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Wistar Kyoto and Wistar Rats Differ in
Nicotine-Induced Conditioned Taste Avoidance
Jason B. Tanenbaum1, Lisa M. Bollwage1 and
Anthony S. Rauhut 1,2, Department of Psychology1
and Neuroscience Program2, Dickinson College,
Carlisle, PA
Abstract
Purpose
Discussion
Results
The Wistar-Kyoto (WKY) rat is an animal model of
clinical depression. Previous research in the
laboratory suggests that WKY rats are less
responsive to the rewarding and locomotor effects
of nicotine compared to Wistar rats. Such strain
differences may be due to general, non-specific
strain differences in the neuropharmacological
processing of nicotine. Thus, the present
experiment examined if WKY rats were less
responsive to another neuropharmacological aspect
of nicotine compared to Wistar rats.
Specifically, the present study examined if WKY
rats were less responsive to the avoidance
properties of nicotine compared to Wistar rats,
as assessed using the conditioned taste avoidance
(CTA) paradigm. WKY and Wistar rats underwent a
CTA procedure which consisted of 4 alternating
drug and non-drug sessions (counterbalanced).
Drug sessions consisted of 15-min access to
saccharin (0.15) followed immediately by an
injection (s.c.) of either vehicle (physiological
saline) or nicotine (0.2, 0.4 or 0.8 mg/kg). It
was found that WKY rats that received the lowest
nicotine dose (0.2 mg/kg) did not differ from WKY
rats that received the vehicle (i.e., no CTA).
However, WKY rats that received the two highest
nicotine doses (0.4 and 0.8 mg/kg) drank less
than the WKY rats that received the vehicle on
several sessions (i.e., CTAs). Only the Wistar
rats that received the highest nicotine dose (0.8
mg/kg) drank less than Wistar rats that received
the vehicle on several sessions. Thus, WKY rats
were more responsive to the avoidance properties
of nicotine compared to Wistar rats.

• The present experiment found that nicotine
  dose-dependently produced a CTA in WKY rats.
  Specifically, the two highest nicotine doses (0.4
  and 0.8 mg/kg) yielded a CTA whereas the lowest
  nicotine dose (0.2 mg/kg) did not.
• Only highest nicotine dose (0.8 mg/kg) yielded a
  CTA in the Wistar rats.
• Collectively, these results suggest that the WKY
  rats are more responsive to the avoidance
  properties of nicotine relative to the Wistar
  rats.
• These results are consistent with prior studies
  that have shown that WKY rats are responsive to
  other drugs of abuse (e.g., alcohol Cailhol and
  Morméde, 2001).
• Moreover, these results suggest that the
  previously-observed deficit in nicotine
  conditioned place preference by the WKY rats is
  not due to a general, unresponsiveness to the
  behavioral actions of nicotine or a general
  deficit in learning.
• Rather, the results of the present experiment,
  when viewed in tandem with the results of
  previous unpublished research from the
  laboratory, indicate that WKY rats display a
  specific deficit in reward-based learning with
  respect to nicotine.
• This interpretation is consistent with previous
  studies suggesting that WKY display anhedonia
  under certain conditions (Jiao, Pare, and
  Tejani-Butt, 2003 Pare, 2000).

• The purpose of the present study was to examine
  if WKY rats were less responsive to the avoidance
  properties of nicotine compared to Wistar rats,
  as assessed by the conditioned taste avoidance
  (CTA) paradigm.

Consumption Data
Prediction

• If WKY rats are unresponsive to the behavioral
  actions of nicotine, then WKY rats are predicted
  to display a less robust CTA relative to Wistar
  rats.
• If, however, WKY rats are responsive to the
  behavioral actions of nicotine, then WKY rats are
  predicted to display a CTA similar to or more
  than Wistar rats.

• Left Panel. The two highest nicotine doses (0.8
  and 2.0 mg/kg) produced a CTA on several sessions
  and the test session in the WKY rats. ( 0.8
  mg/kg nicotine vs. vehicle 0.4 mg/kg
  nicotine vs. vehicle), p lt .05.
• Right Panel. The highest nicotine dose (0.8
  mg/kg) produced a CTA on the test session only in
  the Wistar rats ( 0.8 mg/kg nicotine vs.
  vehicle), p lt .05.

WKY Wistar
Methods
References
Acclimation 5 Days
Introduction

1. Cailhol, S. Mormède, P. (2001) Conditioned
   taste aversion and alcohol drinking Strain and
   gender differences. Journal of Studies on
   Alcohol, 63, 91-99.
2. Paré, W.P. (2000). Investigatory behavior of a
   novel conspecific by wistar kyoto, wistar,
   spraugue-dawley rats. Brain Research Bulletin,
   53, 759-765.
3. Xilu, J., Paré, W.P., Butt-Tejani, S. (2003).
   Strain differences in the distribution of
   dopomine transporter sites in rat brain. Progress
   in Neuro-Psychopharmacology Biological
   Psychiatry, 27, 913-919.

• Previous research suggests that Wistar Kyoto rats
  are an animal model of clinical depression,
  exhibiting less motor activity and greater
  anhedonia compared to other rat strains (Pare,
  2000).
• Previous unpublished research from the laboratory
  has found that WKY rats failed to display a
  nicotine conditioned place preference or show
  alterations in nicotine-induced changes in
  locomotor activity compared to Wistar rats.
  These results suggest that WKY rats are less
  responsive to the rewarding and locomotor
  properties of nicotine compared to Wistar rats.
• However, the finding that WKY rats failed to
  display a nicotine conditioned place preference
  or nicotine-induced alterations in locomotor
  activity may suggest that WKY rats were
  unresponsive to any behavioral actions of
  nicotine.

24 h
Initial Water Restriction 1 Session 15 min access
to tap water following water removal
24 h
Pretest 1 Session 15 min access to saccharin
(0.15 )
Weight Data
24 h
Acknowledgements
Conditioning 8 SessionsAlternating Drug and
NonDrug Sessions (counterbalanced) Drug Sessions
15 min access to saccharin (0.15) followed
immediately by an injection (s.c) of vehicle
(physiological saline) or nicotine (0.2, 0.4 or
0.8 mg/kg) NonDrug Sessions 15 min access to tap
water in the absence of any injections
This research was supported by a National
Institutes of Health grant (DA019866), awarded to
A. S. Rauhut. We would like to especially thanks
Professor Rauhut for his guidance and support
during this experiment.
48 h after last drug session

• Left Panel. Displays weights of WKY rats over 6
  sessions. No significant group differences were
  observed, p gt 0.05.
• Right Panel. Displays weights of Wistar rats over
  6 sessions. Although no individual group
  differences existed, Wistar rats were heavier and
  gained more weight over time compared to WKY
  rats, ps lt 0.05.

Test 15 min access to saccharin (0.15) in the
absence of any injections