[Abstract Title]. - Society for Neuroscience

Abstract: Chronic pain is detrimental to the quality of daily life in humans. In addition,
depression, anxiety, cognitive impairment, an inability to handle stress and poor sleep patterns
are often co-morbid with chronic pain conditions. Animals in chronic pain may also display
symptoms of anxiety, depression or cognitive impairment and additional stress may exacerbate
these symptoms. This study was undertaken to determine the effect of neuropathic pain and/or
stress on measurements of anxiety, depression and cognition in the rat. Several groups of animals
received partial sciatic nerve ligation (PSNL) and were exposed to various behavioral tests.
Locomotor activity, open field, fear potentiated startle and novel object interaction were utilized
as tests of activity and/or anxiety. Sucrose preference, with or without chronic mild stress, was
utilized as a test of depression. Cognition tests examined were the Morris water maze and novel
object recognition. In the locomotor activity test (light vs. dark), sham animals were less active
in the light while PSNL animals were less active under both conditions. PSNL animals also
displayed a significantly greater startle response in brightly illuminated test chambers. Thus, the
neuropathic animals exhibited an anxious phenotype in the locomotor activity and fear
potentiated startle tests. However, there was no difference between sham and PSNL animals in
the open field (light vs. dark) or novel object interaction tests. Sucrose preference tests were
employed to operationally define anhedonia (an inability to feel joy). Specifically, anhedonia in
animals is defined as a reduction in sucrose intake relative to the control group and baseline
intake values. Chronic mild stress decreased sucrose intake in all animals, however there was no
significant difference between sham and PSNL rats. There was no significant difference between
sham and PSNL rats in either the Morris water maze or novel object recognition test. Normal
animals performed poorly in these assays, therefore, Sprague-Dawley rats may not be the
optimal strain for use in cognition tests. In conclusion, while significant differences between
sham and PSNL animals were observed in locomotor activity and fear potentiated startle, there
was little difference between sham and PSNL rats in behavioral tests of depression and
cognition. It is possible that PSNL develops insufficient ongoing or spontaneous pain to produce
robust effects in these models.
Disclosures: M.J. Piesla , Wyeth Research, A. Employment (full or part-time); A. Joshi,
Wyeth Research, A. Employment (full or part-time); T.A. Cummons, Wyeth Research, A.
Employment (full or part-time); J.E. Harrison, Wyeth Research, A. Employment (full or parttime);
L. Leventhal, Wyeth Research, A. Employment (full or part-time); G.T. Whiteside,
Wyeth Research, A. Employment (full or part-time).
Poster
267. Pain: Pain Models II
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 267.6/FF12
Topic: D.08.j. Pain models