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Título

Why Sloths are so Sloth? Is the Bradypus a physiological parkinsonian animal model?

Resumo

INTRODUCTION: There is no natural animal model for Parkinson's disease, only experimental animal models that do not help in understanding the pathophysiology and natural evolution of the disease. The Bradypus Variegatus (Common Sloth) is a tropical forest animal (atlantic forest) that has the unique behavior of slowness and bradykinesia being called a Sloth. To this day, it is not known why it was so slow (including study of physiology, pathology, hormone dosages, etc.)
PURPOSE: to describe and correlate the characteristics of motor behavior and physiology of the Bradypus Variegatus with Parkinson's disease, discussing the possibility of being a physiologically determined “Parkinsonian” animal model.
METHOD: data collection based on a literature review on the study of the Common Sloth and its bradykinesia. Animal neuroanatomy, neurophysiology and animal behavior studies, with special attention to data related to Parkinson's disease.
RESULTS: Bradypus has several “Parkinsonian” features. The most common is bradykinesia. However, paradoxical kinesis is also exist (agile when threatened. It has quick strikes with its claw in threats and fights. Hypomimia with reduced blinking and facial expression, smell too. Predominance of flexor tone (flexor muscles are antigravity), with posture of flexor rigidity most of the time. Slow transit colon with a frequency of 1 evacuation per 10 days. Slow responses to painful stimulus. In summary, 1) marked bradykinesia 2) Paradoxical kinesis 3) very slow intestinal transit 4) Sialorrhea 5) facial hypomimia with reduced blinking 6) reduced sense of smell 7) predominance of postural flexor tone with clear flexor hypertonia are common signs of Bradypus and also to parkinsonian patients. These characteristics are useful in their animal lifestyle (they lives in trees) and this “hypokinetic-hypertonic extrapyramidal status” favors them to remain in the trees, even during sleep, without fatigue.
CONCLUSION: This is the first description in the literature that correlates Bradypus with Parkinson's disease and places it as the first natural animal parkinson’s model, not from a pathological point of view, but with a natural and sucessful "Parkinsonian status".

Palavras Chave

PARKINSON'S DISEASE , BRADYPUS , NEUROPHYSIOLOGY , SLOTHS , BRADYKINESIA , ANIMAL MODEL, PHYSIOLOGY, PARKINSONISM