Modification by physostigmine of the cardiovascular responses to intracerebroventricular administration of 5-hydroxytryptamine in rats.
In rats the effect of inhibition of the brain cholinesterase activity on the pressor and heart rate responses to 5-hydroxytryptamine (5-HT), administered into the lateral cerebral ventricle (l.c.v.) was examined. After administration of physostigmine (twice in a small dose of 2.5 micrograms l.c.v., 20 and 15 min before the second injection of 5-HT), the pressor effect of 5-HT (5 micrograms) was strongly reduced or almost abolished, its pure tachycardia was reduced or reversed into a bradycardia and its pure bradycardia was diminished or reversed into a tachycardia. The type of the cardiovascular response to ACh (5 micrograms l.c.v., 20 min after the second administration of 5-HT) indicates that the modification of the cardiovascular response to 5-HT was accompanied by inhibition of the brain cholinesterase activity. Thus, it seems that a functionally competent cholinesterase in the brain is necessary for the generation of the 5-HT-induced pressor response. The present experiments provide further evidence that there is a cholinergic link in the pathway by which serotonergic mechanisms in the preoptic-anterior hypothalamic area rise blood pressure and support the idea that the same link exists in the pathway(s) mediating the heart rate responses to intracerebroventricular administration of 5-HT.
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D001921:Brain / Q000187:drug effects; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D007276:Injections, Intraventricular; D008297:Male; D010830:Physostigmine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000008:administration & dosage / Q000494:pharmacology*
D012701:Serotonin; D010830:Physostigmine; D000109:Acetylcholine