Repeated administrations of dopamine receptor agents affect lithium-induced state-dependent learning in mice.
The influence of repeated administration of dopamine receptor agents on the effect of lithium on lithium-induced state-dependent learning was examined in mice. Immediate post-training intraperitoneal (i.p.) administrations of lithium (10 and 20 m/kg) decreased the step-down latency of a single-trial inhibitory avoidance task. This was fully or partly reversed by pre-test administration of the same doses of the drug, with maximum response at the dose of 10 mg/kg, suggesting state-dependent learning was induced by lithium. Here, it has also been shown that repeated intracerebroventricular administrations of a mixed D1/D2 dopamine receptors agonist apomorphine (once daily injections of 0.5 microg/mouse for three consecutive days followed by five days of no drug treatment) increased the effect of lower doses of pre-test lithium (1.25, 2.5 and 5 mg/kg, i.p.) on the reinstatement of the step-down latency decreased by post-training lithium (10 mg/kg). On the contrary, not only repeated administrations of the dopamine D1 receptor antagonist SCH 23390 (0.5 and 1 microg/mouse) but also the dopamine D2 receptor antagonist sulpiride (0.3 and 1 microg/mouse) disrupted the state-dependent learning induced by lithium. These results suggest that state-dependent learning induced by lithium may be altered by repeated pretreatment of dopamine receptor agents.
Zarrindast
Mr
M
Department of Pharmacology, Tehran University of Medical Sciences, Tehran, Iran. zarinmr@ams.ac.ir
Madadi
F
F
Ahmadi
S
S
D000818:Animals; D018692:Antimanic Agents / Q000494:pharmacology*; D001058:Apomorphine / Q000494:pharmacology; D001362:Avoidance Learning / Q000187:drug effects; D001552:Benzazepines / Q000494:pharmacology; D015259:Dopamine Agents / Q000494:pharmacology*; D018491:Dopamine Agonists / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology; D007276:Injections, Intraventricular; D007858:Learning / Q000187:drug effects*; D018021:Lithium Chloride / Q000494:pharmacology*; D008297:Male; D051379:Mice; D011954:Receptors, Dopamine / Q000187:drug effects*; D013469:Sulpiride / Q000494:pharmacology
D018692:Antimanic Agents; D001552:Benzazepines; D015259:Dopamine Agents; D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D011954:Receptors, Dopamine; C534628:SCH 23390; D013469:Sulpiride; D018021:Lithium Chloride; D001058:Apomorphine