A New Tool to Study Parkinsonism in the Context of Aging: MPTP Intoxication in a Natural Model of Multimorbidity

The diurnal rodent Octodon degus (O. degus) is considered an attractive natural model for Alzheimer’s disease and other human age-related features. However, it has not been explored so far if the O. degus could be used as a model to study Parkinson’s disease. To test this idea, 10 adult male O. degus were divided into control group and MPTP-intoxicated animals. Motor condition and cognition were examined. Dopaminergic degeneration was studied in the ventral mesencephalon and in the striatum. Neuroinflammation was also evaluated in the ventral mesencephalon, in the striatum and in the dorsal hippocampus. MPTP animals showed significant alterations in motor activity and in visuospatial memory. Postmortem analysis revealed a significant decrease in the number of dopaminergic neurons in the ventral mesencephalon of MPTP animals, although no differences were found in their striatal terminals. We observed a significant increase in neuroinflammatory responses in the mesencephalon, in the striatum and in the hippocampus of MPTP-intoxicated animals. Additionally, changes in the subcellular expression of the calcium-binding protein S100β were found in the astrocytes in the nigrostriatal pathway. These findings prove for the first time that O. degus are sensitive to MPTP intoxication and, therefore, is a suitable model for experimental Parkinsonism in the context of aging.     

Infant-mother recognition in a social rodent (octodon degus).

Octodon degus (degu), a biparental species with precocious offspring is a potential model for the study of social attachment and related affective disorders such as depression. This study investigates the nature of the social bond between young degus and their mothers with a special emphasis on infant-mother recognition. We tested young degus in a potentiation paradigm to determine if social contact, particularly with the mother, can modulate an infant's vocal response to isolation. One week later, animals were presented with a choice between their mother and an unfamiliar female or a sample of familiar and unfamiliar nesting materials. Subsequently, the ability of whole litters to discriminate between their mother and unfamiliar females was tested. We observed that infant degus alter their isolation response after brief social contact. Degu infants readily distinguish between familiar and unfamiliar nesting materials but fail to differentiate between their mother and unfamiliar females in an identical setting. Nevertheless, entire litters show a preference for their mothers when tested similarly in a group, demonstrating a perhaps socially facilitated ability to recognize the biological mother at an early age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)