Excretion and measurement of corticosterone and testosterone metabolites in bank voles (Myodes glareolus)
The bank vole is a commonly used model species in behavioral and ecophysiological studies. Thus, presenting a validated method for noninvasive monitoring of corticosterone and testosterone secretion is of high relevance. Here, we evaluated the effect of time of day and an ACTH challenge test on measured fecal corticosterone (FCM) and testosterone (FTM) metabolites in both sexes. Furthermore, we performed radiometabolism experiments for both steroids and sexes to study metabolism and excretion of 3H-corticosterone and 3H-testosterone. FCM and FTM were analysed with a 5α-pregnane-3β,11β,21-triol-20-one enzyme immunoassay (EIA) and a testosterone (measuring 17β-hydroxyandrostanes) EIA, respect…
Population sex-ratio affecting behavior and physiology of overwintering bank voles (Myodes glareolus)
Many boreal rodents are territorial during the breeding season but during winter become social and aggregate for more energy efficient thermoregulation. Communal winter nesting and social interactions are considered to play an important role for the winter survival of these species, yet the topic is relatively little explored. Females are suggested to be the initiators of winter aggregations and sometimes reported to survive better than males. This could be due to the higher social tolerance observed in overwintering females than males. Hormonal status could also affect winter behavior and survival. For instance, chronic stress can have a negative effect on survival, whereas high gonadal ho…
Secondhand horror: effects of direct and indirect predator cues on behavior and reproduction of the bank vole
Risk recognition by prey is of paramount importance within the evolutionary arms race between predator and prey. Prey species are able to detect direct predator cues like odors and adjust their behavior appropriately. The question arises whether an indirect predation cue, such as the odor of scared individuals, can be detected by conspecifics and subsequently affects recipient behavior. Parents may also transfer their experience with predators to their offspring. In two experiments, we assessed how direct and indirect predation cues affect bank vole (Myodes glareolus) foraging behavior, reproduction, and pup fitness. Weasel (Mustela nivalis) odor served as the direct cue, whereas the odor o…
Imaging correlates of behavioral impairments: An experimental PET study in the rat pilocarpine epilepsy model
Abstract Psychiatric comorbidities are prevalent in patients with epilepsy and greatly contribute to the overall burden of disease. The availability of reliable biomarkers to diagnose epilepsy-associated comorbidities would allow for effective treatment and improved disease management. Due to their non-invasive nature, molecular imaging techniques such as positron emission tomography (PET) are ideal tools to measure pathologic changes. In the current study we investigated the potential of [18F]fluoro-2-deoxy- d -glucose ([18F]FDG) and 2′-methoxyphenyl-(N-2′-pyridinyl)-p-18F-fluoro-benzamidoethylpiperazine ([18F]MPPF) as imaging correlates of neurobehavioral comorbidities in the pilocarpine …
Changing winter conditions in the boreal forest : the effects of fluctuating temperature and predation risk on activity and physiological stress level in bank voles
Due to global climate change, the winter conditions in the North are predicted to change, as the time with an intact insulating snow cover gets shorter or disappears altogether. For small mammals, this could cause exposure to strong temperature fluctuations and increased predation risk, inducing severe stress and leading to alterations in the physical condition and behavior. To test this, we exposed bank voles (Myodes glareolus) to different temperature regimes and cues of predator threat under laboratory conditions. The test animals experienced either a stable but cool temperature regime resembling the stable conditions under snow cover, or an unstable temperature regime with cold nights a…
Toward evidence-based severity assessment in rat models with repeated seizures: II. Chemical post-status epilepticus model.
Objective: Considering the complexity of neuronal circuits and their epilepsy-associated alterations, epilepsy models cannot be completely replaced by in vitro experimental approaches. Decisions about ethical approval of in vivo studies require a thorough weighing of the animal's burden and the benefit regarding the expected gain in knowledge. Methods: Based on combined behavioral, biochemical, and physiological analyses, we assessed the impact on animal well-being and condition in different phases of the pilocarpine post–status epilepticus (SE) model in rats. Results: As a consequence of SE, increased levels of impairment were evident in the early postinsult phase and late chronic phase, w…
Toward evidence-based severity assessment in rat models with repeated seizures: III. Electrical post-status epilepticus model
Objective Ethical approval of experiments in chronic epilepsy models requires a careful balancing of the expected gain-in-knowledge with the level of distress. Thus recommendations for evidence-based severity assessment and classification are urgently needed for preclinical epilepsy research. Methods Therefore, we have completed a comprehensive analysis of alterations in behavioral, biochemical, and physiological parameters in a rat electrical post-status epilepticus model. Selected parameters were repeatedly analyzed during different experimental phases to obtain information about the level of distress throughout the course of the model. Results Behavioral patterns comprised an increase in…
Toward evidence-based severity assessment in rat models with repeated seizures: I. Electrical kindling
Objective: Rodent epilepsy models can significantly contribute to our understanding of pathophysiological mechanisms and to validation of biomarker and target candidates. Evidence-based severity assessment is a presupposition for the ethical evaluation of animal experimentation allowances as well as for the development of efficacious refinement concepts. Methods: Aiming to improve our understanding of the impact of experimental procedures and repeated seizures, we have completed a comprehensive behavioral and biochemical analysis assessing various parameters that can inform about the influence of an electrical kindling paradigm on well-being in rats. Thereby, we have focused on the immediat…