Elsevier

Neuroscience Letters

Volume 93, Issues 2–3, 11 November 1988, Pages 158-163
Neuroscience Letters

Autoradiographic and electrophysiological evidence for excitatory amino acid transmission in the periaqueductal gray projection to nucleus raphe magnus in the rat

https://doi.org/10.1016/0304-3940(88)90074-2Get rights and content

Abstract

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 NRM with a latency of 2–12 ms. With many cells, microelectrophoretic application of the excitatory amino acid antagonists, kynurenate and γ-d-glutamyl-glycine, resulted in a reversible reduction of the PAG-evoked response. Selective antagonists of N-methyl-d-aspartate (NMDA) were less effective. It is suggested that neurones in the ventrolateral PAG projecting to NRM utilize an excitatory amino acid or structurally related compound as a transmitter, and that this transmitter acts on receptors of the non-NMDA type.

References (21)

There are more references available in the full text version of this article.

Cited by (45)

  • D2 Receptors in the Periaqueductal Gray/Dorsal Raphe Modulate Peripheral Inflammatory Hyperalgesia via the Rostral Ventral Medulla

    2021, Neuroscience
    Citation Excerpt :

    Since then, several studies have demonstrated that the PAG and RVM are primary sites of analgesic action by opioids (Pert and Yaksh, 1975; Manning et al., 1994; Lane et al., 2005) and cannabinoids (Hohmann et al., 2005). It was long thought that antinociceptive actions of this pathway were mediated by opioid inhibition of GABAergic interneurons in the PAG (Vaughan and Christie, 1997; Vaughan et al., 1997) leading to activation of glutamatergic projections to the RVM (Wiklund et al., 1988; Beitz, 1990; Reichling and Basbaum, 1990). In turn, activation of RVM neurons with terminal projections in the dorsal horn of the spinal cord would result in inhibition of ascending nociceptive signals.

  • Descending modulation of pain: The GABA disinhibition hypothesis of analgesia

    2014, Current Opinion in Neurobiology
    Citation Excerpt :

    The predominant ‘lateral inhibition’ model assumes disinhibition of an excitatory glutamatergic projection from the PAG to the RVM [2•] (Figure 1b). The involvement of an excitatory projection was partly deduced based on early anatomical evidence suggesting that PAG–RVM projection neurons are glutamatergic [36,37]. Indeed, a recent study has shown that retrogradely labelled PAG–RVM projection neurons form a distinct population from inhibitory GABAergic neurons identified using GAD67-GFP transgenic mice [29••].

View all citing articles on Scopus
View full text