Both alpha1-adrenergic and D(1)-dopaminergic neurotransmissions are involved in phenylpropanolamine-mediated feeding suppression in mice.
The anorectic action of phenylpropanolamine (PPA) has been attributed to the activation of alpha1 adrenoceptors. It is unknown whether dopamine (DA) receptor subtype was involved in this action. With a treating dose higher than those used in previous reports and a testing period mainly in the dark phase of a circadian rhythm, we found that DA-ergic transmission was also involved in PPA anorexia. Pretreatment of phentolamine or prazosin could partly block PPA-induced anorexia, confirming the involvement of alpha1 adrenoceptor subtype. In addition, pretreatment of haloperidol or SCH 23390 could also partly block PPA anorexia, revealing the involvement of D(1) receptor subtype. Moreover, co-administration of prazosin and SCH 23390 could completely block PPA anorexia, confirming the co-involvement of alpha1 and D(1) receptor subtypes. These findings suggested that both subtypes of alpha1 adrenoceptor and D(1) receptor were involved in the anorectic action of PPA.
Cheng
Juei-Tang
JT
Department of Pharmacology, College of Medicine, National Chung Kung University, 70107 Tainan City, Taiwan, ROC.
Kuo
Dong-Yih
DY
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D001067:Appetite Depressants / Q000494:pharmacology*; D018492:Dopamine Antagonists / Q000494:pharmacology; D004435:Eating / Q000502:physiology*; D008297:Male; D051379:Mice; D010665:Phenylpropanolamine / Q000494:pharmacology*; D018340:Receptors, Adrenergic, alpha-1 / Q000187:drug effects / Q000502:physiology*; D017447:Receptors, Dopamine D1 / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D001067:Appetite Depressants; D018492:Dopamine Antagonists; D018340:Receptors, Adrenergic, alpha-1; D017447:Receptors, Dopamine D1; D010665:Phenylpropanolamine