Further Characterization of
Nociception-Related and Arterial
Pressure-Related Neuronal Responses
in the Nucleus Reticularis
Gigantocellularis of the Rat

Kuo, Terry B.J.; Yang, Cheryl C.H.; Chan, Julie Y.H.; Tsai, Hsing-Fei; Chan, Samuel H.H.

doi:10.1159/000456938

Cited by 1 publication

(1 citation statement)

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“…[16][17][18] Cholinergic neurons in the NRGC/NRGCa mainly project from the PPT, 6) and microinjections of carbachol into the PPT also produce dose-dependent antinociception. 12,19,20) In the present study, the results of the HP and TF tests showed that carbachol microinjected into the NRGC/NRGCa induced antinociception in a dose-related manner.…”

Section: Discussionmentioning

confidence: 99%

Effects of Microinjected Carbachol on the Antinociceptive Response to Noxious Heat Stimuli.

Abe

Kikuta

Kato

et al. 2003

Biological & Pharmaceutical Bulletin

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The rostral ventrolateral medulla (RVLM), which includes the nucleus reticularis gigantocellularis (NRGC)/nucleus reticularis gigantocellularis alpha (NRGCa) and the lateral reticular nucleus, plays a major role in maintaining tonic vasomotor tone and is critical in the reflex control of blood pressure. 1,2) In addition, the RVLM modulates one of the physiological functions of antinociception via cholinergic neurons. 3,4) Immunohistochemical studies have shown that the RVLM is extensively innervated with cholinergic neurons 5) that mainly project from the pedunculopontine tegmental nucleus (PPT), 6) then efferently extend to the spinal cord. In fact, small-medium cholinergic neurons and choline acetyltransferase mRNA have been identified in small cells of the NRGC/nucleus reticularis paragigantocellularis (NRPG). 7) These observations suggest that cholinergic neurons play an important role in the RVLM, including NRGC/NRGCa.Anticholinesterase and cholinergic mimetics exert analgesic effects in humans, 8,9) monkeys, 10) rats and mice. 11)Moreover, the administration of carbachol into the nucleus raphe magnus induces pronounced antinociception that is reversed by atropine and muscarinic antagonists. 12) Injections of muscarinic agonists into the spinal cord also have antinociceptive effects on responses to noxious heat stimuli via muscarinic receptors. 11,13) We reported that either systemically-administered or RVLM-injected morphine enhances ACh release in the RVLM, and that the local application of morphine via a microdialysis probe induces an increase in both tail withdrawal and hot-plate responses.14) Thus, the cholinergic system in the central nervous system may be considered to have a key role in endogenous pain control.Thus, the present study investigates whether a direct injection of the cholinergic agonist, carbachol, into the NRGC/NRGCa evokes antinociception, and examines the participation of antinociceptive events in rats. MATERIALS AND METHODSAnimals Male Wistar rats, weighing 250 to 350 g at the time of the experiments, were purchased from Charles River Japan, Inc. All animals were housed individually under automatically controlled environmental conditions and 12 h light-dark cycles, and were handled in accordance with the guidelines for animal care and use published by the National Institute of Health. The rats had free access to food and water. All animals were quarantined in centralized animal facilities for at least seven days after arrival from the supplier.Preparation for Microinjection After an acclimation period, the animals were anesthetized with sodium pentobarbital (50 mg/kg, i.p.) and placed in a stereotaxic apparatus. A midline incision was made on the scalp, and a burr hole was drilled for a 27-gauge stainless-steel cannula (guide cannula) that was firmly placed using dental acrylic and anchored to the skull using stainless-steel screws. Drugs were injected through a 30-gauge stainless-steel cannula, the tip of which extended 4 mm beyond the tip of the guide cannula into the NRGC/NRGCa a...

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