The effects of somatostatin (SOM) after intravenous application and intracerebral microinjection into the medullary nucleus raphe magnus (NRM) or into the periaqueductal gray (PAG) on the spinal nociceptive transmission was quantitatively studied in the anesthetized cat. Noxious heat-evoked responses of multireceptive lumbar spinal dorsal horn neurons were reversibly depressed to 56.6 +/- 9.7% ...

Selective retrograde labelling was used as an autoradiographic method to identify possible excitatory amino acid afferents to nucleus raphe magnus (NRM). Injections of 25-50 nl 10(-2) or 10(-3) M D-[3H]aspartate into the NRM resulted in prominent labelling of cells in ventrolateral mesencephalic periaqueductal gray (PAG). Electrophysiologically, stimulation in ventrolateral PAG excited cells in...

A descending inhibitory mechanism from the periaqueductal gray (PAG) to the spinal cord through the nucleus raphe magnus (NRM) is strongly involved in endogenous analgesic system produced by acupuncture stimulation. In addition to the PAG to NRM system which descends in the medial pathway of the brain stem, the nucleus reticularis lateralis (NRL) situated in the lateral part of the brain stem i...

Introduction: The antinociceptive effect of morphine is, in part, mediated through the activation of a descending pathway. One of the major components of this pathway is the nucleus raphe magnus (NRM). Our previous study demonstrated the involvement of NRM in the analgesic effect of morphine microinjected into the nucleus cuneiformis (NCF) in a descending manner. The aim of the current study...

a b s t r a c tintroduction: the nucleus cuneiformis (ncf) and ventrolateral periaqueductal gray (vlpag), two adjacent areas, mediate the central pain modulation and project to the nucleus raphe magnus (nrm). methods: this study examined whether the antinociceptive effect of morphine microinjected into the ncf is influenced by inactivation of vlpag and nrm in rats. animals were bilaterally micr...

BACKGROUND The nucleus raphe magnus (NRM) is involved in thermoregulatory processing. There is a correlation between changes in the firing rates of the cells in the NRM and the application of the peripheral thermal stimulus. INTRODUCTION we examined the effect of reversible inactivation and excitation of NRM on mechanisms involved in tail blood flow (TBF) regulation in hypothermia. METHODS ...

Hyperexcitable reflex blinks are a cardinal sign of Parkinson's disease. The first step in the circuit linking the basal ganglia and brainstem reflex blink circuits is the inhibitory nigrostriatal pathway (Basso et al., 1996). The current study reports the circuits linking the superior colliculus (SC) to trigeminal reflex blink circuits. Microstimulation of the deep layers of the SC suppresses ...

Recently, a novel cholinergic channel modulator, (R)-5-(2-azetidinylmethoxy)-2-chloropyridine (ABT-594), was shown to produce potent analgesia in a variety of rodent pain models when administered either systemically or centrally into the nucleus raphe magnus (NRM). The purpose of the present study was to investigate the possible supraspinal contribution of ABT-594 by assessing its ability to in...

Recent studies showed that oxytocin plays an important role in nociceptive modulation in the central nervous system. The present study was undertaken to investigate the role of oxytocin in antinociception in the nucleus raphe magnus (NRM) of rats and the possible interaction between oxytocin and the opioid systems. Intra-NRM injection of oxytocin induced dose-dependent increases in hindpaw with...

Although the importance of the nucleus raphe magnus in descending inhibitory control of nociception is clear, it is not known whether these effects are equivalent for different types of nociception. Thus, we examined the differential inhibition of behavioral responses evoked by A or C fiber thermonociceptor activation by electrical stimulation of nucleus raphe magnus neurons as well as the invo...