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Glutamate receptors in the dorsal hippocampus mediate the acquisition, but not the expression, of conditioned place aversion induced by acute morphine withdrawal in rats.

Hou YY, Liu Y, Kang S, Yu C, Chi ZQ, Liu JG - Acta Pharmacol. Sin. (2009)

Bottom Line: Conditioned place aversion (CPA) induced by naloxone-precipitated morphine withdrawal were assessed.However, intra-DH microinjection of D-AP5 or NBQX after conditioning but before the testing session had no effect on the expression of CPA.Our results suggest that NMDA and AMPA receptors in the dorsal hippocampus are involved in the acquisition, but not in the expression, of the negative motivational components of acute morphine withdrawal in rats.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.

ABSTRACT

Aim: To evaluate the role of glutamate receptors in the dorsal hippocampus (DH) in the motivational component of morphine withdrawal.

Methods: NMDA receptor antagonist D-AP5 (5 microg/0.5 microL per side) or AMPA receptor antagonist NBQX (2 microg/0.5 microL per side) was microinjected into DH of rats. Conditioned place aversion (CPA) induced by naloxone-precipitated morphine withdrawal were assessed.

Results: Preconditioning microinjection of D-AP5 or NBQX into the DH impaired the acquisition of CPA in acute morphine-dependent rats. However, intra-DH microinjection of D-AP5 or NBQX after conditioning but before the testing session had no effect on the expression of CPA.

Conclusion: Our results suggest that NMDA and AMPA receptors in the dorsal hippocampus are involved in the acquisition, but not in the expression, of the negative motivational components of acute morphine withdrawal in rats.

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Effects of intra-DH infusion of D-AP5 or NBQX on conditioned place aversion in saline-treated rats. The columns show the time spent in the drug-paired compartment in the preconditioning (Pre) or testing (test) sessions (A) and the CPA score (B). D-AP5 (5 μg/0.5 μL per side), NBQX (2 μg/0.5 μL per side) or vehicle (0.5 μL/side) was bilaterally microinfused into the dorsal hippocampus 10 min before pairing on the second day of the conditioning session. Data are expressed as means±SEM.
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fig3: Effects of intra-DH infusion of D-AP5 or NBQX on conditioned place aversion in saline-treated rats. The columns show the time spent in the drug-paired compartment in the preconditioning (Pre) or testing (test) sessions (A) and the CPA score (B). D-AP5 (5 μg/0.5 μL per side), NBQX (2 μg/0.5 μL per side) or vehicle (0.5 μL/side) was bilaterally microinfused into the dorsal hippocampus 10 min before pairing on the second day of the conditioning session. Data are expressed as means±SEM.

Mentions: To examine whether intra-DH injection of D-AP5 or NBQX produced conditioned place preference (CPP) or CPA in the absence of morphine treatment, D-AP5 or NBQX was injected into the bilateral dorsal hippocampus of saline-treated rats. No significant differences (P<0.05, Student's t test) were observed in the vehicle, D-AP5 or NBQX-injected groups between the time spent in the drug-paired compartment during the testing session (542.5±53.0 s, 565.6±59.8 s and 532.0±58.2 s, respectively) and that spent during the preconditioning session (553.4±25.4 s, 571.0±32.3 s and 537.9±33.4 s, respectively) (Figure 3A). One-way ANOVA indicated no significant differences in CPA score among groups (F(2, 17)=0.005; P>0.05) (Figure 3B). These data showed that neither CPP nor CPA was induced by intra-DH injection of vehicle, D-AP5 or NBQX, suggesting that D-AP5 and NBQX alone have no motivational effects when injected at this dose into the dorsal hippocampus.


Glutamate receptors in the dorsal hippocampus mediate the acquisition, but not the expression, of conditioned place aversion induced by acute morphine withdrawal in rats.

Hou YY, Liu Y, Kang S, Yu C, Chi ZQ, Liu JG - Acta Pharmacol. Sin. (2009)

Effects of intra-DH infusion of D-AP5 or NBQX on conditioned place aversion in saline-treated rats. The columns show the time spent in the drug-paired compartment in the preconditioning (Pre) or testing (test) sessions (A) and the CPA score (B). D-AP5 (5 μg/0.5 μL per side), NBQX (2 μg/0.5 μL per side) or vehicle (0.5 μL/side) was bilaterally microinfused into the dorsal hippocampus 10 min before pairing on the second day of the conditioning session. Data are expressed as means±SEM.
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Related In: Results  -  Collection

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fig3: Effects of intra-DH infusion of D-AP5 or NBQX on conditioned place aversion in saline-treated rats. The columns show the time spent in the drug-paired compartment in the preconditioning (Pre) or testing (test) sessions (A) and the CPA score (B). D-AP5 (5 μg/0.5 μL per side), NBQX (2 μg/0.5 μL per side) or vehicle (0.5 μL/side) was bilaterally microinfused into the dorsal hippocampus 10 min before pairing on the second day of the conditioning session. Data are expressed as means±SEM.
Mentions: To examine whether intra-DH injection of D-AP5 or NBQX produced conditioned place preference (CPP) or CPA in the absence of morphine treatment, D-AP5 or NBQX was injected into the bilateral dorsal hippocampus of saline-treated rats. No significant differences (P<0.05, Student's t test) were observed in the vehicle, D-AP5 or NBQX-injected groups between the time spent in the drug-paired compartment during the testing session (542.5±53.0 s, 565.6±59.8 s and 532.0±58.2 s, respectively) and that spent during the preconditioning session (553.4±25.4 s, 571.0±32.3 s and 537.9±33.4 s, respectively) (Figure 3A). One-way ANOVA indicated no significant differences in CPA score among groups (F(2, 17)=0.005; P>0.05) (Figure 3B). These data showed that neither CPP nor CPA was induced by intra-DH injection of vehicle, D-AP5 or NBQX, suggesting that D-AP5 and NBQX alone have no motivational effects when injected at this dose into the dorsal hippocampus.

Bottom Line: Conditioned place aversion (CPA) induced by naloxone-precipitated morphine withdrawal were assessed.However, intra-DH microinjection of D-AP5 or NBQX after conditioning but before the testing session had no effect on the expression of CPA.Our results suggest that NMDA and AMPA receptors in the dorsal hippocampus are involved in the acquisition, but not in the expression, of the negative motivational components of acute morphine withdrawal in rats.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.

ABSTRACT

Aim: To evaluate the role of glutamate receptors in the dorsal hippocampus (DH) in the motivational component of morphine withdrawal.

Methods: NMDA receptor antagonist D-AP5 (5 microg/0.5 microL per side) or AMPA receptor antagonist NBQX (2 microg/0.5 microL per side) was microinjected into DH of rats. Conditioned place aversion (CPA) induced by naloxone-precipitated morphine withdrawal were assessed.

Results: Preconditioning microinjection of D-AP5 or NBQX into the DH impaired the acquisition of CPA in acute morphine-dependent rats. However, intra-DH microinjection of D-AP5 or NBQX after conditioning but before the testing session had no effect on the expression of CPA.

Conclusion: Our results suggest that NMDA and AMPA receptors in the dorsal hippocampus are involved in the acquisition, but not in the expression, of the negative motivational components of acute morphine withdrawal in rats.

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