Studies on the mechanisms of L-dopa-induced salivary secretion.
Systemic administration of L-dopa and dopamine elicited a marked and sustained secretory response in the rat's submaxillary glands. These effects were blocked by pretreatment with phentolamine plus propranolol. Acute unilateral sympathectomy (decentralization or denervation) reduced the response to L-dopa by about 41-48%. But it left unchanged the secretory response to dopamine. Chemical sympathectomy by hexamethonium caused a similar reduction (45%) in the secretory response to L-dopa while parasympathectomy was unable to modify the salivary secretion caused by L-dopa or dopamine. Pretreatment with haloperidol reduced the salivary secretion to L-dopa in normal animals (unoperated glands), while the response to dopamine was unaffected. On the other hand, haloperidol did not alter the salivary response to L-dopa in animals with surgical sympathectomy (denervation) as compared to the same animals treated with L-dopa alone. From this study we conclude that the salivary secretion induced by L-dopa is mediated by both central and peripheral mechanisms. Dopaminergic receptors may be involved in the central effect and alpha- and beta-receptors in the peripheral response.
D000818:Animals; D004298:Dopamine / Q000494:pharmacology; D005260:Female; D006220:Haloperidol / Q000494:pharmacology; D006584:Hexamethonium Compounds / Q000494:pharmacology; D007980:Levodopa / Q000494:pharmacology*; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D051381:Rats; D012472:Salivation / Q000187:drug effects*; D013363:Submandibular Gland / Q000187:drug effects; D013564:Sympathetic Nervous System / Q000187:drug effects
D006584:Hexamethonium Compounds; D007980:Levodopa; D006220:Haloperidol; D004298:Dopamine; D009638:Norepinephrine