Unoperated Control Mice Research Articles

Mouse Behavior in the Open-field Test after Meloxicam Administration.

Several analgesics are suggested for pain management in mice. Nonsteroidal antiinflammatories (NSAIDs), such as meloxicam can be administered for the treatment of inflammation and acute pain; however, several side effects can occur which include gastrointestinal ulceration and renal and hepatic toxicity. We previously performed a pilot study to test the antinociceptive activity of meloxicam in mice, but we observed behavioral changes in unoperated control mice. These observations spurred further investigation. One hypothesis for the result was potential differences in formulation between commercial brands of meloxicam. Thus, this current study aimed to evaluate the effects of 3 different commercial brands of meloxicam (20 mg/kg) in the general activity of mice using the open field test. Our results showed that meloxicam had several effects on mouse behavior and caused the formation of skin lesions at the injection site, depending on the brand of the drug. The most significant adverse effect observed was decreased exploratory activity. Grooming frequency was reduced in all groups. These adverse effects might be related to the quality of the drugs because meloxicam formulations can contain crystal polymorphisms that affect drug quality and efficacy. This study points out the importance of drug quality variation that can affect the outcome of behavioral studies in mice.

Chronic Compression of the Dorsal Root Ganglion Enhances Mechanically Evoked Pain Behavior and the Activity of Cutaneous Nociceptors in Mice.

Radicular pain in humans is usually caused by intraforaminal stenosis and other diseases affecting the spinal nerve, root, or dorsal root ganglion (DRG). Previous studies discovered that a chronic compression of the DRG (CCD) induced mechanical allodynia in rats and mice, with enhanced excitability of DRG neurons. We investigated whether CCD altered the pain-like behavior and also the responses of cutaneous nociceptors with unmyelinated axons (C-fibers) to a normally aversive punctate mechanical stimulus delivered to the hairy skin of the hind limb of the mouse. The incidence of a foot shaking evoked by indentation of the dorsum of foot with an aversive von Frey filament (tip diameter 200 μm, bending force 20 mN) was significantly higher in the foot ipsilateral to the CCD surgery as compared to the contralateral side on post-operative days 2 to 8. Mechanically-evoked action potentials were electrophysiologically recorded from the L3 DRG, in vivo, from cell bodies visually identified as expressing a transgenically labeled fluorescent marker (neurons expressing either the receptor MrgprA3 or MrgprD). After CCD, 26.7% of MrgprA3+ and 32.1% MrgprD+ neurons exhibited spontaneous activity (SA), while none of the unoperated control neurons had SA. MrgprA3+ and MrgprD+ neurons in the compressed DRG exhibited, in comparison with neurons from unoperated control mice, an increased response to the punctate mechanical stimuli for each force applied (6, 20, 40, and 80 mN). We conclude that CCD produced both a behavioral hyperalgesia and an enhanced response of cutaneous C-nociceptors to aversive punctate mechanical stimuli.

Functional and Physiological Effects of Treadmill Training Induced by Buspirone, Carbidopa, and L-DOPA in Clenbuterol-Treated Paraplegic Mice

Background. Chronic spinal cord injury may be complicated by weight loss, muscle atrophy, and bone loss. Objective. The authors identified a combination pharmacotherapy using buspirone, carbidopa, and L-DOPA (BCD) that elicits bouts of locomotor-like movements in spinal cord–transected (Tx) mice. They then evaluated the effects of 8 weeks of treadmill training in Tx mice that received BCD or BCD + clenbuterol, a monoaminergic agent with anabolic properties, on locomotor function, muscle atrophy, adipose tissue loss, and bone density measures. Methods. Induced locomotor movement, adipose tissue, skeletal muscle, and femoral bone properties were compared in unoperated control mice, operated controls (untreated, untrained Tx mice), and 2 groups of treated, trained Tx mice (Tx + BCD, Tx + BCD + clenbuterol) that also received training. Results. BCD- and BCD + clenbuterol–treated mice showed comparable levels of locomotor movements that significantly improved over time. Soleus muscle mass and soleus and extensor digitorum longus cross-sectional area significantly increased in both groups of BCD-treated mice, with greater effects in BCD + clenbuterol–treated animals. Fiber type conversion, adipose tissues, bone mineral density, and content were reduced in all Tx groups compared with unoperated control mice. Conclusion. These findings suggest that locomotor movement and muscle properties can be restored to near-normal levels after several weeks of BCD treatment, regular training, and clenbuterol in completely paraplegic animals.

Peritoneal repairing cells: a type of bone marrow derived progenitor cells involved in mesothelial regeneration

The peritoneal mesothelium exhibits a high regenerative ability. Peritoneal regeneration is concomitant with the appearance, in the coelomic cavity, of a free-floating population of cells whose origin and functions are still under discussion. We have isolated and characterized this cell population and we have studied the process of mesothelial regeneration through flow cytometry and confocal microscopy in a murine model lethally irradiated and reconstituted with GFP-expressing bone marrow cells. In unoperated control mice, most free cells positive for mesothelin, a mesothelial marker, are green fluorescent protein (GFP). However, 24 hrs after peritoneal damage, free mesothelin+/ GFP+ cells appear in peritoneal lavages. Cultured lavage peritoneal cells show colocalization of GFP with mesothelial (mesothelin, cytokeratin) and fibroblastic markers. Immunohistochemical staining of the peritoneal wall also revealed colocalization of GFP with mesothelial markers and with procollagen-1 and smooth muscle α-actin. This was observed in the injured area as well as in the surrounding not-injured peritoneal surfaces. These cells, which we herein call peritoneal repairing cells (PRC), are very abundant 1 week after surgery covering both the damaged peritoneal wall and the surrounding uninjured area. However, they become very scarce 1 month later, when the mesothelium has completely healed. We suggest that PRC constitute a type of monocyte-derived cells, closely related with the tissue-repairing cells known as ‘fibrocytes’ and specifically involved in peritoneal reparation. Thus, our results constitute a synthesis of the different scenarios hitherto proposed about peritoneal regeneration, particularly recruitment of circulating progenitor cells and adhesion of free-floating coelomic cells.

Surgical stress reduces mortality from endotoxin shock.

Surgical stress has been considered a preliminary to multiple organ failure through what has been termed a "two-hit" mechanism. Recent evidence, however, suggests that such stress has a beneficial influence in reducing endotoxin [lipopolysaccharide (LPS)]-mediated lethality. This study has been an effort to clarify whether and how LPS-mediated septic shock is prevented by a previous insult with mild (laparotomy) or severe (hepatectomy) surgical stress. LPS was injected intraperitoneally into mice after two-thirds hepatectomy or laparotomy only. Survival rates, and protein and messenger RNA (mRNA) levels for tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) were measured. Most of the unoperated control mice died within 3 days after the LPS challenge. Mortality following LPS injection was reduced after laparotomy only or hepatectomy (P<0.05). A significant reduction in the mortality was observed from 2 days to 7 days after laparotomy only, and from 2 days to 4 weeks after hepatectomy. Correspondingly, the increase in the serum levels of TNF-alpha and IL-6 induced by the LPS injection was partially impaired by either laparotomy only or hepatectomy at an early (2 days) postoperative stage (P<0.05). At a later (7 days) stage, however, the serum level of IL-6 and its mRNA level in the spleen were elevated after the LPS challenge more quickly in the hepatectomy group than in the unoperated control group ( P<0.05). Surgical stress reduces LPS-induced lethality through biphasically regulating the levels of TNF-alpha and IL-6 production.

Increased synthesis of heparin affin regulatory peptide in the perforant path lesioned mouse hippocampal formation.

Heparin affin regulatory peptide (HARP), also known as pleiotrophin or heparin-binding growth-associated molecule, is a developmentally regulated extracellular matrix protein that induces cell proliferation and promotes neurite outgrowth in vitro as well as pre- and postsynaptic developmental differentiation in vivo. Here we have investigated the expression of HARP mRNA and protein in the perforant path lesioned C57B1/6 mouse hippocampal formation from 1 to 35 days after surgery. This type of lesion induces a dense anterograde and terminal axonal degeneration, activation of glial cells, and reactive axonal sprouting within the perforant path zones of the fascia dentata and hippocampus as well as axotomy-induced retrograde neuronal degeneration in the entorhinal cortex. Analysis of sham- and unoperated control mice showed that HARP mRNA is expressed in neurons and white and gray matter glial cells as well as vascular and pial cells throughout the normal, adult brain. Lesioning induced high levels of HARP mRNA in astroglial-like cells in the denervated zones of fascia dentata and hippocampus as soon as day 2 postlesion. This expression reached maximum at day 4, and declined toward normal at day 7-14. Combined HARP in situ hybridization and glial fibrillary acidic protein (GFAP) immunohistochemical staining and double immunofluorescent stainings for GFAP and HARP at day 4 postlesion showed colocalization of HARP mRNA and protein to hypertrophic GFAP-immunopositive astrocytes in the denervated areas. Finally, the axotomized entorhinal layer II neurons, which expressed high levels of HARP mRNA in the normal brain, exhibited a marked decline in hybridization signal after axotomy. The induction of high levels of HARP mRNA and protein in astrocytes in the denervated areas of fascia dentata and hippocampus is of particular interest as astrocytes and astrocyte-derived factors are known to be implicated in axonal growth and regeneration and in rescuing injured neurons.

Loss of Function ofTrp53,but NotApc,Leads to the Development of Esophageal Adenocarcinoma in Mice with Jejunoesophageal Reflux

Introduction. APCandTP53are tumor suppressor genes known to be altered frequently in human esophageal adenocarcinoma (EAC), which arises as a complication of reflux disease. To determine the functional role of these genes in the development of EAC, we have created reflux in mice gene-targeted for eitherTrp53orApc.Methods.Wild-type (WT), p53-knockout (Trp53−/−), orApc-mutated (ApcMin/+) mice were generated in our breeding colony. Total gastrectomy with esophagojejunostomy was performed at 6 weeks of age, creating jejunoesophageal reflux. Unoperated control mice were maintained under identical conditions. Mice were sacrificed at 30 weeks of age. Histology of the esophagus and jejunal anastamosis or gastroesophageal junction was reviewed by a single pathologist blinded to the genotype of the animal.Results.The esophagus was normal in all of the unoperated mice (6ApcMin/+, 6 WT, and 6Trp53−/−). All operated mice (6ApcMin/+, 12 WT, and 4Trp53−/−) had esophagitis, with squamous hyperplasia and early focal ulceration. Barrett's metaplasia was identified in 33% of the operatedApcMin/+(2/6) and 25% of theTrp53−/−(1/4) mice, but not in the WT mice. Of 4 operatedTrp53−/−mice, all developed severe dysplasia of the squamous epithelium and 2 (50%) had EAC on histology, although no gross tumors were seen. No severe dysplasia or carcinoma was identified in any of theApcMin/+or WT mice.Conclusions.Loss of eitherTrp53orApcleads to the development of columnar metaplasia, whereas loss ofTrp53,but notApc,leads to development of cancer in mice with jejunoesophageal reflux.

The correlation between cholecystectomy and fecal bile acids, and large-bowel cancer induced with 1,2-dimethylhydrazine in mice.

The relationship between cholecystectomy and large-bowel cancer development was investigated in animal models. Female ICR mice underwent cholecystectomy, and received 15 weekly intragastric administrations (Experiment 1) or 10 weekly subcutaneous injections (Experiment 2) of 15 mg/kg body weight of large-bowel carcinogen 1,2-dimethylhydrazine (DMH). Autopsy at 28 weeks after surgery showed that cholecystectomized mice had a nonsignificantly increased incidence of large-bowel carcinomas, compared to sham-operated and/or unoperated control mice (85 vs. 64 percent in Experiment 1; 31 vs. 16 and 20 percent in Experiment 2). Cholecystectomy alone without DMH treatment did not produce any cancer. Cholecystectomized mice excreted a significantly increased level of primary bile acids but an unchanged level of secondary bile acids in the feces, compared with unoperated control mice. It is obvious that cholecystectomy enhanced the development of DMH-induced, large-bowel carcinomas along with the change of fecal bile acid composition, suggesting that changes of bile acid metabolism after cholecystectomy may enhance or promote large-bowel carcinogenesis in man as well. This association of cholecystectomy and large-bowel cancer is not a strong one, however, as presented in epidemiologic as well as experimental studies.

Tumor growth: suppression in mice by submanidibular gland extirpation.

Transplanted A-10 breast adenocarcinomas grew more slowly in young-adult male A/HeJ mice from which the submandibular glands had been extirpated than in sham-operated or unoperated control mice of the same strain. The mitotic index was lower in tumors from experimental animals than in those from controls. Vascularization about the tumor margins was also less prominent. The C1300 neuroblastoma grew more slowly in sialoadenectomized mice than in controls. Modulation of tumor growth by factors of salivary gland origin may have been responsible for these effects.

Effect of neonatal thymectomy on the experimental enteric infection of germfree mice with a mouse adenovirus (author's transl)

The enteric infection and the appearance of antibodies and immunoglobulins were examined in neonatally thymectomized germfree ICR mice.Mouse adenovirus (MAD), strain K-87, was used in this study. Thymectomy was done within 24 hours after birth. MAD was inoculated orally to 4-to 6-week-old mice through a metal tube inserted into the stomach. The infectivity titer of the virus and the titer of neutralizing antibodies were determined in DKI mouse kindey tissue culture. Titration of the 3 classes of immunoglobulin was performed by the precipitation in agarose gel.In unoperated control mice, no viral growth was seen 3 weeks after challenge. In the thymectomized mice, however, a clear prolongation of viral growth was observed.Neutralizing antibodies in the serum began to increase in titer in the control mice 2 weeks after challenge. In the operated mice, the appearance of neutralizing antibodies was retarded. These antibodies in the intestinal wall and contents began to increase in titer in the control mice 3 weeks after challenge, but their appearance was retarded in the thymectomized mice.Immunoglobulin examinations were carried out to clarify the status of IgA, IgG, and IgM.The titers of IgA both in the serum and in the intestinal wall and contents were significantly lower in the thymectomized mice than in the control mice. IgG in the serum increased a little within the uninfected germfree mouse level in the control mice, but decreased in the thymectomized mice. IgM in the serum was within the uninfected germfree mouse level both in the control and in the thymectomized mice.IgG and IgM in the intestinal wall and contents were undetectable both in the operated and in the unoperated mice.Thus, prolonged growth of the virus was observed in the neonatally thymectomized germfree mice.At the same time, the appearance of neutralizing antibodies both in the serum and in the intestinal wall and contents was retarded. As there was no correlation between viral growth and the presence of serum antibody, it seemed that the delayed appearance of local neutralizing antibody might have prolonged viral growth in the thymectomized mice.Retardation of the appearance of IgA in the intestinal tract, which was undetectable in the uninfected germfree mice, was also observed in the thymectomized mice. This finding lends support to the presumption that the neutralizing antibody may belong to the IgG class of immunoglobulin.