Cooling to 10 degrees C and treatment with Cyclosporine A improve cerebral recovery following prolonged hypothermic circulatory arrest in a chronic porcine model.

OBJECTIVE: This study was undertaken to assess whether cooling to 10 degrees C and/or treatment with Cyclosporine A (CsA) can reduce neurological injury during prolonged hypothermic circulatory arrest (HCA) in a chronic animal model. METHODS: In this blinded study, 24 pigs (20-23 kg) were randomized to HCA for 90 min at 20 degrees C (n=8), at 10 degrees C (n=8), or at 10 degrees C with 5 mg/kg CsA (n=8). CsA (or placebo) were given intravenously before and for 3 days after HCA. Hemodynamics and neurophysiological data were monitored periodically throughout the experiment and for 3 h after HCA, as well as intracranial pressure (ICP), which has been shown to correlate with outcome. Daily neurological/behavioral evaluation (mental status, coordination and appetite; 12=normal and 0=coma or death) was carried out until sacrifice on postoperative day (POD) 3. RESULTS: Overall survival rate was 83.3%: one 20 degrees C control, two 10 degrees C controls, and one 10 degrees C/CsA pig died and were replaced. Basic hemodynamic data revealed no significant differences between groups. ICP differed significantly among the groups during the first 3 h postoperatively (P=0.003 by repeated measures ANOVA); it was higher in the 20 degrees C group than in the 10 degrees C/CsA or 10 degrees C control groups. Recovery of visual evoked potentials was significantly better in the 10 degrees C/CsA group than in the 10 degrees C control group; no recovery was seen by 3 h in the 20 degrees C control group. Postoperative behavioral scores also differed significantly between the groups, P=0.03: a good behavioral outcome--a score >9 on POD3--was more prevalent among CsA-treated pigs (75%) than among 10 degrees C controls (50%), or 20 degrees C controls (12.5%, P=0.06). CONCLUSIONS: The data suggest that cooling to 10 degrees C and CsA treatment are both of benefit in improving cerebral recovery after HCA when compared with untreated 20 degrees C controls, and may be synergistic.

Spatial distribution of Bax and Bcl-2 in osteocytes after bone fatigue: complementary roles in bone remodeling regulation?

Osteocyte apoptosis appears to play a key role in the mechanism by which osteoclastic resorption activity targets bone for removal, because osteocyte apoptosis occurs in highly specific association with microdamage and subsequent remodeling after fatigue. However, beyond terminal deoxynucleotidyl transferase (TdT)-mediated deoxyuridine triphosphate (dUTP)-biotin nick end labeling (TUNEL) assay, little is known about the mechanisms controlling osteocyte apoptosis in vivo. In the current studies, expression of Bax, a proapoptotic gene product, and Bcl-2, an antiapoptotic gene product, was determined in osteocytes of fatigued rat bone using immunocytochemical staining and compared with TUNEL staining patterns. Bax and Bcl-2 were evident in osteocytes by 6 h after loading. Moreover, Bax and Bcl-2 in osteocytes were expressed differently as a function of distance from microdamage sites. The peak of Bax expression and TUNEL+ staining in osteocytes was observed immediately at the microcrack locus, which is where bone resorption occurs in this system; in contrast, Bcl-2 expression, the antiapoptotic signal, reached its greatest level at some distance (1-2 mm) from microcracks. These data suggest that near sites of microinjury in bone, those osteocytes that do not undergo apoptosis are prevented from doing so by active protection mechanisms. Moreover, the zone of apoptotic osteocytes around microcracks was effectively "walled in" by a surrounding halo of surviving osteocytes actively expressing Bc1-2. Thus, the expression pattern of apoptosis-inhibiting gene products by osteocytes surrounding the apoptotic osteocyte at microdamage sites also may provide important signals in the guidance of resorption processes that occur in association with osteocyte apoptosis after fatigue.

Proapoptotic protein glyceraldehyde-3-phosphate dehydrogenase: a possible site of action of antiapoptotic drugs.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) has long been recognized as a classical glycolytic protein and has been used as a "housekeeping" gene in studies of genetic expression and regulation. However, recent advances reveal that GAPDH displays diverse nonglycolytic functions depending on its subcellular localization. Among those functions, one of the most intriguing is likely to be the induction of apoptosis. Previous works by our group and others have demonstrated that the overexpression of GAPDH and its subsequent nuclear translocation appear to be implicated in the initiation of one or more apoptotic cascades and also in the etiology of some neurological diseases. This review addresses new data demonstrating that a protein, referred to as proapoptotic protein GAPDH, with a quite mundane function in healthy cells behaves very differently during cell suicide, and summarizes emphatically the importance of this protein as a putative molecular target in developing antiapoptotic therapeutic agents for the treatment of certain neurodegenerative disorders.

Dose-dependent loss of motor function after unilateral medial forebrain bundle rotenone lesion in rats: a cautionary note.

The organic pesticide rotenone is a neurotoxin suspected to cause Parkinson's disease (PD) symptoms by selectively targeting and compromising the survival of dopaminergic neurons. Rotenone in rodent models reproduces key features of human PD by impairing the mitochondrial electron transport chain, leading to intracellular alpha-synuclein aggregates and functional impairments typical for PD. The present study characterized the dose-response relationship of standard rotenone concentrations in motor impairments in a rat model. Rats received a single medial forebrain bundle injection of 4, 8, or 12µg of rotenone. Animals were assessed in skilled limb use, skilled and non-skilled walking and exploratory activity as well as drug-induced rotation. The results revealed rotational bias and stable impairments in skilled walking and gross motor function up to five weeks post injection. However, transient motor deficits facilitated rapid improvement of skilled reaching success. Mainly the temporal aspects of skilled and non-skilled motor performance were responsive to different rotenone concentrations. By contrast, drug-induced rotation and nigral TH+ cell loss were not influenced by different rotenone doses. Rats infused with 8µg and 12µg seemed to have reached a ceiling effect in motor deficits as they were not distinguishable in behavioral measures. Most strikingly, the stereological and morphological analyses revealed non-specific toxicity of vehicle and rotenone infusions that caused macroscopic lesions beyond nigral boundaries. These findings suggest that sensitivity of comprehensive motor tests to subtle modulation of dopamine function is independent of dopamine cell loss per se. Furthermore, caution is advised concerning non-specific toxicity of rotenone and vehicle substances in experimental animal models.