Altered cholinergic mechanisms and blood pressure regulation in the rostral ventrolateral medulla of DOCA-salt hypertensive rats.
We examined whether cholinergic transmission in the rostral ventrolateral medulla (RVLM) of deoxycorticosterone acetate-salt hypertensive rats (DHR) is enhanced and the enhancement is involved in the maintenance of hypertension in DHR, and whether cholineacetyltransferase (ChAT) activities and ChAT mRNA expression are enhanced in neurons intrinsic to the RVLM of DHR. Rats were anesthetized, paralyzed, and artificially ventilated. Unilateral microinjection of cholinergic agents into the RVLM produced a pressor response. The pressor response to physostigmine was greater in DHR than in control rats, whereas the response to carbachol was the same in both sets of rats. Bilateral microinjection of scopolamine into the RVLM produced a decrease in blood pressure. The depressor response was greater in DHR than in control rats. The number of ChAT-activity-detected neurons in the RVLM was greater in DHR than in control rats. The number of ChAT mRNA-expressing neurons in the RVLM was also clearly greater in DHR than in control rats. These results demonstrate that cholinergic transmission in the RVLM is enhanced in DHR, and this enhancement may play a role in the maintenance of hypertension in DHR. It is probable that enhanced activity of cholinergic neurons intrinsic to the RVLM is at least in part, responsible for the enhanced cholinergic transmission in the RVLM of DHR.
Kubo
T
T
Department of Pharmacology, Showa College of Pharmaceutical Sciences, Machida, Tokyo, Japan.
Fukumori
R
R
Kobayashi
M
M
Yamaguchi
H
H
D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D002795:Choline O-Acetyltransferase / Q000378:metabolism*; D002800:Cholinesterase Inhibitors / Q000494:pharmacology; D003900:Desoxycorticosterone / Q000494:pharmacology*; D006651:Histocytochemistry; D006973:Hypertension / Q000139:chemically induced / Q000201:enzymology / Q000503:physiopathology*; D017403:In Situ Hybridization; D008297:Male; D008526:Medulla Oblongata / Q000502:physiology*; D008845:Microinjections; D010830:Physostigmine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012601:Scopolamine / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology*; D009435:Synaptic Transmission / Q000502:physiology
D002800:Cholinesterase Inhibitors; D003900:Desoxycorticosterone; D012965:Sodium Chloride; D010830:Physostigmine; D012601:Scopolamine; D002795:Choline O-Acetyltransferase