N. raphe magnus lesions disrupt stimulation-produced analgesia from ventral but not dorsal midbrain areas in the rat

Prieto, Gustavo; Cannon, J. Timothy; Liebeskind, John C.

doi:10.1016/0006-8993(83)91282-9

Cited by 120 publications

(35 citation statements)

References 12 publications

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“…Finally, lesion studies demonstrate that the RVM plays a major role in the antinociceptive actions of the PAG. Large electrolytic lesions of the RVM block the analgesia produced in behaving animals by electrical stimulation and microinjection of morphine in the PAG (Prieto et al, 1983;Young et al, 1984). In anesthetized rats, bilateral lesions of RVM or blockade by lidocaine microinjection antagonize the inhibition by PAG stimulation of both spinally mediated reflexes (Sandkiihler and Gebhart, 1984;Lovick, 1985) and dorsal horn neurons (Gebhart et al, 1983).…”

mentioning

confidence: 99%

Evidence for two classes of nociceptive modulating neurons in the periaqueductal gray

Heinricher¹,

Cheng²,

Fields³

1987

J. Neurosci.

111

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The midbrain periaqueductal gray (PAG) and the rostral ventromedial medulla (RVM) are important links in a neuronal network that modulates nociceptive transmission. In the RVM, 2 classes of cells have been identified that show changes in activity at the time of the tail-flick response (TF) elicited by noxious heat (Fields et al., 1983a). We now report that neurons in the PAG region also show changes in activity related to TF. Extracellular recordings were made from the PAG and the ventrally adjacent tegmentum at sites from which it was possible to inhibit TF using stimulating currents of 10 microA or less. Cell activity, time of TF occurrence, and tail temperature were recorded during 5 repetitions of the heat stimulus. Periresponse and peristimulus histograms were plotted with reference to the TF and tail temperature, respectively. A significant number of neurons in the PAG region showed changes in activity that preceded the TF. “Midbrain On- cells” (13.6% of the sample) displayed an abrupt increase in firing just prior to the TF. “Midbrain Off-cells” (4.4%) paused just prior to the TF. The remaining neurons (241 of 294, or 82%) did not exhibit changes in firing prior to the TF. Thus, cells with changes in activity related to the TF are present in the PAG region as well as in the RVM. The PAG has a large projection to the RVM, and microinjection of morphine in the PAG increases activity of RVM Off-cells and decreases that of RVM On-cells.(ABSTRACT TRUNCATED AT 250 WORDS)

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mentioning

confidence: 99%

Evidence for two classes of nociceptive modulating neurons in the periaqueductal gray

Heinricher¹,

Cheng²,

Fields³

1987

J. Neurosci.

111

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“…The apparent functional differentiation between dorsal PAG (Analgesia-PAG group) and ventral PAG and the dorsal raphe nucleus ventral to it (most of No Analgesia group) is parallel to the differentiation obtained by Liebeskind and his co-workers (Cannon, Prieto, Lee, & Liebeskind, 1982;Prieto, Cannon, & Liebeskind, 1983). They found that stimulation in dorsal PAG produced increased tail-flick latencies that outlasted the stimulation and were unaffected by naloxone or by lesions in medullary nucleus raphe magnus.…”

Section: Discussionmentioning

confidence: 62%

Tactile discrimination following analgesia-producing brainstem stimulation in the rat

Frommer

1985

Psychobiology

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Female albino rats were trained on a standard tactile discrimination and implanted with subcutaneous heating coils and stimulating electrodes aimed at analgesia-producing sites in brainstem. The effectiveness of brain stem stimulation in producing analgesia was assessed by measuring increase in latency offace wiping elicited by heating the subcutaneous coils about 30 sec after brain stimulation. Stimulation was then introduced 15 sec before or at the start of one of the six daily massed tactile discrimination trials. Errors and response latencies on the test discrimination trials were compared with errors and latencies on the immediately preceding and subsequent trials. Eight rats increased latency of face wiping and had electrodes in dorsal periaqueductal gray (P AG). Their performance on the tactile discrimination was disrupted on trials immediately following stimulation. Four other rats also showed increased face-wiping latencies but had electrodes outside dorsal PAG. Their discrimination performance was less consistently affected by brain stimulation. The remaining seven rats did not show increased face-wiping latencies. Their electrodes were also outside dorsal PAG, and they showed latency increases only when stimulation occurred at the start oftest trials. These data indicate that analgesia-producing brainstem stimulation can affect performance on a tactile discrimination task as well as on the reaction to noxious stimulation.

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“…Although it would have been interesting to compare possible differential effects of dorsal versus ventral placements in the present investigation, electrode placement was not specifically manipulated. Only a small number of our placements ended in the extreme ventral location investigated by Prieto et al (1983). Visual inspection of the data did not reveal any systematic differences in antagonist effect between dorsal and ventral placements.…”

Section: Histologymentioning

confidence: 95%

Neurochemical mechanisms of stimulation-produced analgesia: Comparison of tests involving tonic and phasic pain

Thorn

Plotkin

1984

Psychobiology

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Male albino rats were implanted with bipolar electrodes into the periaqueductal gray. Focal brain stimulation-produced analgesia (SPA), as measured by the formalin test and the tail-flick test, was challenged with either naloxone (3 mg/kg) or methysergide (1 mg/kg). Naloxone failed to reverse SPA when the formalin test was used; mean pain ratings remained close to analgesic values after the opiate antagonist was administered. However, methysergide (a serotonin receptor blocker) did attenuate the analgesia significantly. When the tail-flick test was used to measure antinociception, both methysergide and naloxone attenuated the analgesia. The data suggest that a nonopioid (serotonergic) system is involved in the reduction of both tonic and phasic pain, whereas a naloxone-reversible opiatergic system is also involved in phasic pain.

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N. raphe magnus lesions disrupt stimulation-produced analgesia from ventral but not dorsal midbrain areas in the rat

Cited by 120 publications

References 12 publications

Evidence for two classes of nociceptive modulating neurons in the periaqueductal gray

Evidence for two classes of nociceptive modulating neurons in the periaqueductal gray

Tactile discrimination following analgesia-producing brainstem stimulation in the rat

Neurochemical mechanisms of stimulation-produced analgesia: Comparison of tests involving tonic and phasic pain

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