Autoradiographic mapping of cerebral blood flow responses to cholinergic stimulation of the rat substantia innominata: modulatory effect of galanin.
In order to analyze the precise cerebrovascular effects of a specific cholinergic stimulation of the rat substantia innominata and their modulation by galanin, cerebral blood flow was measured by the [14C]-iodoantipyrine autoradiographic method in anesthetized (urethane and alpha-chloralose), artificially ventilated male Sprague-Dawley rats that received a microinjection into the substantia innominata of saline (n = 7), or 63 pmol of galanin (n = 8), or 50 nmoles of carbachol (n = 6) or a coinjection of carbachol and galanin (n = 8). Significant carbachol-induced cerebral blood flow increases were noted in ipsilateral cortices (+36%, p < 0.01 in the cingulate to +82%, p < 0.01 in the parietal somatosensory cortices), but also in ipsilateral hippocampus and ipsilateral thalamus. These cerebral blood flow increases were abolished by the coinjection of carbachol and galanin, while infusions of galanin alone failed to affect cerebral blood flow. Cholinergic stimulation of the substantia innominata represents thus a good model for the analysis of the detailed pharmacological properties of the cholinergic vasodilatatory basalocortical system. The existence of an inhibitory galaninergic modulation of this system could be of particular interest, in terms of cerebrovascular reactivity, in various neurodegenerative states.
Barbelivien
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A
University of Caen, UMR 6551 CNRS, Cyceron, France.
MacKenzie
E T
ET
Dauphin
F
F
D000818:Animals; D001345:Autoradiography; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D018678:Cholinergic Agents / Q000494:pharmacology*; D019004:Galanin / Q000494:pharmacology*; D008297:Male; D008845:Microinjections; D051381:Rats; D017207:Rats, Sprague-Dawley; D013377:Substantia Innominata / Q000187:drug effects*
D018678:Cholinergic Agents; D019004:Galanin