Isoflurane and Ketamine/Xylazine Anesthesia do not Influence the Neuroprotective Effects of Simvastatin in a Model of Permanent Cerebral Ischemic Injury in C57BL/6J Mice.

Laboratory mice with Middle Cerebral Artery Occlusion (MCAO) represent the main animal models for ischemic stroke research. Appropriate anesthetic protocols are essential, as anesthetic agents might affect the central nervous system (CNS) and therefore interfere with the outcome of pre-clinical ischemic stroke studies. In the present study we sought to investigate whether isoflurane, a widely used inhalational anesthetic, has any effect on MCAO mice pretreated with simvastatin, a well-known neuroprotective compound, compared with the administration of injectable ketamine/xylazine combination. Forty adult C57Bl/6J mice randomly allocated into four groups underwent ischemic injury by permanent coagulation of the Middle Cerebral Artery (MCA): Group A (n=11) animals were anesthetized with ketamine/xylazine, Group B (n=9) with isoflurane, Group C (n=9) with ketamine/xylazine after pretreatment with simvastatin 2h before permanent Middle Cerebral Artery Occlusion (pMCAO) and Group D (n=11) with isoflurane after similar pretreatment with simvastatin. The potential neuroprotective effect of the anesthetics was evaluated in terms of brain infarct volumes and neuron death. No significant differences, both quantitatively and qualitatively, were detected in brain lesions measured up to 7 days after pMCAO when comparing isoflurane inhalational anesthesia to ketamine/xylazine injectable anesthesia. Group C mice (simvastatin-treated ketamine/xylazine) had a significantly reduced brain infarct volume compared to Group A mice (non-simvastatin ketamine/xylazine) (P<.0005). Similarly Group D mice (simvastatin-treated isoflurane) had a significantly reduced brain infarct volume compared to Group B mice (non-simvastatin isoflurane) (P<.0005). No difference between morphology and number of apoptotic neurons was detected due to the two different anesthetic regimens. These results demonstrated the safe use of the established anesthetic agent isoflurane in mice where simvastatin is investigated as a neuroprotective compound.

Distraction-like phenomena in maxillary bone due to application of orthodontic forces in ovariectomized rats.

Background: Orthodontic forces may not only influence the dentoalveolar system, but also the adjacent and surrounding cortical bone. Aim: Since there is very limited information on this issue, we aimed to study the possible changes in maxillary cortical bone following the application of heavy orthodontic forces in mature normal and osteoporotic rats. Materials and Methods: Twenty-four 6-month-old female rats were selected and divided into an ovariectomized group and a normal group. In both groups, the rats were subjected to a 60 gr* orthodontic force on the upper right first molar for 14 days. Results: In both groups, histological sections showed that the application of this force caused hypertrophy and fatigue failure of the cortical maxillary bone. The osteogenic reaction to distraction is expressed by the formation of subperiosteal callus on the outer bony side, resembling that seen in distracted bones. Conclusion: From this study we concluded that heavy experimental orthodontic forces in rats affect the maxillary cortical bone. The osteogenic reaction to these forces, expressed histologically by subperiosteal callus formation, is similar to that seen in distraction osteogenesis models.