Involvement of dopamine D(2) receptors in complex maze learning and acetylcholine release in ventral hippocampus of rats.
In the current study we focus on the involvement of dopamine D(2) receptors in the ventral hippocampus in memory performance and acetylcholine release. Using the aversively motivated 14-unit T-maze (Stone maze) the injection of raclopride, a D(2) receptor antagonist, into the ventral hippocampus (8 microg/kg) was found to impair memory performance. Co-injection of quinpirole, a D(2) receptor agonist (8 microg/kg), overcame the impairment in performance. Microdialysis study revealed that quinpirole infusion (10-500 microM) into the ventral hippocampus stimulated acetylcholine release in a dose-dependent manner, and systemic injection of quinpirole (0.5 mg/kg, i.p.) also stimulated acetylcholine release in the ventral hippocampus. Infusion of eticlopride, another D(2) receptor antagonist, into the ventral hippocampus suppressed acetylcholine release in the hippocampus induced by systemic injection of quinpirole. Taken together, we suggest that D(2) receptors in the ventral hippocampus are involved in memory performance, possibly through the regulation of acetylcholine.
Umegaki
H
H
Department of Geriatrics, University of Nagoya Graduate School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya, 466-8550, Japan. umegaki@tsuru.med.nagoya-u.ac.jp
Munoz
J
J
Meyer
R C
RC
Spangler
E L
EL
Yoshimura
J
J
Ikari
H
H
Iguchi
A
A
Ingram
D K
DK
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D001362:Avoidance Learning / Q000502:physiology; D018491:Dopamine Agonists / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology; D005502:Food; D006624:Hippocampus / Q000378:metabolism*; D008297:Male; D018782:Maze Learning / Q000502:physiology*; D017551:Microdialysis; D051381:Rats; D011916:Rats, Inbred F344; D017448:Receptors, Dopamine D2 / Q000187:drug effects / Q000502:physiology*; D012201:Reward
D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D017448:Receptors, Dopamine D2; D000109:Acetylcholine