Activation of cholinergic pathways from the septum to the subfornical organ area under hypovolemic condition in rats.
In urethane-anesthetized rats, extracellular concentrations of acetylcholine (ACh) in the region of the subfornical organ (SFO) in response to electrical stimulation of the septum and hypovolemia were monitored with in vivo microdialysis methods. Repetitive electrical stimulation (500 microA, 5-20 Hz) of the medial septum significantly increased dialysate ACh concentrations in the region of the SFO. Non-hypotensive hypovolemia caused by subcutaneous administration of polyethylene glycol (PEG, 30%, 5 ml) elicited significantly increased ACh levels in the region of the SFO. The hypovolemia-induced ACh release was attenuated by microinjection of the local anesthetic lidocaine (2%, 0.2 microl) into the medial septum. These results suggest that septal cholinergic pathways to the SFO area may be activated under the hypovolemic condition.
D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D002799:Cholinergic Fibers / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D004326:Drinking / Q000187:drug effects / Q000502:physiology*; D004558:Electric Stimulation; D020896:Hypovolemia / Q000139:chemically induced / Q000378:metabolism* / Q000503:physiopathology; D008012:Lidocaine / Q000494:pharmacology; D008297:Male; D017551:Microdialysis; D009434:Neural Pathways / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D011092:Polyethylene Glycols / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D020665:Septum of Brain / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D013356:Subfornical Organ / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
D011092:Polyethylene Glycols; D008012:Lidocaine; D000109:Acetylcholine