Bodyweight, locomotion, and behavioral responses of the naked mole rat (Heterocephalus glaber) to lipopolysaccharide administration.

The naked mole rat has unique biologic characteristics that include atypical inflammatory responses. Lipopolysaccharide induces inflammation which triggers brain centers controlling feeding, and behavior to result in "sick animal behavior". We characterized the bodyweight, locomotor, and other behavioral responses of this rodent to lipopolysaccharide administration. Lipopolysaccharide caused weight losses, which were not prevented by TAK 242. In the open field test, lipopolysaccharide did not depress locomotion, while urination, defecation, and activity freezing were rare. The animals exhibited walling but not rearing and fast backward movements that were unaffected by lipopolysaccharide. Failure to depress locomotion suggests either a unique immunity-brain crosstalk or motor responses/centers that tolerate depressive effects of inflammation. The absence of activity freezing and rarity of urination and defecation suggests that novel environments or lipopolysaccharide do not induce anxiety, or that anxiety is expressed differently in the animal. The absence of rearing could be due to the design of the animal's locomotor apparatus while fast backward movement could be a mechanism for quick escape from threats in the tunnels of their habitat. Our results elucidate the unique biology of this rodent, which elicits interest in the animal as a model for inflammatory research, although the findings require mechanistic corroborations.

Imiquimod does not elicit inflammatory responses in the skin of the naked mole rat (Heterocephalus glaber).

OBJECTIVE: Naked mole rat (Heterocephalus glaber) has recently attracted interest in biomedical research due to its exceptional longevity, cancer resistance and tolerance to potentially harmful conditions or stimuli. Given its unique attributes, this study was designed to characterize inflammatory skin reactions of this animal to topical application of imiquimod, a toll-like receptor 7 and 8 agonist that triggers psoriasis-like skin reaction. RESULTS: Imiquimod did not cause the expected psoriasis-like skin changes. There was no epidermal thickening and a straight epidermo-dermal boundary was maintained. There was no parakeratosis and the granular layer of epidermis was well formed. In the dermis, there was no leukocyte infiltration. This points to an exceptional nature of inflammatory/immune responses of this animal, but the mechanism could not be explained by our results. Naked mole rat could be a valuable negative model for studying psoriasis and other inflammatory skin conditions but as a prerequisite, there is need for further investigations to establish the mechanisms behind its lack of response to imiquimod.

A gross morphometric study of olfactory brain components in the rufous sengi ( Elephantulus rufescens ) / Estudio morfométrico de los componentes olfativo del cerebro en el rufo sengi ( Elephantulus rufescens )

The gross morphometric features of mammalian olfactory system components show variations that may be attributed to dietary and ecological factors. We analyzed volumes and linear dimensions of olfactory brain components (OBC) namely, olfactory bulb (OB), olfactory tract (OT) and olfactory stria (OS) in an Afrotherian insectivore, the rufous sengi. These findings were then compared with those obtained previously in dogs (carnivore), goats (herbivore) and humans (omnivore). Volumes, lengths and breadths of the OBC were compared with those of the cerebral hemisphere (CH) and the whole brain (WB) by working out their ratios (%). In the sengi, the volume of OBC: WB was 1.03 %, length of OBC: CH = 58.08 % and breadth of OB: CH = 28.97 %. In an earlier report by Kavoi & Jameela respective values for the above parameters were 0.03 %, 21.47 % & 8.94 % in humans, 0.77 %, 51.87 % & 29.73 % in goats and 1.95 %, 72.30 % & 42.91 % in dogs. These observations suggest that the anatomical design of OBC happens in a manner that mimics an animal's level of reliance on the sense of smell vis-à-vis feeding lifestyles, habitat and dynamics of evolution.

Las características morfométricas de los componentes del sistema olfativo de los mamíferos muestran variaciones que pueden atribuirse a factores dietéticos y ecológicos. Analizamos los volúmenes y las dimensiones lineales de los componentes cerebrales olfativos (CCO), es decir, la médula oblonga (MO), el tracto olfatorio (TO) y la estría olfatoria (SO) en un insectívoro de Afrotherian, el sengi rufo. Estos hallazgos fueron comparados con los obtenidos previamente en perros (carnívoros), cabras (herbívoros) y humanos (omnívoros). Los volúmenes, longitudes y anchuras de los CCO se compararon con los del hemisferio cerebral (HC) y el cerebro completo (CC) mediante el cálculo de sus proporciones (%). En el sengi, el volumen de los CCO: CC fue de 1,03 %, la longitud de CCO: HC = 58,08 % y la amplitud de MO: HC = 28,97 %. En un informe anterior de Kavoi & Jameela, los valores respectivos para los parámetros anteriores fueron 0,03 %, 21,47 % y 8,94 % en humanos, 0,77 %, 51,87 % y 29,73 % en cabras y 1,95 %, 72,30 % y 42,91 % en perros. Estas observaciones sugieren que el diseño anatómico de la CCO se realiza de una manera que imita el nivel de confianza de un animal en el sentido del olfato en relación con los estilos de vida, el hábitat y la dinámica de la evolución.

A case of cranium bifidum with meningocele in Ayrshire calf.

BACKGROUND: Congenital cranial bone defects predispose to herniation of meninges, sometimes with brain tissue involvement, to form a cerebrospinal fluid (CSF)-filled cyst in the head. Such defects mainly results from focal failure of neural tube closure during fetal development and has been reported in various species of domestic mammals. CASE PRESENTATION: A one week old Ayrshire calf with a fluctuant swelling on parieto-occipital region of the head was referred to the faculty. The calf was always lying on lateral recumbency and exhibited resistance to deep palpation around the swelling and neck flexion. Embedded to the midline of the dorso-caudal surface of the cyst's wall was a hard longitudinally oriented structure. The case was diagnosed as meningocele by means of radiographic examination. As the likelihood to full recovery was greatly reduced due to the negative impact already meted on brain tissue by intracranial pressure, the calf was euthanized on grounds of animal welfare and the diagnosis confirmed by anatomopathological findings which also revealed a circular bone defect in parieto-occipital region of the skull vault and a flattened bony structure embedded to the cyst's wall. CONCLUSION: Anatomopathological findings confirmed the diagnosis as cranial bifidum with meningocele at the parieto-occipital region of the skull vault. The presence of a bony structure embedded to the wall of meningeal sac was rather unusual and could not be sufficiently explained. It was however thought to, most likely, represent a part of interparietal bone that failed to get incorporated into squamous part of occipital bone as a result of the defect. The report also highlights challenges that work against timely delivery of urgent veterinary interventions in rural set ups of Africa and rest of the developing world, often leaving veterinarians with animal welfare consideration as main determinant of intervention measures.