Cold arousal - A mechanism used by hibernating bats to reduce the energetic costs of disturbance.

During the season of hibernation, temperate bats alternate between prolonged bouts of torpor with reduced body temperature and short arousals with a return to normothermy. Hibernating bats are sensitive to non-tactile stimuli and arouse following changes in microclimatic conditions or disturbance from other bats, potential predators, or humans. Here, we used temperature data loggers to register the skin temperature of 38 Myotis myotis bats over two winters (between January and March), during which regular visits were made to the hibernaculum. Two kinds of arousal were observed, normothermic (Tsk > 25 °C) and cold (Tsk < 15 °C). Although bats responded to the presence of a researcher by arousals of both kinds, cold arousals were more frequent (63.8%). We found that mass loss was not affected by the number of disturbances, however it was in positive relationship with the mass at the beginning of the observation and differed between sex and age categories. Furthermore normothermic bats crawling among cluster-mates initiated arousal cascades, which mainly consisted of cold arousals. We failed to detect any effect of age or sex on the number of arousals initiated by normothermic individuals. Warming by only a few degrees requires less energy than a normothermic arousal and we propose it is sufficient to activate the sensory system in order to assess the relevance of external stimuli. Our results indicate that cold arousals reflect a physiological and behavioural adaptation aimed at avoiding the energetic costs of disturbance that can lead to depletion of fat reserves.

Asoxime (HI-6) impact on dogs after one and tenfold therapeutic doses: assessment of adverse effects, distribution, and oxidative stress.

Asoxime (HI-6) is a well known oxime reactivator used for counteracting intoxication by nerve agents. It is able to reactivate acetylcholinesterase (AChE) inhibited even by sarin or soman. The present experiment was aimed to determine markers of oxidative stress represented by thiobarbituric acid reactive substances and antioxidants represented by ferric reducing antioxidant power, reduced and oxidized glutathione in a Beagle dog model. Two groups of dogs were intramuscularly exposed to single (11.4 mg/kg.b.wt.) or tenfold (114 mg/kg.b.wt.) human therapeutically doses of HI-6. HI-6 affinity for AChE in vitro was evaluated in a separate experiment. Complete serum biochemistry and pharmacokinetics were also performed with significant alteration in blood urea nitrogen, creatine phosphokinase, glucose and triglycerides. Blood samples were collected before HI-6 application and after 30, 60, and 120 min. The overall HI-6 impact on organism is discussed.

Assessment of low-molecular-weight antioxidants in Francisella tularensis infected hosts: comparison of two rodents with different susceptibility to tularemia.

OBJECTIVES: Bacterium Francisella tularensis is the causative agent of tularemia disease. It is a zoonosis accompanied with high mortality when untreated. Small rodents and hares, in particular, are natural reservoirs of tularemia. Despite physiological similarity of common hosts, tularemia exerts different mortality rates. The pathogenesis of tularemia is still not fully understood. The main pathway is associated with proliferation in macrophages after activation by reactive oxygen species in phagosomes. DESIGN: A fully virulent strain of F. tularensis subsb. holarctica was used for infection of laboratory BALB/c mice (Mus musculus) and common voles (Microtus arvalis) representing murine and microtine species. The total level of low-molecular- weight antioxidants (LMWA) in plasma was assayed by cyclic voltammetry. RESULTS: It was found that common voles are more resistant to tularemia progression when compared to mice. When LMWA assayed, surprising changes in LMWA levels were found. Both mice and common voles were infected with high dose resulting in overall mortality. While there was a quick depletion of LMWA in plasma in mice, common voles were even able to increase LMWA. CONCLUSION: It seems that LMWA play an important role in the organism s protection during tularemia. The ability to compensate the LMWA losses and increase levels of antioxidants in common voles is probably responsible for its lower susceptibility to tularemia.