title: Regional cerebral blood flow responses to neurochemical stimulation of the substantia innominata in the anaesthetized rat.
abstract: Since electrical stimulation of neurones may activate not only cell bodies but also neuronal fibres, this study aimed to test a selectively cholinergic neurochemical stimulation of the rat substantia innominata (SI) by the local microinjection of carbachol; the effects of this acetylcholine agonist were compared with glutamate. Cortical and subcortical cerebral blood flow (CBF) were measured in anaesthetized rats with the [14C]iodoantipyrine method by the tissue sampling technique immediately following the intracerebral (SI) microinjection of saline, 50 nmol of carbachol or glutamate. Carbachol microinjection into the SI induced a transient but significant vasodilation in frontoparietal motor (+28%) and temporal (+41%) cortices, that lasted for less than 10 min. Glutamate did not elicit any significant CBF modifications when compared to control rats although a significant interhemispheric asymmetry after microinjection was observed in the frontoparietal motor cortex. This latter observation would suggest that the glutamate-induced cortical response is less pronounced than that elicited by carbachol. Overall, these results demonstrate that a selective cholinergic stimulation of the SI can induce a transient cortical vasodilation and further confirms the hypothesis of a muscarinic modulation of CBF via this basal structure.
authors.affiliation: University of Caen, URA 1829 CNRS, France.
authors.forename: A
authors.initials: A
authors.lastname: Barbelivien
authors.forename: E T
authors.initials: ET
authors.lastname: MacKenzie
authors.forename: F
authors.initials: F
authors.lastname: Dauphin
mesh_terms: D000758:Anesthesia; D000818:Animals; D002217:Carbachol / Q000008:administration & dosage / Q000494:pharmacology; D002560:Cerebrovascular Circulation / Q000187:drug effects / Q000502:physiology*; D018679:Cholinergic Agonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D008845:Microinjections; D051381:Rats; D017207:Rats, Sprague-Dawley; D013268:Stimulation, Chemical; D013377:Substantia Innominata / Q000502:physiology*; D014664:Vasodilation / Q000187:drug effects
chemical_list: D018679:Cholinergic Agonists; D018698:Glutamic Acid; D002217:Carbachol