PMID- 10036262
OWN - NLM
STAT- MEDLINE
DCOM- 19990817
LR  - 20171213
IS  - 0022-3077 (Print)
IS  - 0022-3077 (Linking)
VI  - 81
IP  - 2
DP  - 1999 Feb
TI  - Physiological properties of raphe magnus neurons during sleep and waking.
PG  - 584-95
AB  - Neurons in the medullary raphe magnus (RM) that are important in the descending 
      modulation of nociceptive transmission are classified by their response to 
      noxious tail heat as ON, OFF, or NEUTRAL cells. Experiments in anesthetized 
      animals demonstrate that RM ON cells facilitate and OFF cells inhibit nociceptive 
      transmission. Yet little is known of the physiology of these cells in the 
      unanesthetized animal. The first aim of the present experiments was to determine 
      whether cells with ON- and OFF-like responses to noxious heat exist in the 
      unanesthetized rat. Second, to determine if RM cells have state-dependent 
      discharge, the activity of RM neurons was recorded during waking and sleeping 
      states. Noxious heat applied during waking and slow wave sleep excited one group 
      of cells (ON-U) in unanesthetized rats. Other cells were inhibited by noxious 
      heat (OFF-U) applied during waking and slow wave sleep states in unanesthetized 
      rats. NEUTRAL-U cells did not respond to noxious thermal stimulation applied 
      during either slow wave sleep or waking. ON-U and OFF-U cells were more likely to 
      respond to noxious heat during slow wave sleep than during waking and were least 
      likely to respond when the animal was eating or drinking. Although RM cells 
      rarely respond to innocuous stimulation applied during anesthesia, ON-U and OFF-U 
      cells were excited and inhibited, respectively, by innocuous somatosensory 
      stimulation in the unanesthetized rat. The spontaneous activity of >90% of the RM 
      neurons recorded in the unanesthetized rat was influenced by behavioral state. 
      OFF-U cells discharged sporadically during waking but were continuously active 
      during slow wave sleep. By contrast, ON-U and NEUTRAL-U cells discharged in 
      bursts during waking and either ceased to discharge entirely or discharged at a 
      low rate during slow wave sleep. We suggest that OFF cell discharge functions to 
      suppress pain-evoked reactions during sleep, whereas ON cell discharge 
      facilitates pain-evoked responses during waking.
FAU - Leung, C G
AU  - Leung CG
AD  - Department of Pharmacological and Physiological Sciences and the Committee on 
      Neurobiology, The University of Chicago, Chicago, Illinois 60637, USA.
FAU - Mason, P
AU  - Mason P
LA  - eng
GR  - DA-05698/DA/NIDA NIH HHS/United States
GR  - DA-07861/DA/NIDA NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - J Neurophysiol
JT  - Journal of neurophysiology
JID - 0375404
SB  - IM
MH  - Action Potentials/physiology
MH  - Anesthesia
MH  - Animals
MH  - Behavior, Animal/physiology
MH  - Electrodes, Implanted
MH  - Electroencephalography
MH  - Electromyography
MH  - Hot Temperature
MH  - Male
MH  - Neurons/*physiology
MH  - Pain Measurement
MH  - Physical Stimulation
MH  - Raphe Nuclei/*physiology
MH  - Rats
MH  - Rats, Sprague-Dawley
MH  - Sleep/*physiology
MH  - Wakefulness/*physiology
EDAT- 1999/02/26 00:00
MHDA- 1999/02/26 00:01
CRDT- 1999/02/26 00:00
PHST- 1999/02/26 00:00 [pubmed]
PHST- 1999/02/26 00:01 [medline]
PHST- 1999/02/26 00:00 [entrez]
AID - 10.1152/jn.1999.81.2.584 [doi]
PST - ppublish
SO  - J Neurophysiol. 1999 Feb;81(2):584-95. doi: 10.1152/jn.1999.81.2.584.