TITLE:
Relationships of open-field behaviour with anxiety in the elevated zero-maze test: Focus on freezing and grooming
AUTHORS:
Sira Díaz-Morán, Celio Estanislau, Toni Cañete, Gloria Blázquez, Andrea Ráez, Adolf Tobeña, Albert Fernández-Teruel
KEYWORDS:
Genetically Heterogeneous NIH-HS Stock; Elevated Zero-Maze; Open-Field; Freezing; Grooming
JOURNAL NAME:
World Journal of Neuroscience,
Vol.4 No.1,
January
16,
2014
ABSTRACT:
The National Institutes of
Health Genetically Heterogeneous Rat Stock (NIH-HS) is a unique tool for genetic
studies of complex traits due to its high genetic heterogeneity and to its high
level of genetic recombinants accumulated along many outbreeding generations.
In the present study, 90 NIH-HS male rats were tested for anxiety/fearfulness
in the elevated zero-maze and in the open-field test in order to investigate
the associations among defensive responses from both tests and, in particular,
those among open- field self-grooming and freezing. These associations were
evaluated by means of a correlational-factorial approach and an analysis of differences
between sub- groups displaying extreme scores in representative variables. The
final factor analysis revealed a first factor with high loadings of all
variables from the zero-maze (“Maze
timidity/conflict” factor), and a second (independent) factor dominated
by open-field crossings (-0.74), rearings (-0.62) and freezing (0.65), with
lower loadings of open-field grooming (-0.39) and stretched attend postures, as
well as of entries and time (loadings of -0.32 to -0.25) in the open sections
of the zero-maze (“Open Behavior
inhibition/ desinhibition” factor), suggesting that open-field self-grooming
is a response associated to activity, in the present study, rather than to
inhibition. Furthermore, the finding that grooming in the OF loaded negatively
in a second factor supports a
relationship between grooming and dearousal. Present results, thus, are in
accordance with the usefulness of these tests for the purposes they are
commonly employed and add new evidence supporting their concurrent validity, as
indicated by the relationships observed among measures from both tests.