Autophagy is an important cellular process in maintenance of protein homeostasis. Emerging evidence indicates differential roles of autophagy in cellular function under different pathophysiologic conditions. In some circumstance, autophagy results in cell survival, wheras in other situations it results in cell death. Endotoxin affects neurons in the nucleus tractus solitarii (NTS), baroreceptor afferent terminal site in the brain stem, resulting in cardiovascular depression. The aim of this study was to examine whether modulation of autophagic activity in NTS and other brain regions subserving cardiovascular regulation are associated with cardiovascular depression during experimental endotoxemia. Adult male Sprague-Dawley rats received continuously intraperitoneal infusion via osmotic minipump of lipopolysaccharide (LPS, 2.5 mg/kg/day) or normal saline (NS). Body weight (BW) and systolic blood pressure (SBP) were recorded in animals on days 1, 2, 3, 5, 7, 10, and 14 after LPS treatment. Western bolotting was used to assess the expression of autophagic activity marker, microtubule-associated protein 1 light chain 3 (LC3). Rapamycin (0.55 mg/Kg/day), chemical reported to activate autophagy, was infused continuously into the lateral ventricle of the endotoxemic rats for 7 days via osmotic minipump. Both BW and SBP of rats were decreased in the initial 5 days, followed by a gradual return to baseline after LPS treatment. There was a trend in the decrease in autophagic activity (using the ratio of LC3-¢º/LC3-I as an experimental index) at NTS. However, there is no apparent association between the change in autophagic activity at NTS and the LPS-induced cardiovascular depression. In addition, there was no obvious change in the autophagic activity at RVLM, hypothalamus and hippocampus. Intracranial infusion of rapamycin, a mTOR inhibitor that maintains cellular autophagic activity, resulted in a further enhancement of cardiovascular depression induced by LPS. These results suggest that continuously intraperitoneal infusion via osmotic minipump of LPS result in decreases of body weight and systolic blood pressure. However, the present study provides no direct evidence to support for a cause-and-effect role of autophage at NTS, RVLM, hypothalamus as well as hippocampus in the LPS-induced cardiovascular depression during experimental endotoxemia.

Dysfunction of Mitochondrial Respiratory Chain in Rostral Ventrolateral Medulla During Experimental Endotoxemia Sepsis is a complex pathophysiologic state resulting from an exaggerated whole-body inflammatory response to infection or injury. Metabolic disturbances, abnormal regulation of blood flow and diminished utilization of oxygen at the cellular level may account for tissue damage and lead to multiple organ failure and death. As the primary site of cellular energy generation is the mitochondrion, it presents itself as an important target for the septic cascade. In this regard, the notion that bioenergetic failure due to mitochondrial dysfunction contributes to organ failure during sepsis has received attention. We established the low frequency fluctuations in the systemic arterial pressure signals are related to the sympathetic neurogenic vasomotor tone, and reflect the functional integrity of the brain stem. Their origin is subsequently traced to the premotor sympathetic neurons at the rostral ventrolateral medulla (RVLM), whose neuronal activity is intimately related to the ¡§life-and-death¡¨ process. Based on a rat model of experimental endotoxemia that provides continuous information on changes in neuronal activity in the RVLM, the present study was undertaken to evaluate whether changes in mitochondrial respiratory functions are associated with death arising from sepsis. We also evaluated the efficacy of a new water-soluble coenzyme Q10 (CoQ10, ubiquinone) formula in the protection against fatality during endotoxemia by microinjection into bilateral RVLM. Dysfunction of Mitochondrial Respiratory Chain in Rostral Ventrolateral Medulla During Experimental Endotoxemia in the Rat We investigated the functional changes in mitochondrial respiratory chain at the RVLM in an experimental model of endotoxemia that mimics systemic inflammatory response syndrome. Experiments were carried out in adult male Sprague-Dawley rats that were maintained under propofol anesthesia. Intravenous administration of E. coli lipopolysaccharide (LPS; 30 mg/kg) induced progressive hypotension, with death ensued within 4 hours. The sequence of cardiovascular events during this LPS-induced endotoxemia can be divided into a reduction (Phase I), followed by an augmentation (Phase II; ¡§pro-life¡¨ phase) and a secondary decrease (Phase III; ¡§pro-death¡¨ phase) in the power density of the vasomotor components (0-0.8 Hz) of systemic arterial pressure (SAP) signals. Enzyme assay revealed significant decrease of the activity of NADH cytochrome c reductase (Complex I+III) and cytochrome c oxidase (Complex IV) in the RVLM during all 3 phases of endotoxemia. On the other hand, the activity of succinate cytochrome c reductase (Complex II+III) remained unaltered. Neuroprotective Effects of Coenzyme Q10 at Rostral ventrolateral Medulla Against Fatality During Experimental Endotoxemia in the Rat CoQ10 is a highly mobile electron carrier in the mitochondrial respiratory chain that also acts as an antioxidant. We evaluated the neuroprotective efficacy of CoQ10 against fatality in an experimental model of endotoxemia, using a novel water-soluble formulation of this quinone derivative. In Sprague-Dawley rats maintained under propofol anesthesia, intravenous administration of E. coli LPS (30 mg/kg) induced experimental endotoxemia. Pretreatment by microinjection bilaterally of CoQ10 (1 or 2 mg) into RVLM significantly diminished mortality, prolonged survival time, and reduced the slope or magnitude of the LPS-induced hypotension. CoQ10 pretreatment also significantly prolonged the duration of Phase II endotoxemia and augmented the total power density of the vasomotor components of SAP signals in Phase II endotoxemia. The increase in superoxide anion production induced by LPS at the RVLM during Phases II and III endotoxemia was also significantly blunted. Conclusion The present study revealed that selective dysfunction of respiratory enzyme Complexes I and IV in the mitochondrial respiratory chain at the RVLM is closely associated with fatal endotoxemia. CoQ10 provides neuroprotection against fatality during endotoxemia by acting on the RVLM. We further found that a reduction in superoxide anion produced during endotoxemia at the RVLM may be one of the mechanisms that underlie the elicited neuroprotection of CoQ10. These findings therefore open a new direction for future development of therapeutic strategy in this critical, complicated and highly fatal condition known as sepsis.

Background: Prior studies show that sickness induces anxiety as rated by subjective reports but have not linked this to overt behavior in humans. This study investigates the expression of distress during experimental sickness, its relation to self-reported anxiety, and the moderating role of gender in the association between overt distress and self-rated anxiety. Methods: 21 participants (18-34 yrs, 10 women) were semi-randomly chosen from a placebo-controlled, double-blind, within-subject experiment, in which participants were intravenously injected with a bacterial endotoxin lipopolysaccharide (LPS, 0.8 ng/kg body weight) triggering a transient inflammatory reaction and an acute state of sickness. In the current study, we coded the participants’ expression of moans, sighs and deep breaths (overt distress) during sickness from the video recordings of the experiment and analyzed these parameters in relation to the state part of the State Trait Anxiety Inventory (Spielberger et al., 1979) that was collected during the experiment. Results: The frequency of overt distress increased strongly during experimental sickness (1-3h post-injection of LPS) compared to baseline. The level of overt distress was not related to subjective feelings of anxiety. No clear difference was found between men and women in the frequency of expressed distress during sickness. Interestingly however, there was an inverted relation between anxiety and the expression of distress in women, so that women who reported higher anxiety expressed less distress overtly (ß = -0.52, p = 0.018). Conclusions: Experimental sickness strongly induces an increase of moans, sighs and deep breaths, but these are not directly associated with the level of state anxiety reported. The results also suggest that moans, sighs and deep breaths might have a different function in men and women.