Abstract

MICHELAN, Clotilde Maria; MICHELAN, Lílian Daltro; PAULA, Hugo M. G. de  and  KATSUMASA, Hoshino. Imobilidade tônica e imobilidade do nado forçado em cobaias. Rev. etol. [online]. 2006, vol.8, n.2, pp. 89-95. ISSN 1517-2805.

The evolutionary origin and the physiological mechanisms responsible for the multiple forms of behavioral responses expressed by movements arrest are still poorly understood. The present study determined if tonic immobility (TI), the last antipredatory defensive response of many animals, is related to the immobility observed in the forced swimming situation (FSI = Forced Swimming Immobility), which, by its turn, is considered a manifestation equivalent to the psychiatric depression. Previous forced swimming did not change the time of TI and the duration of FSI was not affected by the previous submission to the TI inducing condition, both in male and female guinea-pigs (Cavia porcellus). It is concluded that these immobilities have distinct adaptive functions, with different origins and neural mechanisms. Additionally, the absence of an action of the forced swimming on the TI raises the question on the use of a single session of swimming to induce depressive-like manifestations.

Keywords : Tonic immobility; Forced swimming; Immobility responses; Guinea pigs.

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