Univ Sao Paulo, Psychobiol Postgrad Program, Sch Philosophy Sci & Literature Ribeirao Preto, BR-14040901 Ribeirao Preto, SP - Brazil
 Univ Sao Paulo, Dept Physiol, Fac Med Ribeirao Preto, BR-14049900 Ribeirao Preto, SP - Brazil
 Univ Sao Paulo, Dept Morphol Stomatol & Physiol, Dent Sch Ribeirao Preto, BR-14040904 Ribeirao Preto, SP - Brazil
Total Affiliations: 3
Behavioural Brain Research;
JAN 1 2011.
Web of Science Citations:
Tonic immobility behavior (TI) is an innate response characterized by profound motor inhibition that is exhibited by prey when physical contact with a predator is prolonged and the situation inescapable. The periaqueductal gray matter (PAG) is intimately associated with the somatic and autonomic components of defensive reactions. This study investigated whether the TI response was able to recruit specific functional columns of the PAG by examining c-fos immunolocalization in guinea pigs. In the TI group, the innate response was invoked in animals through inversion and physical contention for at least 15 min. In the control group, the animals were physically manipulated only. Our results demonstrate that the defensive behavior of TI is capable of promoting the expression of Fos protein in different areas of the PAG, with higher levels of staining in the ventrolateral (vI) and lateral (I) columns. In addition, our results demonstrate increased Fos immunoreactivity (FOS-IR) in the dorsal raphe nucleus, the Edinger-Westphal nucleus, the cuneiform nucleus and the superior colliculus. In contrast, there were no significant alterations in the number of FOS-IR cells in the inferior colliculus or the oculomotor nucleus. Analysis of the results suggests that neuronal activation after the TI response differs by functional column of the PAG. (C) 2010 Elsevier B.V. All rights reserved. (AU)