title: Functional mapping of the periaqueductal gray matter involved in organizing tonic immobility behavior in guinea pigs.
abstract: 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 (vl) and lateral (l) 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.
authors.affiliation: Psychobiology Post-graduation Program, School of Philosophy, Science and Literature of Ribeirão Preto of the University of São Paulo, 14040-901 Ribeirão Preto, SP, Brazil.
authors.forename: Eveline Bis
authors.initials: EB
authors.lastname: Vieira
authors.forename: Leda
authors.initials: L
authors.lastname: Menescal-de-Oliveira
authors.forename: Christie Ramos Andrade
authors.initials: CR
authors.lastname: Leite-Panissi
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001931:Brain Mapping; D006168:Guinea Pigs; D046353:Immobility Response, Tonic / Q000502:physiology*; D007150:Immunohistochemistry; D008297:Male; D009474:Neurons / Q000502:physiology*; D010487:Periaqueductal Gray / Q000502:physiology*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism
chemical_list: D016760:Proto-Oncogene Proteins c-fos