, and morning sickness. We hypothesized that GDF15 causes emesis and that its anorectic effects are related to this function. Here, we examined feeding and emesis and/or emetic-like behaviors in three different mammalian laboratory species to help elucidate the role of GDF15 in these behaviors. Data show that GDF15 causes emesis in Suncus murinus (musk shrews) and induces behaviors indicative of nausea/malaise (e.g., anorexia and pica) in non-emetic species, including mice and lean or obese rats. We also present data in mice suggesting that GDF15 contributes to chemotherapy-induced malaise. Together, these results indicate that GDF15 triggers anorexia through the induction of nausea and/or by engaging emetic neurocircuitry.

Generation and characterization of Suncus murinus intestinal organoid: a useful tool for studying motilin secretion

Motilin, a 22-amino-acid peptide produced in the upper small intestine, induces strong gastric contraction in fasted state. In many rodents, motilin and its cognate receptors exist as pseudogenes, which has delayed motilin research in the past decades. Recently, the house musk shrew (Suncus murinus) was developed as a useful model for studying motilin and gastrointestinal motility. However, due to a lack of motilin-producing cell lines and difficulties in culturing small intestinal cells, the regulatory mechanisms of motilin secretion and its messenger RNA (mRNA) transcription have remained largely unclear. In this study, we generated small intestinal organoids from S. murinus for the first time. Using methods similar to mouse organoid generation, we found crypt-like budding structures 3 days after isolating intestinal tissues. The organoids grew gradually with time. In addition, the generated organoids were able to be passaged and maintained for 6 months or longer. Motilin messenger RNA (mRNA) and immunopositive cells were observed in both S. murinus intestinal organoids and primary tissues. This is the first report of intestinal organoids in S. murinus, and our results suggest that S. murinus intestinal organoids could be useful for analyzing motilin secretion and transcription.

Molecular cloning and analysis of Suncus murinus group IIA secretary phospholipase A2 expression

The intestinal epithelial monolayer forms a mucosal barrier between the gut microbes and the host tissue. The mucosal barrier is composed of mucins and antimicrobial peptides and proteins (AMPs). Several animal studies have reported that Paneth cells, which occupy the base of intestinal crypts, play an important role in the intestinal innate immunity by producing AMPs, such as lysozyme, Reg3 lectins, α-defensins, and group IIA secretory phospholipase A2 (GIIA sPLA2). The house musk shrew (Suncus murinus) has only a few intestinal commensal bacteria and is reported to lack Paneth cells in the intestine. Although the expression of lysozyme was reported in the suncus intestine, the expression of other AMPs has not yet been reported. Therefore, the current study was focused on GIIA sPLA2 expression in Suncus murinus. GIIA sPLA2 mRNA was found to be most abundant in the spleen and also highly expressed in the intestine. Cells expressing GIIA sPLA2 mRNA were distributed not only in the crypt, but also in the villi. In addition, intragastric injection of lipopolysaccharide increased GIIA sPLA2 expression in the small intestine of suncus. These results suggest that suncus may host unique AMP-secreting cells in the intestine.

Hematological and biochemical reference values of Asian house shrews (Suncus murinus) in Bangladesh

Background and Aim:

Determining reference values for hematological and biochemical parameters of Asian house shrew (Suncus murinus) is important for wildlife research to protect human health in surrounding communities. This study aimed to establish the reference values for selected hematology and serum clinical chemistry analyses that may contribute to research on shrew in future.

Materials and Methods:

Blood samples (n=51) were collected from shrews between July and December 2015, Bangladesh, to estimate the levels of hemoglobin (Hb), packed cell volume (PCV), total leukocyte count (TLC), total erythrocyte count (TEC), lymphocyte, monocyte, neutrophil, eosinophil, basophil, calcium, phosphorus (P), sodium (Na), chloride (Cl), urea, glucose, total protein (TP), creatinine, and alanine transaminase (ALT).

Results:

Although the values did not differ significantly among sexes, age was found to be a significant factor. Hb, PCV, TEC, glucose, and P were higher in males; eosinophil, Na, Cl, TP, and ALT were higher among females. Adults had significantly greater urea and glucose (p<0.05) while juveniles had insignificantly higher values for TLC, PCV, neutrophil, P, and TP.

Conclusion:

This study provides the first reference values for this species in Bangladesh and can be used to guide wildlife research studies.

GABAergic and glutamatergic neurons in the brain regulate phase II of migrating motor contractions in the Suncus murinus

Gastric contractions exhibit characteristic motor patterns in the fasted state, known as migrating motor contractions (MMC). MMC consist of three periodically repeated phases (phase I, II and III) and are known to be regulated by hormones and the autonomic and enteric nervous systems. However, the central regulation of gastric contractions in the fasted state is not completely understood. Here, we have examined the central effects of motilin, ghrelin, γ-aminobutyric acid (GABA) and L-glutamate signaling on gastric MMC by using suncus (Suncus murinus) as an animal model, because of their similar gastric motor patterns to those observed in humans and dogs. Intracerebroventricular (i.c.v.) administration of motilin and ghrelin had no effect on phase I and II contractions, respectively. Conversely, i.c.v. administration of GABA_A receptor antagonist, during phase I of the MMC, evoked phase II-like contractions and significantly increased the motility index (MI). This was compared with the i.c.v. administration of GABA which inhibited spontaneous phase II contractions with a significantly decreased MI. In addition, i.c.v. administration of L-glutamate during phase I also induced phase II-like irregular contractions with a significant increase in the MI. Taken together with previous findings, these results suggest that central GABAergic and glutamatergic signaling, with the coordination of both peripheral motilin and ghrelin, regulate phase II contractions of MMC in the fasted state.

Occurrence of Orientia tsutsugamushi, the Etiological Agent of Scrub Typhus in Animal Hosts and Mite Vectors in Areas Reporting Human Cases of Acute Encephalitis Syndrome in the Gorakhpur Region of Uttar Pradesh, India

Outbreaks of acute encephalitis syndrome (AES) with high fatality and disability, are reported every year in the Gorakhpur region of Uttar Pradesh, India, with the etiology of >60% of the cases being attributed to scrub typhus. In the present study, the prevalence of Orientia tsutsugamushi, the etiological agent of scrub typhus, was investigated among animal hosts and their ectoparasitic trombiculid mites prevalent in AES-reported areas of Gorakhpur. A total of 154 rodents/shrews were collected using 777 Sherman traps set in 12 study villages, and the overall trap rate was 19.8%. In total, 2726 trombiculid mites belonging to 12 species were collected from 154 rodents/shrews trapped. The shrew mouse Suncus murinus was the predominant animal species (78.6%) collected. The principal vector mite Leptotrombidium deliense was the predominant species (82.7%), and its index was 14.6 per animal. Of 114 rodent/shrew sera samples screened through the Weil-Felix test, 57% were positive for antibodies against O. tsutsugamushi. Of 128 blood samples tested by polymerase chain reaction (PCR), one rodent sample was positive for the gene encoding 56 kDa protein and 25 for 60 kDa. Among 2726 mite samples tested as 315 pools through nested PCR, seven pools were positive for 56 kDa gene. Phylogenetic analysis confirmed circulation of Gilliam, Karp, and TA678 serotypes of O. tsutsugamushi in Gorakhpur. The study clearly demonstrated natural infection of O. tsutsugamushi in both small-animal hosts and vector mites in the AES-reporting villages of Gorakhpur, which confirms transmission of the scrub typhus pathogen in this region. The high infestation rate of L. deliense with O. tsutsugamushi infection indicates that the people living in the rural villages of Gorakhpur are at risk of infection with scrub typhus, which might lead to AES.

Prevalence and diversity of gastrointestinal helminths in free-ranging Asian house shrew (Suncus murinus) in Bangladesh

Background and Aim

Asian house shrew (Suncus murinus), a widely distributed small mammal in the South Asian region, can carry helminths of zoonotic importance. The aim of the study was to know the prevalence and diversity of gastrointestinal (GI) helminths in free-ranging Asian house shrew (S. murinus) in Bangladesh.

Materials and Methods

A total of 86 Asian house shrews were captured from forest areas and other habitats of Bangladesh in 2015. Gross examination of the whole GI tract was performed for gross helminth detection, and coproscopy was done for identification of specific eggs or larvae.

Results

The overall prevalence of GI helminth was 77.9% (67/86), with six species including nematodes (3), cestodes (2), and trematodes (1). Of the detected helminths, the dominant parasitic group was from the genus Hymenolepis spp.(59%), followed by Strongyloides spp.(17%), Capillaria spp. (10%), Physaloptera spp. (3%), and Echinostoma spp.(3%).

Conclusion

The finding shows that the presence of potential zoonotic parasites (Hymenolepis spp. and Capillaria spp.) in Asian house shrew is ubiquitous in all types of habitat (forest land, cropland and dwelling) in Bangladesh. Therefore, further investigation is crucial to examine their role in the transmission of human helminthiasis.

Brain Activation by H1 Antihistamines Challenges Conventional View of Their Mechanism of Action in Motion Sickness: A Behavioral, c-Fos and Physiological Study in Suncus murinus (House Musk Shrew)

Motion sickness occurs under a variety of circumstances and is common in the general population. It is usually associated with changes in gastric motility, and hypothermia, which are argued to be surrogate markers for nausea; there are also reports that respiratory function is affected. As laboratory rodents are incapable of vomiting, Suncus murinus was used to model motion sickness and to investigate changes in gastric myoelectric activity (GMA) and temperature homeostasis using radiotelemetry, whilst also simultaneously investigating changes in respiratory function using whole body plethysmography. The anti-emetic potential of the highly selective histamine H₁ receptor antagonists, mepyramine (brain penetrant), and cetirizine (non-brain penetrant), along with the muscarinic receptor antagonist, scopolamine, were investigated in the present study. On isolated ileal segments from Suncus murinus, both mepyramine and cetirizine non-competitively antagonized the contractile action of histamine with pK _b values of 7.5 and 8.4, respectively; scopolamine competitively antagonized the contractile action of acetylcholine with pA₂ of 9.5. In responding animals, motion (1 Hz, 4 cm horizontal displacement, 10 min) increased the percentage of the power of bradygastria, and decreased the percentage power of normogastria whilst also causing hypothermia. Animals also exhibited an increase in respiratory rate and a reduction in tidal volume. Mepyramine (50 mg/kg, i.p.) and scopolamine (10 mg/kg, i.p.), but not cetirizine (10 mg/kg, i.p.), significantly antagonized motion-induced emesis but did not reverse the motion-induced disruptions of GMA, or hypothermia, or effects on respiration. Burst analysis of plethysmographic-derived waveforms showed mepyramine also had increased the inter-retch+vomit frequency, and emetic episode duration. Immunohistochemistry demonstrated that motion alone did not induce c-fos expression in the brain. Paradoxically, mepyramine increased c-fos in brain areas regulating emesis control, and caused hypothermia; it also appeared to cause sedation and reduced the dominant frequency of slow waves. In conclusion, motion-induced emesis was associated with a disruption of GMA, respiration, and hypothermia. Mepyramine was a more efficacious anti-emetic than cetirizine, suggesting an important role of centrally-located H₁ receptors. The ability of mepyramine to elevate c-fos provides a new perspective on how H₁ receptors are involved in mechanisms of emesis control.

Action of Bacopa monnieri to antagonize cisplatin-induced emesis in Suncus murinus (house musk shrew)

Bacopa monnieri (BM, family Scrophulariaceae) is used in several traditional systems of medicine for the management of epilepsy, depression, neuropathic pain, sleep disorders and memory deficits. The present study investigated the potential of BM methanol (BM-MetFr) and BM n-butanol fractions (BM-ButFr) to reduce chemotherapy-induced emesis in Suncus murinus (house musk shrew). Cisplatin (30 mg/kg, i.p.) reliably induced retching and/or vomiting over a 2 day period. BM-MetFr (10-40 mg/kg, s.c.) and BM-ButFr (5-20 mg/kg, s.c.) antagonized the retching and/or vomiting response by ∼59.4% (p < 0.05) and 78.9% (p < 0.05), respectively, while the 5-HT₃ receptor antagonist, palonosetron (0.5 mg/kg, s.c.), reduced the response by ∼71% (p < 0.05). The free radical scavenger/antioxidant, N-(2-mercaptopropionyl)-glycine (30-300 mg/kg, s.c.) reduced the retching and/or vomiting response occurring on day one non-significantly by 44% (p > 0.05). In conclusion, the n-butanol fractions of BM have anti-emetic activity comparable with palonosetron and MPG. BM may be useful alone or in combination with other anti-emetic drugs for the treatment of chemotherapy-induced emesis in man.

The important role of ghrelin on gastric contraction in Suncus murinus

Ghrelin, a peptide hormone produced in the stomach, has been known to be involved in the regulation of gastric contraction in humans and rodents. To elucidate the detailed mechanisms of ghrelin on gastric contractions, we used Suncus murinus, a recently established small animal model for gastrointestinal motility. S. murinus produces motilin, a family peptide of ghrelin, and its stomach anatomy and physiological patterns of gastric contractions, in fed and fasted states, are closely similar to humans. Ghrelin administration in phase II, and latter half of phase I, of the migrating motor contractions (MMC) enhanced gastric motility in S. murinus. In addition, we showed that ghrelin and motilin coordinately stimulated strong gastric contractions in vitro and in vivo. We also demonstrated that a pretreatment with a ghrelin antagonist, D-Lys3-GHRP6, inhibited the effects of motilin-induced gastric contractions, and a γ-aminobutyric acid (GABA) antagonist reversed this inhibition. Our results suggest that ghrelin is essential for motilin-induced gastric contractions and that ghrelin-mediated GABAergic neurons are involved in this neural pathway.

Impact of electrical stimulation of the stomach on gastric distension-induced emesis in the musk shrew

BACKGROUND

Gastric electrical stimulation (GES) is implicated as a potential therapy for difficult-to-treat nausea and vomiting; however, there is a lack of insight into the mechanisms responsible for these effects. This study tested the relationship between acute GES and emesis in musk shrews, an established emetic model system.

METHODS

Urethane-anesthetized shrews were used to record emetic responses (monitoring intra-tracheal pressure and esophageal contractions), respiration rate, heart rate variability, blood pressure, and gastrointestinal electromyograms. We investigated the effects of acute GES pulse duration (0.3, 1, 5, and 10 ms), current amplitude (0.5, 1, and 2 mA), pulse frequency (8, 15, 30, and 60 Hz), and electrode placement (antrum, body, and fundus) on emesis induced by gastric stretch, using a balloon.

KEY RESULTS

There were four outcomes: (i) GES did not modify the effects of gastric stretch-induced emesis; (ii) GES produced emesis, depending on the stimulation parameters, but was less effective than gastric stretch; (iii) other physiological changes were closely associated with emesis and could be related to a sub-threshold activation of the emetic system, including suppression of breathing and rise in blood pressure; and (iv) a control experiment showed that 8-OH-DPAT, a reported 5-HT1A receptor agonist that acts centrally as an antiemetic, blocked gastric stretch-induced emesis.

CONCLUSIONS AND INFERENCES

These results do not support an antiemetic effect of acute GES on gastric distension-induced emesis within the range of conditions tested, but further evaluation should focus on a broader range of emetic stimuli and GES stimulation parameters.

The importance of systematic approaches in the study of emesis

Nausea and vomiting are among the most basic of human experiences and unfortunately accompany a wide variety of clinical treatments as side effects. Despite decades of research, the neural mechanisms of nausea and vomiting (emesis) remain elusive. TRPV1 represents a possibly overlooked and understudied pharmacological target with anti-emetic potential.

The proximal gastric corpus is the most responsive site of motilin-induced contractions in the stomach of the Asian house shrew

The migrating motor complex (MMC) is responsible for emptying the stomach during the interdigestive period, in preparation for the next meal. It is known that gastric phase III of MMC starts from the proximal stomach and propagates the contraction downwards. We hypothesized that a certain region of the stomach must be more responsive to motilin than others, and that motilin-induced strong gastric contractions propagate from that site. Stomachs of the Suncus or Asian house shrew, a small insectivorous mammal, were dissected and the fundus, proximal corpus, distal corpus, and antrum were examined to study the effect of motilin using an organ bath experiment. Motilin-induced contractions differed in different parts of the stomach. Only the proximal corpus induced gastric contraction even at motilin 10(-10) M, and strong contraction was induced by motilin 10(-9) M in all parts of the stomach. The GPR38 mRNA expression was also higher in the proximal corpus than in the other sections, and the lowest expression was observed in the antrum. GPR38 mRNA expression varied with low expression in the mucosal layer and high expression in the muscle layer. Additionally, motilin-induced contractions in each dissected part of the stomach were inhibited by tetrodotoxin and atropine pretreatment. These results suggest that motilin reactivity is not consistent throughout the stomach, and an area of the proximal corpus including the cardia is the most sensitive to motilin.

The involvement of TRPV1 in emesis and anti-emesis

Diverse transmitter systems (e.g. acetylcholine, dopamine, endocannabinoids, endorphins, glutamate, histamine, 5-hydroxytryptamine, substance P) have been implicated in the pathways by which nausea and vomiting are induced and are targets for anti-emetic drugs (e.g. 5-hydroxytryptamine₃ and tachykinin NK₁ antagonists). The involvement of TRPV1 in emesis was discovered in the early 1990s and may have been overlooked previously as TRPV1 pharmacology was studied in rodents (mice, rats) lacking an emetic reflex. Acute subcutaneous administration of resiniferatoxin in the ferret, dog and Suncus murinus revealed that it had “broad–spectrum” anti-emetic effects against stimuli acting via both central (vestibular system, area postrema) and peripheral (abdominal vagal afferents) inputs. One of several hypotheses discussed here is that the anti-emetic effect is due to acute depletion of substance P (or another peptide) at a critical site (e.g. nucleus tractus solitarius) in the central emetic pathway. Studies in Suncus murinus revealed a potential for a long lasting (one month) effect against the chemotherapeutic agent cisplatin. Subsequent studies using telemetry in the conscious ferret compared the anti-emetic, hypothermic and hypertensive effects of resiniferatoxin (pungent) and olvanil (non-pungent) and showed that the anti-emetic effect was present (but reduced) with olvanil which although inducing hypothermia it did not have the marked hypertensive effects of resiniferatoxin. The review concludes by discussing general insights into emetic pathways and their pharmacology revealed by these relatively overlooked studies with TRPV1 activators (pungent an non-pungent; high and low lipophilicity) and antagonists and the potential clinical utility of agents targeted at the TRPV1 system.

The complete mitogenome of Asian House Shrews, Suncus murinus (Soricidae)

The Asian House Shrew, Suncus murinus belongs to the family Soricidae, and widely distributes in East, Southeast and South Asia, Southwest Island in the Pacific Ocean and East Africa. In this study, the complete mitochondrial genome sequence of Suncus murinus was determined. The mitogenome is 17,240 bp in length and contains 13 protein-coding genes, 2 ribosomal RNA genes, 22 transfer RNA genes, and a control region, with a base composition of 33.0% A, 32.7% T, 21.2% C and 13.1% G. The present study contributes to illuminating taxonomic status of S. murinus, and may facilitate further investigation of the molecular evolution of Soricidae.

The differential antiemetic properties of GLP-1 receptor antagonist, exendin (9-39) in Suncus murinus (house musk shrew)

The use of glucagon-like peptide-1 (7-36) amide (GLP-1) receptor agonists for the treatment of type 2 diabetes mellitus is commonly associated with nausea and vomiting. Previous studies using Suncus murinus revealed that the GLP-1 receptor agonist, exendin-4, induces emesis via the brainstem and/or hypothalamus. The present study investigated the mechanism of exendin-4-induced emesis in more detail. Ondansetron (1 mg/kg, s.c.) and CP-99,994 (10 mg/kg, s.c) failed to reduce emesis induced by exendin-4 (3 nmol, i.c.v.), suggesting that 5-HT3 and NK1 receptors are not involved in the mechanism. In other studies, the GLP-1 receptor antagonist, exendin (9-39), antagonised emesis and c-Fos expression in the brainstem and the paraventricular hypothalamus induced by the chemotherapeutic drug cisplatin (30 mg/kg, i.p.; p < 0.05), but not the emesis induced by nicotine (5 mg/kg, s.c.; p > 0.05), or copper sulphate pentahydrate (120 mg/kg, p.o.; p > 0.05). GLP-1 receptors may therefore represent a potential target for drugs to prevent chemotherapy-induced emesis in situations where 5-HT3 and NK1 receptor antagonists fail.

Delineation of vagal emetic pathways: intragastric copper sulfate-induced emesis and viral tract tracing in musk shrews

Signals from the vestibular system, area postrema, and forebrain elicit nausea and vomiting, but gastrointestinal (GI) vagal afferent input arguably plays the most prominent role in defense against food poisoning. It is difficult to determine the contribution of GI vagal afferent input on emesis because various agents (e.g., chemotherapy) often act on multiple sensory pathways. Intragastric copper sulfate (CuSO4) potentially provides a specific vagal emetic stimulus, but its actions are not well defined in musk shrews (Suncus murinus), a primary small animal model used to study emesis. The aims of the current study were 1) to investigate the effects of subdiaphragmatic vagotomy on CuSO4-induced emesis and 2) to conduct preliminary transneuronal tracing of the GI-brain pathways in musk shrews. Vagotomy failed to inhibit the number of emetic episodes produced by optimal emetic doses of CuSO4 (60 and 120 mg/kg ig), but the effects of lower doses were dependent on an intact vagus (20 and 40 mg/kg). Vagotomy also failed to affect emesis produced by motion (1 Hz, 10 min) or nicotine administration (5 mg/kg sc). Anterograde transport of the H129 strain of herpes simplex virus-1 from the ventral stomach wall identified the following brain regions as receiving inputs from vagal afferents: the nucleus of the solitary tract, area postrema, and lateral parabrachial nucleus. These data indicate that the contribution of vagal pathways to intragastric CuSO4-induced emesis is dose dependent in musk shrews. Furthermore, the current neural tracing data suggest brain stem anatomical circuits that are activated by GI signaling in the musk shrew.

The effect of 5-HT and electrical field stimulation on the contractility of the whole isolated urinary bladder of Suncus murinus

The present study used the whole isolated urinary bladder of Suncus murinus, to investigate the effect of exogenously added serotonin (5-HT) and electrical field stimulation (EFS) in the absence and presence of methysergide, a 5-HT1/2/7 receptor antagonist or the selective 5-HT7 receptor antagonist, SB269970. Further experiments investigated the involvement of potassium channel, cholinergic and purinergic systems in mediating the contractile response to EFS. Pre-treatment with methysergide reduced and increased the contractile responses to 5-HT and EFS, respectively. Pre-treatment with SB269970 increased the responses to 5-HT without modifying the EFS-induced contractions. EFS-induced contractions were not modified by pre-treatment with atropine (10μM), α-β-methylene ATP or glibenclamide. EFS-induced contractions were attenuated by cromakalim (10µM) or atropine (0.1 µM). In conclusion, the 5-HT2 receptors are likely to play a role in mediating the contractile response to 5-HT in detrusor muscle. Furthermore, EFS-induced contractions are mediated through cholinergic and an unknown neurotransmitter which is modulated by K(ATP) channels in the detrusor muscle of Suncus murinus.

Experimental infection of three laboratory mouse stocks with a shrew origin Bartonella elizabethae strain: an evaluation of bacterial host switching potential

BACKGROUND

Bartonella elizabethae has been reported as a causative agent of human illnesses and strains of this bacterium are commonly isolated from commensal small mammals in Asia.

METHODS

Since the zoonotic potential of a pathogen is often related to its host switching ability, we explored the capacity of a B. elizabethae strain to host switch by subcutaneously inoculating groups of Swiss Webster, BALB/c, and C57BL/6 mice with the bacteria at a range of doses.

RESULTS

A low number of mice in each of the three groups showed susceptibility to infection at high doses (10(5) and 10(6) bacteria), and developed bacteremias of 6-8 weeks duration.

CONCLUSION

The capacity of this B. elizabethae strain to switch hosts can have important public health consequences for humans in areas of Asia where many small mammal populations have high bartonellae infection prevalences and live as commensals with humans.

Surgical anatomy of the innervation of pylorus in human and Suncus murinus, in relation to surgical technique for pylorus-preserving pancreaticoduodenectomy

AIM: To clarify the innervation of the antro-pyloric region in humans from a clinico-anatomical perspective.

METHODS: The stomach, duodenum and surrounding structures were dissected in 10 cadavers, and immersed in a 10mg/L solution of alizarin red S in ethanol to stain the peripheral nerves. The distribution details were studied to confirm innervations in the above areas using a binocular microscope. Similarly, innervations in 10 Suncus murinus were examined using the method of whole-mount immunohistochemistry.

RESULTS: The innervation of the pyloric region in humans involved three routes: One arose from the anterior hepatic plexus via the route of the suprapyloric/supraduodenal branch of the right gastric artery; the second arose from the anterior and posterior gastric divisions, and the third originated from the posterior-lower region of the pyloric region, which passed via the infrapyloric artery or retroduodenal branches and was related to the gastroduodenal artery and right gastroepiploic artery. For Suncus murinus, results similar to those in humans were observed.

CONCLUSION: There are three routes of innervation of the pyloric region in humans, wherein the route of the right gastric artery is most important for preserving pyloric region innervation. Function will be preserved by more than 80% by preserving the artery in pylorus-preserving pancreaticoduodenectomy (PPPD). However, the route of the infrapyloric artery should not be disregarded. This route is related to several arteries (the right gastroepiploic and gastroduodenal arteries), and the preserving of these arteries is advantageous for preserving pyloric innervation in PPPD. Concurrently, the nerves of Latarjat also play an important role in maintaining innervation of the antro-pyloric region in PPPD. This is why pyloric function is not damaged in some patients when the right gastric artery is dissected or damaged in PPPD.