Post-training intrahippocampal infusion of nicotine prevented spatial
memory retention deficits by the Cyclooxygenase-2-specific inhibitor celecoxib
in rats
M. Sharifzadeh1, M. Tavasoli1, N. Naghdi2,
A. Ghanbari1, M. Amini1 and A. Roghani3,4
1Department of Toxicology
and Pharmacology, School of Pharmacy, Tehran University of Medical Sciences,
Tehran, Iran
2Department of Pharmacology, Iran Pasteur Institute, Tehran, Iran.
3Department of Pharmacology and Neuroscience, Texas Tech University Health
Sciences Center, Lubbock, TX, USA
4Texas Institute of Environmental and Human Health, Texas Tech University,
Lubbock, TX, USA
In the present work, we have investigated the effects of nicotine, infused
in the rat dorsal hippocampus several minutes after infusion of celecoxib,
on memory retention in the Morris water maze. Rats were trained for 3
days, each day, included two blocks and each block contained 4 trials.
Test trials were conducted 48 h after surgery. Bilateral intrahippocampal
infusion of celecoxib (0.1 M) increased escape latency and travel distance
in rats, indicating significant impairment in spatial memory retention.
We also examined effects of bilateral infusion of nicotine (0.5, 1.0,
and 2.0 µg/side) on memory retention. Infusion of 1 µg nicotine
significantly decreased escape latency and travel distance but not swimming
speed, compared to controls, suggesting memory retention enhancement by
nicotine at this concentration. In separate experiments, bilateral infusion
of nicotine, infused 5 min after 0.1 M celecoxib infusion, showed escape
latency, travel distance and swimming speed profiles very similar to the
control animals. Brain tissues from several of these animals were subjected
to immunohistochemical staining analysis with anti-COX-2 antibodies. These
analyses showed that COX-2 infusion alone qualitatively reduced the number
and density of COX-2-containing neurons in the dorsal hippocampus, and
that the immunostaining pattern was qualitively similar to controls for
rats receiving a combination of celecoxib and nicotine. These results
suggest that nicotine prevented or reversed the adverse effects of celecoxib
on spatial memory retention and protected or restored the immunostaining
pattern of COX-2 neurons in the rat dorsal hippocampus..
Paper presented
at Measuring Behavior 2005
, 5th International Conference on Methods and Techniques
in Behavioral Research, 30 August - 2 September 2005, Wageningen, The
Netherlands.
© 2005 Noldus
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