Behavioural effects of 7-OH-DPAT are solely due to stimulation of dopamine D2 receptors in the shell of the nucleus accumbens; jaw movements.
The goal of this study was to determine whether the dopamine D3 receptor in limbic structures plays a role in the shell-specific and dopamine-dependent display of jaw movements in rats. When combined with the dopamine D1 receptor agonist (+/-)-6-chloro-7,8-dihydroxy-3-allyl-1- phenyl-2,3,4,5-tetrahydro-1 H-3-benzazepine (SKF 82958, 5 micrograms), the putative dopamine D3 receptor agonist (+/-)-7-hydroxy-N, N-di-n-propyl-2-aminotetralin (7-OH-DPAT, 10 micrograms) produced repetitive jaw movements following injection into the shell, but not the core, of the nucleus accumbens. This behaviour was only partially inhibited by local blockade of dopamine D1 receptors (R(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1 H-3-benzazepine, SCH 23390, 500 ng), dopamine D2 receptors (domperidone, 50 and 100 ng) or dopamine D2/3 receptors (l-sulpiride, 25 ng). Combined blockade of both dopamine D1 and D2 receptors in the shell completely antagonized the jaw movements elicited by the cocktail of SKF 82958 and 7-OH-DPAT. Replacing 7-OH-DPAT by another putative dopamine D3 receptor agonist, S(+)-(4aR, 10bR)-3,4,4a,10b-tetrahydro-4-propyl-2H,5H-[I]benzopyrano[4, 3-b]-1, 4-oxazin-9-ol (PD 128,907, 10 micrograms), in the cocktail did not produce jaw movements, when administered into the shell. Injection of the cocktail of SKF 82958 and 7-OH-DPAT into the ventrolateral striatum, which contains nearly no dopamine D3 receptors, also elicited jaw movements. It is concluded that mesolimbic dopamine D3 receptors play no role in the dopamine-dependent and shell-specific jaw movements: the contribution of 7-OH-DPAT in the cocktail of SKF 82958 and 7-OH-DPAT to the display of jaw movements is solely due to its ability to activate dopamine D2 receptors.
Koshikawa
N
N
Department of Pharmacology, Nihon University School of Dentistry, Tokyo, Japan.
Miwa
Y
Y
Adachi
K
K
Kobayashi
M
M
Cools
A R
AR
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D001552:Benzazepines / Q000494:pharmacology; D001578:Benzopyrans / Q000494:pharmacology; D004294:Domperidone / Q000494:pharmacology; D018491:Dopamine Agonists / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology; D004347:Drug Interactions; D007568:Jaw / Q000502:physiology*; D008297:Male; D009068:Movement; D009714:Nucleus Accumbens / Q000187:drug effects* / Q000378:metabolism; D010078:Oxazines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017448:Receptors, Dopamine D2 / Q000819:agonists*; D013764:Tetrahydronaphthalenes / Q000494:pharmacology*
D001552:Benzazepines; D001578:Benzopyrans; D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D010078:Oxazines; D017448:Receptors, Dopamine D2; D013764:Tetrahydronaphthalenes; C062458:3,4,4a,10b-tetrahydro-4-propyl-2H,5H-(1)benzopyrano(4,3-b)-1,4-oxazin-9-ol; D004294:Domperidone; C071262:SK&F 82958; C031349:7-hydroxy-2-N,N-dipropylaminotetralin