The aim of this study was to compare the systemic hemodynamic effects of four commonly used anesthetic regimens in mice that were chronically instrumented for direct and continuous measurements of cardiac output (CO). Mice (CD-1, Swiss, and C57BL6 strains) were instrumented with a transit-time flow probe placed around the ascending aorta for CO measurement. An arterial catheter was inserted into the aorta 4 or 5 days later for blood pressure measurements. After full recovery, hemodynamic parameters including stroke volume, heart rate, CO, mean arterial pressure (MAP), and total peripheral resistance were measured with animals in the conscious state. General anesthesia was then induced in these mice using isoflurane (Iso), urethane, pentobarbital sodium, or ketamine-xylazine (K-X). The doses and routes of administration of these agents were given as required for general surgical procedures in these animals. Compared with the values obtained for animals in the conscious resting state, MAP and CO decreased during all anesthetic interventions, and hemodynamic effects were smallest for Iso (MAP, -24 +/- 3%; CO, -5 +/- 7%; n = 15 mice) and greatest for K-X (MAP, -51 +/- 6%; CO, -37 +/- 9%; n = 8 mice), respectively. The hemodynamic effects of K-X were fully antagonized by administration of the alpha(2)-receptor antagonist atipamezole (n = 8 mice). These results indicate that the anesthetic Iso has fewer systemic hemodynamic effects in mice than the nonvolatile anesthetics.

Objective To better understand the contribution of age to the development of osteoarthritis (OA). Methods Surgical destabilization of the medial meniscus (DMM) was used to model OA in 12 week-old and 12 month-old male C57/BL6 mice. OA severity was evaluated histologically. RNA used for microarrays and real-time PCR was isolated from joint tissue collected from the medial side of the joint, including cartilage, meniscus, subchondral bone, and joint capsule with synovium. Computational analysis was used to identify patterns of gene expression and immunohistochemistry to evaluate tissue distribution of selected proteins. Results OA was more severe in older mice than young. Only 55 genes showed a similar expression with DMM-induced OA in the two age groups while 493 genes showed differential expression, the majority having increased expression in older mice. Functional categories for similarly expressed genes included extracellular matrix and cell adhesion related genes; differentially expressed genes included muscle structure and development and immunoglobulin domain genes. Comparison of expression in the sham control joints revealed an age-related decrease in matrix gene expression and an increase in immune and defense response genes. IL-33 was present in multiple joint tissue cells while CCL21 was more localized to chondrocytes and meniscal cells. Periostin was found in the extracellular matrix of cartilage and meniscus. Conclusion Age affects both the basal pattern of gene expression in joint tissues and the response to surgically-induced OA. Examining tissue from the joint beyond only cartilage revealed novel genes and proteins that would be important to consider in OA.

Osteoarthritis (OA) is the most common form of arthritis and has multiple risk factors including joint injury. The purpose of this study was to characterize the histologic development of OA in a mouse model where OA is induced by destabilization of the medial meniscus (DMM model) and to identify genes regulated during different stages of the disease, using RNA isolated from the joint “organ” and analyzed using microarrays. Histologic changes seen in OA, including articular cartilage lesions and osteophytes, were present in the medial tibial plateaus of the DMM knees beginning at the earliest (2 week) time point and became progressively more severe by 16 weeks. 427 probe sets (371 genes) from the microarrays passed consistency and significance filters. There was an initial up-regulation at 2 and 4 weeks of genes involved in morphogenesis, differentiation, and development, including growth factor and matrix genes, as well as transcription factors including Atf2, Creb3l1, and Erg. Most genes were off or down-regulated at 8 weeks with the most highly down-regulated genes involved in cell division and the cytoskeleton. Gene expression increased at 16 weeks, in particular extracellular matrix genes including Prelp, Col3a1 and fibromodulin. Immunostaining revealed the presence of these three proteins in cartilage and soft tissues including ligaments as well as in the fibrocartilage covering osteophytes. The results support a phasic development of OA with early matrix remodeling and transcriptional activity followed by a more quiescent period that is not maintained. This implies that the response to an OA intervention will depend on the timing of the intervention. The quiescent period at 8 weeks may be due to the maturation of the osteophytes which are thought to temporarily stabilize the joint.

Angiotensin-(1-7) ] is an endogenous peptide of the renin-angiotensin system with vasodilator and antiproliferative properties. Our previous studies showed that Ang-(1-7) reduced serum-stimulated growth of human lung cancer cells in vitro through activation of a unique AT (1-7) receptor. The current study investigates the effect of Ang-

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Mice lacking AT(1A) receptors for ANG II have a defect in urinary concentration manifested by an inability to increase urinary osmolality to levels seen in controls after thirsting. This defect results in extreme serum hypertonicity during water deprivation. In the basal state, plasma vasopressin levels are similar in wild-type controls and Agtr1a -/- mice. Plasma vasopressin levels increase normally in the AT(1A) receptor-deficient mice after 24 h of water deprivation, suggesting that the defect in urine concentration is intrinsic to the kidney. Using magnetic resonance microscopy, we find that the absence of AT(1A) receptors is associated with a modest reduction in the distance from the kidney surface to the tip of the papilla. However, this structural abnormality seems to play little role in the urinary concentrating defect in Agtr1a -/- mice since the impairment is largely reproduced in wild-type mice by treatment with an AT(1)-receptor antagonist. These studies demonstrate a critical role for the AT(1A) receptor in maintaining inner medullary structures in the kidney and in regulating renal water excretion.

Objective:Accurate histological assessment of osteoarthritis (OA) is critical in studies evaluating the effects of interventions on disease severity. The purpose of the present study was to develop a histological grading scheme that comprehensively and quantitatively assesses changes in multiple tissues that are associated with OA of the stifle joint in mice.Design:Two representative midcoronal sections from 158 stifle joints, including naturally occurring and surgically induced OA, were stained with H&E and Safranin-O stains. All slides were evaluated to characterize the changes present. A grading scheme that includes both measurements and semiquantitative scores was developed, and principal components analysis (PCA) was applied to the resulting data from the medial tibial plateaus. A subset of 30 tibial plateaus representing a wide range of severity was then evaluated by 4 observers. Reliability of the results was evaluated using intraclass correlation coefficients (ICCs) and area under the receiver operating characteristic (ROC) curve.Results:Five factors were retained by PCA, accounting for 74% of the total variance. Interobserver and intraobserver reproducibilities for evaluations of articular cartilage and subchondral bone were acceptable. The articular cartilage integrity and chondrocyte viability factor scores were able to distinguish severe OA from normal, minimal, mild, and moderate disease.Conclusion:This newly developed grading scheme and resulting factors characterize a range of joint changes in mouse stifle joints that are associated with OA. Overall, the newly developed scheme is reliable and reproducible, characterizes changes in multiple tissues, and provides comprehensive information regarding a specific site in the stifle joint.

Age is an important predictor of neuromuscular recovery after peripheral nerve injury. Insulin-like growth factor 1 (IGF-1) is a potent neurotrophic factor that is known to decline with increasing age. The purpose of this study was to determine if locally delivered IGF-1 would improve nerve regeneration and neuromuscular recovery in aged animals. Young and aged rats underwent nerve transection and repair with either saline or IGF-1 continuously delivered to the site of the nerve repair. After 3 months, nerve regeneration and neuromuscular junction morphology were assessed. In both young and aged animals, IGF-1 significantly improved axon number, diameter, and density. IGF-1 also significantly increased myelination and Schwann cell activity and preserved the morphology of the postsynaptic neuromuscular junction (NMJ). These results show that aged regenerating nerve is sensitive to IGF-1 treatment.