The effects of acute stress and acute corticosterone administration on the immobility response in rats.
The immobility response is an innate antipredatory behavior in a broad variety of species. The immobility response varies in its postural components but in general is characterized by an absence of movement and a relative unresponsiveness to stimuli. Experimentally in rats, clamping the neck followed by body inversion and manual restrain elicits a response called "immobility by clamping the neck". Stress reactions protect animals against predators and are characterized by activation of the sympathetic and hypothalamic-pituitary-adrenal systems. However, in mammals, the role of acute stress as a modulator of immobility response has been less studied. The aim of our study was to assess the effects of acute stress and the injection of corticosterone (5mg/kg, ip) on immobility by clamping the neck in rats. We observed that either previous acute stress caused by forced exposure to elevated open platform or application of a heat-pain stimulus to the rat's tail during the immobility increased the duration of the immobility response caused by clamping the neck. Also, the corticosterone produced a rapid increase (15 min after injection) in the duration of this immobility response. Our results show that the acute stress, in rats, is a facilitator of the immobility response and suggest a possible nongenomic rapid action of corticosterone over brain structures that control this behavior.
Zamudio
Sergio R
SR
Department of Physiology, National School of Biological Sciences, National Polytechnic Institute, México D.F., Mexico. zrzamudio@hotmail.com
Quevedo-Corona
Lucía
L
Garcés
Linda
L
De La Cruz
Fidel
F
D000208:Acute Disease; D000704:Analysis of Variance; D000818:Animals; D003345:Corticosterone / Q000378:metabolism*; D046352:Freezing Reaction, Cataleptic / Q000502:physiology*; D006358:Hot Temperature; D008297:Male; D009333:Neck; D009483:Neuropsychological Tests; D010146:Pain; D010812:Physical Stimulation; D051381:Rats; D017208:Rats, Wistar; D012149:Restraint, Physical; D013315:Stress, Psychological; D013623:Tail; D013997:Time Factors
D003345:Corticosterone