Female cats, but not males, adjust responsiveness to arousal in the voice of kittens.

BACKGROUND: The infant cry is the most important communicative tool to elicit adaptive parental behaviour. Sex-specific adaptation, linked to parental investment, may have evolutionary shaped the responsiveness to changes in the voice of the infant cries. The emotional content of infant cries may trigger distinctive responsiveness either based on their general arousing properties, being part of a general affect encoding rule, or based on affective perception, linked to parental investment, differing between species. To address this question, we performed playback experiments using infant isolation calls in a species without paternal care, the domestic cat. We used kitten calls recorded in isolation contexts inducing either Low arousal (i.e., isolation only) or High arousal (i.e., additional handling), leading to respective differences in escape response of the kittens. We predicted that only females respond differently to playbacks of Low versus High arousal kitten isolation calls, based on sex-differences in parental investment. RESULTS: Findings showed sex-specific responsiveness of adult cats listening to kitten isolation calls of different arousal conditions, with only females responding faster towards calls of the High versus the Low arousal condition. Breeding experience of females did not affect the result. Furthermore, female responsiveness correlated with acoustic parameters related to spectral characteristics of the fundamental frequency (F0): Females responded faster to kitten calls with lower F0 at call onset, lower minimum F0 and a steeper slope of the F0. CONCLUSIONS: Our study revealed sex-specific differences in the responsiveness to kitten isolation calls of different arousal conditions independent of female breeding experience. The findings indicated that features of F0 are important to convey the arousal state of an infant. Taken together, the results suggest that differences in parental investment evolutionary shaped responsiveness (auditory sensitivity/ motivation) to infant calls in a sex-specific manner in the domestic cat.

Vocal correlates of sender-identity and arousal in the isolation calls of domestic kitten (Felis silvestris catus).

INTRODUCTION: Human speech does not only communicate linguistic information but also paralinguistic features, e.g. information about the identity and the arousal state of the sender. Comparable morphological and physiological constraints on vocal production in mammals suggest the existence of commonalities encoding sender-identity and the arousal state of a sender across mammals. To explore this hypothesis and to investigate whether specific acoustic parameters encode for sender-identity while others encode for arousal, we studied infants of the domestic cat (Felis silvestris catus). Kittens are an excellent model for analysing vocal correlates of sender-identity and arousal. They strongly depend on the care of their mother. Thus, the acoustical conveyance of sender-identity and arousal may be important for their survival. RESULTS: We recorded calls of 18 kittens in an experimentally-induced separation paradigm, where kittens were spatially separated from their mother and siblings. In the Low arousal condition, infants were just separated without any manipulation. In the High arousal condition infants were handled by the experimenter. Multi-parametric sound analyses revealed that kitten isolation calls are individually distinct and differ between the Low and High arousal conditions. Our results suggested that source- and filter-related parameters are important for encoding sender-identity, whereas time-, source- and tonality-related parameters are important for encoding arousal. CONCLUSION: Comparable findings in other mammalian lineages provide evidence for commonalities in non-verbal cues encoding sender-identity and arousal across mammals comparable to paralinguistic cues in humans. This favours the establishment of general concepts for voice recognition and emotions in humans and animals.

The Mongolian gerbil as a model for inflammatory bowel disease.

Mongolian gerbils are used as biomedical research models for a variety of diseases and are in some cases suited better than other rodents for basic research and therapeutic studies. The aim of this study was to establish and characterize a dextran sulphate sodium (DSS)-induced model in gerbils for the human inflammatory bowel disease (IBD) and to utilize them for a therapeutic study in vivo. Four concentrations (0.5%, 1%, 2% and 4%) of DSS were administered via drinking water for 7 days; based on these results, a concentration of 3% DSS was given for 9 days in a second approach. Fluid uptake and general clinical condition were assessed daily using a clinical score. Caecum and colon were scored histologically. Fluid uptake was affected by addition of DSS to the drinking water. First clinical symptoms were observed at day 4 of DSS treatment with a considerable increase in clinical score parameters only in gerbils receiving 2% or 4% DSS. Histologically, ulceration and inflammation were observed predominantly in the caecum of gerbils treated with at least 1% DSS; reproducible inflammation in the colon required at least 2% DSS. Using 3% DSS for 9 days, considerably more inflammation was induced in the colon, comparable with lesions usually observed in the mouse model. Using an optimized protocol, DSS treatment induces reproducibly typhlocolitis in Mongolian gerbils, rendering them as a useful model for IBD.

The head turn paradigm to assess auditory laterality in cats: influence of ear position and repeated sound presentation.

In most humans, speech is predominantly processed by the left hemisphere. This auditory laterality was formerly thought to be an exclusive human characteristic, but is now suggested to have pre-human origins. In studies on auditory laterality in nonhuman animals, the head turn paradigm has become very popular due to its non-invasive character. Although there are implications that the head turn direction indicates functional dominance of the contralateral hemisphere in processing a given sound, the validity of the paradigm is under debate. To validate the paradigm via comparison with imaging or electrophysiological methods, it is first necessary to establish turning biases at the individual level. Recently, the domestic cat, a common model in hearing research, has been found to show turning biases at the group level. To assess individual turning asymmetries in cats, we repeatedly presented kitten isolation calls and assessed whether differences in conveyed arousal changed the previously described left-wards lateralisation of conspecific vocalizations. Based on responses to 50 playback presentations (25 of high and 25 of low arousal), we calculated individual head turn indices. Based on the total data set, we found no consistent individual turning bias, irrespective of call category or sex of the receiver. Although the playback paradigm was chosen carefully to reduce any effects of lateralized loudness perception or changes in motivation due to habituation, individual head turn biases changed significantly in concordance with habituation to repeated playback-presentations and was predictable by small deflections in ear position prior to listening. When splitting the data set according to a decline in responsiveness after seven playback presentations, we revealed an initial left turning bias for most of our subjects (i.e., significant at the group level). We propose that this left turning bias is related to right hemisphere dominance in processes like vigilance behaviour or general arousal rather than on auditory processing, as such. Our findings suggest that both the experimental sequence and sound level differences, induced by asymmetric ear positions, strongly influence the outcome of the head turn paradigm and should be taken into account when evaluating auditory laterality at the behavioural level.

The complement anaphylatoxin C3a receptor (C3aR) contributes to the inflammatory response in dextran sulfate sodium (DSS)-induced colitis in mice.

Inflammatory bowel diseases are a critical public health issue, and as treatment options remain limited, there is a need to unravel the underlying pathomechanisms in order to identify new therapeutic targets. Complement activation was found in patients suffering from inflammatory bowel disease, and the complement anaphylatoxin C5a and its receptor C5aR have been implicated in disease pathogenesis in animal models of bowel inflammation. To further characterize complement-related pathomechanisms in inflammatory bowel disease, we have investigated the role of the anaphylatoxin C3a receptor in acute dextran sulfate sodium-induced colitis in mice. For this, colitis was induced in C3a receptor-deficient BALB/c and C57BL/6 mice, and disease severity was evaluated by clinical and histological examination, and by measuring the mRNA expression or protein levels of inflammatory mediators in the tissue. C3a receptor deficiency was partially protective in BALB/c mice, which had significantly reduced weight loss, clinical and histological scores, colon shortening, and CXCL-1/KC mRNA, myeloperoxidase and interleukin-6 tissue levels compared to the corresponding wild type mice. In C57BL/6 mice the differences between wild type and C3a receptor-deficient animals were much smaller and reached no significance. Our data demonstrate that the contribution of C3a receptor to disease pathogenesis and severity of dextran sulfate sodium-induced colitis in mice depends on the genetic background. Further studies will be required to clarify whether targeting of C3a receptor, possibly in combination with C5a receptor, might be considered as a therapeutic strategy for inflammatory bowel disease.

Paw preference is not affected by postural demand in a nonprimate mammal (Felis silvestris catus).

Previously, it has been thought that handedness is unique to humans. Recently, it has been found that hand or paw preferences are common among a variety of vertebrate species. Different models have been put forth to describe the evolution of primate handedness. In this study we aimed to explore whether these models can also be used to predict manual laterality in nonprimate mammalian groups. The cat (Felis silvestris catus) is a good nonprimate model for manual laterality, as cats frequently use paws to catch and hold prey. Cats were exposed to two standardized manual laterality tasks, differing in postural demand. Subjects (N = 28) were forced to use either a stable or unstable body posture (i.e., sitting or standing vs. vertical clinging) to extract food items from a plastic box attached at two different heights. We revealed that cats exhibited paw preferences at an individual level with about 40% left, 30% right, 30% nonlateralized subjects. Postural demand was linked to task difficulty: the unstable body posture was found to be significantly more difficult than the stable body posture. However, these differences in postural demand and task difficulty did not lead to differences in direction or strength of paw preference. Findings suggested that nonprimate mammals differ from primates in their sensitivity to task related factors, such as postural demand. Results coincide with those of some prosimians, providing support for the hypothesis that postural demand and the associated task complexity became influencing factors on manual laterality in the course of primate evolution.

Hygienic monitoring of Mongolian gerbils: which mouse viruses should be included?

The Mongolian gerbil (Meriones unguiculatus) serves as an animal model for a wide range of diseases. A practical limitation in its use is the definition of the hygienic status, as not much is known about viruses that potentially infect gerbils and might be transmitted to other rodents. As successful re-derivation was recently described for gerbils, we now aimed at investigating which mouse viruses induce seroconversion in gerbils and might be transmitted to mice. Gerbils were inoculated with viral agents of mice and co-housed with mouse contact sentinels. Seroconversion in gerbils was observed after oronasal inoculation with Sendai virus (SeV), mammalian orthoreovirus serotype 3 (Reo-3) and rotavirus A (RV-A, EDIM), seroconversion to RV-A also in sentinel mice. Pneumonia virus of mice (PVM) was not detected by serology but by polymerase chain reaction in gerbils and respective sentinel mice. No seroconversion towards or transmission of murine hepatitis virus, murine norovirus, minute virus of mice or mouse cytomegalovirus was detected. Anti-gerbil IgG antibodies did not increase sensitivity of indirect immunofluorescence (IFA) compared with anti-mouse IgG. In conclusion, seroconversion to SeV, Reo-3 and RV-A as well as transmission of RV-A and PVM indicate that these agents should be included in health monitoring of gerbils. Furthermore, anti-mouse IgG is suitable as a secondary antibody for IFA with gerbil serum.