The antinociception produced by microinjection of a cholinergic agonist in the ventromedial medulla is mediated by noradrenergic neurons in the A7 catecholamine cell group

Nuseir, Khawla; Heidenreich, Byron A.; Proudfit, Herbert K.

doi:10.1016/s0006-8993(98)01195-0

Cited by 43 publications

(27 citation statements)

References 26 publications

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“…In the present study, LH-induced antinociception was blocked by administration of cobalt chloride in a dose shown to block synaptic activity in the area of microinjection (Kretz, 1984;Nuseir et al, 1999;Holden et al, 2002). This finding is suggestive that unidentified LH neurons send axons to the RVM and activate serotonergic neurons that then alter nociceptive responses in the spinal cord dorsal horn.…”

Section: Discussionsupporting

confidence: 71%

Lateral hypothalamic-induced antinociception may be mediated by a substance P connection with the rostral ventromedial medulla

Holden

Pizzi

2008

Brain Research

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Section: Discussionsupporting

confidence: 71%

Lateral hypothalamic-induced antinociception may be mediated by a substance P connection with the rostral ventromedial medulla

Holden

Pizzi

2008

Brain Research

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“…Synaptic terminals that contain dopamine-β-hydroxylase appear to form synapses both with identified spinothalamic tract neurons (Westlund et al, 1990), and with unidentified dorsal horn neurons (Hagihira et al, 1990; Doyle and Maxwell, 1991a; Doyle and Maxwell, 1991b). Behavioral studies have shown that stimulating the A7 area using electrical or chemical applications produces nociceptive modulation (Yeomans et al, 1992; Yeomans, 1992; Holden et al, 1999; Nuseir et al, 1999; Nuseir and Proudfit, 2000; Holden and Naleway, 2001; Min et al, 2008; Bajic and Commons, 2010; Min et al, 2010). …”

Section: Introductionmentioning

confidence: 99%

The posterior hypothalamus exerts opposing effects on nociception via the A7 catecholamine cell group in rats

et al. 2012

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Stimulation of the posterior hypothalamic area (PH) produces antinociception in rats and humans, but the precise mechanisms are unknown. The PH forms anatomical connections with the parabrachial area, which contains the pontine A7 catecholamine cell group, a group of spinally projecting noradrenergic neurons known to produce antinociception in the dorsal horn. The aim of the present study was to determine whether PH-induced antinociception is mediated in part through connections with the A7 cell group in female Sprague-Dawley rats, as measured by the tail flick and foot withdrawal latency. Stimulation of the PH with the cholinergic agonist carbachol (125 nmol) produced antinociception that was blocked by pretreatment with atropine sulfate. Intrathecal injection of the α2-adrenoceptor antagonist yohimbine reversed PH-induced antinociception, but the α1-adrenoceptor antagonist WB4101 facilitated antinociception. Intrathecal injection of normal saline had no effect. In a separate experiment, cobalt chloride, which reversibly arrests synaptic activity, was microinjected into the A7 cell group and blocked PH-induced antinociception. These findings provide evidence that the PH modulates nociception in part through connections with the A7 catecholamine cell group through opposing effects. Antinociception occurs from actions at α2-adrenoceptors in the dorsal horn, while concurrent hyperalgesia occurs from actions of norepinephrine at α1-adrenoceptors. This hyperalgesic response likely attenuates antinociception from PH stimulation.

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“…31,38 The microinjection of CoCl 2 into the RVM in derm-sap–treated animals caused a significant increase in tail-flick latencies in the absence of vlPAG stimulation (Fig.2C; P <0.05; 2-way ANOVA with repeated measures; n = 5). In contrast, CoCl 2 had no effect on baseline tail-flick latencies in saporin-treated animals (Fig.…”

Section: Resultsmentioning

confidence: 91%

Alterations in the rostral ventromedial medulla after the selective ablation of μ-opioid receptor expressing neurons

Harasawa

Johansen

Fields

et al. 2016

Pain

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The rostral ventromedial medulla (RVM) exerts both inhibitory and excitatory controls over nociceptive neurons in the spinal cord and medullary dorsal horn. Selective ablation of mu-opioid receptor (MOR)-expressing neurons in the RVM using saporin conjugated to the MOR agonist dermorphin–saporin (derm-sap) attenuates stress and injury–induced behavioral hypersensitivity, yet the effect of RVM derm-sap on the functional integrity of the descending inhibitory system and the properties of RVM neurons remain unknown. Three classes of RVM neurons (on-cells, off-cells, and neutral cells) have been described with distinct responses to noxious stimuli and MOR agonists. Using single unit recording in lightly anesthetized rats, RVM neurons were characterized after microinjections of derm-sap or saporin. Derm-sap treatment resulted in a reduction in on-cells and off-cells when compared to saporin controls (P < 0.05). The number of neutral cells remained unchanged. After derm-sap treatment, RVM microinjections of the glutamate receptor agonist homocysteic acid increased tail-flick latencies, whereas the MOR agonist DAMGO had no effect. Furthermore, electrical stimulation of the periaqueductal gray produced analgesia in both derm-sap and saporin controls with similar thresholds. Microinjection of kynurenic acid, a glutamate receptor antagonist, into the RVM disrupted periaqueductal gray stimulation–produced analgesia in both saporin-treated and derm-sap– treated rats. These results indicate that MOR-expressing neurons in the RVM are not required for analgesia produced by either direct or indirect activation of neurons in the RVM.

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The antinociception produced by microinjection of a cholinergic agonist in the ventromedial medulla is mediated by noradrenergic neurons in the A7 catecholamine cell group

Cited by 43 publications

References 26 publications

Lateral hypothalamic-induced antinociception may be mediated by a substance P connection with the rostral ventromedial medulla

Lateral hypothalamic-induced antinociception may be mediated by a substance P connection with the rostral ventromedial medulla

The posterior hypothalamus exerts opposing effects on nociception via the A7 catecholamine cell group in rats

Alterations in the rostral ventromedial medulla after the selective ablation of μ-opioid receptor expressing neurons

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