Severity assessment in mice subjected to carbon tetrachloride.

The Directive 2010/63 EU requires classifying burden and severity in all procedures using laboratory animals. This study evaluated the severity of liver fibrosis induction by intraperitoneal carbon tetrachloride (CCl4) injections in mice. 29 male C57BL/6N mice were treated three times per week for 4 weeks with an intraperitoneal injection (50 µl) of either 0.6 ml/kg body weight CCl4-vehicle solution, germ oil (vehicle-control) or handling only. Severity assessment was performed using serum analysis, behavioral tests (open field test, rotarod, burrowing and nesting behavior), fecal corticosterone metabolite (FCM) measurement, and survival. The most significant group differences were noticed in the second week of treatment when the highest AST (1463 ± 1404 vs. 123.8 ± 93 U/L, p < 0.0001) and nesting values were measured. In addition, respective animals showed lower moving distances (4622 ± 1577 vs. 6157 ± 2060 cm, p < 0.01) and velocity in the Open field, identified as main factors in principal component analysis (PCA). Overall, a 50% survival rate was observed within the treatment group, in which the open field performance was a good tracer parameter for survival. In summary, this study demonstrates the feasibility of assessing severity in mice using behavioral tests and highlight the open field test as a possible threshold parameter for risk assessment of mortality.

Towards optimized anesthesia protocols for stereotactic surgery in rats: Analgesic, stress and general health effects of injectable anesthetics. A comparison of a recommended complete reversal anesthesia with traditional chloral hydrate monoanesthesia.

Although injectable anesthetics are still widely used in laboratory rodents, scientific data concerning pain and distress during and after stereotactic surgery are rare. However, optimal anesthesia protocols have a high impact on the quality of the derived data. We therefore investigated the suitability of recommended injectable anesthesia with a traditionally used monoanesthesia for stereotactic surgery in view of optimization and refinement in rats. The influence of the recommended complete reversal anesthesia (MMF; 0.15mg/kg medetomidine, 2mg/kg midazolam, 0.005mg/kg fentanyl; i.m.) with or without reversal and of chloral hydrate (430mg/kg, 3.6%, i.p.) on various physiological, biochemical and behavioral parameters (before, during, after surgery) was analyzed. Isoflurane was also included in stress parameter analysis. In all groups, depth of anesthesia was sufficient for stereotactic surgery with no animal losses. MMF caused transient exophthalmos, myositis at the injection site and increased early postoperative pain scores. Reversal induced agitation, restlessness and hypothermia. Even the low concentrated chloral hydrate led to peritonitis and multifocal liver necrosis, corresponding to increased stress hormone levels and loss in body weight. Increased stress response was also exerted by isoflurane anesthesia. Pronounced systemic toxicity of chloral hydrate strongly questions its further use in rodent anesthesia. In view of undesired effects of MMF and isoflurane, thorough consideration of anesthesia protocols for particular research projects is indispensable. Reversal should be restricted to emergency situations. Our data support further refinement of the current protocols and the importance of sham operated controls.

High frequency stimulation of the entopeduncular nucleus sets the cortico-basal ganglia network to a new functional state in the dystonic hamster.

High frequency stimulation (HFS) of the internal pallidum is effective for the treatment of dystonia. Only few studies have investigated the effects of stimulation on the activity of the cortex-basal ganglia network. We here assess within this network the effect of entopeduncular nucleus (EP) HFS on the expression of c-Fos and cytochrome oxidase subunit I (COI) in the dt(sz)-hamster, a well-characterized model of paroxysmal dystonia. In dt(sz)-hamsters, we identified abnormal activity in motor cortex, basal ganglia and thalamus. These structures have already been linked to the pathophysiology of human dystonia. EP-HFS (i) increased striatal c-Fos expression in controls and dystonic hamsters and (ii) reduced thalamic c-Fos expression in dt(sz)-hamsters. EP-HFS had no effect on COI expression. The present results suggest that EP-HFS induces a new network activity state which may improve information processing and finally reduces the severity of dystonic attacks in dt(sz)-hamsters.