Basal forebrain control of cortical cerebral blood flow is independent of local cortical neurons.
To determine whether intrinsic cortical neurons participate in mediating increases in cortical cerebral blood flow (CBF) in response to electrical stimulation of the basal forebrain (BF), cortical CBF was assessed by laser-Doppler flowmetry in rats before and after unilaterally removing local cortical neurons with the excitotoxin ibotenic acid (IBO). On the first day of testing, CBF responses to right and left BF stimulation were nearly identical in right and left frontal cortices, corresponding to the frequency of stimulation, up to a maximum at 25 Hz (+180%). Subsequently, animals received a unilateral microinjection of IBO and a contralateral microinjection of phosphate-buffered saline (PBS) into the responsive cortical sites. After five days, responses in lesioned cortices were remarkably intact both in comparison to the contralateral PBS-injected site and to the same site tested prior to lesioning on day 1. IBO lesions of the response sites were histologically confirmed to extend through the entire depth of the frontal cortex and to encompass a large surface area (7.7 +/- 0.5 mm2). These results indicate that local cortical neurons are not critical to the mediation of increases in cortical CBF as elicited by BF stimulation. This study further supports the role of the BF as a distinct intracerebral neurogenic regulator of cortical CBF.
Linville
D G
DG
Department of Neurobiology, Montreal Neurological Institute, Quebec, Canada.
Williams
S
S
Arneric
S P
SP
D000818:Animals; D002540:Cerebral Cortex / Q000098:blood supply* / Q000166:cytology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D007051:Ibotenic Acid; D008297:Male; D009474:Neurons / Q000502:physiology*; D016548:Prosencephalon / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D007051:Ibotenic Acid