RESUMO
The sensation of pain is associated with increased mortality, but it is unknown whether pain perception can directly affect aging. We find that mice lacking TRPV1 pain receptors are long-lived, displaying a youthful metabolic profile at old age. Loss of TRPV1 inactivates a calcium-signaling cascade that ends in the nuclear exclusion of the CREB-regulated transcriptional coactivator CRTC1 within pain sensory neurons originating from the spinal cord. In long-lived TRPV1 knockout mice, CRTC1 nuclear exclusion decreases production of the neuropeptide CGRP from sensory endings innervating the pancreatic islets, subsequently promoting insulin secretion and metabolic health. In contrast, CGRP homeostasis is disrupted with age in wild-type mice, resulting in metabolic decline. We show that pharmacologic inactivation of CGRP receptors in old wild-type animals can restore metabolic health. These data suggest that ablation of select pain sensory receptors or the inhibition of CGRP are associated with increased metabolic health and control longevity.
Assuntos
Longevidade , Transdução de Sinais , Canais de Cátion TRPV/metabolismo , Animais , Proteína de Ligação a CREB/metabolismo , Caenorhabditis elegans , Células Cultivadas , Dieta , Feminino , Insulina/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mutação , Neurônios/metabolismo , Nociceptores/metabolismo , Canais de Cátion TRPV/genética , Fatores de Transcrição/metabolismoRESUMO
Yersinia pestis was introduced to North America around 1900 and leads to nearly 100% mortality in prairie dog (Cynomys spp.) colonies during epizootic events, which suggests this pathogen may exert a strong selective force. We characterized genetic diversity at an MHC class II locus (DRB1) in Gunnison's prairie dog (C. gunnisoni) and quantified population genetic structure at the DRB1 versus 12 microsatellite loci in three large Arizona colonies. Two colonies, Seligman (SE) and Espee Ranch (ES), have experienced multiple plague-related die-offs in recent years, whereas plague has never been documented at Aubrey Valley (AV). We found fairly low allelic diversity at the DRB1 locus, with one allele (DRB1*01) at high frequency (0.67-0.87) in all colonies. Two other DRB1 alleles appear to be trans-species polymorphisms shared with the black-tailed prairie dog (C. ludovicianus), indicating that these alleles have been maintained across evolutionary time frames. Estimates of genetic differentiation were generally lower at the MHC locus (F ST = 0.033) than at microsatellite markers (F ST = 0.098). The reduced differentiation at DRB1 may indicate that selection has been important for shaping variation at MHC loci, regardless of the presence or absence of plague in recent decades. However, genetic drift has probably also influenced the DRB1 locus because its level of differentiation was not different from that of microsatellites in an F ST outlier analysis. We then compared specific MHC alleles to plague survivorship in 60 C. gunnisoni that had been experimentally infected with Y. pestis. We found that survival was greater in individuals that carried at least one copy of the most common allele (DRB1*01) compared to those that did not (60% vs. 20%). Although the sample sizes of these two groups were unbalanced, this result suggests the possibility that this MHC class II locus, or a nearby linked gene, could play a role in plague survival.
Assuntos
Comitês de Cuidado Animal , Bem-Estar do Animal , Embrião não Mamífero/efeitos dos fármacos , Fidelidade a Diretrizes/legislação & jurisprudência , Oligonucleotídeos/administração & dosagem , Peixe-Zebra/embriologia , Animais , Eutanásia Animal , Fidelidade a Diretrizes/organização & administração , Injeções , Modelos AnimaisRESUMO
Clostridium piliforme is an obligate intracellular bacterium that causes enterohepatic disease in many animal species. C. piliforme infections are commonly subclinical in laboratory rats and mice, and little is known about host regulation of disease or of the effects of C. piliforme infections on investigations that use subclinically infected animals. To assess host regulation of subclinical C. piliforme infections and the effects of those infections on laboratory mice, the expression of the pro-inflammatory cytokines tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) was evaluated at 0, 1, 3, 7, 14 and 28 days after inoculation with C. piliforme. Subclinical infection was induced in weanling C. piliforme-susceptible DBA/2 or -resistant C57BL/6 mice with either a toxic or a non-toxic C. piliforme strain. Hepatic lesions and bacteria were demonstrated histologically in both mouse strains for 14 days after inoculation with the toxigenic bacterial strain, but were never demonstrated histologically following inoculation with the non-toxigenic strain. Hepatic TNF-alpha and IFN-gamma mRNA and serum protein levels were similarly elevated in both mouse strains 1 day after inoculation with both C. piliforme strains, as evaluated by reverse transcription PCR and enzyme-linked immunosorbent assays, respectively. Elevation of IFN-gamma persisted for 14 days after inoculation; TNF-alpha remained elevated at 28 days after inoculation.
Assuntos
Infecções por Clostridium/veterinária , Clostridium/imunologia , Interferon gama/biossíntese , Doenças dos Roedores/imunologia , Fator de Necrose Tumoral alfa/biossíntese , Animais , Clostridium/genética , Clostridium/isolamento & purificação , Infecções por Clostridium/imunologia , DNA Bacteriano/análise , Endotoxinas/análise , Feminino , Interferon gama/genética , Fígado/imunologia , Fígado/microbiologia , Fígado/patologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos DBA , RNA Mensageiro/análise , Reação em Cadeia da Polimerase Via Transcriptase Reversa/veterinária , Fator de Necrose Tumoral alfa/genéticaRESUMO
The relationship among ammonia levels, cage-changing frequency, and bedding types is an important and potentially controversial topic in the laboratory animal science community. Some bedding options may not provide sufficient urine absorption and bacterial regulation to minimize ammonia production during the interval between cage changes. High intracage ammonia levels can cause subclinical degeneration and inflammation of nasal passages, rhinitis and olfactory epithelial necrosis in exposed mice. Here we sought to compare the effects of 4 commonly used bedding substrates (1/4-in. irradiated corncob, reclaimed wood pulp, aspen wood chips, and recycled newspaper) on ammonia generation when housing female C57BL/6 mice in static and individually ventilated caging. Intracage ammonia levels were measured daily for 1 wk (static cage experiment) or 2 wk (IVC experiment). The results of this study suggest that the corncob, aspen wood chip, and recycled newspaper beddings that we tested are suitable for once-weekly cage changing for static cages and for changing every 2 wk for IVC. However, ammonia levels were not controlled appropriately in cages containing reclaimed wood pulp bedding, and pathologic changes occurred within 1 wk in the nares of mice housed on this bedding in static cages.
Assuntos
Amônia/análise , Roupas de Cama, Mesa e Banho/normas , Abrigo para Animais/normas , Bem-Estar do Animal , Animais , Animais de Laboratório , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Papel , Ventilação/normas , MadeiraRESUMO
Disuse atrophy of both muscle and bone can occur rapidly during periods of inactivity. In several rodent models developed for the study of disuse atrophy, immobilization is induced by prolonged cage restraint, hind limb unloading, tenotomy, sciatic nerve block or sciatic denervation. In less tractable species such as wild-caught hibernating rodents, the sciatic denervation model is superior in terms of both animal welfare and applicability to the characteristics of natural cases of disuse atrophy. The authors describe a refined surgical approach to sciatic denervation in golden-mantled ground squirrels (Callospermophilus lateralis), a hibernating species, that improves animal welfare and reduces the incidence of post-operative complications such as autotomy.
Assuntos
Denervação/métodos , Denervação/veterinária , Modelos Animais de Doenças , Transtornos Musculares Atróficos , Nervo Isquiático/cirurgia , Sciuridae/cirurgia , Bem-Estar do Animal/normas , AnimaisRESUMO
Prairie dogs (Cynomys spp.) are highly susceptible to Yersinia pestis, with ≥99% mortality reported from multiple studies of plague epizootics. A colony of Gunnison's prairie dogs (Cynomys gunnisoni) in the Aubrey Valley (AV) of northern Arizona appears to have survived several regional epizootics of plague, whereas nearby colonies have been severely affected by Y. pestis. To examine potential mechanisms accounting for survival in the AV colony, we conducted a laboratory Y. pestis challenge experiment on 60 wild-caught prairie dogs from AV and from a nearby, large colony with frequent past outbreaks of plague, Espee (n = 30 per colony). Test animals were challenged subcutaneously with the fully virulent Y. pestis strain CO92 at three doses: 50, 5,000, and 50,000 colony-forming units (cfu); this range is lethal in black-tailed prairie dogs (Cynomys ludovicianus). Contrary to our expectations, only 40% of the animals died. Although mortality trended higher in the Espee colony (50%) compared with AV (30%), the differences among infectious doses were not statistically significant. Only 39% of the survivors developed moderate to high antibody levels to Y. pestis, indicating that mechanisms other than humoral immunity are important in resistance to plague. The ratio of neutrophils to lymphocytes was not correlated with plague survival in this study. However, several immune proteins with roles in innate immunity (VCAM-1, CXCL-1, and vWF) were upregulated during plague infection and warrant further inquiry into their role for protection against this disease. These results suggest plague resistance exists in wild populations of the Gunnison's prairie dog and provide important directions for future studies.
Assuntos
Imunidade Inata , Peste/veterinária , Sciuridae/imunologia , Animais , Anticorpos Antibacterianos/sangue , Feminino , Masculino , Peste/sangue , Peste/imunologia , Peste/mortalidadeRESUMO
Over the past 40 yr, epizootics of plague (Yersinia pestis) in northern Arizona have reduced populations of the Gunnison's prairie dog (Cynomys gunnisoni), with the exception of a large population found in the Aubrey Valley (AV). To examine potential mechanisms accounting for their survival, we collected prairie dog serum samples in 2005-2006 from AV and a neighboring population near Seligman (SE), Arizona. We quantified gene expression at 58 diverse immune proteins using a multiplexed enzyme-linked immunosorbent assay panel. We found a subset of proteins important in coagulation and inflammation (tissue factor [TF], calbindin [Cal], and thrombopoietin [TPO]) and T-cell responses (CD40L and CD40) that were present in AV at levels two to eight times greater than SE. These results suggest that AV and SE animals might differ in their ability to mount an immune response.
Assuntos
Surtos de Doenças/veterinária , Ectoparasitoses/veterinária , Peste/veterinária , Doenças dos Roedores/epidemiologia , Sciuridae , Animais , Arizona , Suscetibilidade a Doenças/veterinária , Ectoparasitoses/epidemiologia , Ectoparasitoses/imunologia , Feminino , Masculino , Peste/epidemiologia , Peste/imunologia , Dinâmica Populacional , Sciuridae/imunologia , Sciuridae/microbiologia , Yersinia pestis/isolamento & purificaçãoRESUMO
Since the anthrax attacks of 2001, the emphasis on developing animal models of aerosolized select agent pathogens has increased. Many scientists believe that nonhuman primate models are the most appropriate to evaluate pulmonary response to, vaccines for, and treatments for select agents such as Yersinia pestis (Y. pestis), the causative agent of plague. A recent symposium concluded that the cynomolgus macaque (Macaca fascicularis) plague model should be characterized more fully. To date, a well-characterized cynomolgus macaque model of pneumonic plague using reproducible bioaerosols of viable Y. pestis has not been published. In the current study, methods for creating reproducible bioaerosols of viable Y. pestis strain CO92 (YpCO92) and pneumonic plague models were evaluated in 22 Indonesian-origin cynomolgus macaques. Five macaques exposed to doses lower than 250 CFU remained free of any indication of plague infection. Fifteen macaques developed fever, lethargy, and anorexia indicative of clinical plague. The 2 remaining macaques died without overt clinical signs but were plague-positive on culture and demonstrated pathology consistent with plague. The lethal dose of plague in humans is reputedly less than 100 organisms; in this study, 66 CFU was the dose at which half of the macaques developed fever and clinical signs (ED(50)), The Indonesian cynomolgus macaque reproduces many aspects of human pneumonic plague and likely will provide an excellent model for studies that require a macaque model.
Assuntos
Vacinas Bacterianas/uso terapêutico , Macaca fascicularis/microbiologia , Vacina contra a Peste/uso terapêutico , Peste/microbiologia , Peste/veterinária , Yersinia pestis/patogenicidade , Aerossóis , Animais , Anticonvulsivantes/farmacologia , Anticonvulsivantes/toxicidade , Apetite/efeitos dos fármacos , Vacinas Bacterianas/administração & dosagem , Temperatura Corporal/efeitos dos fármacos , Chlorocebus aethiops/microbiologia , Moduladores GABAérgicos/farmacologia , Moduladores GABAérgicos/toxicidade , Macaca mulatta/microbiologia , Atividade Motora/efeitos dos fármacos , Peste/imunologia , Especificidade da Espécie , Tiletamina/farmacologia , Tiletamina/toxicidade , Zolazepam/farmacologia , Zolazepam/toxicidadeRESUMO
The lipolytic enzyme hepatic lipase (HL) may facilitate mobilization of cholesterol substrate for ovarian steroidogenesis. We investigated whether HL was necessary for optimum reproduction in the female mouse by analyzing breeding performance and ovarian responses to gonadotropins in HL-/- mice. HL-/- female mice bred with HL-/- males had the same pregnancy success rate and pup survival rate as did wild-type (WT) mice but had significantly smaller litters, producing 1.7 fewer pups per litter. Mice were primed with eCG/hCG, and at 6 h post-hCG the HL-/- mice had smaller ovaries than did the WT mice. HL deficiency specifically affected ovarian weight; adrenal gland weights did not differ between WT and HL-/- mice. HL-/- mice weighed more than age-matched WT mice. Between the two mouse genotypes, uterine weights were the same, indicating that estrogen production was equivalent. However, the HL-/- ovaries produced significantly less progesterone than did the WT ovaries within 6 h of hCG stimulation. HL-/- ovaries had the same number of large antral follicles as did the WT ovaries but had fewer hemorrhagic sites, which represent ovulations, fewer corpora lutea, and more oocytes trapped in corpora lutea. We suggest that reduced progesterone synthesis following hCG stimulation attenuated the final maturation of preovulatory follicles, resulting in smaller ovaries. Furthermore, reduced progesterone production limited the expression of proteolytic enzymes needed for tissue remodeling, resulting in fewer ovulations with a corresponding increase in trapped or unovulated oocytes and providing a possible explanation for the smaller litter size observed in spontaneously ovulating HL-/- mice.