ISSN:
1432-1106
Keywords:
Ventrolateral periaqueductal grey matter
;
Nucleus raphe magnus
;
Nucleus raphe obscurus
;
Rostral ventrolateral medulla
;
GABA
;
Rat
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract Experiments were carried out in urethane-anaesthetised rats to determine whether the inhibition of neurones in the rostral ventrolateral medulla (RVLM) induced by stimulation in the ventrolateral periaqueductal grey matter (PAG), is mediated via a relay in the medullary raphe nuclei. Electrical stimulation in the ventrolateral part of the PAG (20-ms trains, 7 pulses, 5–100 μA) inhibited ongoing activity of neurones in the RVLM for periods of 10–120 ms (mean 43.6 ms). The duration of the inhibition was reduced by 51.1% after microinjection of GABA (40–160 nmol in volumes of 200–400 nl, 9/12 sites), but not 165 mM NaCl (8/8 sites) in nucleus raphe magnus (NRM) and the rostral half of nucleus raphe obscurus (NRO). In a further series of experiments, activation of neuronal perikarya at 17 sites in NRM or NRO by microinjection of d,l-homocysteic acid (5–40 nmol in volumes of 50–400 nl) inhibited ongoing activity of 9 out of 14 neurones in the RVLM, the other 5 being excited. We suggest that the inhibitory effect on neurones in the RVLM, which can be evoked by stimulation in the ventrolateral PAG, is mediated indirectly by activation of an inhibitory projection to the RVLM from NRM and the rostral half of NRO.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00230299
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