[Effects of corticosterone on the activity of the neurons in the rostral ventrolateral medulla of rats].
Spontaneous discharges of the rostral ventrolateral medulla (RVLM) neurons were extracellularly recorded by multi-barrelled microelectrodes in urethane-anesthetized rats. A total of 145 neurons were recorded: 33 were cardiovascular, 31 were nociceptive modulating, and 81 were unknown functional. The cardiovascular neurons were electrophysiologically identified through activating baroreceptor reflex by electrical stimulation of the aortic nerve and by intravenous injection of phenylephrine. Of the 33 cardiovascular neurons, 25 (76%) increased in firing rate after iontophoretical application of corticosterone sulfate (CORT), and 8 (24%) failed to respond. Of the 31 nociceptive modulating neurons excited by noxious stimulation, the firing rate decreased in 19 (64%), increased in 2 (6%), and did not respond in 10 (30%) after iontophoresis of CORT. Of the remaining 81 unknown functional neurons, 32 (40%) were excited, 5 (6%) inhibited, and 44 (54%) were not affected by CORT. These results demonstrate that CORT may modulate the activities of the neurons in RVLM through fast non-genomical effect, suggesting that the mechanism of the fast actions of CORT may play an important role in integration of the cardiovascular, nociceptive modulating activity under some conditions such as stress.
Wang
W Z
WZ
Department of Physiology, The Second Military Medical University, Shanghai 200433. wangwz@smmu.edu.cn
Rong
W F
WF
Wang
C M
CM
Wang
J W
JW
Wang
J J
JJ
Yuan
W J
WJ
D000818:Animals; D003345:Corticosterone / Q000031:analogs & derivatives* / Q000494:pharmacology*; D004558:Electric Stimulation; D004594:Electrophysiology; D007478:Iontophoresis; D008297:Male; D008526:Medulla Oblongata / Q000502:physiology*; D008839:Microelectrodes; D009474:Neurons / Q000502:physiology; D009619:Nociceptors / Q000502:physiology*; D011311:Pressoreceptors / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
C024200:corticosterone sulfate; D003345:Corticosterone