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Defensive behavior and hippocampal cell proliferation : differential modulation by naltrexone during stress Holmes, Melissa Marie
Abstract
The present study was designed to investigate the role of endogenous opioids in both the expression of defensive behaviors and the suppression of cell proliferation that are induced by exposure to predator odor, trimethyl thiazoline (TMT). Adult male rats were injected with either naltrexone (5mg/kg) or saline 30 minutes prior to being transferred to a testing chamber where they were exposed to either TMT (250 ul) or control odor (distilled water 250 u.1). Rats were videotaped and the expression of defensive and non-defensive behaviors was scored over the first fifteen minutes of exposure. Bromodeoxyuridine (BrdU, 200mg/kg), a thymidine analogue, was injected i.p. 15 minutes after exposure to the odors and the rats were perfused 1 hour after BrdU administration. As previously reported, the expression of defensive behaviors was increased after exposure to TMT. Pre-treatment with naltrexone attenuated the expression of defensive behaviors (defensive burying and directed stretch approach), independent of any drug effects on ability to perform the required motor patterns. TMT exposure rapidly suppressed the number of proliferating (BrdU-ir positive) cells in the dentate gyrus. In addition, naltrexone administration alone suppressed cell proliferation in the dentate gyrus. Thus, consistent with other reports, endogenous opioids mediate the expression of defensive behaviors in response to predator odor exposure. Furthermore, endogenous opioids may play a regulatory role in the control of cell proliferation in the dentate gyrus of adult male rats.
Item Metadata
Title |
Defensive behavior and hippocampal cell proliferation : differential modulation by naltrexone during stress
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2001
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Description |
The present study was designed to investigate the role of endogenous opioids in both the
expression of defensive behaviors and the suppression of cell proliferation that are induced by
exposure to predator odor, trimethyl thiazoline (TMT). Adult male rats were injected with either
naltrexone (5mg/kg) or saline 30 minutes prior to being transferred to a testing chamber where
they were exposed to either TMT (250 ul) or control odor (distilled water 250 u.1). Rats were
videotaped and the expression of defensive and non-defensive behaviors was scored over the
first fifteen minutes of exposure. Bromodeoxyuridine (BrdU, 200mg/kg), a thymidine analogue,
was injected i.p. 15 minutes after exposure to the odors and the rats were perfused 1 hour after
BrdU administration. As previously reported, the expression of defensive behaviors was
increased after exposure to TMT. Pre-treatment with naltrexone attenuated the expression of
defensive behaviors (defensive burying and directed stretch approach), independent of any drug
effects on ability to perform the required motor patterns. TMT exposure rapidly suppressed the
number of proliferating (BrdU-ir positive) cells in the dentate gyrus. In addition, naltrexone
administration alone suppressed cell proliferation in the dentate gyrus. Thus, consistent with
other reports, endogenous opioids mediate the expression of defensive behaviors in response to
predator odor exposure. Furthermore, endogenous opioids may play a regulatory role in the
control of cell proliferation in the dentate gyrus of adult male rats.
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Extent |
2263215 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-08-05
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0103822
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2001-11
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.