The effects of the enantiomers of the dopamine agonist N-0437 on food consumption and yawning behaviour in rats.
The enantiomers of the potent and selective dopamine (DA) D-2 receptor agonist 2-(N-propyl-N-thienylethyl-amino)-5-hydroxytetralin, N-0437, were tested for their effects on palatable food consumption and yawning behaviour in rats. (-)-N-0437 (1.0 and 5.0 mumols/kg). This confirms the agonistic action of (-)-N-0437 on postsynaptic receptors as food consumption is considered to be related to stimulation of postsynaptic DA receptors. Yawning behaviour was stimulated by (-)-N-0437 (0.5 mumol/kg) and could be antagonized by the autoreceptor-selective antagonist (+)-UH 232 (25 mumols/kg), which suggests an agonistic action on DA autorecptors. (+)-N-0437 (5.0 and 10.0 mumols/kg) also reduced food consumption and the effect could be antagonized by YM 09151-2 (0.03 mumol/kg). The weaker effect of (+)-N-0437 on food intake in comparison to that induced by (-)-N-0437 can be explained if it assumed that (+)-N-0437 is a partial agonist. (+)-N-0437 did not induce yawning behaviour in rats, suggesting that autoreceptors mediating the release of DA may be involved in stimulating yawning by DA agonists.
Timmerman
W
W
Department of Pharmacy, State University of Groningen, The Netherlands.
Rusk
I N
IN
Tepper
P
P
Horn
A S
AS
Cooper
S J
SJ
D000818:Animals; D015259:Dopamine Agents / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects*; D008297:Male; D009281:Naphthalenes / Q000494:pharmacology*; D051381:Rats; D011954:Receptors, Dopamine / Q000187:drug effects; D013237:Stereoisomerism; D013764:Tetrahydronaphthalenes / Q000494:pharmacology*; D013876:Thiophenes / Q000494:pharmacology*; D015000:Yawning / Q000187:drug effects*
D015259:Dopamine Agents; D009281:Naphthalenes; D011954:Receptors, Dopamine; D013764:Tetrahydronaphthalenes; D013876:Thiophenes; C047508:rotigotine