Abstract: This paper demonstrates that the rhesus monkey provides an excellent model to study mechanisms underlying human anxiety and fear and emotion regulation. In previous studies with rhesus monkeys, stable, brain, endocrine, and behavioral characteristics related to individual differences in anxiety were found. It was suggested that, when extreme, these features characterize an anxious endophenotype and that these findings in the monkey are particularly relevant to understanding adaptive and maladaptive anxiety responses in humans. The monkey model is also relevant to understanding the development of human psychopathology. For example, children with extremely inhibited temperament are at increased risk to develop anxiety disorders, and these children have behavioral and biological alterations that are similar to those described in the monkey anxious endophenotype. It is likely that different aspects of the anxious endophenotype are mediated by the interactions of limbic, brain stem, and cortical regions. To understand the brain mechanisms underlying adaptive anxiety responses and their physiological concomitants, a series of studies in monkeys lesioning components of the neural circuitry (amygdala, central nucleus of the amygdala and orbitofrontal cortex) hypothesized to play a role are currently being performed. Initial findings suggest that the central nucleus of the amygdala modulates the expression of behavioral inhibition, a key feature of the endophenotype. In preliminary FDG positron emission tomography (PET) studies, functional linkages were established between the amygdala and prefrontal cortical regions that are associated with the activation of anxiety.

Abstract: Conservation of endangered species in zoos and other protected areas has saved several species from extinction. The Przewalski horse (Equus ferus przewalskii) is one of that species and, being an attractive large ungulate, it is a “flagship species” for conservation projects. Reintroduction into its former habitat is accompanied by many difficulties and is a great challenge. Semireserves have been defined as enclosures large enough to maintain groups of Przewalski horses throughout all seasons of the year without any supplemental provisioning. The animals are kept isolated from external human influences as far as possible, except for necessary interventions such as veterinary care. Hence, the purpose is not limited to preparing animals for survival under natural conditions, but is equally related to the need to gain experience in establishment of free-ranging populations. Naturally, horses live in groups in which all individuals are long-term acquainted with each other and a stable hierarchical system is established. In conservation management an integration of horses into strange groups is often need but at the same time implies social fights, stress and risks for the animals. We investigated the integration process of 4 Przewalski horses from Zoo Leipzig into the herd of 5 Przewalski horses in the semireserve Liebenthal (Brandenburg, Germany). Before transportation the social structure was determined in both the herd in Zoo Leipzig and in Liebenthal. After transportation the social hierarchy and the individual dominance indices were determined by daily observation. Continuous records of activity and feeding were taken from several individuals using the ETHOSYS-storage telemetry system. The automatically recorded behaviours were analysed for daily and ultradian rhythms and used for stress detection by calculating a value (DFC) representative for regularity and stability of rhythmic structures. In zoo conditions, the behaviour was very regular and the daily pattern nearly identical from day to day as expressed by DFC´s near of 100%. After transportation, the behaviour became much less regular, DFC´s dropped significantly, recovered slowly and stabilised on values typically for semireserve conditions. Social bindings and dominances of the former two herds were mainly retained. As an important result, long lasting and stepwise transition from zoo to natural habitats with special training using new observing techniques can be strongly recommended.

Abstract: The effects of transporting horses facing either forwards or backwards were compared by transporting six thoroughbred horses in pairs in a lorry on one journey facing in the direction of travel, and on another journey facing away from the direction of travel, over a standard one-hour route. Heart rate monitors were used to record their heart rate before, during and after the journey and the horses' behaviour was recorded by scan sampling each horse every other minute. The average heart rate was significantly lower (P < 0.05) when the horses were transported facing backwards, and they also tended to rest on their rumps more (P = 0.059). In the forward-facing position, the horses moved more frequently (P < 0.05) and tended to hold their necks in a higher than normal position and to vocalise more frequently (P = 0.059). During loading the average peak heart rate was 38 bpm lower (P < 0.05) when the horses were backed into the horse box for rear-facing transport than when they were loaded facing forwards. However, there was no difference between transport facing forwards or backwards in terms of the peak unloading heart rate, or the average heart rate during loading or unloading. The horses seemed to find being transported less physically stressful when they were facing backwards than when they were facing forwards.

Abstract: Most of the experimental observations on facilitated transport have been done with millipore filters, and all the theoretical studies have assumed homogeneous spatial properties. In striated muscle there exist membranes that may impede the diffusion of the carrier myoglobin. In this paper a theoretical study is undertaken to analyze the transport in the presence of membranes in the diffusion path. For the numerical computations physiologically relevant values of the parameters were chosen. The numerical results indicate that the presence of membranes tends to decrease the facilitation. For the nonlinear chemical kinetics of the reaction of oxygen with the carrier, this decrement also depends on the location of the membranes. At the higher oxygen concentration side of each membrane the flow of combined oxygen is transferred to the flow of dissolved oxygen. The reverse process occurs at the lower concentration side. Jump discontinuities of the concentration of the oxygen-carrier compound at each membrane are associated with these transfers. The decrement of facilitation is due to the cumulative effect of these jump discontinuities.

Abstract: Based on plasma cortisol concentrations it is widely accepted that transport is stressful to horses. So far, cortisol release during transport has not been evaluated in depth by non-invasive techniques such as analysis of salivary cortisol and faecal cortisol metabolites. Transport also causes changes in heart rate and heart rate variability (HRV). In this study, salivary cortisol, faecal cortisol metabolites, heart rate and HRV in horses transported by road for short (one and 3.5 h) and medium duration (8 h) were determined. With the onset of transport, salivary cortisol increased immediately but highest concentrations were measured towards the end of transport (4.1 ± 1.6, 4.5 ± 2.6, 6.5 ± 1.8 ng/ml in horses transported for one, 3.5 and 8 h, respectively). Faecal cortisol metabolite concentrations did not change during transport, but 1 day after transport for 3.5 and 8 h had increased significantly (p < 0.01), reflecting intestinal passage time. Compared to salivary cortisol, changes in faecal cortisol metabolites were less pronounced. Heart rate increased and beat-to-beat (RR) interval decreased (p < 0.05) with the onset of transport. Standard deviation of heart rate increased while root mean square of successive RR differences (RMSSD) decreased in horses transported for 3.5 (from 74 ± 5 to 45 ± 6 ms) and 8 h (from 89.7 ± 7 to 59 ± 7 ms), indicating a reduction in vagal tone. In conclusion, transport of horses over short and medium distances leads to increased cortisol release and changes in heart rate and HRV indicative of stress. The degree of these changes is related to the duration of transport. Salivary cortisol is a sensitive parameter to detect transient changes in cortisol release.