Sham Counterparts Research Articles

Randomized controlled trial: effects of acupuncture on pregnancy rates in women undergoing in vitro fertilization

To evaluate the influence of "true" versus "sham" acupuncture on pregnancy rates (PRs) in women undergoing IVF. Randomized controlled trial, double-blinded with independent observer. Academic infertility clinic. One hundred sixty patients <38 years old undergoing IVF with or without intracytoplasmic sperm injection. Subjects were randomly allocated to the true or sham group and underwent acupuncture 25 minutes before and after ET. Subjects completed a McGill Pain Questionnaire regarding their clinical symptoms during ET. Clinical PR and clinical symptoms during ET. While the overall clinical PR was 51.25%, there was no significant difference between the arms of the study (true = 45.3% vs. sham = 52.7%); 33.1% of the patients had ultrasound-documented singleton pregnancy, and 15% of patients had twin gestations, while one patient in the true arm had a triplet gestation. There were significant differences in the subjective, affective, and total pain experience between both arms. The subjects in the true arm described their acupuncture session as being more "tiring" and "fearful" and experienced more "achiness" compared with their sham counterparts. There was no statistically significant difference in the clinical or chemical PRs between both groups. Patients undergoing true acupuncture had differing sensory experiences compared with patients in the sham arm. There were no significant adverse effects observed during the study, suggesting that acupuncture is safe for women undergoing ET.

Experimental Chagas’ disease in orchiectomized Calomys callosus infected with the CM strain of Trypanosoma cruzi

The incidence and progression of disorders associated with an unbalanced immune response has among many factors the gender as a contributory factor. The aims of this work were to evaluate the effects of orchiectomy and the immune response during the experimental Trypanosoma cruzi infection. Young adult, male Calomys callous were i.p. inoculated with 1 × 10 5 blood trypomastigotes of the CM strain of T. cruzi and divided in groups: Control, Sham and Castrated. Castrated group displayed significantly lower values for prostate and seminal vesicle weights indicating a drastic drop of testosterone plasmatic levels. Orchiectomized animals also displayed lesser number of blood parasites, enhanced lytic antibody percentage, splenocyte proliferation and NO concentration when compared to its sham and control counterparts, indicating that steroid gonadal ablation actually influences immune response triggering a more efficient cellular and humoral response which led animals to become more resistant against T. cruzi infection.

Adenoviral endothelial nitric oxide synthase (NOS) expression in the paraventricular nucleus (PVN) inhibits mean arterial blood pressure in renal wrap hypertension

PVN nitric oxide (NO) has been implicated in hypertension. Moreover, PVN neuronal NOS is reduced during the onset of renal wrap hypertension. Thus, we hypothesized that increasing PVN NO would reduce the increase in mean arterial pressure (MAP) observed in renal wrap hypertension. In male sprague dawley rats radiotelemetry transmitters were implanted for MAP and heart rate (HR) measures. Baseline MAP and HR were obtained for one week. Adenoviruses (Ad) encoding eNOS or lacZ (a marker gene/control) were then microinjected into the PVN [1 x 109 pfu; bilateral (200nl/site)]. After one week of MAP and HR baseline measures post PVN Ad injections, renal wrap/sham surgeries were performed. Neither Ad LacZ nor Ad eNOS alone had effects on MAP or HR. Renal wrap surgery significantly increased MAP in both Ad LacZ and Ad eNOS wrap animals compared to sham counterparts. Five days post surgery the Ad eNOS wrap animals had a significantly lower MAP compared to Ad LacZ wrap rats (Ad LacZ wrap: 137 + 4; Ad eNOS wrap: 124 + 9; Ad Lac Z sham: 104 + 3; Ad eNOS sham: 107 + 5; p&lt;0.05), with maximal inhibition occurring 10 days post wrap (Wrap Ad Lac Z: 146 + 6 vs. Ad eNOS: 123 +12 mm Hg, p&lt;0.05). In conclusion, these data demonstrate that an increase in eNOS in the PVN, potentially increasing PVN NO, results in a blunting of MAP in renal wrap hypertension further demonstrating the role of PVN NO in blood pressure regulation in hypertension.

The importance of endogenous nutrition of chicks from divergent strains for growing tested by deutectomy

Effects of yolk sac removal (deutectomy) upon performance of chicks from three divergent strains were tested to evaluate the importance of endogenous nutrition on the post-hatch phase. Chicks from three different strains (Hy-Line W98, Cobb 500, and JA57) were submitted to a surgery procedure after hatching. Half of them had the residual yolk removed, and the other constituted a sham-deutectomized group. After operation, chicks were designated to a 3 x 2 factorial design (3 strains x 2 presence/absence of yolk sac), in a total of six experimental groups and ten replications of two to four birds. During 14 experimental days all birds were fed ad libitum a 21% CP and 3050 kcal/kg EM mash diet. Data were analyzed by ANOVA, and Tukey's test (p<0.05). Relative yolk sac weights were similar among chicks from different breeders, averaging 11.7% to 13.5%. Comparing to sham-operated, deuctetomized chicks had lower weight gain at 7 and 14d, indicating that endogenous nutrition, via yolk sac, is very important to galliform birds whatever their strain. Hy-line deutectomized chicks gained 40% less body weight at the 7th day as compared to their sham counterparts. Analysis of the same criterion to Cobb and JA57 groups revealed a decrease of 16.1% and 10.8%, respectively, on weight gain efficiency. At the 14th rearing day, Hy-Line chicks had the lowest weight gain, followed by JA57s' and Cobbs'. The results suggested that chicks selected for fast growth are less dependent on endogenous nutrition, responding better when exogenous nutrition is associated to yolk assimilation.

Disruption of Bax Protein Prevents Neuronal Cell Death but Produces Cognitive Impairment in Mice following Traumatic Brain Injury

Apoptosis contributes to delayed neuronal cell death in traumatic brain injury (TBI). To investigate if Bax plays a role in neuronal cell death and functional outcome after TBI, Bax gene disrupted (null) mice and wild-type (WT) controls were subjected to the controlled cortical impact (CCI) model of TBI. Motor function in WT and Bax null mice was evaluated using the round beam balance and the wire grip test on days 0-5. Spatial memory was assessed using a Morris Water Maze adopted for mice on days 14-18 post-injury. For histopathological analysis, animals were sacrificed 24 h and 21 days post-injury. In all three behavioral tests, the sham and TBI-injured Bax null mice performed significantly worse than their WT sham and TBI-injured counterparts. However, Bax null mice exhibited a higher percentage of surviving neurons in the CA1 and CA3 regions of hippocampus measured at 21 days post-injury. At 24 h after trauma, Bax null mice had fewer TUNEL positive cells in the CA1 and dentate regions of hippocampus as compared to WT mice, suggesting that deletion of the Bax gene ameliorates hippocampal cell death after TBI. Sham-operated Bax null mice had significantly greater brain volume as compared to WT mice. Thus, it is possible that Bax deficiency in the transgenic mice produces developmental behavioral effects, perhaps due to Bax's role in regulating cell death during development.

Endurance Training Modulates Lymphocyte Function in Rats with Post-MI CHF

Exercise training restores innate immune system cell function in post-myocardial infarction (post-MI) rats. However, studies of the involvement of lymphocyte (Ly) in the setting of the congestive heart failure (CHF) are few. To address this issue, we investigated the function of Ly obtained from cervical lymph nodes from post-MI CHF rats submitted to treadmill running training. Twenty-five male Wistar rats were randomly assigned to the following groups: rats submitted to ligation of the left coronary artery, which were sedentary (MI-S, N = 7, only limited activity) or trained (MI-T, N = 6, on a treadmill (0% grade at 13-20 m.m) for 60 min.d, 5 d.wk, for 8-10 wk); or sham-operated rats, which were sedentary (sham-S, N = 6) or trained (sham-T, N = 6). The incorporation of [2-C]-thymidine by Ly cultivated in the presence of concanavalin A (Con A) and lipopolysaccharide (LPS), cytokine production by Ly cultivated in the presence of phytohemagglutinin (PHA), and plasma concentration of glutamine were assessed in all groups, 48 h after the last exercise session. Proliferative capacity was increased, following incubation with Con-A in the MI groups, when compared with the sham counterparts. When incubated in the presence of PHA, MI-S produced more IL-4 (96%) than sham-S (P < 0.001). The training protocol induced a 2.2-fold increase in the production of interleukin-2 (P < 0.001) of the cells obtained from the cervical lymph nodes of MI-T, compared with MI-S. The moderate endurance training protocol caused an increase in IL-2 production, and a trend toward the reversion of the Th1/Th2 imbalance associated with IL-4 production increased in the post-MI CHF animal model.

Peripheral oxygen‐sensing cells directly modulate the output of an identified respiratory central pattern generating neuron

Breathing is an essential homeostatic behavior regulated by central neuronal networks, often called central pattern generators (CPGs). Despite ongoing advances in our understanding of the neural control of breathing, the basic mechanisms by which peripheral input modulates the activities of the central respiratory CPG remain elusive. This lack of fundamental knowledge vis-à-vis the role of peripheral influences in the control of the respiratory CPG is due in large part to the complexity of mammalian respiratory control centres. We have therefore developed a simpler invertebrate model to study the basic cellular and synaptic mechanisms by which a peripheral chemosensory input affects the central respiratory CPG. Here we report on the identification and characterization of peripheral chemoreceptor cells (PCRCs) that relay hypoxia-sensitive chemosensory information to the known respiratory CPG neuron right pedal dorsal 1 in the mollusk Lymnaea stagnalis. Selective perfusion of these PCRCs with hypoxic saline triggered bursting activity in these neurons and when isolated in cell culture these cells also demonstrated hypoxic sensitivity that resulted in membrane depolarization and spiking activity. When cocultured with right pedal dorsal 1, the PCRCs developed synapses that exhibited a form of short-term synaptic plasticity in response to hypoxia. Finally, osphradial denervation in intact animals significantly perturbed respiratory activity compared with their sham counterparts. This study provides evidence for direct synaptic connectivity between a peripheral regulatory element and a central respiratory CPG neuron, revealing a potential locus for hypoxia-induced synaptic plasticity underlying breathing behavior.

The Role of the Vagus Nerve in Mediating the Long‐Term Anorectic Effects of Leptin

Leptin, the product of the obese (ob) gene, is mainly known for its regulatory role of energy balance by direct activation of hypothalamic receptors. Recently, its function in the acute control of food intake was additionally attributed to activation of the vagus nerve to regulate meal termination. Whether vagal afferent neurones are involved in longer term effects of leptin on food intake, however, remains undetermined. Using vagotomised (VGX) rats, we sought to clarify the contributions of vagal afferents in mediating the long-lasting effect of leptin on appetite suppression. Intraperitoneal (i.p.) injection of leptin (3.5 mg/kg) attenuated food intake at 4, 6, 8 and 24 h and body weight at 24 h postinjection in SHAM-operated rats; however, this response was not abrogated by vagotomy. In a separate study using immunohistochemistry, we observed leptin-induced Fos expression in the nucleus tractus solitarii, a brain structure where vagal afferent fibres terminate. This signal was not attenuated in VGX animals compared to the SHAM group. Moreover, leptin treatment led to a similar level of nuclear STAT3 translocation, a marker of leptin signalling, in the hypothalami of SHAM and VGX animals. In addition to the effects of leptin, vagotomy surgery itself resulted in a decrease of 24 h food intake. Analyses of brains from saline-treated VGX animals revealed a significant induction of Fos in the nucleus tractus solitarii and changes in agouti-related peptide and pro-opiomelanocortin mRNA expression in the hypothalamus compared to their SHAM counterparts, indicating that the vagotomy surgery itself induced a modification of brain activity in areas involved in regulating appetite. Collectively, our data suggest that vagal afferents do not constitute a major route of mediating the regulatory effect of leptin on food intake over a period of several hours.

Compensated volume overload increases the vulnerability of heart mitochondria without affecting their functions in the absence of stress

Although mitochondrial dysfunction has often been associated to heart failure, it has been suggested that it may represent only a late phenomenon in the disease process. We hypothesized that mitochondrial vulnerability to stress could be impaired in hypertrophied but non-decompensated hearts at a time when overt mitochondrial defects are not yet apparent. In the present study, hypertrophic remodeling was induced by means of an aorto-caval fistula (ACF) in WKHA rats and experiments were performed 12 weeks post surgery. At this time, ACF animals displayed normal contractile function, tissue oxidative capacity as well as mitochondrial membrane potential and respiratory function. However, compared to sham, mitochondria from ACF animals were more vulnerable to anoxia–reoxygenation injury in vitro as indicated by a greater impairment of oxidative phosphorylation and a greater dependence of respiration on exogenous NADH. Addition of the PTP inhibitor CsA restored respiratory function to the level observed in mitochondria from sham animals. Likewise, mitochondria from ACF displayed a greater sensitivity to Ca 2+-induced PTP opening in vitro compared to their sham counterparts. In addition to the greater vulnerability of mitochondria in vitro, mitochondrial PTP opening measured in situ in perfused hearts was greater following ischemia–reperfusion in ACF animals than in their sham counterparts. This was associated with a more impaired functional recovery and greater tissue damage during reperfusion in hearts from ACF vs sham. Taken together, these results indicate that, in response to volume overload, mitochondria may display increased vulnerability in the absence of any sign of dysfunction under baseline unstressed conditions, at a time when adverse ventricular remodelling is observed but systolic dysfunction and decompensation have not occurred yet.

Impact of the annexin 1 system on focal cerebral ischaemia‐reperfusion injury in mice

Stroke is a leading cause of death worldwide. We have addressed the role of exogenous and endogenous annexin 1 (AnxA1) in murine focal ischaemia, with intravital microscopy. Littermate wildtype (WT) and AnxA1 null mice were subjected to middle cerebral artery occlusion for 1 h and 24 h reperfusion. Neurological deficit, infarct volume and leukocyte-endothelial cell interactions (LEI) were determined. Results: Ischaemia-reperfusion increased LEI in both WT and AnxA1 null mice. Adherent leukocytes were increased in comparison to sham counterparts in both WT (472±77 vs. 0 cells) and AnxA1 null mice (728±113 vs.33±33 cells). Human recombinant AnxA1 (1 μg dose, given 0, 6, and 18 h, 28 nmol/mouse) restored WT phenotype in ANXA1 null mice. Given 3 times, peptide Ac2-26 (100 μg or 33 nmol) inhibited infarct volume (33±2% vs. 45±6% in vehicle animals). This protective effect was mirrored by reduced leukocyte adhesion, compared to vehicle animals. The formyl peptide receptor (FPR) antagonist Boc2, prevented the inhibitory effect of peptide Ac2–26. Conclusions: Endogenous AnxA1 exerts a tonic inhibitory role on cerebral vessel reactivity post-reperfusion. Pharmacologically, an AnxA1-derived peptide exerted protective actions by activating a receptor of the FPR family. These findings might be of potential interest for the development of new therapeutics for stroke.

Sex differences in inflammatory cytokine production in hepatic ischemia-reperfusion

BackgroundThe inflammatory response to hepatic ischemia-reperfusion (I/R) is associated with an increase in cytokine production. Studies have documented that sex hormones modulate both the innate and adaptive immune responses, and that females are more robust than males. The aim of this study was to determine whether a sex difference in cytokine response to hepatic I/R exists under normal pathophysiologic condition without hormone intervention.MethodsAdult C57BL/6 mice underwent 90 min of hepatic ischemia followed by various reperfusion periods (0, 1.5, 3, 6 hr). Plasma cytokine TNF-α, IL-6, MIP-2, and KC were measured. Liver injury was assessed by plasma alanine transaminase (ALT) levels and liver histopathology.ResultsA reperfusion time-dependent increase in hepatocellular injury was observed in both males and females, as indicated by increasing levels of plasma ALT and liver histopathology. The plasma cytokines were significantly increased in both female and male I/R groups compared to their respective sham counterparts. However, there was a significant difference in cytokine kinetics between the female and male I/R groups. Female mice initially had a higher level of IL-6, KC, and MIP-2 in response to I/R, which began to decline after 3 hr of reperfusion and were significantly lower than the male I/R counterparts by 6 hr of reperfusion. In contrast, the hepatocellular injury and TNF production were only moderately lower in female IR than male IR.ConclusionThe study underscores role of the gender in differential inflammatory cytokine expression in response to hepatic I/R, which may reflect the host response outcome.

Persistent HIF-1alpha activation in gut ischemia/reperfusion injury: potential role of bacteria and lipopolysaccharide.

In both animal models of hemorrhagic shock and clinical settings, shock-induced gut ischemia has been implicated in the development of the systemic inflammatory response syndrome and distant organ injury, yet the factors transducing these events remain to be fully determined. Because hypoxia-inducible factor (HIF-1), a transcription factor composed of oxygen-labile HIF-1alpha and constitutive HIF-1beta subunits, regulates the physiologic/pathophysiologic response to hypoxia and ischemia, we examined the HIF-1 response in two rat models of gut ischemia-reperfusion. We found that ileal nuclear HIF-1alpha protein levels were induced in rats subjected to trauma (laparotomy) plus hemorrhagic shock for 90 min relative to their trauma sham-shock and naïve counterparts and that this trauma hemorrhagic shock-induced mucosal HIF-1alpha protein response persisted after 1 h and 3 h of reperfusion. Likewise, in a model of isolated gut ischemia-reperfusion injury, where the superior mesenteric artery was occluded for 45 min, nuclear HIF-1alpha were induced in the gut mucosa relative to their sham counterparts and persisted after 1 h and 3 h or reperfusion. Similar to the in vivo response, in vitro hypoxia induced HIF-alpha expression in three different enterocyte cell lines (rat IEC-6 and human Caco-2 and HT-29 cell lines). However, in contrast to the in vivo response, HIF-1 expression rapidly disappeared on subsequent reoxygenation. Because in vivo enterocytes are exposed to bacteria, we tested whether the in vitro HIF-1alpha response would persist on reoxygenation if the enterocytes were cocultured with bacteria. P. aeruginosa, an enteric bacterium, markedly induced enterocyte HIF-1alpha protein levels under normoxic conditions. Furthermore, the addition of P. aeruginosa during either the hypoxic or reoxygenation phase prevented the degradation of HIF-1alpha protein levels. Moreover, the observation that lipopolysaccharide induced HIF-1alpha expression in a time-dependent manner in IEC-6 cells indicated that the induction of HIF-1 by exposure to P. aeruginosa is not dependent on bacterial viability. In conclusion, these results suggest that HIF-1alpha activation is an early reperfusion-independent event in models of gut ischemia-reperfusion and that this HIF-1alpha response is potentiated by the presence of P. aeruginosa or lipopolysaccharide.

Characterization of the expression of inducible nitric oxide synthase in rat and human liver during hemorrhagic shock.

It has been previously shown that the inducible nitric oxide (NO) synthase (iNOS; NOS-2) is elevated after hemorrhage, and that iNOS-derived NO participates in the upregulation of inflammation as well as lung and liver injury postresuscitation from shock. The purpose of this study was to elucidate the time course of iNOS mRNA expression, as well as the cellular and subcellular localization of iNOS protein in the liver posthemorrhage in rats subjected to varying durations of hemorrhagic shock (HS; mean arterial blood pressure [MAP] = 40 mmHg) with or without resuscitation. Expression of iNOS mRNA in rat liver by real-time reverse transcriptase (RT)-PCR demonstrated iNOS upregulation in shocked animals as compared with their sham counterparts as early as 60 min after the initiation of hemorrhage. By 1 h of HS, iNOS protein was detectable in rat liver by immunofluorescence, and this expression increased with time. Immunofluorescence localized iNOS primarily to the hepatocytes, and in particular to hepatocytes in the centrilobular regions. This analysis, confirmed by immunoelectron microscopy, revealed that iNOS colocalizes with catalase, a peroxisomal marker. Furthermore, we determined that iNOS mRNA is detectable by RT-PCR in liver biopsies from human subjects with HS (MAP < 90 mmHg) associated with trauma (n = 18). In contrast, none of the seven nontrauma surgical patients studied had detectable iNOS mRNA in their livers. Collectively, these results suggest that hepatic iNOS expression, associated with peroxisomal localization, is an early molecular response to HS in experimental animals and possibly in human patients with trauma with HS.

Neonatal ventral hippocampal damage modifies serum corticosterone and dopamine release responses to acute footshock in adult Sprague-Dawley rats.

Rats with excitotoxic neonatal ventral hippocampal lesions (NVHL) manifest in early adulthood a variety of behavioral and neurochemical abnormalities mimicking those seen in patients with schizophrenia. Some of these aberrations implicate malfunction of the midbrain dopamine systems. We studied NVHL effects on dopamine release in the rat frontal cortex, nucleus accumbens, and striatum during acute stress caused by inescapable continuous footshock (0.45 mA). Serum total corticosterone and prolactin levels were used as peripheral indices of stress. As an indirect index of dopamine release, tissue 3-methoxytyramine levels attained in vivo 10 min after monoamine oxidase inhibition was assayed in rats sacrificed by instantaneous microwave fixation of the brain tissue. Nonshocked NVHL rats showed significantly less nucleus accumbens' 3-methoxytyramine accumulation than their sham counterparts. Frontal cortical 3-methoxytyramine levels rose similarly after 20-min footshock in both groups of rats, but while it normalized after 60-min footshock in the sham rats, it did not decrease in the NVHL rats. Nucleus accumbens' 3-methoxytyramine was significantly elevated after either 20-min or 60-min footshock in both groups, whereas striatal 3-methoxytyramine was significantly elevated in the NVHL rats only. Serum corticosterone showed similar elevations in the sham and NVHL rats, but the patterns differed in that there was no attenuation after 60-min footshock in the latter. The lesion did not affect serum prolactin response. These data indicate that neonatal ventral hippocampal damage enhances and prolongs certain neural and neuroendocrine responses to acute physical stressor(s), and thus may affect adaptation and enhance detrimental effects of stress.

Ventral hippocampal lesions affect anxiety but not spatial learning

Rats with cytotoxic ventral hippocampal lesions which removed approximately 50% of the hippocampus (including dentate gyrus) starting from the temporal pole, displayed a reduction in freezing behaviour following the delivery of an unsignalled footshock in an operant chamber. This was more plausibly a result of reduced susceptibility to fear than a result of a lesion-induced increase in general motor activity. There was no consistent difference between sham and lesioned animals in spontaneous locomotor activity, or locomotion following acute or chronic treatment with amphetamine. In contrast, ventral hippocampal lesioned animals were quicker to pass from the black to the white box during a modified version of the light/dark exploration test, and were quicker to begin eating during tests of hyponeophagia. Furthermore, rats with ventral hippocampal lesions defecated less than their sham counterparts both during open field testing and in extinction sessions following contextual conditioning. In contrast to these clear lesion effects, there were no signs of any spatial learning impairment either in the watermaze or on the elevated T-maze. Taken together these results suggest that the ventral hippocampus may play a role in a brain system (or systems) associated with fear and/or anxiety, and provide further evidence for a distinct specialisation of function along the septotemporal axis of the hippocampus.

Contribution of cyclooxygenase 2 to liver regeneration after partial hepatectomy.

Partial hepatectomy (PH) triggers a rapid regenerative response in the remaining tissue to reinstate the organ function and the cell numbers. Among the molecules that change in the course of regeneration is an accumulation of prostaglandin E2 in the sera of rats with PH. Analysis of the cyclooxygenase (COX) isoenzymes in the remnant liver showed the preferential expression of COX-2 in hepatocytes. Cultured regenerating hepatocytes expressed significant levels of COX-2, a process that was not observed in the sham counterparts. Maximal expression of COX-2 was detected 16 h after PH with increased levels present even at 96 h. Pharmacological inhibition of COX-2 activity with NS398 shunted the up-regulation of cell proliferation after PH, which suggests a positive interaction of prostaglandins with the progression of the cell cycle. Similar results were obtained after PH of mice lacking the COX-2 gene. The expression of COX-2 in regenerating liver was concomitant with a decrease in CCAAT-enhancer binding protein (C/EBP-a) level and an increase in the expression of C/EBP-b and C/EBP-d. These results suggest a contribution of the enhanced synthesis of prostaglandins to liver regeneration observed after PH.

Mice Lacking tPA, uPA, or Plasminogen Genes Showed Delayed Functional Recovery after Sciatic Nerve Crush

Axonal outgrowth during peripheral nerve regeneration relies on the ability of growth cones to traverse through an environment that has been altered structurally and along a basal lamina sheath to reinnervate synaptic targets. To promote migration, growth cones secrete proteases that are thought to dissolve cell-cell and cell-matrix adhesions. These proteases include the plasminogen activators (PAs), tissue PA (tPA) and urokinase PA (uPA), and their substrate, plasminogen. PA expression and secretion are upregulated in regenerating mammalian sensory neurons in culture. After sciatic nerve crush in mice, there was an induction of PA mRNAs in the sensory neurons contributing to the crushed nerve and an upregulation of PA-dependent activity in crushed nerve compared with sham counterparts during nerve regeneration. To further assess the role of the PA system during peripheral nerve regeneration, PA-dependent activity as well as recovery of sensory and motor function in the injured hindlimb were assessed in wild-type, tPA, uPA, and plasminogen knock-out mice. Protease activity visualized by gel zymography showed that after nerve crush, the upregulation of PA activity in the tPA and uPA knock-out mice was delayed compared with wild-type mice. Recovery of sensory function was assessed by toe pinch, footpad prick, and the toe-spreading reflex. All knock-out mice demonstrated a significant delay in hindlimb response to these sensory stimuli compared with wild-type mice. For each modality tested, the uPA knock-out mice were the most dramatically affected, showing the longest delay to initiate a response. These studies clearly showed that PAs were necessary for timely functional recovery by regenerating peripheral nerves.

Region-specific bone mass changes in rat mandibular condyle following ovariectomy.

The effects of estrogen deficiency on the mandible have been indicated; however, there have been only a few reports on the mandibular condyle. To clarify the region-specific changes of condyles following estrogen deficiency, we histomorphometrically studied the anterior and posterior regions of condyles in sham-operated (Sham) and ovariectomized (Ovx) female Fischer rats, since it has been reported that rat occlusal force loads mainly onto the anterior part of the condyle. The anterior and posterior regions of condyles showed significantly different bone dynamics. The bone volume in the anterior region of the Sham group increased to 79.9% with aging, but that of the posterior region remained at ca. 60%. In the Ovx group, the bone volume of the posterior region significantly declined to 42.7% until 60 days post-ovariectomy, although no changes occurred in the anterior region. As compared with the Sham counterparts, both regions of the Ovx group showed high bone turnover and revealed significantly low bone volume at 60 days (p < 0.01). Regional differences between anterior and posterior regions were more emphasized in the Ovx than in the Sham group. The osteoclast number and amount of eroded surface in the Ovx were higher in the posterior than in the anterior region, with significance at 30 and/or 60 days (p < 0.05). The mineralized surface at 14 days and the bone formation rate at 60 days in the Ovx posterior region were significantly lower than those in the Ovx anterior region (p < 0.05). Consequently, a net bone loss occurred in the posterior region of the mandibular condyle in ovariectomized rats, owing to region specificity and estrogen deficiency.

Influence of male gonadal hormones on the parasitemia and humoral response of male Calomys callosus infected with the Y strain of Trypanosoma cruzi.

Effects of orchiectomy on male Calomys callosus infected with the Y strain of Trypanosoma cruzi were studied. Male C. callosus of the same age and weight were divided into three groups: intact, sham operated, and castrated. After 1 month they were inoculated (i.p.) with 4000 blood trypomastigotes. Parasitemia was lower in orchiectomized animals than in the intact and sham groups. Hormone replacement with decanoate testosterone raised the parasitemia of castrated animals to levels similar to those of their intact and sham counterparts. Antibody levels were monitored by complement-mediated lysis. The trypomastigote lysis percentage varied through the course of infection, according to hormonal status and number of parasites during the acute phase. The most significant differences were found on the 30th day after infection, when lytic antibodies of intact males were high compared to the orchiectomized and sham groups. Higher resistance with lower lysis indexes were observed after orchiectomy, compared to intact and sham males.

Akt1 kinase and dynamics of insulin resistance in denervated muscles in vivo

Basal and insulin-stimulated activity of Akt1 kinase and uptake of 2-deoxy-D-glucose (2-DG) were measured in soleus (slow-twitch) and plantaris (fast-twitch) muscles of rats at 1 and 3 days after sectioning the sciatic nerve in one hindlimb of the animals. At 1 day after surgery, the insulin-stimulated activity of Akt1 kinase in denervated soleus and plantaris muscles remained unchanged, but the insulin-stimulated 2-DG uptake by these muscles was reduced by 71 and 61%, respectively, compared with the corresponding muscles of the contralateral sham (control) hindlimb. At 3 days, the insulin-stimulated activity of Akt1 kinase in the denervated soleus and plantaris muscles was 86 and 71% lower, respectively, than in their sham counterparts. At this time point, the denervated soleus muscles showed no increase in 2-DG uptake in response to insulin. In contrast, the denervated plantaris muscle exhibited the same absolute level of insulin-stimulated 2-DG uptake as the sham plantaris muscle; however, the insulin-induced increment in 2-DG uptake was reduced by 60%, whereas basal 2-DG uptake was increased by 251% compared with the sham plantaris muscle. None of the denervated muscles showed a decrease in the abundance of Akt1 kinase. The results demonstrate that the causes of insulin resistance in denervated muscles are dependent on time after surgery. Initially, they involve only mechanisms downstream of Akt1 kinase (day 1), whereas at day 3 they also involve mechanisms upstream of, and including, Akt1 kinase.