Disease relevance of Periaqueductal Gray

• These results suggest that inputs of spinomesencephalic tract neurons to the periaqueductal gray may evoke important components of the systemic response to the neurogenic hyperalgesia produced by intradermal capsaicin [1].
• Certain neuropeptides can facilitate lordosis by acting on midbrain periaqueductal gray (PAG) in estrogen-primed female rats [2].
• Dermorphin (DM), microinjected at 0.4 nmoles/rat into various sites of the periaqueductal gray matter (PAG), provokes complete inhibition of intestinal propulsion always coupled with full analgesia and catalepsy [3].
• Arterial hypertension induced by microinjections of N-methyl-D-aspartate (NMDA) (2 nmol/rat) into the midbrain periaqueductal gray matter was used to assess the involvement of opioid receptors (mu, delta and kappa) in modulating pressor periaqueductal gray neurons [4].
• We found that the structure-activity relationship of neurotensin-induced antinociception was different from that required for the stimulation of intracellular cyclic GMP production in neuroblastoma clone N1E-115 and the binding to N1E-115 cells, human brain tissue, or rat periaqueductal gray [5].

Psychiatry related information on Periaqueductal Gray

• Activation of neurons in the midbrain periaqueductal gray matter (by electrical stimulation, opiates, and possibly psychological factors) excites neurons of the rostral medulla, some of which contain serotonin [6].
• RATIONALE: Escape reactions induced by electrical stimulation of the dorsolateral periaqueductal gray (dlPAG) are inhibited by local administration of benzodiazepine (BZ) or serotonin (5-HT) receptor agonists [7].
• A significant, but clearly subtotal reversal of the elevated hot-plate response latencies produced by periaqueductal gray morphine was produced by intrathecal phentolamine and methysergide [8].
• Approach responses for mesencephalic central gray stimulation are facilitated by D-amphetamine or food deprivation [9].
• RESULTS: Cal injected into lateral cerebral ventricle (LCV) or periaqueductal gray (PAG) increased obviously the pain threshold to 49 +/- 22% or to 68 +/- 12% (P < 0.01), respectively [10].

High impact information on Periaqueductal Gray

• Stereotaxically guided administration of antibodies to cerebroside sulfate into the periaqueductal gray region, the most sensitive brain region in which to demonstrate inhibition of this response, antagonizes the effect of morphine and beta-endorphin [11].
• The periaqueductal gray matter is a responsive site for mu receptor agonist- and neurotensin-induced inhibition of intestinal transit [12].
• To resolve this paradox, we examined the effects of morphine and fentanyl in acute brain slices of the locus coeruleus and the periaqueductal gray from beta-arrestin2 knockout mice [13].
• Here we have combined a microarray analysis of differential gene expression among five selected brain regions, including the amygdala, cerebellum, hippocampus, olfactory bulb, and periaqueductal gray, with in situ hybridization [14].
• Here, the development of a sensitive method for measuring cannabinoids by atmospheric pressure-chemical ionization mass spectrometry permitted measurement of the release of the endogenous cannabinoid anandamide in the periaqueductal gray (PAG) by in vivo microdialysis in the rat [15].

Chemical compound and disease context of Periaqueductal Gray

• The administration of the excitatory amino acid glutamate into the periaqueductal gray (PAG) or ventromedial medulla (VM) resulted in a reliable, short lasting elevation in the tail flick and hot plate response latencies in rats [16].
• Modulation of lordosis behaviour in the female rat by corticotropin releasing factor, beta-endorphin and gonadotropin releasing hormone in the mesencephalic central gray [17].
• Effects of intra-hippocampal injection of interleukin-2 on pain threshold and formaldehyde-induced substance P-like immunoreactivity in periaqueductal gray and spinal cord [18].

Biological context of Periaqueductal Gray

• High levels of enkephalinase and mu opioid binding sites were present at the level of the periaqueductal gray matter and in the substantia gelatinosa of the spinal cord, regions where only sparse delta opioid receptors could be detected [19].
• The induction of Fos protein was used to identify neurons in the periaqueductal gray that were activated synaptically by chemical stimulation at sites in the anterior hypothalamus from which either increases or decreases in arterial blood pressure were evoked (pressor sites and depressor sites, respectively) [20].
• Because the cellular basis of the effects of diphenhydramine on periaqueductal gray neurons had not been reported, we also examined the effects of diphenhydramine on the baseline-firing rate and synaptic transmission using in vivo and in vitro methods [21].
• We showed recently that conditioned fear to context induces Fos expression in the ventrolateral periaqueductal gray [Neuroscience (1997) 78, 165-177] [22].
• Intra-dorsal periaqueductal gray injection of serotonin or drugs that mimic its effects inhibits escape induced by electrical or chemical stimulation of this brainstem area [23].

Anatomical context of Periaqueductal Gray

• Receptor density changes are paralleled by increases in methionine-enkephalin content in the striatum, nucleus accumbens, periaqueductal gray, and hypothalamic areas of chronic naltrexone-treated rats relative to control rats [24].
• The CCK is probably secreted from neurons in the lateral parabrachial, the periaqueductal gray, and/or the dorsal raphe nuclei [25].
• In the brainstem a dense innervation of DOR-immunoreactive (-IR) fibers was found in several nuclei such as spinal trigeminal nuclei, midline raphe nuclei, parabrachial nuclei, periaqueductal gray matter (PAG), interpeduncular nucleus, ans substantia nigra [26].
• Medial preoptic area afferents to periaqueductal gray medullo-output neurons: a combined Fos and tract tracing study [27].
• Microinjections of DAMGO into the periaqueductal gray, parabrachial nucleus, or fourth ventricle structures 1-2 mm away from the LC had no effects on the development of an HR CR [28].

Associations of Periaqueductal Gray with chemical compounds

• When this substance, termed anodynin, is microinjected into rat periaqueductal gray matter, it causes a profound, long-lasting analgesia which is prevented by prior injection of the opiate antagonist naloxone [29].
• The periaqueductal gray and the nucleus paragigantocellularis were found to provide both a neurotensin and a serotonin projection to this raphe nucleus [30].
• The differential expression of 16 NMDA and non-NMDA receptor subunits in the rat spinal cord and in periaqueductal gray [31].
• The peptidergic organization of the cat periaqueductal gray. II. The distribution of immunoreactive substance P and vasoactive intestinal polypeptide [32].
• Sensitization of STT cells by 8-bromo-cGMP increased the responses of deep WDR STT cells to both weak and strong mechanical stimulation of the skin and simultaneously attenuated the inhibition of the same neurons produced by stimulation in the periaqueductal gray (PAG) [33].

Gene context of Periaqueductal Gray

• For the periaqueductal gray, prominent mRNAs were GluR-A, -B, and NR1 [31].
• In situ hybridization showed that relaxin-3 mRNA is predominantly expressed in the dorsomedial ventral tegmental nucleus of the brainstem (aka nucleus incertus), as well as in discrete cells in the lateral periaqueductal gray and in the central gray nucleus [34].
• The expression of Ntsr2 mRNA was greater than that of Ntsr1 in the periaqueductal gray (PAG) and the rostral ventral medulla (RVM) [35].
• We have identified a NT analog of the NT(8-13) fragment, NT27, that selectively causes only the hypothermic response in vivo, when microinjected into the periaqueductal gray (PAG) of rats [36].
• Freeze-substitution of tissue was performed with anhydrous methanol and 0.5% uranyl acetate at -90 degrees C. Semi-thin Lowicryl sections were used for light microscopic visualization of B-50 in the ventromedial mesencephalic central gray substance [37].

Analytical, diagnostic and therapeutic context of Periaqueductal Gray

• 5-Hydroxytryptamine was applied by iontophoresis to 55 neurons in the dorsolateral periaqueductal gray matter [38].
• The periaqueductal gray of 5 rats was processed for immunocytochemistry using an antiserum to glutamate decarboxylase [39].
• Injection of antibodies into the periaqueductal gray caused decrease of the effect of electroacupuncture whereas intrathecal administration of Fab-fragment substance P antibodies caused a marked potentiation [40].
• In sections immunostained for tracer and adenosine deaminase by double immunofluorescence, some fibres in the periaqueductal gray matter and around Mes V somas were found to be labelled for both the lectin and the enzyme [41].
• In the immunoblotting assay, we found that PI3K gamma is dense in the periaqueductal gray and lower medulla regions that include several key sites for the production of opioid-induced antinociception [42].

References